MSU RETURNING MATERIALS: P1ace in book drop to remove this checkout from LIBRARIES ._:__. your record. FINES Win be charged if book is returned after the date stamped below. 3"; c... I} ZJ ._l A 3 O 5 EVALUATION OF SIX PRACTICAIITIIAPEA.DIETS FROM SEVERAL.COUNTRIES USING A.SAIURAITON KINETIC MODEL By Ibrahim El-Shishtawy Hassan Belal .A DISSEREfiETON Submitted to Michigan State University in partial fulfillment of the requirements for the degree of DOCTOR.OF PHILOSOPHY Fisheries and Wildlife 1987 4T qq 51733;, W mworsmmmmamoms MWWWMAWWMCM 'meprimryobjectiveotthissuuywastodmsmtetmta satuatimkineticmdelcanbeusedtodescribethediet(m1trient) respmse relationship in fish. Five practical tilapia feeds tran Hotxduras, 'mailand, Parana, Indonesia, ardtheUnited States cmtainhgdifferentlevelsofgmssenergyardothermtximtswere eadxfedattengradedlevelstothetrmeereplicategruzpsofg; Mfmlmmeanweigh’cim- renfishpergrmpwemtsted forfiveweeksintengallmaquariadesignedtopreventfishfrun ingestirgtbeirfeces. Feedintakelevelswexeo, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 5.0,ard7.0percentofthefish livewetweightpeu: daydividedintotwoequalfeedixgsadjustedueeldy. 'me dietary(rn1trients)-respmse of the five practical tilapia dietsfitthesatm‘atimxineticmodel. gmmghtgainam net n1trient (cnfle protein, gross energy, crude fat, calcium, picsphoms, nagresitmand zinc) depositimwere decribed as a fmctim of the dietary (nutrient) intake graphically am nnnerically. Cmparisasofthefivedietsarfitheirmtrientstopmmutegg mmgrtgainormtmrtrientdepositimarebasedon parameters calculated fran the saturatim kinetic model: 21) Pm“ (mximmrespaseofmnnmfirgerlimsasaremltof feedinga specific diet or mtrient, 2) KO.5 (dietary nutrient intake level tlutproducedhalfmaxinlmresparsebythefish), 3) Ir-O (the dietaryormtrientintakeatmainterwacelevel (nogainorloss). Application of the mdel provided useful outpatisms of diets (urtrierrts) as well as intonation ember-hing maxim efficiency, overall efficiency, and rates of diet (mrtrient) utilization fran different sources. If price informatim were available the diets caddhavebemevaluatedecamicallybasedmvarimsfeeding regimes. Price tines gnax feeding level or maxim efficiency would provide valuable cost/bemfit irnfomatim. DEDICATION To nly father and late mother, shmoerest gratitude for their constant love and support. AWE My sincere appreciation to the members of my doctoral committee; Dr. D.L. Carling, Dr. D. U11rey, Dr. D. Polin and Dr. M.T. Yckayama for their guidance throughout my research period; to Dr. L. Preston Mercer (head of the Biochemistry Department, Oral Roberts University Medical School), for his generous guidance in developing my research; to Dr. D.L. Garling, my major professor, for his many hours of assistance, encouragement and guidance; to my wife, Barbara and daughter, Signe, for their love and laughter throughout my studies; to my in-laws, Mary and Stanley Johnson, for their generous financial support of my dissertation; and to my friends Abdel Moez Abdalla, Abdel Fattah El-Sayed, for their assistance in the fisheries laboratory; and to Phyllis Whetter for her many bars of laboratory assistance; and lastly to Elizabeth S. Rimpau for her generous access to the Animal Science Laboratory. iii TABIEOFCDNTENTS PAGE mgrOFm0000 OOOOOOOOOOOOOOO 000000000000.0.000000000...000 Vi II. III . mmmw0000000 0000000000 00.00.00.000 0000000000 1 WWeeeooeeeeeeoeeeeeeeeoeeeeooeeeooee 5 Protein Requiramts for Tilapias.................. 19 Energy tsfor Tilapias................... 20 Essential FattyAcids ........... ....... 24 Dietary Carbohydrate ........... ..... ....... 26 Minerals .................... . ..... 27 MERIAISANDMEIHOIBH ........ ............. ..... .. 30 mm]- mitiom0000000000000......0..000.000000 30 Fish ..... 31 Fish Feeds......................................... 31 Mathematical andStatistical Analysis.............. 33 W0.00..00.0.000000......000..00000. 0000000000 37 Diem Arnly5i8000000000000000000..000..0.00000000 38 Growth 000.00.00.00000000000000000000.000000000000.. 4o NetMMitionooeeeeeeoeeooeeeoeeeeeeoeeeeee 53 we mmW000.00.00.000.000.00000000000 66 Crude Fat Dep051tion 78 Dietary Minerals Content of the Test Diets. . . . ..... 91 Dietary CalciumResponse..... ........ . ..... 91 Dietary Magnesium ResponselOS Diem ijmm000.0000.000.000.0000000.00.00118 Dietary PhosphorusResponse........ ............ ....130 iv ME OF CDNI'ENTS (Continued) PAGE V. DISGJSSIw000..00.0.00000.00000000000000000000.0000144 Energy Deposition..................................149 Dietary Protein ResponselSO Dietary Crude Fat Dep051tion152 Magnesium Deposrtion153 Dietary Calcium Deposition.........................154 Zinc Deposrtion154 Dietary Phosphorus Deposition......................155 W0 WYMD”WSIW.00000000000000.0.00.000000.0157 W m00000000.0000000000000000...0.0000000.....00000159 mm I00... 0000000 0000.00.00.00...0.0000000000000000...000.170 LIS‘I‘OF'I'ABIES PAGE Protein requirements (85) for maximum growth of different tilapias of various size groups (from.El-Sayed 1987) ............................... 21 Dietary energy and protein requirements of Tilapia zillii at different feeding rates and experimental durations....... ........ 22 Calculated energy distribution of protein catabolized by ammonotelic, ureotelic, and uricotelic animals (Smith, et a1. 1978) . ....... 23 Dietary protein to energy ratios requiranents for different species of tilapias (modified from El-Sayed 1987)................................ ..... 25 Proximate analysis of the five Tilapia diets (Ache 1980) ............... . ........................ 39 Total food intake, weight gain (ro), and the theoretical response (rc) of Q. niloticus fed varying percentages of the Honduran tilapia feed ........................... . ......... . ........ . . 41 Total food intake, weight gain (ro), and the theoretical response (rc) of Q. nilotifls fed varying percentages of the IIhailand tilapia feed Total food intake, weight gain (re), and the theoretical response (rc) of Q. niloticms fed varying percentages of the Panamanian tilapia fw.00000.000000.0000....000 000000 000000000000 ..... 43 Total food intake, weight gain (re), and the theoretical response (re) of Q. n_i_l___cticus fed varying percentages of the Indonesran tilapia feed 000000000000000000 0....000000000000000000..00.. 44 vi LIST OF TABLES (continued) PAGE 10. Total food intake, weight gain (re), and the theoretical response (re) of Q. niloticus fed varying percentages of the U.S. t lap‘a feed ......... 45 11. Parameters derived from fitting intake and weight gain per gran of fish/five week period as a function offoodintakelevelasapercentageoffish body weight .......................................... 51 12. Total (gross) energy intake, observed deposition (ro), and calculated energy deposition (re) of Q. n_ilotigué fed varying percentages of the Honduran tilapia feed 13. Total (grcss) energy intake, observed deposition (re), and calculated energy deposition (re) of Q. miloticus fed varying percentages of the Thailand tilapia fw 000000000000000000000000 0 0000000000000000 . 0 0 0 0 0 0 0 55 14. Total (gross) energy intake, observed deposition (re), and calculated energy deposition (re) of Q. [111' oticus fed varying percentages of the Panamanian tilapia feed 15. Total (gross) energy intake, observed deposition (re), and calculated energy deposition (re) of Q. 11; loticus fed varying percentages of the Indonesian tilapia feed 16. Total (gross) energy intake, observed deposition (ro) , and calculated energy deposition (re) of Q. 1;); loticus fed varying percentages of the U.S. tilapia fa 000000000000000000000000000000000 000.000.000.000. 58 17. Parameters derived from fitting dietary gross energy (kcal/g/five weeks) intake and total deposition kcal per fish for a five-week period. . . . . . . 64 18. Crude protein intake, observed deposition (re), and calculated deposition (rc) of 9. Di loticus fed varying percentages of the Honduran tilapia feed. . . .. . 67 19. Crude protein intake, observed deposition (re), and calculated deposition (re) of Q. niloticus fed varying percentages of the Thailand tilapia feed ...... 68 20. Crude protein intake, observed deposition (ro), and calculated deposition (re) of Q. mdotig fed varying percentages of the Panamanian tilapia feed. . . . 69 vii LIST OF TABLES (Continued) 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. PAGE Crude protein intake, observed deposition (re) , and calculated deposition (re) of Q. nilngs fed varying percentages of the Indonesian tilapia feed.... 70 Crude protein intake, observed deposition (re), and calculated deposition (re) of Q. was fed varying percentages of the U.S. tilapia feed ..... 71 Parameters derived from fitting dietary protein intake (mg protein/g of fish/five-week period) and protein deposition (ng protein/g fish/five- week period) for each of the five tilapia practical diets ............... . . . . . ............................. 77 Crude fat intake, observed deposition (re) , and calculated deposition (re) of Q. was fed varying percentages of the Honduran tilapia feed ...... 79 Crude fat intake, observed deposition (ro) , and calculated deposition (rc) of Q. nilotifl fed varying percentages of the Thailand tilapia feed Crude fat intake, observed deposition (re), calculated deposition (re) of 9. mg lgcus fed varying percentages of the Panamanian tilapia f 000000000000000 .0000000000.0.000....0.000.0..000.. 81 Crude fat intake, observed deposition (ro) , and calculated deposition (rc) of Q. n_iloticus fed varying percentages of the Indonesian tilapia feed Crude fat intake, observed deposition (re) , calculated deposition (rc) of 9. W fed varying percentages of the U. S. tilapia feed 00000000 0.0000000000000000000.000.0000000000000000 83 Parameters derived from the model equation for dietary crude fat deposition vs dietary crude fat intake (W/g finiveMS)0000000000....000.00.000.000000. 89 Calcimn, phosmorus, magnesium and zinc analysis of theteStadietS (m 1975) 0000000 .0000000000000 00000 92 Magnesium intake, observed deposition (ro) , and calculated deposition (re) of Q. n_i lothcu_s fed varying percentages of the Honduran tilapia feed .............. 93 viii LIST OF mus (Continued) 32. 33. 34. 35. 36. 37. 38. 39. 40. 41. 42. PAGE Magnesium intake, observed deposition (ro) , and calculated deposition (re) of _Q. niLthicus fed varying percentages of the Thailand tilapia feed. . . . . . ...... . . 94 Magnesium intake, observed deposition (ro) , calculated deposition (re) of Q. _n_il__oticus fed varying percentages of the Panamanian tilapia feed............ ..... ......... 95 Magnaium intake, observed deposition (ro) , and calculated deposition (rc) of 0. EAL—oticus fed varying percentages of the Indonesian tilapia fa 0000000000000000000000000000 0000000000000... 000000 96 Magnesium intake, observed deposition (re) , and calculated deposition (rc) of _Q. was fed varying percentages of the U.S. tilapia feed 97 Parameters derived from fitting magnesium intake (ng/g fish initial weight/five-week) and magnesium deposition ( g/g fish/five-week period103 Calcium intake, observed deposition (re) , and calculated deposition (re) of Q. ni__l_____oticus fed varying percentages of the Honduran tilapia feed ......................... 106 Calcium intake, observed deposition (ro) , and calculated deposition (rc) of _Q. ni__l___oticus fed varying percentages of the Thailand tilapia feed ........ . .......... . . . . .107 Calcium intake, observed deposition (re) , and calculated deposition (re) of Q. ni_l__oticus fed varying percentages of the Panamanian tilapia feed108 Calcium intake, observed deposition (re) , and calculated deposition (re) of _Q. was fed varying percentages oftheIndonesiantilapia feed ..... 109 Calcium intake, observed deposition (re) , and calailated deposition (re) of Q. Q'loticus fed varying percentages Of merSe tilapia fw00.0.0000.0.000.00.000.00000.0110 Parameters derived from dietary calcium levels (ng/g fish initial weight/ five weeks) and calcium deposition (mg/g fish/five-week period)116 LIST OF TABLES (Continued) 43. 44. 45. 46. 47. 48. 49. 50. 51. 52. 53. 54. PAGE Zinc intake, observed deposition (ro) , calculated deposition (re) of 9. 1g loticus fed varying percentages of theHondurantilapia feed119 Zinc intake, observed deposition (ro) , calculated deposition (rc) of Q. ni___loticus fed varying percentages of the Thailand tilapia feed. . . . . .................. 120 Zinc intake, observed deposition (ro) , calculated deposition (rc) of Q. gtloticus fed varying percentages of the Panamanian tilap:.a feed ........................ 121 Zinc intake, observed deposition (ro), calculated deposition (rc) of Q. niloticus fed varying percentages of the Indonesian tilapia feed ........................ 122 Zinc intake, observed deposition (re) , calculated deposition (re) of Q. niloticus fed varying percentages Of meUOSO tilapia fa... 0000000 0000.0..000000000.000123 Parameters derived from dietary zinc intake levels (fi/g fish initial weight/five weeks) and zinc deposition (fl/g finiveMMid)0000.0.00.000000000000.0.0129 Phosphorus intake, observed deposition (re) , calculated deposition (re) of Q. niloticus fed varying percentages oftheHondurantilapia feed. ..... 131 Phosphorus intake, observed deposition (rc) , calculated deposition (re) of Q. niloticus fed varying percentages oftheThailandtilapia feed ......... 132 Phosphorus intake, observed deposition (re) , calculated deposition (re) of Q. niloticus fed varying percentages ofthePanamanian tilapia feed133 Phosphorus intake, observed deposition (ro) , calculated deposition (rc) of _Q. niloticus fed varying percentages of the Indonesian tilapia feedl34 Phosphorus intake, observed deposition (re) , calculated deposition (m) of Q. niloticus fed varying percentages of the U.S. tilapia feed ................... ...........135 Parameters derived from dietary phosphorus levels (mg/g fish initial weight/five weeks) and phosphorus deposition (mg/g fisIVfive-week period) ............... 141 FIGURE LIST OF FIGURES PAGE Utilization of a nutrient in the production of a physiological response (Mercer 1982) ................... 12 Theoretical nutrient response curve of feed intake vs weight gain deposition of Q. niloticus fed the Honduran diet. (The dotted line is the 95% confidence limit and the (X)sarethe observedgroupmeans,n=3). ........ 46 Theoretical nutrient response curve of feed intake vs weight gain deposition of Q. niloticus fed the Thailand diet. (The dotted line is the 95% confidence limit and the (X)s are the observed group means, n=3)............ 47 Theoretical nutrient response curve of feed intake vs weight gain deposition of Q. niloticus fed the Panamanian diet. (The dotted line is the 95% confidence limit and the (X)s are the observed group mean, n=3) ............. 48 Theoretical nutrient response curve of feed intake vs weight gain deposition of Q. niloticus fed the Indonesian diet. (The dotted line is the 95% confidence limit and the (X)saretheobservedgroupmeans, n=3).... ........ 49 Theoretical nutrient response curve of feed intake vs weight gain deposition of Q. niloticus fed the U.S. diet. (The dotted line is the 95% confidence limit and the (X)s arethe observedgroupmeans, n=3) 50 Theoretical nutrient resporee curve of total energy intake vs total energy deposition of Q. 911' oticms fed the Honduran diet. (The dotted line is the 95% confidence limit and the (X)s are the observed group mean, n=3) ............................... ............... 59 Theoretical nutrient response curve of total energy intake vstotalenergydepositionofg. Mfedthe Thailand diet. (The dotted line is the 95% confidence limitandthe (X)saretheobservedgroupmean, n=3) ................................................... 60 xi LIST OF FIGURES (Continued) 10. ll. 12. 13. 14. 15. 16. 17. PAGE Theoretical nutrient response curve of total energy intake vstotalenergydepositimofg.nj;ot1cusfedthe Panamanian diet. (Thedottedline isthe95% confidence limitandthe(X)saretheobservedgroupman, n=3) .......... 61 Theoretical nutrient response curve of total energy intake vs total energy deposition of Q. 311' otiws fed the Indonesian diet. (The dotted line is the 95% confidence limit and the (X)s are the observed group man, n=3) ................................................... 62 Theoretical nutrient response curve of total energy intake vs total energy deposition of Q. [11' lotiws fed the U.S. diet. (The dotted line is the 95% confidence limit and the (X)s are the observed group mean, n=3) ............. . ..................................... 63 Theoretical nutrient response curve of crude protein intake vs crude protein deposition of Q. n_iloticus fed the Honduran diet. (The dotted line is the 95% confidence limit and the (X)s are the observed group man, n=3)... 72 Theoretical nutrient resporse curve of crude protein intake vs crude protein deposition of Q. niloticus fed the Thailand diet. (The dotted line is the 95% confidence limit and the (X)s are the observed group man, n=3)... 73 Theoretical nutrient response curve of crude protein intake vs crude protein deposition of Q. m; loticus fed the Panamanian diet. (The dotted line is the 95% confidence limit and the (X)s are the observed group man, n=3)... 74 Theoretical nutrient response curve of crude protein intake vs crude protein deposition of Q. n_i____loticus fed the Indonesian diet. (The dotted line is the 95% confidence limit and the (X)s are the observed group man, n=3)... 75 Theoretical nutrient response wrve of crude protein intakevscrudeprcteindepositicnofg. nilgt_ic_n§ fedthe U.S. diet. (The dotted line is the 95% confidence limit andthe (X)saretheobservedgroupman,n=3)... ...... 76 Theoretical nutrient response curve of crude fat intake vs crude fat deposition of 9. Eu oticus fed the Honduran diet. (The dotted line is the 95% confidence limit and the (X)s are the observed group mean, n=3)... 84 Xii LIST OF FIGURES (Continued) 18. 19. 20. 210 22. 23. 24. 25. 26. 27. PAGE Theoretical nutrient response curve of crude fat intake vs crude fat deposition of Q. niloticus fed the Thailand diet. (Thedotted line isthe 95% confidence limitand the (X)s aretheobservedgroupman, n=3)............. 85 Theoretical nutrient response curve of crude fat intake vs crude fat deposition of Q. n; oticus fed the Panamanian diet. (The dotted lire is the 95% confidence limit and the (X)s arethe observedgroupman, n=3)... 86 Theoretical nutrient response curve of crude fat intake vs crude fat deposition of Q. niloticus fed the Indonesian diet. (The dotted line is the 95% confidence limit and the (X)s are the observed group man, n=3)... 87 Theoretical nutrient response curve of crude fat intake vs crude fat deposition of Q. niloticus fed the U.S. diet. (The dotted line is the 95% confidence limit and the (X)s arethe observedgroupman,n=3)..... ..... 88 Theoretical nutrient resporee curve of magnesium intake vs magnesium deposition of _Q. niloticus fed the Honduran diet. (The dotted line is the 95% confidence limit and the (X)s arethe observedgroupmean, n=3)....... 98 Theoretical nutrient response curve of magnesitnn intake vs magnesium deposition of Q. niloticus fed the Thailand diet. (The dotted line is the 95% confidence limit and the (X)saretheobservedgroupman, n=3)...... ....... 99 Theoretical nutrient response curve of mgresium intake vs magnesium deposition of 9. Di loticus fed the Panamanian diet. (The dotted li ne is the 95% confidence limit and the (X)s are the observed group nean, n=3).............100 Theoretical nutrient response curve of magnesium intake vs magnesium deposition of Q. m‘loti'cus fed the Indonesian diet. (The dotted line is the 95% confidence limit and the (X)s are the observed group man, n=3).............101 Theoretical nutrient response curve of magnesium intake vs magnesium deposition of Q. n; cam fed the U.S. diet. (The dotted line is the 95% confidence limit and the (X)s arethe observedgrcupnean, n=3)102 Theoretical nutrient response curve of calcium intake vs calcium deposition of _Q. niloticms fed the Honduran diet. (The dotted line is the 95% confidence limit and the (X)s are the observed group nean, n=3)111 xiii LIST OF FIGURES (Continued) 280 29. 30. 31. 32. 33. 34. 35. 36. 37. PAGE Theoretical nutrient response curve of calcium intake vs calcium deposition of Q. Hi loticus fed the Thailand diet. (Thedottedlineisthe95% confidence limitandthe (X)s are the observedgroupman, n=3)112 Theoretical nutrient response curve of calcium intake vs calcium deposition of Q. nilotig fed the Panananian diet. (The dotted line is the 95% confidence limit and the (X)s are the observed group man, n=3).............113 Theoretical nutrient response curve of calcium intake vs calcium deposition of Q. m; loticms fed the Indonesian diet. (The dotted line is the 95% confidence limit and the (X)s are the observed group man, n=3).............114 Theoretical nutrient response curve of calcium intake vs calcirnn deposition of Q. m fed the U.S. diet. (Thedottedlineisthe95% confidence limitandthe (X)s are the observedgroupman, n=3)115 Theoretical nutrient response curve of zinc intake vs zinc deposition of Q. niloticus fed the Honduran diet. (The dotted line isthe 95% confidence limitandthe (X)sare the observedgroupman, n=3)124 Theoretical nutrient response curve of zinc intake vs zinc deposition of Q. niloti'ws fed the Thailand diet. (The dotted line is the 95% confidence limit andthe (X)s are the observedgroupnean, n=3)125 Theoretical nutrient response curve of zinc intake vs zinc deposition of _Q. niloticus fed the Panamanian diet. (The dotted line is the 95% confidence limit andthe (X)s are the observedgroupnean, n=3)126 Theoretical nutrient response curve of zinc intake vs zinc deposition of Q. 111' loticus fed the Inbnesian diet. (The dottedline isthe95% confidence limitandthe (X)sare the observedgroupman, n=3)127 Theoretical mitrient response curve of zinc intake vs zinc deposition of 9. 111m fed the U.S. diet. (The dotted lineisthe95% confidence limitandthe (X)sarethe observedgroupnean, n=3)128 Theoretical nutrient response curve of phosphorus intake vs phosphorus deposition of (_D. nilgi'cus fed the Honduran diet. (The dotted line is the 95% confidence limit and the (X)s are the observed group nean, n=3).............136 xiv LIST OF FIGURES (Continued) 38. 39. 40. 41. PAGE Theoretical. nutrient response curve of phosphorus intake vs phosphorus deposition of 9. W fed the Thailand diet. (The dotted line is the 95% confidence limit and the (X)s are the observed group man, n=3).............137 Theoretical nutrient response curve of phosphorus intake vs phosphorus deposition of Q. m loticus fed the Panamanian diet. (The dotted line is the 95% confidence limit and the (X)s are the observed group man, n=3)...138 Theoretical mitrient response curve of phosphorus intake vs phosphorus deposition of 9. Mg fed the Indoresian diet. (The dotted line IS the 95% confidence limitandthe (X)saretheobservedgroupman, F3).00..000.0...00000000000000000.0...0.0....0....0.00139 Theoretical nutrient resporee curve of phosphorus intake vs phosphorus depositicm of Q. niloticus fed the U.S. diet. (The dotted line is the 95% confidence limit and the (X)s are the observed group man, n=3).............140 XV CHAPTER I INTRDIIJCI'ION Tilapia (Appendix 1) probably have been raised as a source of human food for over 4500 years. The harvest of Tilapia was illustrated on an Egyptian tomb dating back to 2500 B.C. (Bardach et a1. 1972) . In the 1900's and particularly the last 40 years, Tilapia have been transplanted from Africa and the Middle East to many countries around the world. Tilapia have become a major source of protein in many of the developing countries (Pullin and Lowe-McConnel 1982). Tilapia demonstrate a rapid growth rate on low protein diets compared to many other cultured fishes. They are efficient in utilizing poor quality natural food such as blue green algae. Tilapia tolerate a wide range of environmental conditions such as water temperatures and dissolved oxygen levels (Pullin and Iowe-McConnel 1982) . Under intensive culture, their production can be as high as 70-100 kg/hectare/day without a loss in food conversion. This efficiency is due to the Tilapia's excellent utilization of artificial feed and natural food (Allison et al 1976; T‘al and Ziv 1978; Rakocy and Allison 1980) . Efforts to produce high quality animal protein for human consumption through aquaculture often have been directed toward intensive fish production using formulated foods (King and Garling 1983) . In fish nutrition research, therefore, efforts have been directed towards development of standardized nethodology (Smith 1971 and Cho et a1. 1982) to detect small differences in fish diet or nutrient quality. Many of these efforts were unsuccessful. Classical animal nutrition nethods are not directly adaptable to fish as will be discussed later. Therefore, new techniques are needed to evaluate dietary nutrients for fish (Tilapia) . According to the National Research Council (1981) inexpensive computers and programmable calculators will promote development of sophisticated models to predict comparative feed value, specific animal requirements , and the prediction of the production response of fish to a particular diet. Feeds would be evaluated on the basis of how they supply energy and nutrients for a specific fish's production response in comparison to the other feeds available at the sane tine. Feeds would be evaluated, diets formulated, and animal response predicted by relatively complex computer program that would use a detailed Chemical and physical description of each feed and a knomedge of the biochemical , physiological and physical processes involved in animal netabolism. A general equation based on physiological responses to different environmental factors was developed by Morgan et a1. (1975) . This model is based on the interaction between a dependent variable, the observed response (r), and an independent variable, nutrient intake (I), which is described by the equation: r = (bKi + and + I“) Where: r = observed response of the organism (body weight gain or nutrient deposition at specific intake level per day) = nutrient intake b = ordinate intercept Rmax = maximum response :3 ll slope factor apparent kinetic order of the responsewithrespecttoIasInbecones neglegablecomparedtoKI). XI = nutrition constant This model is based on the enzym kiretic equations (Michaelis- Menten 1913 and Hill 1913) . This model has been experimentally tested as a nutritional indice on many animals (rats, mice, chickens, turkeys, and man) in neasuring weight gain, net nutrient deposition, dietary requirenents, tissue enzyne levels, plasna nutrient levels and others (Mercer 1980) . The model (Morgan et a1. 1975) provides a continuous response curve. It can be used as a predictive nutritional model which could be expanded to provide an economic analysis of fish diets. The model will enable the quantitative assessment of aquaculture feeds in many of the developing countries . It provides a full dietary evaluation in a short period of time (five weeks) using equipment that is available in most of the developing countries. It will, hopefully, aid such international organizations as the Food and Agriculture Organization (FAO) and the United States Agency for International Development (USAID) in attaining their goal of increasing animal protein consumption in the world. The present study was carried out to compare six practical Tilapia feeds used in Egypt, Honduras, Panama, Indonesia, Thailand and the United States. Diets from Honduras, Panama, Indonesia and Thailand were provided by participants in the United States Agency for International Development (USAID) Title XII Collaborative Research Support Project (CRSP) in Pond Dynamics Aquaculture. The four parameters (h, K, I, N, Raax) were estimated for growth, crude protein deposition, crude fat deposition, gross energy accumulation, total mineral deposition, and specific minerals (calcium, phosphorus, magnesium and zinc) for comparison between all diets. Each diet was fed to Q; niloticus fingerlings at ten food intake levels (3 replicate tanks/ intake level/ feed) for a period of five weeks. The quantitative predictive curves were computer generated using a computer program provided by Dr. L. Preston Mercer (personal commmication, Department of Biochemistry, School of Medicine and Dentistry, Oral Roberts University, Tulsa, Oklahoma) and compared statistically using multiple nonlinear regression analysis (Draper and Smith 1966) . CHAPTERII LITERA'IUREREVIEW Dietary evaluation of animal growth depends upon a simple relationship that was developed by Winberg (1956) that is referred to as the Energy Balance Equation: Ration (x absorption factor) = metabolism + growth Absorption factor (digestability coefficient) and/or metabolism are essential in evaluating fish diets in terms of growth (weight gain per unit of time) . The apparent digestability coefficient for any nutrient and/or gross energy can be determined in vivo by the "Direct Method" (the total collection technique). This technique relies on quantitative measurement of the ingested (food) and egested (feces) materials used in the equation: D% = the percentage digestability I = amount of nutrient ingested E = amount of nutrient egested A second technique for measuring the apparent digestability coefficient is called the "Indirect Method" or the "Indicator Method." An external indicator is a indigestible substance that is added to the test diet in a small quantity (1-2%). An internal indicator is a naturally occurring nondigestable carponent in a diet as a constant proportion. Indicators should not affect digestion or palatability of the test diet. Additiorally, their concentration should be easily determined. The percentage of the indicator is measured in the food and a sample of the feces to estimate the digestability coefficient by the equation: . - . . _ _ MW Digestibility — 100 (100 x % indicator in the feces ) Errors in quantitative fecal collection is a major source of under or over-estimation of the digestability coefficient. The quantitative measurements of egested materials is difficult under aquatic environmental conditions without accepting a level of significant error. The major source of error is fecal leaching in the water and/ or fish stress depending on the collection technique. There are several methods to collect fish feces: 1) dissecting the fish gut after sacrificing the fish and collecting its fecal materials; 2) manual stripping of live fish from the abdomiral cavity to obtain a fecal sample: 3) aral suctioning (Windell et a1. 1978); 4) collecting feces deposited in the aquarium using a fine dip net (Windell et a1. 1974): 5) siphoning the feces using a specially designed aquarium (Biddington 1980); 6) settling columns attached to the aquarium drain system (Cho et al. 1975): 7) the mechanically rotating filter screen (Choubert et al. 1982): 8) the mtabolism chamber (Smith 1971) . Techniques 1, 2, and 3 were developed to overcome the problem of leaching by collecting feces directly from the intestinal tract of the fish. These three procedures have caused underestimation of the digestion coefficient since incompletely digested materials mixed with body fluid, intestinal epithelium, and excess enzymes were collected along with the fecal sample (Cho et al. 1982) . Additionally, gastric motility was probably affected by force feeding fish used in the experiment . Force feeding reduced the evacuation rate in walleye (Stizostedion Vitreum Vitreum) by one-half over voluntary feeding (Windell et al. 1966) . Cho et al. (1975) used tanks measuring 55 x 10 x 35cm with a sloping bottom. A drain pipe is connected to the sloping bottom and to a stand pipe positioned over an acrylic settling column (10cm dia x 40cm high). Fish are freely fed in this system for 9-16 hours. The tanks are then cleaned of food particles by draining and replacing one-third of the tank's water. After a feeding period, feces are collected for 9-16 hours. At the end of the collection period the settlingcolmmisopenedandthefecesareremoved. Choubertetal. (1982) collected fish feces from the tank drairage water by passing the water through a moving metallic screen. Feces were removed mechanically from the water by the screen. . In methods 4, 5, 6, and 7 leaching of dissolved materials into the water is the single major error which causes over-estimation of digestibility. When fecal samples were kept in the water for only one hour, the digestability for dry matter, protein and lipids dropped by 11.5 percent, 10 percent, and 3.7 percent, respectively (Windell et a1. 1978). Smith (1971) developed a mtabolism chamber to permit separate and quantitative collection of feces, urine, and gill excretions. 'Ihe fishareconfinedinatube. Thewatersurrmniirgthefishinthe frontofthechamber (5 gallon) isseparatedbyarubberdamfromthe rearofthechamber. Urineiscollectedthroughacatheterintoa bottle outside the chamber. The fish are force fed a masured amount of feed daily. After a three-day adaptation period, waste collection is made for four or five days. Fish are anesthetized during handling and force feeding. This method is used to measure digestibility and metabolizability. Stress caused by confinement, anesthesia, and force feeding is the major problem associated with this procedures. Stress inhibits absorption (Shadler 1979) , causes hyperglycemia, elevates muscle blood lactate, serium cholesteral , skin mucus secretion, and oxygen consumption (Love 1980) . Smith (personal cammmication) claimed that stress was reduced to "normal" levels by injecting pure oxygen into the metabolic chamber to reduce blood lactate. However, blood lactate is not a good indicator of confinement stress since lactic acidosis results from araercbic muscle glycolysis (Wedemyer 1976) . Other more appropriate stress indicators were not measured. The second part of Winberg ' s equation for dietary evaluation is metabolism. Several methods have been developed to measure the energy budget of fish. In 1976, Smith modified adiabetic calorimetry for use with fish. He utilized the direct calorimetry procedure (Hill 1911) which is based on measuring heat production using thermal equivalent. Smith (1976) reported that the direct calorimetry method is less sensitive to metabolic fluctuations when compared to indirect calorimetry using the oxygen consumption method (Brett 1979) . The indirect calorimetry method measures the wt of oxygen consumed during a specific period of time multiplied by an oxycalorific equivalent. Application of this method assumes that dietary nutrients such as carbohydrates, lipids, and proteins are being digested and metabolized in the same proportion which they occur in the diet (Brafield 1985) . This assumption is due to the difficulty of measuring fecal , urine, and gill excretions. Additionally, this procedure ignores anaerobic metabolism. The indirect calorimetry method can be improved by using oxygen, carbon dioxide and ammonia (Brafield & Llewellyn 1982) . The application of this method is based upon accurately measuring the oxygen consumption, ammonia production, and carbon dioxide production. Unfortunately, large amounts of carbon dioxide can be present in the water (especially hard water) wl'iich, in turn, supresses the release of carbon dioxide from fish (Kutty 1968) . Ammonia excretion by fish is also affected by the concentration of ammonia in the water (Goldstein et a1 . 1982) . 10 we to the complexity and the difficulty of measuring the mtabolizability of nutrients, the net deposition or growth (the last partoftheWinbergequation) hasbeenusedtoevaluate fishdietsand establish the nutrient requirements of fish. The most commonly applied growth model for dietary evaluation has been the linear model or straight-line equation. 1X 1 Y = a0 + a Thismodel iseasytouseanivaluableindescribingthenutritional response over a linear range of response of nutritional intake. Over a wide intake range of nutrient intakes, the growth response, however, is not linear. Therefore, the logarithmic form of equation 1 used to describe the curvilinear relationship over a wide range of nutrient intake equation 2: Y=ao+allch 2 At very low levels of nutrient intake, the biological response appears to deviate from the principle (Almquist 1953) . Hegsted and Neff (1970) observed that linear equations are sufficient for the middle area of the response curve, but at higher nutrientinputsanextraparameterofthequadraticmodelbecame significant: 11 Y=a0+alx+a2X2 3 However, the quadratic model is still inadequate in describing the lower end of the biological curve. If another parameter is added to equation 3 , the equation will not satisfy the criterion of a mathematical or a biological significance (Mercer 1980) . A new model was developed by Morgan et al (1975) based on the enzyme kinetic equation (Michaelis-Menten 1913 and Hill 1913) . The theoretical derivation of this model was developed by Mercer (1982) . The effects of a nutrient in a physiological system may be regarded as the results of physicochemical interactions between the nutrient and various macromolecular components of the organism. These specific interactions give use to organize functions which collectively are described as the metabolic activity or responses of the organisms . It is possible to conceptualize a sequence of events by which a nutrient elicits its characteristic response. This sequence is shown in Figure 1. Almost every aspect of nutrient utilization is mediated by specific interactions with a macromolecule such as an enzyme. If oneassmesthatthere isarate-limitingstepinthesequence, then the magnitude of response would be a function of the rate-limiting step. Such a rate-limiting step has been postulated by Almquist (1953) . The interaction of the nutrient with a specific site on the macromolecule (receptor) would give rise to a physiological response and the magnitude of the response would be directly proporticral to 12 NUTRIENT INTAKE DIGESTION ABSORBTION DISTRIBUTION METABOLISM EXCRETION NUTRIENT- MACROMOLECULAR INTERACTION PHYSIOLOGICAL RESPONSE Figure 1 . Utilization of a nutrient in the production of a physiological response (Mercer 1982) . 13 the number of receptors occupied by the mItriemt. This concept allows one to apply the law of mass action to the system and derive an appropriate equation governing the quantitative relationship between nutrient and response. In the following example, a mrtrient, (I), combines with a receptor, (M), to yield the complex MI which produces the physiological response pr in a manner proportional to concentration of MI: "1 I+M : MI k2 pr=k3 [MI] (where K1, k2, and K3 are constants and [] denotes concentration) At equilibrium: E II Jr '13" =KI (where KI is also a constant) Next, if Mt is defined as the total receptor concentration so that [Mt] = [M] + [MI], them: 14 [Mt - M11 [I1 _ [MI] ’ KI Rearrangerent gives: 11m: _LI_1_ [Mt] KI-ttI] If Hflmax is the maximal physiological response of the system when all receptors are occupied: Payee] _PL__.[E_1 Pam ‘th This equation is identical to the Michaelis—Menten equation (Hegsted and Neff 1970) and could be useful in describing physiological responses to nutrients, based on the model in Figure 1 . 15 It meets the criteria of observed phenomena, that is a continuous response to graded levels of intake and the law of diminishing returns (Almquist 1953) . However, equation 4 has two limitations which do not coincide with observed responses . First, the equation only describes a hyperbola, while many responses are found experimentally to be sigmoidal (n>1) in nature (Allison 1964). This problem may be overcome by adding the parameter n (the apparent kinetic order) to the equation: _M pr K1 + [I]n The equation can vary from a hyperbola to a sigmoidal (n>1) curve as n increases above 1. This approach has been utilized in enzyme kinetics and is known as the "Hill equation" (Hill 1913) . The second limitation to equation 5 is that the equation describes a curve which passes through the point (0, 0) of an (X, Y) coordinate system. This does not allow the prediction of responses such as weight loss. Adding the parameter, b, (b = X intercept) removes this restriction. n pr = Ppmaxnu +b 6 K1 + [11“ 16 Rearrangerent gives: PRmax [I]n + bK1 + bIn K1 + [1]“ pr Ifwelet (PRmax+b) =lguaxardsimplifyprtor,wehavethe four-parameter mathematical model for physiological responses: _ 10K1 + me [I]n 7 K1 + [1]“ r This can be more conveniently written: b[K.5]n + 131” [1]“ r - 8 [K.5]n + [I]n where: r = physiological response 1 = nutrient intake or concentration in the diet b=interceptontheraxis Phax=maximumresponse n apparent kinetic order KO.5 = intake for 1/2 (Rmax-b) 17 This model satisfactorily describes all areas of the biological response curve over a wide range of nutrient intakes . The saturation kinetic model by Morgan et al. (1975) has been tested on rats, mice, chicks, swine and man. Many nutrient responses have been studied using this model such as protein, amino acids, selenium, mercury, cadmium, calcium, phosphorus, biotin, pyrodoxe, vitamin B12 , vitamin A, vitamin D, thiamin. The type of measured responses utilized in these studies have been: weight gain, serum albumin, hemoglobin, hematocrit, total sermm protein, carcass gain of amino acids, tissue enzyme levels, serum B folate, tissue cadmium, blood clotting, 12, plasma, vitamin A, tibia femur ash, liver weight, gram protein/total liver weight, mg INA/g liver, mg INA/g liver carcass nitrogen, and total food intake (Mercer 1980) . When graded levels (i.e. , dietary nutrient concentrations) of an essential nutrient are fed over a range from zero to levels which surpass maximum dietary response levels, a hand drawn response S-shape curve will be observed. The various sections of the curve have been identified by Mercer (1982) . ' Threshold - the lower range of nutrient concentrations which produce zero or negligible responses by the organism. A positive response (b > 0) with zero slope at a low dietary nutrient level implies eldogelous stores of that nutrient; Deficient - the range in which the slope of response increases, but the genetic potential of the animal is not fully expressed: 18 Adgu_ate - the portion of the curve at which the slope moves from positive towards zero (or a plateau). The geletic potential (assuming no other limiting nutrient) is fully expressed but no "margin of safety" exists for stress, pathology, etc. flimal - the range (rather than the point) of maximal response; m-the intake level atwhichtheresponseisdiminished. An excessive dietary level of a nutrielt can lead to displacement of other essential nutrients and/or impaired metabolism. For example, when a group of rats were fed an experimental diet with different levels of protein the sigmoidal (n>1) curve was gelerated based on the four parameters (b, Rmax' Ko.5, N). The results were used to predict daily food intake, daily weight gain, and the efficieoy of food conversion (daily weight gain/daily food intake) as a function of dietary protein concentration (Mercer et al. 1981) . In another study (Mercer et al. 1984), the physiological response (weight gain and food intake) to graded levels of essential amino acids in an experimental diet yielded sigmoidal (n>1) shaped response curves that were analyzed by the four parameter models. These response curves were similar to those seen in the protein concentration studies (Mercer et al. 1981) . Gustafson et al. (1984) found that the recommended level of an amino acid mix and/or an individual amiro acid for rats by Rogers and Harper (1965) were on the maximum plateau of the curve and were near the point where the curve just approached Pmax’ Thus, the reccmmelded levels appeared to be optimal. 19 Therefore, the model could be used to determine the nutrient requiretents of rats (animals or fish). The model also was used to compare the efficiency of two protein sources (soy vs. casein) (Mercer et al. 1978) . The Morgan et al. (1975) model is useful in comparing other nutrients as well. An evaluation of protein quality based on thegrowthresponseofratsusingthefolrparametermodelwas successfully done by Foldin et a1. (1977) . Following this study, a new protein quality evaluation index was developed by Mercer and Gistafson (1984) called the actual protein utilization (APU) . Finally, the model was used to predict the dietary cadmium toxicity utilizing the daily weight gain as an indicator (Gustafson and Meroer 1984). A recent study by Anrett (1985) used the hyperbolic form (n = 1) of the model's equation. Annett compared several types of natural food sources for tilapia. However, some of his results showed poor curve fitting values (r = 0.52). His values would probably have had a closer fit if he had used the four parameter equation developed by Morgan et al. (1975) . Protein W‘ ts for Tilapias Protein requirements for tilapia have been determined based on feeding techniques developed for terrestrial animals. Fish were fed a diet containing graded levels of high quality protein (casein: gelatin = 3:1) over a specific period of time (10 weeks), and the observed protein level providing optimum growth was considered the requirement (T‘acon and Cowey 1985) . 20 fl Protein requiretents for tilapia ranged from 25-56 percent crude protein in the diet (Table 1). Fish size, species differeoes, experimental duration, and feeding rates have probably had a significant impact on optimum protein level for growth. Geerally, staller size fish require higher protein intake than the larger size fish. Dietary energy and protein requirements for one species of tilapia (_T_. zillii) weight 1.5-2 9 varied from 3.00-3.74 kcal ME/g feed and 30-40 percent protein (Table 2) . This variability is probably due to feeding rates and/or experimental duration. Teshima (1986) reported that feeding rate affects the growth rates of Q. niloticus . m Rggm’ ts of Tilapias Fish require less energy for growth than warm blooded animals because fish (ectotherms) 1) donotexpendelergytomaintaina constantbodyterperature; 2) bouyancyreducesenergyrequiretentto maintain position in the water, and 3) ammonia is the major protein catabolism eid product which is energy efficielt (Table 3) when compared to urea or uric acid (Smith 1976) . The optimum ratio of protein to metabolizable energy that produced maximum growth in the channel catfish (Garling and Wilson 1976) was 24 percent protein 2.75 kcal ME/g protein and produced growth similar to diets containing 28 percent protein and 3.41 kcal MEI/g protein. 21 . “mood. woos moon glee—noon!!! d omno “ohms. £9833 no.8 omumn 86303: .d o.n “Hoods uses—gum 95 $353 mm 90.55 .m m4. Home 4o um mans omumm manhood: d mun .HooHo 5.03 Em mouths om moons—o .0. mum Good Am um mung canon Waging .d m3 883 .do um 9:52. canon 323 .H SA 38.: goo oo ”salsa—log .o. and $3: woman: 3:8 33.8 .H Ym some Banana on 23? .H mum; “whose . 30533 a mono Snow 9055me .o Ta 38: 4o no Bums mmuom 3:? .9. mod Hood Am um Eamon. mm mBUoflc d 35 Amends 30533 a no.6 ooumn 86303: .o. wound “whose germ o mean on moouoo .w. mound So? we mocmfiwumm Egg “meadow “996.5 £38m 3mm . Ahmad oomwmudm 80.qu mdoouo ouflm mooflHmS mo moflomflp gang «0 5g gonna: you 8 mugs? 502 .H manna. 22 “homes nosmmnem 5:033 pg swam may no womucwpnwm a mo nova nor—Hooded min o o on o.m Amends .Ho #0 pawn: owé m 0H mm mo.m Amends .Hm um gamma. hoé v s ovlmm m.m A289 Amxwgv #:0on games omen cowuouoo ago.» » \mz Manx Em Egg goowm :vaoum Edema. .mcoflohdo dong? oco 8pm.“. 8.600s ucwuwuuflo up gain o. fissile. mo 33% fiwugm one g Ema .N 038. 23 mm.N hm.m emé >50 #02 SA 84 on o H38. 86 £6 £6 5090.25 no 503330: 86 25 So .630.on can 003500.80 uooooum 3003 So So So mammogram 8890 3mm; Be £0565 08m 86 86 mmé as: 385 03328.50: SA and mad woos 03830: «an am...“ 36 EB >380 managed 3.0 poo 3.0 $3 wmoH Sewage ohm ohm 2mm Amos >905 $80 ohoox ohms. odds COUUE 6H2 OHHD 8ND MMCQEEN any? 6090993 .Amsme . .H0 u0 dud—5v wagon 0300035. 20 63300.5 63090650 so 823238 5390 oo :33me >905 803880 .m Some 24 These two diets produced growth rates higher than a diet containing 36 percent protein and 4.07 kcal ME/g protein. This occured despite the fact that the three diets contained almost the same ratio of P/ME. A summary of protein to energy ratios requirements for tilapia are provided in Table 4 . Essential Fatg Acids Barr and Burr (1919, 1930) introduced the concept of the essential fatty acids (EPA) which are necessary for normal physiological functions in animals. Animals (fish) are not able to synthesize W-6 and w-3 essential fatty acids fran W-9 non-essential fatty acids (NRC 1983) . Stasby (1982) reported that fish oil contain long chain W-3 fatty acids rather than W-6 fatty acids. The major essential fatty acid present in fish is 20:5 W-3 where that of terrestrial animal is 18:2 W-6 (linoleic acid) (Jauncy 1982) . Water salinity and temperature probably have an effect on essential fatty acid content in fish; marine fish have higher levels of w-s fatty acids than freshwater fish and both fishes have higher levels of W-3 fatty acids than W-6 (Halver 1980) . W-6/W—3 ratio was found to decrease with increasing water temperature (Halver 1980) . Sane fish, however, are able to synthesize 18:W-3 and 18:W-6 fatty acids (Cowey and Sargent 1979) . The essential fatty acid requirements of Tilapia gill}; was one percent of the diet of 18:2W-6 or 20:4W-6 (Kanazana et a1. 1980). 25 300.3 40 00 903 8 Eco ms 2. mm $003 40 0.0 Shaman. B 38 we on mm 99.30:: .0 “~00: gnu m: H8030 on 0.0: Woe 0853008 .0 £003 06.030 a 00.053 no H8030 m2 8H mm 2003 05030 a 0805: mo H0930 0: «NH 8 a .0 £003 0960.6 m: 39.30 3 03 mm 883 40 00 Sun: 0: goo ms 8 on 88: 40 00 came: 0: goo me mm mm 383 40 00 0052 0: g8 0: «Snood mm Eden .H gag wad $3000 030m goo 50080 00:00 . 2.02 0020010: 00089: 00333 00 830cm ugh“? you wuggve 0030.“ >998 on 50989 0:0 500099 E08 .v 0.30.5 26 Di gm Carbohydrate Dietarycarbohydrateinfishisusedasaninmediatesourceof dietary energy (Phillips et a1, 1966, 1967; Buhler and Halver 1961) . It could be stored in the fish body as glycogen for short-term energy use (Wendt 1964) or as fat for long-term reserve. It serves as a precusor for many metabolic intermediates such as dispensable amino acids and nucleic acids (NRC 1983) . Carbohydrates are absorbed as simple sugars. All gycolytic enzymes for glycolysis, tricarboxsylic acid cycle, pentose phosphate shunt, gluconeogenesis and glycogen synthesis have been demonstrated in fish (NRC 1983) . Depending on dietary CHO complexity their utilization appears to differ. Channel catfish utilizes polysaccharides for growth more readily than disaccharids or simple sugar (Depree 1966) . ‘Ihe shrimp Penaeus jamnicus, utilizes maltose or polysaccharides better than mono saccharides (glucose) (Abdel-Ramon et al. 1979) . Some fish utilize higher dietary carbohydrate levels than others. Channel catfish (Garling and Wilson 1976, 1977; Likllnani and Wilson 1982) , common carp (Ogino et al. 1976; Shimeno et al. 1977, 1981; Sen et al. 1978) and red sea bream (Furuichi and Yone 1980) utilize higher levels of carbohydrates than yellow tail (Furuichi and Yone 1980) and salmon (Phillips and Brockway 1956) . Low feed conversion were found in cannon carp, red sea bream, and yellow tail fed diets containing over 40 percent, 30 percent and 20 percent dextrin, respectively (Furuichi and Yone 1980) . Garling and Wilson (1977) showed that a diet containing zero carbohydrate levels produced poorer growth in fish 27 than diets containing carbohydrate to lipid ratio between 45 to 4.5. They concluded that digestible carbohydrates can be utilized effectively by channel catfish and can be substituted for lipids in semipurified diets at a rate of 2.25:1 (camesurate with physiological fuel values) within the above range. The growth of g. nilgticus were improved with increasing carbohydrate levels from 0.00 to 40 percent (Anderson et a1 1984) . M Investigations concerning mineral nutrition of 9_. niloticus have been rather limited. Dietary calcium, phosphorus, zinc and magnesium were extensively investigated. Dietary calcium is required for the formation of bone, scales, and skin. Tilapia scales contain 19-24 percent of the total body calcium. This level decreases during starvation and/or spawning periods (Garrod and Newell 1958) . Trout skin contains 40 percent of the total body calcium (Podoliak and Holden 1965; Simikiss 1974) . Fish are able to absorb calcium from feeds via their intestinal tract and from water through the gills. Studies on the availability and absorption of dietary calcium by fish are limited (NRC 1983) . Dietary calcium availability is dependent on the chemical form of dietary calcium. Tricalcium phosphate is the least available form of calcium. Dicalcium phosphate is moderately available. Monocalcium phosphate is the most readily available form of dietary calcium. Calcium absorption in turn, depends on the availability of dietary vitamin D (ergocalciferol and/or chocalciferol) . Vitamin D serves as 28 a precursor to 1 , 25-dihydroxcycholcicalciferol which stimulates calcium absorption. calcium is essential for blood clotting, nerve impulse transmission, osmoregulation and enzymes cofactor. Dietary phosphorus is required along with calcium for the formation of skeletal muscle. The ratio of calcium and phosphorus in bone ranges from about 1.5-2.1 for tilapia (Ogino et al. 1979) . The whole body calcium and phosphorus ratio of various fishes ranges frcm 0.7 to 1.6 (Arai et a1. 1975; Watanabe et al. 1980,b). 'Ihe total body phosphorus is about 0.4-0.5 percent of fresh weight (Ogino and 'I‘akeda 1976) . Phosphorus is essential for many metabolic processes. It is part of adenosine triphosphate, phospholipids, deoxyribonucleic acid (DIA) , ribonucleic acid (RNA) and various coenzymes. It is involved in energy transformation, cellular membrane permeability, genetic coding, and general control of reproduction and growth. It serves as a pH buffer in body fluid and cells (Wasserman 1960) . The minimum dietary phosphorus requirement for g, niloticus is 0.9 (Watanabe et al 1980b) . Zinc is essential for the function of many enzymes. In severe zinc deficiencies the activities of alkline phosphatase (Kirchgessner et al. 1976), liver (Kfcury 1967), retina (Huber and Gershoff 1975) , and liver nuclear 111A dependent RHA-polymerase may be depressed. Dietary zinc has been quantitated for rainbow trout (Ogino and Yang 1978); and the carp (gmrinus _c_ar_pi<_>) (Gatlin et al. 1983) . Canmon deficiency symptars are associated with a lack of zinc in rainbow trout, carp (Ogino and Yang 1978, 1979) , and channel catfish (Gatlin et al. 1983) . Observed symptans are growth retardation and a high incidence of cataracts. Several factors affect the requirement 29 of zinc such as calcium level (Forbes 1960) , phytic acids (Oberleas 1962) and the source of protein (Ziegler et al. 1961; Smith et al. 1962) . Dietary zinc levels up to several hundred do not appear to be injurious to rainbow trout (Ogino and Yang 1979) . Zinc requirements range from 15-30 mg Zn/kg diet for carp and rainbow trout (Gatlin et al. 1983 and Ogino and lang 1978). These values are similar to those required for chickens (Roberson and Schaible, 1958 and Zeigler et al. 1961); rats (Forbes and Yohe 1960); piglets (Shanklin et al 1968), Japanese quail (Fox and Jacobs 1967) and channel catfish (Gatlin et al 1983) . 9_. niloticus zinc requirements probably fall within the same range. Magnesium plays an important role as an essential ion in many fundamental enzymatic reactions. 'Ihese enzymes include: 1) transfer phosphate groups (phosphokinases) , hence magnesium is involved in phosphorylation of glucose in its anaerobic metabolism and oxidative decarborylation in the citric acid cycle requiring thiamin pyrophosphate; 2) acylate coenzyme A in the initiation of fatty acid oxidation (thiokinases) ; 3) hydrolyze phosphate and phosphate groups (phosphatases and pyrophosphatases) for which magnesium is activator; 4) activate amino acids (amino acid acyl synthesis through its action on ribosomal aggregation (Shilis 1984) . Deficiency causes poor growth, anorexia, sluggishness, muscle flaccidity, high mortality, and supresses magnesium levels in the whole body, and bones (NRC 1983) . The minimum dietary requirement for channel catfish is 40 mg/kg when reared in water containing 1.6 ppm magnesium (Gatlin 1984) . Q-IAPTER III WANDI‘IEH‘IOIB Q; niloticus fingerlings were fed ten graduated levels of each of six practical feeds. 'Ihree replicates per feed were fed for five weeks. Feeding levels were based on percentage of the fish wet body weight adjusted weekly. At the beginning and end of the five-week period, the fish were weighed, sacrificed, ground and stored frozen for chemical analyses. Proximate analysis and mineral analyses (Ca, P, Zn, and Mg) were performed on the experimental diets and fish body samples. The results of the dietary intake and the fish responses were analyzed by the four parameters of the saturation kinetic model for dietary evaluation. Cultural Conditions All experimentswerecorductedintheMSUAquacllmrelab in45 specially constructed ten-gallon glass aquariums. Aluminum scream-3 (0.25 square inch mesh) covered the aquarium bottom to prevent the experimental fish from eating their feces. A flow-through system was built as described by Garling and Wilson (1975) . Tanks were cleaned once each week. Well waterwasused inthis study. 'Ihewaterwasaeratedto 30 31 remove excessive iron by filtration units. A gas water heater was used to raise the water temperature from 11.5 i 1°C to 24 -: 1°C. Fish 0. niloticus fingerlings (3 i 1 gram), offspring of _Q._ niloticus obtained from Auburn University in Alabama in 1985, were used as experimental fish. Fish were bred in tanks under controlled conditions. Ten fish were stocked in each tank and were randomly assigned a feeding level. Each tank was considered as an experimental mit. Fish were weighed weekly to adjust feeding levels. At the end of each diet experiment, fish from each tank were weighed, sacrificed, and blended using a commercial blender. The ground fish were frozen at -7.8°C for subsequent body composition analysis. Fish Feeds Five practical tilapia feeds from the developing countries of Honduras, Indonesia, Panama, Thailand, and Egypt were tested. The diets from Honduras, Indonesia, Panama and Thailand were sent to Michigan State University by USAID Title XII C'RSP, Pond Dynamics/Aquaculture. The Egyptian practical tilapia feed was provided by the Egyptian Ministry of Agriculture. A sample of 10 kilograms of the American tilapia feed was obtained from a commercial tilapia farm, Fish Breeders of Idaho. This feed was manufactured by Farmers Union Control Ebmhange, Incorporated of St. Paul , Minnesota . Since all diets were closed-formula feed, dietary ingredient lists were not available. 32 7. All feeds were originally processed as sinking pellets except the feed from Thailand which was an extruded floating pellet. In order to produce feeds of equal and appropriate pellet size, each feed was blended in a Waring commercial blender. Feeds were then mixed with water (200 m1 of 50°C distilled water per 500 g of diet for 20 minutes) usingaUnivex commercial foodmixer. menthedietbeganto clump, itwaspassedthrolghacomeroial foodgrindertoforma spaghetti-like extruded diet. The extruded diet was dried at room temperature for 24 hours in a forced air drying oven. The dried spaghetti-like diet was blended for approximately ten seconds in a Waring blender and the resulting pellets passed through standard sieves to separate pellets sizes. The 0.2mm size pellets were used in this study. The dry weight of each diet (constant weight) was determined using a vacuum oven set at 60°C for 24 hours. The results obtained were: 95.61, 90.77, 97.2, 90.14, 92.41, and 92.32 for pellets from Egypt, Honduras, Indonesia, Panama, Thailand and the United States, respectively. All diets were stored frozen for subsequent analysis and feeding trials. Fflm’ Trials Each feed was fed on a dry weight bases to triplicate tanks of fish as a percentage (0, 0.5, 1.0, 1.5, 2, 2.5, 3, 3.5, 5 and 7%) of the total fish wct weight per tank per day. low levels (0.5, 1 and 1.5%) were fed once a day while higher levels were fed half the total amount twice a day. The daily amount of food was weighed in small 33 vials every three days and kept under refrigeration until fed. A period of five weeks was required to test each experimental diet. However, an additional five weeks were required to test all the experimental feeds together. at higher feeding rates to reach the growth plateau response. At the end of each feeding experiment, fish from each tank were weighed, sacrificed, and blended using a comeroial blender. The ground fish were frozen at -7.8°C for subsequent body corposition analysis . Chemical Analysis Samples of each diet and ground fish were analyzed using standard AOAC (1975) methods for: moisture, crude proteins, crude fat, total energy, ash, calcimm, phosphorus, zinc and magnesium. Moisture was measured using vacuum ovens at 60°C for 16 hours. Crude protein was measured using macro-Kjeldahl. Total ash was measured using a muffle furnace for 16 hours at 600°C. Crude fat was measured using soxhlet apparatus for 16 hours. Anhydrous ether was used as a crude fat solvent. A Parr 1241 Bomb calorimeter was used to determine the gross energy (lovell, 1975). Calcium, phosphorus, zinc and magnesium were measured using an instnmentation laboratory AA/EE Spectrophotometer 951. Mathematical and Statistical.Analy§is The four-parameter saturation kinetic model for physiological response (Mercer 1978) was used to analyze the data as the following example: 34 Nutrient intake1 Nutrient response (unit I (unit/gr fish/day) per day (ro: observed W) (9 W/ gflsh/daY) Diet #1 0.75 0.031 1.20 0.095 1.90 0.176 2.60 0.230 3.30 0.241 (”Nutrients included: protein, carbohydrates, fat, any mineral (Ca, P, Zn, M3) or the diet as a whole. r=(hKI+gmfl)/(I&+In) 1 1. Equation (1) was rearranged to: r = -K.I (r/In) + hmI (1/1“) + Pmax Then the multiple linear regression program was applied to determine the three independent variables at a given (n) . 2 . The theoretical values of (r) were calculated at the specific n. (theoretical response) rjt = -1905. 000.5 Henm 8:3 2.9” 22$ ee.oe e 90 ohm 2.3 eh: emoe 8.0 0 one 022 one son 8.2 3.3 e 006:0 0030 02: no.0 00m eed 2.0 e 0.00 0080 mmem 8.2 e~.m~ 8.2 8.3 0. 5008c 0030 No.8 No.8 edoo 2.00 Koo » .0002 ha <0: 030965 20.02“ 20.305. mgoocom 00.590 503 . some 088 8.08 cocoa» 00300.5 05m 05 mo 9.2.0330 000.5055 .m 0309 4O Metabolizable energy values (ME) of all test diets were calculated based on the physiological fuel value of carbohydrate, protein and lipids of 4, 4, and 9 kcal/g, respectively. ME ranged between 3.2 to 3.5 (Table 5). The test diets, therefore, were not isocaloric diets. The ID, PD diets were isocaloric. 'Ihey contained thehighestMEvalues ofanyofthedietstested. ‘IheADhada slightly lower ME value than the ID and PD. The TD had had a lower ME value than the AD. The HD had the lowest ME value of all diets (see Table 5) . Metabolizable energy value of all diets fell within the dietary requirements of tilapia (Jauncey et al. 1982) . Crude protein to energy ratios (mg crude protein/kcal ME or Cp/ME) were found to be similar in AD, PD and HD. The ID had a higher Cp/ME ratio, while the TD contained the smallest Cp/ME. The experimental diets ranged from 5.2 to 11.4 of crude fat content (10 percent crude fat is the recommerded dietary level for tilapia (Jauncy and Ross 1982) . The AD had the highest crude fat content of all diets and was slightly higher than the recommerded level. The 'ID contained similar crude fat levels to the recamnerded levels . m The effect of the five practical tilapia diets from Honduras, Thailand, Panama, Indonesia, and the U.S. on the growth of 9_. niloticus fingerlings is shown in Table 6, 7, 8, 9 and 10 and graphically in Figures 2, 3, 4, 5, and 6. The parameters of the 41 Table 6. Total food intake, weight gain (no), and the theoretical response (rc) of _Q. niloticus fed varying percentages of the Honduran tilapia feed. 8 swl Intake?‘ :03 m4 0 0.0000 -0.1400 -0.1184 0.5 0.1690 -0.0141 -0.0417 1.0 0.3570 0.1230 0.9420 1.5 0.5530 0.1930 0.2215 2.0 0.7490 0.2370 0.3190 2.5 0.8890 0.4110 0.3724 3.0 1.2060 0.4860 0.4576 3.5 1.4150 0.5300 0.4954 5.0 2.1150 0.5700 0.5677 7.0 3.3800 0.5890 0.6174 1Daily food intake as a percentage of the wet body weight. 2Total intake (mg/g fish/five weeks). 3Total weight gain deposition per gram of fish wet weight during the f ive-week period. 4Calculated weight gain from the saturation kinetic equation (Vbrgan et al. 1975). 42 Table 7. Total food intake, weight gain (re), and the theoretical response (rc) of 9. niloticus fed varying percentages of the Thailand tilapia feed. % 8W1 Intakez re? :03 0 0.0000 0.1568 -0.15 0.5 0.1790 0.0076 0.01 1.0 0.3750 0.0890 0.11 1.5 0.5600 0.1809 0.19 2.0 0.6580 0.2536 0.23 2.5 0.9650 0.3000 0.30 3.0 1.1710 0.3375 0.34 3.5 1.4350 0.3910 0.38 5.0 2.0150 0.4230 0.43 7.0 2.7890 0.4800 0.48 lDaily food intake as a percentage of the wet body weight. 2Total intake (mg/g fish/five weeks). 3Total weight gain deposition per gram of fish wet weight during the f ive-week period. 4Calculated weight gain frcm the saturation kinetic equation (Morgan et al. 1975). 43 Table 8. Total food intake, weight gain (no), and the theoretical response (rc) of Q. niloticus fed varying percentages of the Panamanian tilapia feed. % 8W1 Intake? :09 r04 0 0.0000 -0.1400 -0.13 0.5 0.1810 0.0520 0.03 1.0 0.3870 0.1990 0.20 1.5 0.5730 0.2670 0.30 2.0 0.7910 0.3750 0.39 2.5 1.0340 0.4690 0.46 3.0 1.1610 0.4970 0.49 3.5 1.5080 0.6000 0.54 5.0 2.1400 0.5970 0.60 7.0 3.4700 0.6290 0.65 lDailyfoodintakeasapercentageofttwwetbodyweight. 2Total intake (mg/g fish/five weeks). 3Total weight gain deposition per gram of fish wet weight during the f ive-week period. 4Calculated weight gain fran the saturation kinetic equation (Pbrgan et al. 1975). 44 Table 9. ‘Ibtal food intake, weight gain (re), and the theoretical response (rc) of Q. niloticus fed varying percentages of the Indonesian tilapia feed. % 8W1 Intake2 r03 :0? 0 0.0000 —0.1400 -.011 0.5 0.1790 0.0580 0.00 1.0 0.3840 0.2010 0.21 1.5 0.6090 0.3480 0.41 2.0 0.8620 0.5930 0.56 2.5 1.0810 0.6510 0.65 3.0 0.3040 0.6880 0.72 3.5 1.6170 0.8430 0.78 5.0 2.1310 0.8590 0.84 7. 2.9360 0.8270 0.88 1Daily food intake as a percentage of the wet body weight. zTotal intake:(ngyg fiSh/five weeks). 3Total weight gain deposition per gram of fish wet weight during the five-week period. 4Calmlated weight gain frun the saturation kinetic equation (Morgan et al. 1975). 45 Table 10. Total food intake, weight gain (ro), and the theoretical response (re) of _Q. niloticus fed varying percentages of the U.S. tilapia feed. % swl Intake2 r03 rc‘ 0 0.0000 -0. 1400 -.012 ‘ 0.5 0.1660 -0.0670 -0.09 1.0 0.3530 0.0040 -0.01 1.5 0.5310 0.0710 0.07 2.0 0.7240 0.1330 0.15 2.5 0.9350 0.2120 0.23 3.0 1.1450 0.2840 0.29 3.5 1.3440 0.3640 0.33 5.0 2.1020 0.4530 0.43 7.0 2.9980 0.4560 0.48 lDaily food intake as a percentage of the wet body weight. 2Tbtal intake (mg/g fish/five weeks). 3Total weight gain deposition per gram of fish wet weight during the five-week period. 4Calculated weight gain from the saturation kinetic equation (Morgan et al. 1975). 46 .Amu: .mcmggnmgmfiwummfixv gunmflufia 09032.80 wmm0fi me 0:2 000000 0.5! .008 06.8080 05 000 mfillleiflo E .0. 00 00380000 500 029.03 05 0x35 000“ no «0550 00:000.“ gag H0030uowfi. .m 0.303 .eonmoo.m- ewes zu0mno 05 000 mac 0:.» 98 “En: 00.03% wmm 05 ma m¥AA_umfiKHv0ahv .umdvpaficmsflamn0guHMd”mmmnfimwm Auuo_fiduamexu panwufififim3mflrmgflfiaunmflnmomflcaonflflanmflnucflfiflfifi.dfifiQRHMfiB .¢Mwfififim .‘fiosmoo. .kao uwmgo may mum mfixv mnu_ucm uaafla mocmuflucao wm¢ may m0 2: Bayou was .88 .m5 mfi Bu maulflollflc .0 no 830808 500 “£303 0> 00.3.: 600“ no 05.50 096000.“ £3.35: 3030.305. .0 0.33m .fionmoo.ms HmHa z 0x35 600.0. no 0350 0050900 wfiduwéw Hamwwuoflam . 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PmHo .mDAmxzm\zmfl0 Lm\Lmvmxc m.- to can _- u- ..oaodu_~.o -=._~.- u no .hoaowomtu 3::- an canon»?— o‘h ”anon” .uonomomuuo gunman. a. o..a=_ oak “n.0— .=-=_°0 used.o~n a.» no“ a.u_oa .aoa uo ounuaaohon . .. opauu_ e00. ”_Mua use a“ ..ou=aauoawu.. onaoauoh can. a. u.au._ coo. ugh ”an“. .uuuuo owaoa_. can u an ._o»o_ caugnw one» an guacamog 0.“ u a" .omaommuu ug-wunn “_a. 00 _o>o_ oaaun_ uak "m.°n~ .ouaoanuu ~aomuouoofl =3:- o= ”nu-a— s...“ 2.3 a...“ .2” z... a... z... 2." :5 :2 .2 :4 2...- .3 a... .3... a a a...“ .2“ 2..“ 2...... :2 3... 2... ,3 :2 N2 2... :._ 2...- a... 3... 52.2: a o I: 3...“ 3% 3.3 2... :2 :2- c2 .2 :5 2... 2.. 2...- o: 2.... :5: a a :5“ .2... 2...“ g...“ .2 z... 2...- ,2 :2 NZ 2... a; 2.... s... a... :35: u an 3.2 .2“ 3.3 :5... 2.2. a... .2 2... .2 a... a... .2 a; 2...- 3... 3... 5:22. a an E. 0.“ in z x :0. z a e: ._ a r: Em :5 .0 3:...” 2 a a 0. m- . n N _ . .u‘uwoa 5‘0; .0“. .o ouaaacohon . a. ~o>o_ o.aua_ ‘00“ go gawaoasu a a. weaken .003-0>mu\‘mwu .0 “\a_.u ggu_oa an. o_.a=_ coo“ unmuama .00. no»_umu ”yoga-aha; ._~ u~pue 52 growth model and their derivatives Ir=0, me, me 5 which describe the weight gain for each diet as shown in Table 11. Plnax: shows the maximum theoretical growth response of tilapia for each diet (the genetic potential of the fish towards a specific diet or nutrient. Fish fed the ID had a significant by higher Knax than fish fed all other tasted diets. The 1‘ value for fish fed the PD and AD were not significantly different from thatofHDorTD. Fish fedthePDontheotherhandhada significantly higher PM“ value than that of AD. KO.5: The amount of feed intake that produced half maximum growth response (mg/g fish/five weeks) was highest (poor quality diet) for tilapia fed the TD and AD. The K0.5 values for fish fed HD, PD, ID were not significantly different from each other, and lower than that of the TD and AD. p_: the kinetic order resulted in a sigmoidal (n>1) shaped curve in all growth results. b; the dietary response at zero food intake level (control group were not significantly different, as expected). The dietary maintenance intake level (zero weight gain, (Ir=0) showed that fish fed the PD had the lowest Ir=0 value (best value) followed by the fish fed HD, ID, TD and AD, respectively. 'Ihe maximum dietary growth efficiency (ME) which measures the greatest growth response with the smallest intake value was highest of fish fed PD, 53 TD, and ID, followed by fish fed the HD and AD. The overall dietary grwth efficiency value (the efficiency at the K0.5 me 5 showed a sharpdecrease fromMEvalue infish fedtheTthenoanparedto fish fed all other test diets. The overall growth efficiency was the best in fish fed the ID then PD, HD, TD, and AD, respectively. Net m Defiition The dietary energy intake and the deposited energy in the fish bodies (kcal/gr fish initial weight/five weeks) estimated and calculated in Tables 12, 13, 14, 15 andlé. They are graphically represented in Figures 7, 8, 9, 10 and 11. The parameters of the four parameter model and their derivatives that were achieved by the fish are shown in Table 17. Rmax: The maximum theoretical energy deposition value in the fish fed TD was lower then that of PD. However, Rmax value for fish fed the TD and PD were not significantly different from fish fed any of the three other diets. K0.5: Dietary energy intake that deposit half maximum energy deposition (1/2 Rmax) in the fish varied between diets. The fish fed the ID and the lowest K0.5 value of all diets and was not significantly different from those fed PD or ID. Fish fed ID, TD, and PDhad lowerKO.5 valuesthanthose fedtheAD. Fish fedthefmwere not significantly different from the ones fed the TD nor AD in terms of the K0.5 value. 54 Table 12. Gross energy intake, observed deposition (re), and calculated deposition (rc) of Q. niloticus fed varying percentages of the Honduran tilapia feed. % 3wl Intakez r09 r64 0 0.0000 -0.1570 -0.09 0.5 0.1390 -0.0130 -0.03 1.0 1.6300 0.1570 0.13 1.5 2.5370 0.2200 0.23 2.0 3.5270 0.3310 0.41 2.5 4.1490 0.5960 0.43 3.0 5.6300 0.6230 0.63 3.5 6.6030 0.7140 0.70 5.0 11.0390 0.3350 0.39 7.0 16.3100 1.0210 0.99 1Dailyfoodintakeasaper'centageofthewetbodyweight. 2Total energy intake (kcal/g fish/five weeks). 3Totalenergydepositionpergr'amof fishwetweightduringthe five-week period. 4Calculated energy deposition fran the saturation kinetic equation (Morgan et a1. 1975) . Table 13. Gross energy intake, observed deposition (re), and calculated deposition (rc) of Q. m'loticus fed varying percentages of the Thailand tilapia feed. 96 Bwl Intake2 m3 m4 0 0.0000 -0.2100 -0.17 0.5 0.7400 0.0110 -0.06 1.0 1.5540 0.1350 0.13 1.5 2.3200 0.2600 0.29 2.0 3.1290 0.3920 0.44 2.5 3.9950 0.5260 0.55 3.0 5.1839 0.83250 0.67 3.5 5.9420 0.8250 0.72 5.0 8.3710 0.8500 0.83 7.0 11.5450 0.8390 0.90 103.in foodintakeasaperoentageoftl'ewetbodymimt. 2'I‘otal energy intake (kcal/g fish/five weeks). 3'Ibtalenergydepositionpergramoffishwethightduringthe five-week period. energy deposition frun the saturation kinetic equation (Morgan et a1. 1975) . 4&1culated 56 Table 14. Gross energy intake, observed deposition (to), and calculated deposition (rc) of Q. niloticus fed varying percentages of the Panamanian tilapia feed. % 3W1 Intake.2 r03 rcfl 0 0.0000 -0.2090 -0.20 0.5 0.7100 0.0740 0.05 1.0 1.4900 0.3030 0.23 1.5 2.2600 0.4200 0.46 2.0 3.1200 0.5370 0.60 2.5 4.0700 0.7400 0.72 3.0 4.5300 0.7930 0.77 3.5 5.9400 0.9000 0.37 5.0 3.4400 0.9390 0.99 7.0 12.3500 1.0690 1.09 1Daily food intake as a percentage of the wet body weight. 2Tbtal energy intake (kcal/g fish/five weeks). 3Total energy deposition per gram of fish wet weight during the five-Meek period. 4Calculated energy deposition frcm the saturation kinetic equation (Morgan et a1. 1975) . 57 Table 15. Gross energy intake, observed deposition (1:0), and calculated deposition (rc) of Q. m'loticus fed varying percentages of the Indonesian tilapia feed. % 341 Intake2 :03 m4 0 0.0000 -0.1770 -0.14 0.5 0.8030 0.1110 0.04 1.0 1.6630 0.3030 0.34 1.5 2.6360 0.5490 0.61 2.0 3.7320 0.8780 0.81 2.5 4.6810 0.9150 0.91 3.0 5.6480 0.9550 0.98 3.5 7.0030 0.1060 1.04 5.0 9.2290 1.0930 1.10 7.0 12.7130 1.1040 1.15 J‘Daily foodintakeasaperoerrtageofthewetbodymight. 2mm energy intake (kcal/g fish/five weeks). 3Totalenergydepositionpergramof fishwetweiglrtduringthe five-week period. 4Calculated energy deposition fran the samration kinetic eqaation (Morgan et al. 1975) . 58 Table 16. Gross energy intake, observed depositicm (ro), and calculated deposition (re) of Q. niloticus fed varying percentages of the U.S. tilapia feed. 96 341 Intake2 m3 m4 0 0.0000 -0.1740 -0.19 0.5 0.8900 -0.0920 -0.07 1.0 1.8980 0.0510 0.08 1.5 2.8550 0.2300 0.20 2.0 3.8900 0.3940 0.32 2.5 5.3800 0.4000 0.44 3.0 6.1760 0.4550 0.50 3.5 7.6240 0.5980 0.59 5.0 11.4700 0.7380 0.74 7.0 15.9010 0.8500 0.84 llhily foodintakeasapercentageofthewetbodyweight. Z'I‘otal energy intake (kcal/g fish/five weeks). 3Total energy deposition per gram of fish wet weight during the five-week period. 4 Calcilated (Morgan et a1. 1975) . deposition from the saturation kinetic equation 59 Ann: :89: 95am cognac 05 who moa 05 can use: 00.8.9880 mmm on» mun 05.." 08.0.8 05.. .006 5.96:2. 05. 00.4. maulflollfic .o no 83006006 5.05 now mmgmgmxfifigwgcmowggufiwg 30003005. .0 05.53 HwHD Z0Em2m % «OleN NI 00+mom.a 00+mva.a 00+mmo.a 00+mom.0 00+mom.m . “mm ..aonmvo.a mm.0m n 0mm Xx 00.0 n 000 .... 3 00.0- n n x3.a m mm.“ u c .. . % me.v u m.x . 00 mmm e A 3.0 u .225 .. m .- d ..x U S I . i . 00-0mm 0 m N mm 3 D. / . 00+mso.a m m U. / m e 00+moe.0 m 60 .Amnh.cmma aakgwg0>akka.0ap.kmwngx..9000cmnzana.wxnmmukkvenmmgn.na.35; 0000.8 05.. .0000 65:20 0.0 000 0830:: .o no 83006000 >830 00.0. 0086 m> 0% 060090 000.5 no 0250 09% 0:00.05: 3098005. .0. 0.59... kaD DZ0Emzw a; «Olmom ml «0+mom.a fio+mvv.fi «0+mmo.fi oo+mom.n oo+mpm.m e aonmvo.a gm.hm u 6mm 00.0 n OLH W h0.01 u n .. mw 60..“ H C X . . 9 . . ..«onmmm v Od.m H m.v._ .. .. m mo.0 u me¢ 3 .d D S .1... 4001590 m. 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N . . 0000.00000 00.000 .0000 000 0.000. _0.000 0000000000.. 000000 00000 0000000 000000. 00.. 00»_.00.00000-0.00 .00.:00 .000-0._. 0 .00 .00. :00 000. .0. 00000 65 b: At zero dietary energy intake level (b) there was no significant difference between diets as was expected (control group). The value of n, the kinetic order resulted in a sigmoidal (n>1) curve shape for energy response in all the test diets. The amount of dietary energy intake that produced zero energy deposition in the fish bodies (Ir=0, the maintenance energy level of each diet) was the lowest in the fish fed the PD followed by fish fed the ID, HD, TD, and AD, respectively. Tilapia achieved maximum efficiency of converting the dietary energy to body energy (ME) when they were fed ID. Fish fed PD had lower ME values than that of ID. Fish fed 'ID had lower ME values than that of PD. Fish fed the AD, and HD had similar ME values and were the least efficient when compared to fish fed all other test diets. When the fish fed total dietary energy equivalent to half maximum response energy deposition the overall energy efficiency had slight change when compared to the maximum efficiency. Fish fed ID became the most energy efficient. Fish fed the PD showed a sharp decline in energy efficiency from the maximum efficiency. Fish fed the three other diets had a slight change in their energy efficiency level . All other diets had lower crude fat content than the recommended level . Carbohydrate content of the test diets ranged from 35 to 42 percent of the diet. Q_._ niloticus can efficiently utilize dietary carbohydrates up to 40 percent of the diet (Anderson et a1. 1984) . Dietary fiber contents ranged from 5.87 to 13.01. The recommended level for tilapia is 8 percent (Jauncey and Ross 1982) . The HD, TD, and AD had higher dietary fiber levels than the recanmended one. ‘Ihe 66 ID had a similar fiber level to the recommended level. The PD had a lower dietary fiber level than the reccmnended one. Crude Protein Mme Tables 18, 19, 20, 21 and 22 show the sloping lines for the amount of protein intake and deposition as fish protein in (mgr/gr fish/five-week period) for each diet. Figures 12, 13, 14, 15 and 16 show the above information graphically. Table 29 shows a surrmary of the parameters and the parameter derivatives of the four parameter model that is achieved by the fish. The maximum amount of protein deposition in fish bodies (gnax) for fish fed the experimental diet varied significantly. Fish fed the ID had the highest Knax value when canpared to all other test diets. Protein deposition of fish fed the AD, PD, and HD were not significantly different in terms of their gimme amount of dietary protein fed in order to deposit half the protein deposited in the fish in 1‘er for each diet is represented by KO.5 value. Fish fed the 'ID had the least K0.5 value of all those fed othertestdiets. Fish fedtheHd, PD, Id, andADwerenot significantly different in terns of their K0.5 values. Fish fed zero protein were all not significantly different fran each other in terms of the negative protein deposition value (b) . Dietary protein levels that maintain the original body protein at maintenance level (no gain or loss of body protein) is represented by Ir=0. Fish fed the TD had the least (best) value of Ir=0. Fish fed 67 Table 18. Crude protein intake, observed deposition (ro) , and cawlated deposition (rc) of Q. niloticus fed varying percentages of the Honduran tilapia feed. % ml Intake2 :03 m4 0 0 . 0000 -28 . 0000 -21 . 97 0.5 42.0000 -2.0000 -12.0l 1 . 0 88 . 0000 5. 0000 6. 92 1.5 136.0000 27.oooo 26.09 2.0 135.0000 34.0000 41.94 2.5 219.0000 46.0000 50.67 3.0 297.0000 72.0000 65.22 3.5 348.0000 79.0000 71.77 5.0 531.0000 86.0000 85.19 7.0 805.0000 88.0000 93.19 1Daily foodintakeasapercentageofthewtbodyweight. 2Crude protein deposition (ng/g fish/five weeks). 3'I‘otal crude protein per gram of fish wet weight during the five- week period. 4Calculated crude protein deposition frun the saturation kinetic equation (Morgan et a1. 1975) . 68 Table 19. Crude protein intake, observed deposition (ro) , and caculated deposition (ro) of _Q. niloticus fed varying percentages of the 'Ihailand tilapia feed. % swl Intake2 :03 re4 0 0.0000 -2o.0000 -19.25 0.5 31.0000 1.1000 1.48 1.0 43.0000 13.5000 8.90 1.5 91.0000 25.0000 29.57 2.0 134.0000 36.0000 40.11 2.5 167.0000 41.5000 45.46 3.0 _ 203.0000 51.0000 49.67 3.5 7 248.0000 68.0000 53.43 5.0 349.0000 59.0000 58.57 7.0 484.0000 55.0000 62.15 lDaily food intake as a percentage of the wet body weight. ZCrude protein deposition (mg/g fish/five weeks). 3'Iotal crudeproteinpergramof fishwetweightduringthefive- week period. 4calculated crude protein deposition from the saturation kinetic equation (Morgan et a1. 1975) . 69 Table 20. Crude protein intake, observed deposition (ro) , and caculated deposition (rc) of Q. niloticus fed varying percentages of the Panamanian tilapia feed. % ml Intake2 ro3 m4 0 0.0000 -18.1300 -16.05 0.5 45.3000 7.5400 3.28 1.0 96.0000 29.200 26.14 1.5 145.0000 35.0000 43.07 2.0 200.0000 52.0000 56.87 2.5 261.0000 69.0000 67.70 3.0 _ 293.0000 75.0000 72.07 3.5 380.0000 89.0000 80.93 5.0 541.0000 91.0000 90.58 7.0 792.0000 93.0000 98.03 lDaily foodintakeasapercentageofthewetbodyweight. 2Crude protein deposition (mg/g fish/five weeks). 3Totalcruieproteinpergr'amoffishwetweiglrtduringthefive- weekperiod. 4Calculated crude protein deposition frun the saturation kinetic equation (Morgan et al. 1975) . 70 Table 21. Crude protein intake, observed deposition (ro), and caculated deposition (rc) of Q. niloticus fed varying percentages of the Indonesian tilapia feed. % 8W1 1ntake2 r03 rcfi 0 0.0000 -14.50000 -14.98 0.5 58.0000 1.0000 1.68 1.0 126.0000 26.0000 25.88 1.5 193.0000 43.0000 46.06 2.0 281.0000 74.0000 66.04 2.5 353.0000 78.0000 78.04 3.0 426.0000 81.0000 87.34 3.5 528.0000 97.0000 96.97 5.0 696.0000 108.0000 107.50 7.0 958.0000 118.0000 116.96 lDaily food intake as a percentage of the wet body weight. 2Crude protein deposition (Hg/g fish/five weeks). 3'Iotal crudeproteinpergramof fishwetweightdm'irgthe five- week period. 4Calculated crude protein deposition fran the saturation kinetic equation (Morgan et al. 1975) . 71 Table 22. Crude protein intake, observed deposition (ro) , and caculated deposition (rc) of Q. niloticus fed varying percentages of the U.S. tilapia feed. 9. m1 1111:2009.2 m3 m4 0 0.0000 -19.40000 -19.81 0.5 40.8000 -9.8000 -8.37 1.0 86.90000 5.70000 6.36 1.5 130.0000 24.50000 18.83 2.0 177.5000 29.90000 30.06 2.5 229.0000 31.80000 40.05 3.0 280.0000 46.9000 48.03 3.5 329.0000 60.4000 54.22 5.0 515.6000 69.8000 69.75 7.0 767.4000 79.9000 80.59 1Daily food intake as a percentage of the wet body weight. 2Crude protein deposition (mg/g fish/five weeks). 3Total crudeproteinpergramof fishwetweightchringthe five- weekperiod. 4Calculated crude protein deposition fran the saturation kinetic equation (Morgan et a1. 1975) . 72 . 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N . . .536.” .66..66.. 6..6... 66.. 6.6 .6 .666 .6. _e6..6. .6oa-6.....6.. .\6.6.6.. .6. 66.6.66565 =.6.6.. can .56..6. .663-66..\.6.. .6 u .6. 6.6.6.. .6. 6.666. 6.636.. ..666.5 .6..... 66.. ca»..ou 6.6.6.“.6. .nN o.a6. 78 the PD had higher Ir=0 values then the ones fed the TD. Fish fed the ID, AD, arxiHDhadalmosttwicethevalueofthose fedtheTDintern‘s of their Ir=o value The maximum efficiency of converting the dietary protein to fish protein is represented by EM. Fish fed the TD were the most efficient and had the highest me value of all fish fed othertestdiets. Fish fedthePDhadamdilourerEnmvaluetlian those fed the TD. Fish fed the HD, ID and AD had, respectively lower me values. The dietary protein efficiency value when fish fed at their half Knax value is represented by the overall efficiency value. Fish fed all the test diet had slightly lower efficiency values overall then their me value with the same order. Crude Fat Demsition Tables 24, 25, 26, 27, and 28 show the amount of dietary crude fat intake and deposition in fish bodies (mgr/gr fish/five-week period) for each diet. Figures 17, 18, 19, 20 and 21 show the same information graphically. Table 24 shows a summary of the four parameters and their derivatives that are achieved by the fish. I‘nax: represents the maximum theoretical amount of crude fat deposition of fish fed any of the experimental diets. Fish fed the TD andPDhadthelowestlfi valueswhenccmparedtofishonanyother experimental diet. Fish fed the ID resulted in higher Rmax values than those fed the TD and were not significantly different from those 79 Table 24. Crude fat intake, observed deposition (ro) and calculated deposition (rc) of Q. niloticus fed varying peroentages of the Honduran tilapia feed. % 541 Intake2 m3 m4 0 0.0000 -8.0000 -8.08 0.5 10.0000 -3.0000 -2.68 1.0 20.0000 4.0000 3.48 1.5 31.0000 11.0000 10.18 2.0 43.0000 15.0000 17.09 2.5 50.0000 20.0000 20.89 3.0 68.0000 32.0000 29.88 3.5 80.0000 36.0000 35.25 5.0 131.0000 52.0000 53.49 7.0 198.000 70.0000 69.52 lDaily food irrtakeasaperoentageofthewetbodyweight. 2Crude fat intake (mg/g fish/five weeks). 3Total crude fat deposition per gram of fish wet weight during the five-week period. 4Calculated crude fat deposition from the kinetic empation (Morgan et a1. 1975) . 80 Table 25. Crude fat intake, observed deposition (to) and calculated deposition (rc) of Q. niloticus fed varying percentages of the Thailand tilapia feed. % swl Intake2 :63 m4 0 0.0000 -8.0000 -6.26 0.5 17.0000 0.5000 -1.82 1.0 35.0000 7.0000 6.49 1.5 53.0000 16.0000 15.01 2.0 71.0000 19.0000 22.43 2.5 94.0000 28.0000 29.92 3.0 110.0000 33.0000 33.99 3.5 135.0000 45.0000 ' 38.88 5.0 190.0000 46.0000 45.61 7.0 264.0000 48.0000 50.24 1Daily food intakeasaperoentageofthewetbodyweight. zerude fat intake (mg/g fish/five weeks). 3'Ibtalcrude fatdepositionpergramof fishwetweightduringthe five-week period. 4Calculated crude fat deposition fran the kinetic equation (Morgan et al. 1975) . 81 Table 26. Crude fat intake, observed deposition (ro) and calculated depositio (rc) of Q. niloticus fed varying peroentages of the Panananian tilapia feed. a; m1 Intakez m3 m4 0 0.0000 -10.0000 -7.9 0.5 11.0000 4.0000 0.60 1.0 23.0000 16.0000 13.61 1.5 35.0000 21.0000 25.61 2.0 48.0000 31.0000 35.71 2.5 62.0000 42.0000 44.21 3.0 71.0000 58.0000 48.54 3.5 91.0000 57.0000 48.54 5.0 128.0000 62.0000 64.13 7.0 188.0000 70.000 70.85 lDaily food intakeasaperoentageofthewetbodyweight. Crude fat intake (mg/g fish/five weeks). 2 3Total crude fat deposition per gram of fish wet weight during the f ive-week period. 4Calculated crude fat deposition fran the kinetic equation (Morgan et al. 1975) . 82 Table 27. Crude fat intake, observed deposition (to) and calculated deposition (rc) of Q. niloticus fed varying percentages of the Indonesian tilapia feed. % 371 Intake2 to3 re4 0 0.0000 -7.0000 -6.01 0.5 15.0000 7.0000 4.75 1.0 32.0000 21.0000 21.75 1.5 51.0000 33.0000 37.48 2.0 72.0000 58.0000 50.49 2.5 93.0000 55.0000 59.70 3.0 109.0000 63.0000 64.92 3.5 135.0000 75.0000 71.17 5.0 177.0000 78.0000 77.65 7.0 244.0000 82.0000 83.35 1Daily foodintakeasaperoentageofthewetbodyweight. 2Crude fat intake (mg/g fish/five weeks). 3'I’ortal crude fat deposition per gram of fish wet weight during the five-week period. 4C21culated crude fat deposition frcm the kinetic equatim (Morgan et a1. 1975) . 83 Table 28. Crude fat intake, observed deposition (ro) , and calculated deposition (rc) of Q. niloticus fed varying percentages of U.S. tilapia feed. % 341 Intake2 ro3 rt:4 0 0.0000 - 8.0000 -7.88 0.5 18.0000 - 4.0000 -3.92 1.0 37.0000 2.0000 0.84 1.5 56.0000 5.0000 5.68 2.0 76.0000 10.0000 10.73 2.5 98.0000 16.0000 16.15 3.01 120.0000 20.0000 21.37 3.5 141.0000 29.0000 26.16 5.0 218.0000 41.0000 42.07 7.0 329.0000 61.0000 60.8 lDaily foodintakeasaperoentageofthewetbodyveight. ZCrude fat intake (mg/g fish/five weeks). 3Total crude fat deposition per gram of fish wet weight during the five—week period. 4Calculated crude fat dqnsition fran the kinetic equation (Morgan et al. 1975) . 84 . 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Fish fed the AD had the highest Rmax value of all diets and were not significantly different from those fed the HD and ID. The amount of dietary fat fed that resulted in deposition half of the Rmax value of crude fat deposition in fish bodies is represented by K0.5. The fish fed the PD had the lowest (best) KO.5 value as compared to all other test diets. Fish fed the HD had significantly higher (P < 0.05) KO.5 values than the ones fed the PD and TD. Fish fed the AD had the highest KO.5 value of all those fed any of the other diets. Fish fed zero dietary fat had a nonsignificant difference in terms of the negative fat deposition (b) . ‘Ihe kinetic order (n) shows a sigmoidal (n>1( curve relationship between dietary fat intake and deposition in fish bodies. The amount of dietary fat fed to maintain fish body fat at zero fat deposition (maintenance) is represented by 11:0. The fish fed the ID had the lowest Ir=0 value. The value of Ir=0 went up in fish fed the PD, HD, TD and AD, respectively. The maximum efficiency of converting dietary fat to fish body fat represented by ME. The fish fed the Panamanian diet had the highest mevalue of all diets. Then the Enmvalue went down in fish fed the ID, HD, TD and AD, respectively. ‘Ihe dietary fat efficiency when fish fed the K0.5 fat intake (the overall efficiency) as slightly lower than the mevalues of each diet with the same order between diets . 91 Di Lag Minerals Content of the Test Diets Dietary calcium, phosphorus, magnesium and zinc content of the test diets and the recommended levels for tilapia (Jatmcy and Ross 1982) are listed in Table 30. Test feeds contained much higher calcium levels then the recommended one. The ID had more than twice as much calcium as any other diet. The TD and AD had similar calcium content. The PD had slightly less calcium content than the TD and AD. The HD had the least calcium content of all feeds and was about four times the recommerded level. The dietary phosphorus content of the HD, TD and PD fell within the recommended level for tilapia. The ID and AD had higher dietary phosphorus content than the recommended level. The dietary magnesium content of the TD and AD were similar to the recommended level. ‘Ihe HD and ID contained a little over twice the recommended level of magnesium. The ID contained more than triple the recomnerried level of magnesium. Dietary zinc content of all test diets were higher than the recommended level (3-8 times). The ID and PD had the highest dietary zinc content of all diets (7-8 times the reconmerded level). The HI), 'ID and AD had similar dietary zinc content (3-4 times the recommended level). Di gr); Magnesium Rgmnse Tables 31, 32, 33, 34 and 35 show the slope of lines for dietary magnesium fed (intake) and deposition in the fish carcass. Figures 22, 23, 24, 25 and 26 show the above information, graphically. Table 36 summarizes the parameters from the saturation kinetic model. The . Ammma mmom 62m @0583 9..mepr you magma commas-58mm .mfimmn unaam3_muu co ummmma 08.0 05.0 oo.wlm.N ohm NmH0>QH Egg 92 nmo.o mm.o e¢.~H mm.ma .m.o oma.o sm.H m~.nH mm.ov oflmmcoucH oa.o em.~ Ho.m mm.oa cmecmemcmm eoo.o ss.o ma.m em.mH academse Hmo.o ms.H o~.s om.mH caucuses mxxa axxm mx\m Hoz\a 0:3 538mm: mflofimofi 5636 558 H.2msafl «odes mumeo powwow m5. m0 mummies“... DEN can Seance .maocmmonc .5338 .0». 03mm. 93 Table 31. Magnesium intake, observed deposition (ro), and calculated deposition (rc) of Q. niloticus fed varying percentages of the Honduran tilapia feed. % swl Intake2 r03 r84 0 0.0000 -0.29 -0.2 0.5 2.5100 -0.14 -0.1 1.0 5.5000 0.3200 0.1 1.5 8.7000 0.2500 0.4 2.0 11.1900 0.6200 0.7 2.5 13.9000 0.8000 0.8 3.0 19.0000 1.1700 0.11 3.5 22.2000 1.3000 0.12 5.0 33.9700 1.2840 0.14 7.0 51.50 1.45 0.15 1Daily food intake as a percentage of the wet body weight. 2Magnesium intake (mb/g fish/five weeks). 3Total dietary magnesium deposition per gram of fish wet weight during the five-week period. 4'Calculated magnesium deposition frcm the saturation kinetic equation (Morgan et a1. 1975) . 94 Table 32. Magnesium intake, observed deposition (ro), and calculated deposition (no) of Q. niloticus fed varying percentages of the Thailand tilapia feed. % m1 Intake2 r03 m4 0 0.0000 -0.4100 -0.40 0.5 13.0000 0.0170 -0.10 1.0 27.0000 0.2200 0.30 1.5 42.0000 0.4500 0.50 2.0 56.0000 0.6600 0.70 2.5 72.0000 0.7300 0.80 3.0 87.000 0.8700 0.90 3.5 106.0000 1.2000 1.00 5.0 153.0000 1.0300 1.10 7.0 204.0000 1.1200 1.20 lDaily foodintakeasapercentageofthewetbodyweight. 2Magnesium intake (mb/g fish/five weeks). 3Total dietary magnesium deposition per gram of fish wet weight during the five-week period. 4Calculated magnesimn deposition fran the saturatim kinetic equation (Morgan et al. 1975) . 95 Table 33. Magnesium intake, observed deposition (to) , and calculated deposition (rc) of Q. niloticus fed varying peroentags of the Panamanian tilapia feed. 9. awl Inn-.0662 m3 m4 0 0.0000 -0.2600 -0.02 0.5 4.6000 0.1100 0.01 1.0 9.6000 0.7400 0.06 1.5 14.6000 0.8000 0.10 2.0 20.2000 1.1800 0.13 2.5 26.2000 1.5800 0.16 3.0 29.5500 1.9400 0.18 3.5 38.3600 2.2300 0.20 5.0 54.5000 2.1700 0.23 7.0 79.8200 2.4000 0.25 10ai1y foodintakeasaperoentageofthewetbodyweight. ZMagnesium intake (mb/g fish/five weeks). 3Total dietary magnesium deposition per gram of fish wet weight during the five-week period. 4Calculated magnesium deposition fran the saturation kinetic equation Morgan et a1. 1975) . 96 Table 34. Magnesium intake, observed deposition (ro) , and calculated deposition (rc) of Q. niloticus fed varying percentages of the Indonesian tilapia feed. % 8W1 Intake2 :03 rc4 0 0.0000 -0.5200 -0.5 0.5 2.4200 0.0700 0.1 1.0 5.2400 0.5900 0.6 1.5 8.3200 0.9600 1.0 2.0 11.7700 1.2800 1.3 2.5 14.7400 1.5200 1.5 3.0 17.8200 1.7300 1.7 3.5 22.07 1.9800 1.9 5.0 29.0800 2.2700 2.2 7.0 40.10 1.3400 2.4 lDaily foodhmakeasaperomtageofthewetbodyweight. gMagnesium intake (mbyg'fish/five weeks). 3'Ibtal dietary magresium deposition per gram of fish wet weight during the five-week period. 4Calculated magnesium depositim fran the satmatim kinetic equation (Morgan et a1. 1975) . 97 Table 35. Pbgnesium intake, observed deposition (no), and calculated deposition (rc) of _Q. niloticus fed varying percentages of the U.S. tilapia feed. 96 BW1 Intake2 m3 m4 0 0.0000 -0.3500 -.04 0.5 1.0500 -0.1600 -0.1 1.0 2.2300 0.2100 0.1 1.5 3.3700 0.4200 0.3 2.0 4.6200 0.4600 0.5 2.5 5.9200 0.4900 0.7 3.0 7.2600 0.7500 0.8 3.5 8.5300 1.0600 0.9 5.0 13.5400 1.1800 1.10 7.0 19.9600 1.2600 1.30 1Daily foodintakeasaperoentageofthewetbodyweight. zMagnesium intake (mb/g fish/five weeks). , 3Ibtal dietary magnesium deposition per gram of fish wet weight during the five—week period. 4Calculated magnesium deposition frun the sanitation kinetic equation (Morgan et al. 1975) . 98 . . 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N . . ..6e_eea geea-us_e\‘uwe ..u-V eewgmeoeou -u_uueua- use ..ooa-o>s_\e.u.oa ~«_u_e_ gas“ a.... «_oso_ o.aue_ -=_mueuaa seauumu meshes“ use. cosmewu usage-«ens .un n_naa 104 maximum theoretical magnesium deposition response in fish fed the test diets was represented by Rmax value. Fish fed the HD, PD and ID were not significantly different in terms of their Rmax values. Fish fed the AD and HD had similar Rmax values that were not significantly different. Fish fed the AD and TD had lower Raex values than those fed the PD and ID. The dietary magnesium intake (fed) that produces half Knax value of magnesium deposition is represented by KO.5. Fish fed the 'ID had the highest KO. value of all other test diets. Fish 5 fed the ID had slightly better (lower) K0.5 values than the ones fed 'ID. Fish fed the ID had better K0.5 values then those fed the PD and were not significantly different from the ones fed the HD. Fish fed the AD had the best K0.5 value of all diets and were not significantly different from the ones fed the HD. The negative magnesium deposition in fish at zero magnesium intake (b) showed no significant difference between the test diets. The kinetic order (n) showed a sigmoidal (n>1) relationship. The dietary magnesium fed (intake) that was required for maintenance (no gain or loss of body magnesium) in the test diets is represented by Ir=0. Fish fed the AD had the best (lowest) Ir=0 value of all diets, followed by fish fed the ID, PD, HD, and the TD, respectively. The maximum dietary efficiency of depositing the dietary magnesium in the fish bodies is represented by ME. The fish fed the ID had the highest ME value of all those fed other test diets. 105 theMEvaluethenwentdowninfish fedtheAD, PDandI-IDandTD, respectively. ‘Ihe dietary efficiency of depositing the dietary magnesium in the fish bodies when the fish were fed at K0.5 level is called the overall efficiency value. Fish fed the AD had the highest overall efficiency value of all test diets. Fish fed the ID had a sharpdecline intheirEemvalueandweresecondtothose fedtheAD then fish fed the HD, PD and TD, respectively. Di Eu Calcium R§p_onse The results of dietary calcium intake (fed) and calciLnn deposition in the fish bodies are shown in Tables 37, 38, 39, 40, 41 and 42 and graphically in Figures 27, 28, 29, 30 and 31. A sunmary of the four parameters and their derivatives that was achieved by the fish in Table 42. The maximum theoretical calcium deposition in fish fed the experimental diets were represented by pinax' Fish fed the ID had the highest calcium deposition Knax than those fed any of the other test diets. Fish fed the PD, HD, TD, and AD were not significantly different in terms of their Pinax value for calcium deposition. The dietary calcium intake that produced half-maxim response of calcim'n deposition in fish is represented by KO.5 values. Fish fed thePDhadthelwestK0.5valuewhenoomparedtothosefedanyofthe other test diets. Fish fed the HD, TD, and AD were not significantly 106 Table 37 . Calcium intake, observed deposition (no), and calmlated deposition (no) of Q. m'loticus fed varying percentages of the Honduran tilapia feed. % 341 Intake2 r03 rc4 0 0.0000 -0.90000 -0.85 0.5 2.0800 -0.0500 -0.22 1.0 4.4100 0.50000 0.57 1.5 6.8400 1.1800 1.31 2.0 9.3700 1.8600 1.96 2.5 10.9400 2.3300 2.31 3.0 14.9400 2.9800 3.02 3.5 17.5400 4.0100 3.40 5.0 26.6600 3.6960 4.30 7.0 40.4600 5.2400 5.04 lDaily foodintakeasaperoentageofthewetbodyveight. ZCalcium intake (mg/g fish/five weeks) . 3Total calcium deposition per gram of fish wet weight during the five-week period. 4Calculated calcium deposition frcm the saturation kinetic equation 1 (Morgan et al. 1975) . 107 Table 38. Calcium intake, observed deposition (no), and calculated deposition (no) of _Q. niloticus fed varying percentages of the Thailand tilapia feed. 96 341 Intake2 :03 m4 0 0.0000 -0.6000 -.053 0.5 3.4000 0.5000 -0.04 1.0 7.1000 0.7200 0.68 1.5 10.60000 1.4300 1.31 2.0 14.3000 1.7700 1.88 2.5 18.3000 2.0600 2.38 3.0 22.1000 2.5500 2.77 3.5 27.200 3.6300 3.18 5.0 32.7000 3.7300 3.52 7.0 52.8000 4.0500 4.24 I‘Daily foodintakeasaperoentageofthemtbodyweight. ZCalcium intake (mg/g fish/five weeks). 3Total calcium deposition per gram of fish wet weight during the five-week period. 4Calailated calcium deposition from the saturation kinetic equation (Morgan et al. 1975) . 108 Table 39. Calcium intake, observed deposition (ro), and m1a11ated deposition (rc) of Q. niloticus fed varying percentages of the Panamanian tilapia feed. 9. 541 Intake2 :63 m4 0 0.0000 '1.0000 -0.96 0.5 3.60000 0.50000 0.46 1.0 6.40000 1.77000 1.50 1.5 10.6700 2.10000 2.62 2.0 13.50000 2.9700 3.13 2.5 17.6200 3.9400 3.67 3.0 21.2500 4.2000 4.02 3.5 28.1000 4.5100 4.45 5.0 36.5100 4.8900 4.78 7.0 53.8000 4.9300 5.14 1Daily food intake as a percentage of the wet body weight. 2Calcium intake (mg/g fish/five weeks). 3Total calcium deposition per gram of fish wet weight during the five-week period. 4Calculated calcium deposition fran the saturation kinetic equation (Morgan et al. 1975) . 109 Table 40. Calcium intake, observed deposition (ro), and calculated deposition (rc) of Q. niloticus fed varying percentages of the Indonesian tilapia feed. 2 swl Intake? r03 r63 0 0.0000 -1.4600 -1.40 0.5 7.2370 0.3100 0.22 1.0 15.6800 1.8900 1.70 1.5 24.8900 2.9200 2.92 2.0 35.2000 3.2800 3.95 2.5 44.0900 4.6100 4.65 3.0 53.3000 5.4900 5.24 3.5 66.0200 6.2200 5.89 5.0 86.9700 6.9000 6.68 7.0 119.9200 7.2000 7.51 1Daily food intake as a percentage of the wet body weight. 2Calcium intake (mg/g fish/five weeks). 3Total calcium deposition per gram of fish wet weight dm'ing the five—week period. 4Calculated calcium deposition frun the saturation kinetic equation (Morgan et al. 1975) . 110 Table 41. Calcium intake, observed deposition (ro), and calculated deposition (rc) of Q. m’loticus fed varying percentages of the U.S. tilapia feed. 9. awl Intake2 :63 :64 0 0.0000 -1.0000 -1.04 0.5 3.0000 -0.5000 -0.38 1.0 6.4000 0.4000 0.36 1.5 9.3000 1.0000 0.90 2.0 13.1000 1.5000 1.48 2.5 16.9000 1.8000 1.94 3.0 20.7000 2.3000 2.31 3.5 22.4000 2.6000 2.46 5.0 38.0000 2.6000 3.36 7.0 57.0000 4.0000 3.91 lDaily foodintakeasapercentageoftlcwetbodyweight. 2Calcium intake (mg/g fish/five weeks). 3Total calcium deposition per gram of fish wet weig'it during the five-week period. 4Calculated calcium deposition frcxn the saturatim kinetic equation (Morgan et al. 1975) . 111 . .6": 50059556080805.0900A5 gguEH 00.866980 @5063 m... 05. 60806 0...... .006 68568.. 0.6. 600 08148.00 . d 00 8380006 .5880 05 0089:.“ 6.30.80 mo 05.90 008900.“ 9.3.8:... 80.309005. . em 0956... .emeo 24666261..mxzm\em.t 6\6e.mxmc 00395 £3.38 90 0350 096000.» “Egg: 10300005. .mm 0.33m .pmHo m 00:00.: 23010 no 038 36900.0 050% 30300005. .8 0.503 .000o zm 0x005 530000 00 0250 00500000 0:03.00: gag .3 0.930 .FmHo.ma..0xxm\zmfl. u\ue.mxmo_ oauu._ can» a. oucoguu. o.p H a" .oaaoaaou ug-_~.- «_u. a. _o»~_ o_.»=_ can “m.¢_~ .onaonmou _qomuouooaa .anmua- o.~ ”nu-m— as... 2% .2... -.° NN.° mac.° om.c n~.. n~.° pm.. a_._ .9..- -.~_ _~.m .¢.m.= . a u a...“ in :4“ "—.o nN.° _o._- _~.° em._ N..= “—.w n°.~ .°._- um.n— nu.°_ 1) curve relationship in calcium intake and deposition in _O_. niloticus. ‘Ihe amount of calcium fed to maintain zero calcium deposition in fish is represented by IFO. ‘Ihe fish fed the PD had the best Ir=0 value of all those fed the other test diets, then, fish fed the HD, TD, AD, and ID had higher Ir=0 values, respectively. ‘Ihe maxim amount of calcium deposited in the fish bodies with the smallest amount of dietary calcium intake is defined as the maximum efficiency (Eh-Ix) . Fish fed the PD had the highest mevalue of all those fed the other test diets. The ME: value decreased as the fed fed the HD, ID, AD and TD, respectively. The dietary calcium efficiency at K0.5 value is represented by the overall efficiency value. There was a sharp decrease in the dietary efficiency when the mevalues were compared to the overall efficiency value of fish fed the PD and ID. Fish fed the PD had the best overall efficiency value when compared to all others fed the other test diets. Fish fed the Honduran diet had a lower overall efficiency value than those fed the PD. The efficiency values declined in the fish fed the AD, TD, and ID, respectively. 118 Di m Zinc Eggnse The results of dietary zinc intake and zinc deposition in fish (mgr/g fish/five-week period) are shown in Tables 43, 44, 45, 46, and 47. The above information is also shown graphically in Figures 33, 33, 34, 35, and 36. A sunmary of the four parameters and their derivatives that are achieved by the fish are shown in Table 48. The maximum theoretical zinc deposition in fish fed any of the testdiets is representedbyRmax. Fish fedtheIDhadmorethan twice megmxvalue of those fedtheothertestdiets. Fish fed the PD, TD, andADwerenotsignificantly differentintermsoftheirRmax values. FishfedthelhmhadalowerlxaxvaluethanthosefedthePD and were not significantly different from fish fed the 'ID or AD. The dietary zinc intake that produces half Rmax of zinc deposition in fish is represented by K0. Fish fed the ID had higher 5. KO.5 values then those fed any of the other test diets. Fish fed the AD, PD and 'ID were not significantly different in terms of their K0.5 values. Fish fed the HD had the least K0.5 value of all those fed the othertestdiets. At zerodietary zincintaketherewereno significant differences in terms of fish body zinc negative aocunmlations (b). The kinetic order (n) showed a sign‘oidal (n>1) relationship between dietary zinc intake and deposition in the fish bodies. 119 Table 43. zinc intake, observed deposition (no), and calculated deposition (rc) of Q. niloticus fed varying percentages of the HOnduran tilapia feed. 9.: W1 Intake2 m3 m4 0 0.0000 -2.8000 -2.83 0.5 7.8000 -0.3000 -0.25 1.0 16.4000 2.4000 2.41 1.5 21.9000 3.6000 3.65 2.0 35.0000 5.9000 5.61 2.5 41.6000 6.3000 6.26 3.0 56.0000 7.0000 7.22 3.5 66.0000 .7.7000 7.67 5.0 100.0000 8.2000 8.54 7.0 151.0000 9.4000 9.10 lDaily food intakeasapercentage ofthewetbodyweight. 2Zinc intake (mg/g fish/five weeks). 3'I‘otal dietary zinc deposition per gram of fish wet weight during the five-week period. 4'Calculated zinc deposition from the saturation kinetic equation (Morgan et al. 1975) . 120 Table 44. Zinc intake, observed deposition (ro), and calwlated deposition (rc) of Q. niloticus fed varying percentages of the ‘Ihailand tilapia feed. % 8W1 Intake2 :03 r04 0 0.0000 -3.6000 -3.45 0.5 11.0000 0.1400 -O.46 1.0 23.0000 1.6100 1.99 1.5 35.000 3.2200 3.70 2.0 47.0000 5.0800 4.93 2.5 58.0000 5.5600 5.78 3.0 72.0000 6.3800 6.61 3.5 89.0000 8.300 7.36 5.0 125.0000 8.900 8.40 7.0 173.000 8.4500 9.20 lDaily foodirrtakeasaperoentageofthewetbodyweight. 2Zinc intake (mg/g fish/five weeks). 3'Ilotal dietary zinc deposition per gram of fish wet weight during the five-week period. 4'Calcmlated zinc deposition fran the saturation kinetic equation (Morgan et al. 1975) . 121 Table 45. Zinc intake, observed deposition (ro), and calculated deposition (rc) of Q. niloticus fed varying percentages of the Panamanian tilapia feed. % 8W1 Intake2 r'o3 m4 0 0.0000 -2.300 -1.98 0.5 18.0000 0.8300 0.27 1.0 38.0000 4.1700 3.77 1.5 58.0000 5.1600 6.33 2.0 80.0000 6.7600 8.11 2.5 104.0000 10.1600 9.30 3.0 117.0000 11.7200 9.74 3.5 152.0000 10.6900 10.53 5.0 216.0000 10.7000 11.24 7.0 316.0000 11.1100 11.69 lDaily food intakeasapercentageofthewetbodyweight. 22inc intake (mg/g fish/five weeks). 3Total dietary zincdepositionpergramof fishwetweightduringthe five-week period. 4Calculated zinc deposition frcm the saturatim kinetic equation (Morgan et a1. 1975) . 122 Table 46. Zinc intake, observed deposition (re), and calculated deposition (rc) of 9. n_iloticus fed varying percentages of the Indonesian tilapia feed. % swl Intake2 :63 r04 0 0.0000 -3.240 -3.15 0.5 21.0000 0.7100 0.66 1.0 45.0000 4.7500 4.07 1.5 72.0000 6.4000 6.99 2.0 101.0000 9.1200 9.46 2.5 127.0000 10.4400 11.10 3.0 153.0000 12.6400 12.49 3.5 190.0000 14.7300 14.08 5.0 250.0000 16.8000 15.99 7.0 345.0000 17.3000 18.03 lDaily food intakeasaperoerrtageofthewetbodyweight. 22inc intake (mg/g fish/five weeks). 3Total dietary zinc deposition per gram of fish wet weight during the five-week period. 400.1culated zinc deposition fran the saturation kinetic equation (Morgan et al. 1975) . 123 Table 47. Zinc intake, observed deposition (ro), and calculated deposition (rc) of Q. niloticus fed varying percentages of the U.S. tilapia feed. % m1 Intake2 r03 rc4 0 0.0000 -2.7000 -2.74 0.5 8.0000 -1.2300 -1.20 1.0 17.0000 0.8000 0.91 1.5 26.0000 2.4000 2.67 2.0 35.0000 4.9000 4.04 2.5 46.0000 5.1000 5.28 3.0 57.0000 5.7000 6.19 3.5 66.0000 6.4000 6.76 5.0 103.0000 8.7500 8.17 7.0 153.0000 8.900 9.03 1Daily food intakeasaperoentageofthewetbodyweight. 2Zinc intake (mg/g fish/five weeks). 3Total dietary zinc deposition per gram of fish wet weight durixg the five-week period. 4Calculated zinc deposition fran the saturation kinetic equation (Morgan et al. 1975) . 124 Ann: .ggag 05 0.3 £50.13? 3.5a 094005.980 wmmgflgaggc 00600033680503 . .000 833800 gs 05 9.35 0:? no 0230 09% “E035: 3030.505. .hmHo zmmm§fi£qmecu“nomghaumMCmennfiafiHEE.dRfigyfimna ...FMHD Im 9:35 0:3 no 296 3% gang 303.80an .0m $502 .PmHo.mz..mxzm\cm20 Lg\LmofiEVAzH.ozHN >mw.\g‘u_oa _._awaw .uwu u\~u_r\. .qouo_ unaua_ and» .yuaowu unmuuwu saga co._.ov..~ouo-.~um .¢¢ n_pah 130 The dietary zinc fed that maintain body zinc levels at maintenance (no gain or loss) is represented by IFO values for each diet. Fish fed the HD were the most efficient (had the lowest Ir=0 value), followed by those fed the TD, AD, PD and the ID, respectively. The dietary maximmn efficiency of depositing the dietary zinc in the fishisrepresentedbyme. Fish fedthefmhadthehighthnm value of all those fed the other test diets, followed by those fed the TD, AD, ID and PD, respectively. The dietary zinc efficiency when the experimental fish fed at the KO.5 level of each diet is represented by the overall efficiency values. Fish fed the HD were the most efficient in terms of their overall efficiency value followed by those fed the TD, AD, PD and TD, respectively. Di gm Phosphorus RM The dietary phosphorus deposited in the fish bodies as a function of dietary phosphorus intake (fed) each of the experimental tilapia diet are shown in Tables 49, 50, 51, 52, and 53. The same information is shown graphically in Figures 37, 38, 39, 40 and 41. A summary of the four parameters and their derivatives that are achieved by the fish are shown in Table 54. The mximum amount of dietary phosphorus that was deposited in the fish fed each of the experimental diets was represented by Rmax values. Fish fed the PD had the highest gnax value of all those fed test feeds. Fish fed the ID had the higher Pinax value than those fed 131 Table 49. Phosphorus intake, observed deposition (m), and calculated deposition (rc) of Q. m’loticus fed varying percentages of the Honduran tilapia feed. % BW1 Intake2 r03 r04 0 0.0000 -1.3650 -1.45 0.5 3.8500 -0.8400 -0.58 1.0 8.2250 0.9800 0.54 1.5 12.7400 1.0850 1.14 2.0 17.4650 1.2600 1.45 2.5 20.4050 1.3300 1.56 3.0 27.7550 1.3300 1.22 3.5 32.6900 1.9600 1.78 5.0 35.3500 1.9950 1.80 7.0 40.5900 2.0650 1.83 1Daily food intake as a percentage of the wet body weight. 2Phosphorus intake (mg/g fish/five weeks). 3'I‘otal dietaryphosphorus depositionpergramof fishwetweightduringthe five-week period. 4Chlczulated phosphorus deposition frun the saturation kinetic equation (Morgan et a1. 1975) . 132 Table 50. Phosphorus intake, observed deposition (ro), and calcilated deposition (rc) of _Q. niloticus fed varying percentages of the Thailand tilapia feed. % swl Intake2 re? :09 0 0.0000 -1.6800 -1.62 0.5 3.7000 0.0770 -0.17 1.0 7.8050 0.8050 1.02 1.5 11.6500 1.5750 1.77 2.0 14.5600 2.2400 2.19 2.5 20.0900 2.6600 2.75 3.0 24.3950 3.2900 3.06 3.5 29.8900 3.6050 3.36 5.0 42.0350 3.7100 3.77 7.0 58.1000 3.9200 4.08 1Dailyfoodintakeasapercentageofthewetbodyweigt'rt. zPhosphorus intake (mgflg fish/five weeks). 3Total dietary phosphorus deposition per gram of fish wet weight during the five-week period. 4Calculated phosphorus deposition fran the saturation kinetic equation (Morgan et a1. 1975) . 133 Table 51. mosphorus intake, obsexved deposition (ro), and calculated deposition (no) of _O_. m'loticus fed varying percentages of the Panamanian tilapia feed. % swl Intake2 :09 r04 0 0.0000 -l.3650 -0.78 0.5 2.2750 0.4200 -0.39 1.0 4.9000 0.9800 1.03 1.5 7.2450 2.0650 2.55 2.0 10.0450 4.4100 4.05 2.5 13.0500 4.4450 5.17 3.0 14.7000 5.600 5.60 3.5 15.4000 6.7900 5.75 5.0 27.0550 6.5450 6.94 7.0 39.6550 7.5150 7.23 1061in foodintakeasapercentageofthewetbodymight. 2Phosphorus intake (mg/g fish/five weeks). 3Total dietary phosphorus deposition per gram of fish wet weight during the five-week period. 4Calculated phosphorus deposition fran the sanitation kinetic equation (Morgan et al. 1975) . 134 Table 52. Phosphorus intake, observed deposition (no), and calculated deposition (rc) of _Q. niloticus fed varying percentages of the Indonesian tilapia feed. % swl Intake2 :03 rcfl 0 0.0000 -1.2600 -1.20 0.5 2.3500 0.1960 0.04 1.0 5.1000 1.5400 1.57 1.5 8.1000 2.7300 2.85 2.0 11.4500 3.7100 3.95 2.5 14.500 4.5500 4.51 3.0 17.3300 5.1450 4.96 3.5 21.4700 5.4950 5.45 5.0 28.2800 6.0900 5.99 7.0 39.0000 6.3000 6.47 1Dailyfoodintakeasapercentageofthewetbodyweight. ZPhosphorus intake cmg/g fiSh/five weeks). 3Total dietary phosphorus deposition per gram of fish wet weight during the five-week period. 4Calcmlated phosphorus deposition frun the samratim kinetic equation (Morgan et al. 1975) . 135 Table 53. Phosphorus intake, observed deposition (rc), and calculated deposition (rc) of _Q. niloticus fed varying percentages of the U.S. tilapia feed. % Bwl Intake2 r03 m4 0 0.0000 -0.7700 -0.79 0.5 1.5300 -0.3150 -0.20 1.0 3.2400 0.4200 0.31 1.5 4.8900 0.8050 0.69 2.0 6.6600 1.1550 1.02 2.5 8.5500 1.0500 1.29 3.0 9.9000 1.1600 1.44 3.5 12.3450 1.7850 1.68 5.0 19.3350 2.2150 2.12 7.0 28.7550 2.2100 2.45 lDaily food intake as a percentage of the wet body weight. 2Phosphorus intake (mg/g fish/five weeks). 3Total dietary phosphorus deposition per gram of fish wet weight during the five-week period. 4Calculated phosphorus deposition fran the saturation kinetic equation (Morgan et al. 1975) . 136 . Ann: 500.: 953 603.0090 05 0.90 was 05 can use: 0903.300 #8 05 ms.” 0:3 68.0.00 095 .008 59:88 05 000 08! Hold: d .46 833800 030390059 .05 0x35 03050059 mo 05 09898.» ”Egg: Hafiugoflh. .hm 0.93m 4 oo+moo.m: .emHo zm 335 088.33% mo 0% g £20“qu 80309005. .mm 085E % oo+moo.ml .HwHD DZ<.._HmmH§0 00.0990.» 0090:: 90000.09? .c0 08..va . oo+moo.m- .9090 zm 00895.” 03059le no 0280 00:003..» ”Egg flag .3 00530 a oo+woo.m- .FmHo.ma..mx:m\:m.0 Lm\me.AzH.mamozamo:a >mo “ an — 111]. u. ..oaowo_u_u .=._~.z " no ..oauwo_..o .=._~.. a. guacamoh o_h "~.om¢ .uonamo_..u .=._~.. a. o..anm o.h "-o~ .a.=_oo m=OM>uha oag .ou unu_o3 scan ho manuauouoa . a. o.a»=_ coo. .__.= “an a“ ..uoaugog=_... ou.on.o~ 9.». an o.~a=_ oak “gnaw ..ouuo n_go.w_ «An u an ._u>¢_ manuam chum a. uncannuh a.» n a" .owconmo. -=._~u- “gas “a _o.~_ oauuafi u.~ um.°- .uugonu- _¢o«uouoogu .=-_~.- ash "nu-a— s...“ a...“ ...... 3.: .~.° o..° ae.°- no.9 m~.o 99.6 “—.N no._ u~.°- .m.a an." .<.n.= . a a ”In :5” N2“ 2.: w..° .m.° 9.. o~.° _o.. ...c m~.~ nn.~ N._- ..o ”a.” flu\u‘uwoa ~¢a¢wam. .mw. u\u.. m->~_ asho.nmo.q .hauudw no~u go>wuoe wagon-auam ..m o~a¢~ 142 the HD, TD, andAD. Fish fed the 'I‘Dhad ahigherRmaxvalue than those fed the HD and were not significantly different from those fed the AD. The amount of dietary phosphorus fed that produces half Knax of phosphorus deposition in the fish is represented by K0. Fish fed 5. the TD, PD, ID and AD were not significantly different from each other in terms of their KO.5 values. Fish fed the HD had lower KO.5 values than those fed TD, PD, and ID and were not significantly different from those fed the AD. Fish fed zero dietary phosphorus had negative phosphorus deposition were not significantly different in the group of fish fed the HD, PD, ID, and AD. Fish fed no phosphorus of the TD group had significantly higher phosphorus deposition than those fed the PD, ID, and AD and were not significantly different from those fed the HD in terms of the negative phosphorus deposition (b) . The kinetic order (n) showed a sigmoidal (n>1) relationship between dietary phosphorus intake and deposition in the fish. The amount of dietary phosphorus fed at maintenance (no gain or loss) is represented by Ir=0. Fish fed the AD had the best Ir=o value of all diets (lowest dietary phosphorus intake), followed by the group of fish fed the ID, PD, TD and HD, respectively. The maximum efficiency value for dietary phosphorus deposition in the fish for each diet was represented by Em‘. Fish fed the PD had the highest Fin): value followed by the group fed the ID. Fish fed the AD and TD had some me value and were less than that of the group fed the ID. 143 Fish fed the HD had the least me value of all. The efficiency value for dietary phosphorus deposition when fish were fed at KO. 5 value of intake were represented as the overall efficiency value. Fish fed the ID and PD had some and the highest overall efficiency value. Fish fed the TD had lower overall efficiency values than those fed the ID and PD. Fish fed the AD, and HD had similar overall efficiency values and were lower than fish fed the other test diets. CHAPTERV DISCIISSION The primary goal of this study was to show that the saturation kinetic model (Morgan et al. 1975) can be used to describe 9_. niloticus weight gain and net nutrient deposition as a function of diet or nutrient intake. This was demonstrated graphically and numerically (Figures 2-41 and Tables 5-46) in the Results section. rIhese results demonstrated that the physiological responses tested (dietary crude protein deposition, weight gain, net energy deposition, dietary CA, P, Mg, Zn deposition, and dietary crude fat deposition) could be predicted by the saturation kinetic model. The response could be calculated at any intake level using the model equation after estimating four parameters (b, K0.5, N, Rmax): b (KO.5)n + max Ir1 (Ko.5)n + In r: ’Ihesecondgoal ofthisstudywastousethemodelparametersto evaluate practical tilapia diets obtained frcm five different countries . The objective of the dietary evaluation was to determine which diet would maximize Q. niloticus performance in terms of 144 i45 physiological responses (weight gain and net nutrient deposition) and dietary (nutrient) efficiency. ‘Ihere are several possible methods of diet comparisons based on the four parameters of the saturation kinetic model: 1) A ratio of response for specific diet to the response for a standardized diet, at the same food intake level. Since there is no standard g niloticus diet and feed ingredients can vary in quality and composition especially, in different developing countries, this method was not chosen. 2) Comparison based on individual parameters sud: as Rmax (the maximum theoretical response) and/or K0.5 (the feed or nutrient intake at half maximal response). 3) Comparisons based on derivatives of the model such as the maximum efficiency (me), the food (nutrient) intake at maintenance level on zero response (Ir=0; Mercer et a1. 1978), and the dietary or nutrient efficiency at half maximal response me 5. Maximum efficiency (me gives the highest food conversion that a diet or nutrient could possibly have under the experimental corflitions (Mercer et al. 1978) . The efficiency at half maximal response gives the overall efficiency or conversion rate for specific diet or nutrient. ‘Ihe secondandthethirdccmparisonmethodswereused in this study. Ifoneis interestedinapproachingmaximnnresponsemmder certain economical conditions (nutrient or food supply is not limiting 146 in countries such as the United States and Canada) the maximum theoretical response Ignax may be the best comparative choice. The greater the 1% the better the diet or nutrient. On the other hand if one is interested in dietary (nutrient) efficiency or nutrients or food supply is limited, which is the case in most of the developing countries, the efficiency paraneters should be used. The efficiency paraneters include: 1) K0.5, half maximum response; 2) Ir=0, dietary (nutrient) intake for maintenance; 3) Finn-z; maximum efficiency; 4) The overall efficiency values (me 5) . Growth Wang et al. (1985) studied the dietary energy and protein requirements for g niloticus size 3-5g. ‘Ihey reported that _Q. niloticus requires 25 percent crude protein and 67-71 Irng/kcal DE. TheAD, PD, andHDwerevery closetoneetingthesenutrient requirements (Table 5) . The ID had higher levels of protein and protein-energy ratios (32.68 and 94 mng/kcal ME) than the requirements. The TD on the other hand, had lower levels of protein and protein to energy ratio (17.29% and 54 Cp/kcal ME) than the requirerrents. Papontsoglon and Alexis (1986) studied protein requirements of gray mullet by feeding isocaloric diets varying in protein levels and Cp/ME ratio. They found that above 24 percent protein and 53 mng/kcal Me in the diets feed conversion continued to improve with increasing protein and Cp/ME ratio up to 60 percent and 144.93. Jauncy (1979) demonstrated that lower dietary protein level, 147 and increased dietary energy (ME from carbohydrate and/or lipid) for mirror carp, increased the protein efficiency ratio which illustrated that protein was spared by energy sources. Garling and Wilson (1976) demonstrated that optimum Cp/ME ratio produced maximum growth of channel catfish over a range of dietary protein to energy. In my study, the ID with a higher Cp/ME ratio than the optiimzm ratio producedhighergrowthratethantheAD, PD, andHthich contain the optimum Cp/ME: ratios for Q; niloticus. This show that protein quality ofthesetestdietswerenothighenoughtoneettherequirementat optimum levels. ‘Ihe results ofmystudyareinagreementwiththeprevims studies. The ID was superior to all other experimental diets in terms of its growth potential. The maximum theoretical response (Rmax) which neasures the genetic potential of fish towards a specific diet was significantly higher in the ID than all other diets. This is probably due to the fact that the ID contaired a higher level of protein and protein/energy (Cp/ME) ratio which carpensated for poor quality protein as will be demonstrated in further discussion. The TD was not significantly different from the PD and HD in terms of their Rmax value. However, the TD had less dietary protein and Cp/ME ratio thanthePDandHD. 'Ihe'IDwastheonlyextruded-typepelletofthe diets tested. Ectrusion involves extensive wetting and heating when compared to the steam pellet production (Hilton et al. 1981) which could result in formation of bonds between lipids and other carpounds in the feed that cannot be broken. by solvent alone (Pareraz and Melcan 148'. 1978) . Using traditional solvents, therefore, underestimate the dietary fat content of extruded pellets. Linsuman and Iowell (1984) found that acid hydrolysis pretreatment of extruded pellets doubled the yield of crude fat determination. This neans that crude fat determination (Table 1) may have underestimated the dietary fat cmtentofthe'I'DbyasmchasSOpercent. utensiveheatingand wetting improved digestion and absorption. Moist heat also results in theruptureofthestarchgranuleanianirreversiblechangeinthe crystaline structure of the molecule (geletinization) that facilitate the enzymatic attack (Maynard et a1. 1979) . In conclusion the efficient energy source in the TD probably spared the dietary protein and improved the Rmax value of the diet. The relatively lower Rmax value of the AD was probably due to poor efficiency of utilization of the nutrient(s) and souroe(s) (e.g., lower absorption and/or dietary nutrient deficiency) . 'Ihe KO.5 value (the amount of food intake at half maximal response) of the ID was not significantly different from different (P < 0.05) the HI), PD, and 'ID. This indicated that gnax value of these diets did express their efficiency. The AD on the other hand had a higher K0.5 value than that of ID, HD, and PD, but was not significantly different from the TD. This indicted that the AD was less efficient than the ID, PD and HP. maximum efficiency values normally occurred at a lower food intake level than the overall efficiency value of the diets tested. The TD had a relatively high maximum efficiency value when conpared to that of other tested diets. 149 HoWever, this efficiency sharply declined to relatively lower overall efficiency values at higher food intake levels. This probably indicated that a nutrient reduced the dietary efficiency of the TD at higher food intake level, which was most likely related to lower protein content of the TD. All efficiency paraneters (Ir=0, an, and the overall efficiency) indicated the AD had poorer efficiency than all other test diets which support the previous conclusion that the AD was deficient in one or more essential nutrients or the feed was not very well absorbed. Wm Ingrowingfish, partofstoredenergyisstoredasproteinand part is stored as fat (Cho, et al. 1980) . The relative importance of protein and fat deposition depends on several factors. The two major factors are: 1) the balance of the available amino acids of dietary proteinandZ) theammtbywhichthedietaryenergyintakeexceeds the energy expended as heat (Cho et al. 1982) . Proteins of higher biological value promote greater protein deposition than those of low value. Mural et al. (1984, 1985) have demonstrated with carp fingerlings that the higher the protein quality, the higher the energy deposition. When marginal excess of total energy intake (proteins, carbohydrates and fat) exceeds energy expended as heat, this results in deposition of a larger proportion of retained energy as protein. Astheexcessenergyintakeincreasesthetotalammtofprotein deposited increases, but the proportion of the energy retained as fat 150 increasesatafasterratesothat increasingtheenergyintakeleads toanincreaseintheamotmtofenergyretairedasfat (Choetal. 1982). The maximum theoretical energy deposition showed no significant differences between the HD, PD, ID, and AD (P < 0.5). This indicated that Rmax for energy deposition is similar between the test diets. This is in agreenent with the nutritional concept that animals (fish) eat to neet their energy needs. Therefore, depending on the dietary energy efficiency, fish would eat different amcmrts of the test diets to reach Pirax value of energy deposition. The total dietary energy at halfmaximumresponse (KO.5) washigher intheADthanTD, PD, and ID but not different from the HD. This indicates that the AD is less efficient in terms of promoting the conversion of dietary energy to body energy. That is probably due to less energy absorption in the AD. Energy efficiency at maintenance level (Ir=0) showed that the PD was the most efficient followed by the ID, ED, TD, and the AD, respectively. The maximum efficiency values and the overall efficiency is in agreement with the dietary energy efficiency at maintenance level (Ir=0) . The overall dietary energy efficiency for the five diets ranged between 11-26 percent which is in agreerent with what was found in other juvenile fish (Pandian 1967a,b; Yoshida 1970; Chesney and Estenez 1976) . Di Lag Protein 3343mm The amount of protein deposition per unit of protein fed has been 151' recomended by several researchers (Zeitoun et al. 1973; Rumsey and Ketola 1975) as a simple, useful, and practical expression of protein efficiency. The saturation kinetic model that was used in this study, however, gives much more information about dietary protein than a single value for protein efficiency. The model provides maximum protein deposition per gram of fish, the dietary protein intake at half maximum response, the dietary protein level that is necessary for maintenance (zero response), maximum efficiency, the overall efficiency, and gives the researcher opportunity to predict the amount of protein deposition at any dietary intake level during periods of time. Dietary protein quality and protein to energy ratio are the two major factors that affect dietary protein deposition (Cho et al. 1982; Murai et al. 1984, 1985) . The maximum theoretical responses of protein deposition of all tested diets were found to be highly correlated with dietary protein level and Qa/ME ratio (r = 0.99 and = 0.96, respectively). Murai et al. (1984) reported similar results in carp. They found a highly significant correlation coefficient between protein deposition and both dietary protein level and protein to energy ratio (r = 0.91 and r = 0.97, respectively). The ID had the highest dietary protein level and Cp/ME ratio. Therefore the ID had the highest I‘ve): values in terms of protein deposition. The TD had the lowest protein level and ql/ME value, and had the lowest Rmax value of all test diets. The AD, PD, and HD had 152 similar dietary protein levels and Cp/ME ratios and had insignificant differences between the three diets in terms of their Knax of protein deposition value (P < 0.5) . The dietary protein that deposits half 13“”: value of protein in fish bodies (K0.5) was relatively high in the IDthanthatoftheHD, TD, PDandwassimilartothatoftheAD (P< 0.5). This indicates thattheIDandtheADhadless efficient proteinthantheHD, PDandTD. TheK0.5valueoftheTDwasthe lowest value of all feeds, which indicated the best protein efficiency of all diets. The higher efficiency value of the TD was probably due to protein sparing effect since the TD had the lowest dietary protein level an adequate level of available energy (carbohydrate and lipids). Juancy (1979) has demonstrated that at lower protein levels and higher metabolizable energy (CHO and/or lipids) protein efficiency was increased. This result is in agreement of the efficiency result of the TD. Other efficiency parameters (Ir=0, Emax' and the overall efficiency value) showed some efficiency differences that was found in the KO.5 values. The overall dietary protein efficiency ranged between 25-57 percent. Dim Crude Fat Defiition Total dietary fat intake was highly correlated to the maximum body fat deposition (r = 0.91) (P < 0.5) at the me value. Murai et al. (1984) observed a lower correlation (r = 0.67) than what was found inanyfeedingexperimentinanystudy. Muraiandcoworkers . 153 restricted feed intake and could not show the maximum dietary fat deposition. The AD had the highest dietary crude fat content and the highest Rmax value in terms of dietary fat deposition of all test diets (P<0.5). TheTDontheotherhandhadhighercrude fat contentthanthePDbutlwerPhaxvalueintermsof fatdeposition thanthe PD. This indicatedthatdietary fatcontentoftheTDwas utilized to spare protein. There was a high correlation coefficient (r = 0.97) between calculated metabolizable energy values and dietary fat deposition in the ID, HD, and PD. However, the correlation dropped (r=0.7) iftheTDwasaddedandfurtherdropped (r=0.5) iftheAD was added. The low correlation coefficient of the 'ID suggested that proteinwassparedbydietaryenergysources (crude fatand carbohydrate). The low correlation coefficient of the AD was due to low dietary energy efficiency. The efficiency parameters (K0.5, Ir=0, me) and the overall efficiency of converting the dietary fat to body fat in Q; niloticus showed that the PD was the most efficient diet. This was followed by the ID. The TD and HD had half the efficiency of the PD and ID, respectively. The AD was the most efficient. Magngium Depo_sition There was low correlation (r = 0.52, P < 0.5) between the dietary magnesium content and the Rmax value of maximum magnesium deposition. This indicated that magnesium absorption efficiency varied between feeds. Two factors can affect the total body magnesium 154 content, the dietary magnesium intake and the availability of magnesium (Delbert et al. 1982) . The magnesium efficiency parameters (K0.5, Ir=0, Emoc' and the overall efficiency values) showed differences between diets. These difference were probably due to the source of magnesium and/or some other dietary factor. From the dietary magnesium deposition results, it was concluded thatthehigher levels ofmagresiumintheIDandPDwereumecessary and could be decreased. Di elm Calcium Defiition All five tested diets contained higher levels of dietary calcium than levels recommended for tilapia (Table 30). The ID had the highest calcium content of all diets, the highest Rmax value of calcium deposition, and the lowest efficiency value of all tested feeds. The PD, HD, TD and AD had similar dietary calcium content and Rmax value for calcium deposition, however, they varied in their dietary calcium efficiency. These results indicated that dietary calcium efficiency was affected by the calcium intake level (dietary calcium concentration) and calcium availability. Calcium availability is affected by the vitamin D level and/or the chemical form of calcium contained in those diets. Zinc Mition There are several factors that affect dietary zinc requirement levels (maintain an optimum level of zinc in the fish body) such as 155 calcium level (Forbes 1960) , phytic acid (Oberteas 1962) , and protein sources (Zigler et al. 1961 and Smith et al. 1962) . The maximum theoretical response of zinc deposition was highly correlated with the dietary zinc levels of the Indonesian, Honduran, Thailand and American diets (r= 0.99). If you addthevalues ofthe Panamaniandietthe correlation coefficient will drop to r = 0.83. These results show that a factor other than zinc intake affected dietary zinc deposition through reducing zinc absorption. This could have been caused by any of the above factors. Additionally, the Panamanian diet was generally high in mineral content, which could have affected zinc absorption. The Indonesian and Panamanian diets produced the lowest zinc deposition efficiency. This could probably be due to high dietary calcium in the Indonesian diet and also any of the above factors that affect zinc availability. Di fl Phg_sphorus Depgition The maximum theoretical dietary phosphorus deposition was affected by the intake level, which was generally higher than the recommended level of phosphorus (Table 30) with exception of the TD, and the dietary phosphorus efficiency. The PD had the highest dietary phosphorus of all diets and the highest Rmax value of phosphorus deposition. The ID had higher dietary phosphorus content of the HD, TD, andAD. The IDhadhigherRmxvaluethantherm, TDandAD. Dietary phosphorus efficiency parameters (K0.5, Ir=0, me' and the overall efficiency value) (Table 44) showed differences between 156 dietary phosphorus efficiency. That was probably due to the same type of factors that affected calcium absorption (NRC 1983) . CHAPTERVI SUMMARY AND DISCIJSSION It was demonstrated that physiological responses (weight gain, crude fat deposition, crude protein deposition, gross energy deposition, calcium, phosphorus, magnesium and zinc deposition) to graded levels of dietary (nutrient) intake of each of five practical tilapia feeds and can be analyzed by the four parameters of the saturation kinetic model. Be definition, all responses were sigmoidal (n>1); however, some responses were close to being hyperbolic when graphed- In terms of the maximum theoretical response value (Rmax) , the ID had the highest value for weight gain of all tested diets. Other diets tested had similar weight gain response. In terms of the dietary efficiency the ID was the best diet of alltesteddietsbasedonweightgain. ThePDwasthesecondmost efficient diet followed by TD, HD, and AD, respectively. 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Pcult. Sci. 40:1584-1593. Zeitoun, I.H., J.E. Halver, D.E. U11rey and P.I. Tack. 1973. Influence of salinity on protein requirements of coho salmon (Oncorhmus kisutch) smolts. J. Fish. Res. Bd. Can. 30, 1978. APPENDIX I APPENDICES APPENDIX I (El-Sayed, 1987) During the early 1980 ' s, the gems tilapia was subdivided into two genera based on parental care behavior. The geuus Tilapian was restricted to tilapia species which lack parental mouthbrooding of eggsandyoung, whilethesubgenusnamemwaselevatedto germs status and given to the species of tilapia with parental mouthbrooding ofeggsandyoung. Later, thegenus Meredonwas subdivided into two geera: Sarotherodon and Oreochromis based on whether parental females (9.), males (_S.) or both pareutal sexes (S. perform the mouthbrooding behavior. Althouglu there is considerable argument over whether these fishes are truely separate species, for the purpose of this Ph.D. thesis, the geera memes used will follow the current conveution of: Tilapi = species of tilapia which lack mouthbrooding. Sarotherodon = species of tilapia with male or biparental (both male and female) mouthbrooding behavior. Oreochromis = species of tilapia with female mouthbrooding behavior. 170 171 regardless of the genus name used by authors of the original cited papers. The only exception to the use of ourrent tilapia geuera names will be in the literature cited section. The term tilapia will be used to describe all three of these closely related geuera. T nmE UNIV. LIBRARIES l”WWWWIWIIIHHIWIWI 000810071 13 HICH I 13 can 5 WWW” 1:253