EFFECT OF DIETARY ENERGY LEVEL ON EGG PRODUCTION, FATTY LIVER, PLASMA AND YOLK LIPIDS, YOLK CHOLESTEROL AND FATTY ACIDS OF S. C. W. LEGHORN. PULLETS RAISED UNDER SUB-TROPICAL CONDITIONS Thesis for the Degree of Ph. D. MICHIGAN STATE UNIVERSITY ANASTACID [AIDA PALAFOX 1970 ‘. _' a ;" ‘h’fl rhg. , w __fl - IHI-clé This is to certify that the thesis entitled EFFECT OF DIETARY ENERGY LEVEL 0N EGG PRODUCTION, FATTY LIVER, PLASMA AND YOLK LIPIDS, YOLK CHOLESTEROL AND FATTY ACIDS OF S. C. W. LEGHORN PULLETS RAISED UNDER SUB-TROPICAL CONDITIONS presented by ANASTACIO LAIDA PALAFOX has been accepted towards fulfillment of the requirements for PH D POULTRY SCIENCE ' ° degree in ajor professor @M/ 5 (2/2 AVG 0-169 mu mm m LIBRARY BINDE A “i / 6 Met: > WM 300 A 225 ABSTRACT EFFECT OF DIETARY ENERGY LEVEL ON EGG PRODUCTION, FATTY LIVER, PLASMA AND YOLK LIPIDS, YOLK CHOLESTEROL AND FATTY ACIDS OF S. C. W. LEGHORN PULLETS RAISED UNDER SUB-TROPICAL CONDITIONS BY Anastacio Laida Palafox An experiment was conducted with S. C. White Leghorn pullets to study the effect of 16 percent protein layer rations containing 2576, 2682, 2788, 2894 and 3000 kcal M.E./kg on efficiency of egg production, tissue lipids and yolk fatty acids. The birds were raised under sub-trOpical conditions. Increase in dietary energy level significantly increased body weight, egg weight, egg production and daily energy consumption. However, increasing dietary energy con- centration significantly decreased daily feed and protein consumption per egg produced. Daily feed consumption per egg produced decreased with increase in dietary energy level. The concentration of energy in the diet significantly affected liver fat scores. Liver fat scores increased linearly with increase in dietary energy level. Anastacio Laida Palafox The number of eggs produced from 70 through 74 weeks of age and liver fat score of pullets fed the control diet were significantly and negatively correlated. YOlk oleic acid level increased linearly, whereas yolk linoleic acid decreased linearly with increase in dietary energy concentration. For optimum overall efficiency, pullets fed the diet which contained 2894 kcal M.E./kg were superior to those fed the diets which contained 2576, 2682, 2788 and 3000 kcal. M.E./kg. EFFECT OF DIETARY ENERGY LEVEL ON EGG PRODUCTION, FATTY LIVER, PLASMA AND YOLK LIPIDS, YOLK CHOLESTEROLIAND FATTY’ACIDS OF S. C. W. LEGHORN PULLETS RAISED UNDER SUB-TROPICAL CONDITIONS BY Anastacio Laida Palafox A THESIS Submitted to Michigan State University in partial fulfillment of the requirements ‘ for the degree of DOCTOR OF PHILOSOPHY Department of Poultry Science 1970 To my wife and children ii ACKNOWLEDGMENTS It is with pleasure that I express my sincere gratitude to Dr. Cal J. Flegal, Dr. Theo H. Coleman, Dr. Robert K. Ringer, Dr. Duane E. Ullrey and Dr. Howard C. Zindel for their inspiring guidance, unfailing interest and continued encouragement. Grateful thanks are also due to the Community Scholarship Program and the Hawaii Veterans Memorial Scholarship Fund for the Opportunity to continue my grad- uate studies with their scholarship grant. ***** iii TABLE OF CONTENTS Page ACKNOWLEDGMENTS . . . . . . . . . . . . . . . . . . . iii LIST OF TABLES . . . . . . . . . . . . . . . . . . . . vi LIST OF FIGURES . . . . . . . . . . . . . . . . . . . vii INTRODUCTION . . . . . . . . . . . . . . . . . . . . . 1 N REVIEW OF LITERATURE . . . . . . . . . . . . . . . . . CaloriezProtein Ratio . . . . . . . . . . Effect of Dietary Energy Level . . . . . . Body weight . . . . . . . . . . . . . . . . . Feed consumption . . . . . . . . . . . Egg production . . . . . . . . . . . . . . . . Feed efficiency . . . . . . . . . . . . Egg weight . . . . . . . . . . . . . . Mortality . . . . . . . . . . . . . . . . . . Fatty liver . . . . . . . . . . . . . . . . Total plasma lipids . . . . . . . . . . . . . Total yolk lipids . . . . . . . . . . . . . . Total yolk cholesterol . . . . . . . . . . . 0 G3Q~J\J®LDU1¢LUOH»UJN Yolk fatty acids . . . . . . . . . . . . . . . MATERIALS AND METHODS . . . . . . . . . . . . . . . . 11 Part I . . . . . . . . . . . . . . . . . . . . . . ll Brooding and rearing . . . . . . . . . . . . . ll EXperimental design . . . . . . . . . . . . . 11 Part II . . . . . . . . . . . . . . . . . . . 12 Total plasma lipids . . . . . . . . . . . . . 12 Liver fat scores . . . . . . . . . . . . . . . 15 Part III . . . . . . . . . . . . . . . . . . . 16 Total yolk lipids . . . . . . . . . . . . . . 16 Total yolk cholesterol . . . . . . . . . . . . 16 Yolk fatty acids . . . . . . . . . . . . . . . 16 RESULTS AND DISCUSSION . . . . . . . . . . . . . . . . 18 Part I . . . . . . . . . . . . . . . . . . . . . 18 Body weight . . . . . . . . . . . . . . . . . 18 iv TABLE OF CONTENTS Page ACKNOWLEDGMENTS . . . . . . . . . . . . . . . . . . . iii LIST OF TABLES . . . . . . . . . . . . . . . . . . . . vi LIST OF FIGURES . . . . . . . . . . . . . . . . . . . vii INTRODUCTION . . . . . . . . . . . . . . . . . . . . . l N REVIEW OF LITERATURE . . . . . . . . . . . . . . . . . Calorie:Protein Ratio . . . . . . . . . . . . . . 2 Effect Of Dietary Energy Level . . . . . . . . . 3 Body weight . . . . . . . . . . . . . . . . . 3 Feed consumption . . . . . . . . . . . . . . . 3 Egg production . . . . . . . . . . . . . . . . 3 Feed efficiency . . . . . . . . . . . . 4 Egg weight . . . . . . . . . . . . . . . . . . 5 Mortality . . . . . . . . . . . . . . . . . . 5 Fatty liver . . I . . . . . . . . . . . . . . 6 Total plasma lipids . . . . . . . . . . . . . 7 Total yolk lipids . . . . . . . . . . . . . . 7 Total yolk cholesterol . . . . . . . . . . . . 7 Yolk fatty acids . . . . . . . . . . . . . . . 8 [—l H MATERIAISANDMETHODS................ .—l [—J Part I I I O O O O O O O O O O O O O O O O O O O O Brooding and rearing . . . . . . . Experimental design . . . . . . . . .. .. .. .. Hrd Hid Part II . . . . . . . . . . . . . . . . . . 12 Total plasma lipids . . . . . . . . . . . . . 12 Liver fat scores . . . . . . . . . . . . . . . 15 Part III . . . . . . . . . . . . . . . . . . . 16 Total yolk lipids . . . . . . . . . . . . . . 16 Total yolk cholesterol . . . . . . . . . . . . l6 Yolk fatty acids . . . . . . . . . . . . . . . 16 RESULTS AND DISCUSSION . . . . . . . . . . . . . . . . Part I o o o o o o o o o o o o o o o o o o o o 0 Body weight . . . . . . . . . . . . . . . . IHFJH oomoo iv Mortality . . . . . . . . . . . . . . . . Egg weight . . . . . . . . . . . . . . . . Egg production . . . . . . . . . . . . . . Total feed consumption . . . . . . . . . Average Average Average Average Average Average Part II . Liver fat scores . . . Total plasma lipids . Part III . daily feed consumption . . . . . . daily energy consumption . . . . . daily protein consumption . . . . daily feed consumption per egg . . daily energy consumption per egg . daily protein consumption per egg Total yolk lipids . . . . . . . . . . . . Total yolk cholesterol . . . . . . . . YOlk saturated fatty acids . . . . . . . Yolk unsaturated fatty acids . . . . . . . SUMMARY . . . REFERENCES . . Page 21 22 26 31 32 35 36 38 39 40 41 41 44 46 46 46 46 49 52 54 LIST OF TABLES Composition of experimental diets . . . . . EXperimental design and diet allocation in the 5 x 5 Latin square . . . . . . . . . . Effect of dietary energy on body weight and mortality . . . . . . . . . . . . . . . Effect of dietary energy on egg weight . . Effect of dietary energy on hen-day production and feed consumption . . . . . . . . . . . Effect of dietary energy on daily consumption of feed, energy and protein and efficiency of feed, energy and protein utilization. . . . Effect of dietary energy level on fatty liver and plasma lipids . . . . . . . . . . . . . Correlation coefficients of certain traits Effect of dietary energy level on yolk lipids, cholesterol and fatty acids . . . . vi Page 13 14 19 23 27 33 42 45 47 LIST OF FIGURES Page Egg weight every 4 weeks from 22 through 62 weeks . . . . . . . . . . . . . . . . . . . 25 weekly hen—day egg production from 22 through 30 weeks . . . . . . . . . . . . . . . 29 Hen-day egg production from 22 through 74 weeks . . . . . . . . . . . . . . . . . . . 30 vii INTRODUCTION Studies on the effect of different energy concentra- tion in the nutrition of laying chickens have received con- siderable attention since the importance of higher energy rations for broilers was demOnstrated by Scott, Matterson and Singsen (1947). Brown (1964) ably reviewed the use of high energy diets and the use of fats in such diets for poultry. His review revealed that limited information has been published on the use of high energy diets for laying chickens raised under conditions outside of the temperate zones. The objectives of this eXperiment were to study the effects of 16 percent protein layer rations containing 2576, 2682, 2788, 2894 and 3000 kilocalories of metabolizable energy on efficiency of egg production, fatty liver, plasma auui yolk lipids, yolk cholesterol and yolk fatty acids of pullets raised under sub-tropical conditions (180 C to 310 C). REVIEW OF LITERATURE As a background for the studies to be reported herewith, it is of interest to review first pertinent infor- mation on the use of energy in the diets of mature female chickens. Calorie:Protein Rim Berg and Bearse (1957) reported that White Leghorn pullets fed diets with different caloriezprotein ratios laid at different rates of egg production. They used 14 and 16 percent protein rations containing 1100 and 1450 kcal M.E./1b.* ’ The 1450 kcal M.E./1b diet containing 14 percent protein depressed egg production compared to the 14 percent protein diet containing 1100 kcal M.E./lb. The 16 percent protein diets containing 1100 and 1450 kcal M.E./lb were not signif- icantly different. Hocreich §£__l, (1958) fed 17 percent lprcmein diets with or without 6.6 percent yellow grease. The diet containing 6.6 percent yellow grease improved egg production and feed efficiency of White Leghorn pullets. Brrnmn, waring and Squance (1965) demonstrated that the " Optimum caloriezprotein ratio for egg production, expressed as kcal M.E./1b, was realized at ratios of 76 and 78. Effect 9; Dietary Energy Level Bgdy weiqht.--Skinnér, Quisenberry and Couch (1951) reported that body weight of White Leghorn pullets fed high efficiency rations was superior to that of pullets fed the control ration. Hill, Anderson and Dansky (1956) observed that body weight of White Leghorn pullets in production was maintained at somewhat higher levels when fed high energy rations and that body weight tended to increase with in- crease in dietary energy. Lillie and Denton (1965) also reported that body weight of laying chickens increased with increase in dietary energy level. Waring, Addison and Brown (1968) found that there was no simple relationship between body weight and the energy content of the diet although, in general, body weight gain tended to increase with increase in dietary energy. Jackson, Kirkpatrick and Fulton (1969) reported that successive increase in energy in the diet up to 3550 kcal M.E./kg resulted in significant increases in body weight gain. There was a decrease in weight of hens fed the diet containing 4150 kcal M.E./kg. Feed consumption.--Waring, Addison and Brown (1968) repmmted that White Leghorn laying pullets fed high energy diets consumed less than those fed low energy diets. Jackson, Kirkpatrick and Fulton (1969) and Scott, Nesheim and Young (1969) found that feed intake of mature White Leg- 'Iunni pullets decreased with increase in dietary energy level. Egg production.--Results of published experiments evaluating the effects of high energy diets on egg production are controversial. Research Workers do not agree to the beneficial effect of high energy diets on egg production. Skinner, Quisenberry and Couch (1951) reported that egg production of White Leghorn pullets fed high energy diets was superior to that of pullets fed the control ration. Hill, Anderson and Dansky (1956) noted that high energy diets supported the highest egg production during the months Of cold weather, whereas all energy levels were equally effective during the rest of the year. On the other hand, Lillie and Denton (1965) found that dietary energy level did not significantly affect egg production of S. C. W. Leghorn pullets. Waring, Addison and Brown (1968) reported that egg production of Brown Leghorn pullets fed the control diet was significantly superior to that of birds fed diets containing tallow. Jackson, Kirkpatrick and Fulton (1969) found that similar egg production can be obtained with diets containing varyingflmetabolizable”energy concentrations from as low as 2150 kcal M.D./kg to as high as 3070 kcal M.E./kg. Feed efficiency.-—Many researchers are agreed that lligh energy diets improve feed efficiency. Skinner, Quisen- Iberry'and Couch (1951) reported that feed efficiency (feed/ doz eggs) of pullets fed diets containing high energy was superior to that of the control ration. Lillie Q}; g. (1952) found that the inclusion of 8 percent lard in the diet improved feed efficiency. Hill, Anderson and Dansky (11956) also observed that increasing dietary energy with the uSe of fat reduced feed requirements per dozen eggs. Waring, Addison and Brown (1968) noted that feed conversion (9 feed/ g egg) was lower for Brown Leghorn pullets fed high energy diets than that of the control birds. E q weight.--Blamberg, Bossard and Combs (1964) studied the effect of various fats in the diets of pullets maintained in cages. They reported that those fed diets containing added fat laid eggs which were significantly heavier than pullets fed the control ration. The metabo- lizable energy intake appeared to influence egg weight more than linoleic acid intake. According to Jackson, Kirkpatrick and Fulton (1969) egg weight tended to increase linearly with dietary energy level. Mean egg weight significantly in- creased with dietary energy concentration. On the other hand, Lillie and Denton (1965) found that dietary energy did not significantly affect egg weight. Mortality.--Weiss and Fisher (1957) reported that diets containing 5 to 10 percent animal fat increased mor- Atality of White Leghorn pullets. Likewise Donaldson and (Bordon (1960) found that the addition of 3 percent animal fat in the diet caused increased mortality. Jackson, Kirk- patrick and Fulton (1969) noted that in two experiments, tZhere was a very high mortality of birds fed a diet contain- ing 28.5 percent fat. However, there was no apparent effect (If 0 to 15 percent added faE on mortality. On the other hand, Waring, Addison and Brown (1968) fed up to 31.6 percent tallow to laying hens without any uu'l‘usual high mortality. March and Bieley (1963) fed equicaloric diets (2800 kcal M.E./kg) containing 0, 5 and 10 percent fat to laying hens over a period of 11 months. Although the overall mortality was high, supplementation of the diets with fat had no effect on mortality nor did it influence the cause of mortality. Fatty liver.--Fatty liver syndrome (FLS) is a seri— ous problem. It occurs under stress conditions and may lower peak production in laying chickens. This syndrome was first reported in laying hens by Couch (1956). He reported that FLS is a classical example of fatty degeneration of the liver. He recommended the use of choline chloride, vitamin 312, vitamin E and antibiotics to alleviate the depressing effect of fatty liver on egg'production. The importance of FLS has been recognized by many researchers since Couch published his observation in 1956. Barton, Flegal and Schaible (1966) reported that a low- energy, high fiber ration (14.8% protein, 2360 kcal M.E./kg) prevented fatty liver from develOping while fatty livers develOped in birds receiving the high energy diet (15%.pro- tein. 3000 kcal M.E./kg) . Quisenberry §£.§ls (1967) observed that fatty liver Symptoms in commercial layers were not caused nor prevented by dietary calorie level. Duke, Ringer and Wolford (1968) rePortedthat plasma protein level was not a satisfactory index of develOping fatty liver condition. They found no Significant difference in plasma protein level between two dietary groups until a fatty liver condition was well— develOped in one group. Total plasmaglipids.--Limited information has been published on the effect of dietary energy level on the con- centration of total plasma lipids of mature female chickens. However, Greenberg g£_gl,-(l936) reported that the total plasma lipids of non-laying hens averaged 550 mg/100 ml. Lorenz _£.§l, (1938) found that the concentration of total plasma lipids of laying chickens varied from 652 to 2308 mg/100 ml of plasma. A low-fat ration caused a slight decrease in total plasma lipids while a high-fat ration produced no change whatsoever. :9; 1 yolk lipids.--The effect of dietary fat on yolk lipids has received much attention. Reiser _E._L- (1951) reported that the type and amount of dietary fat did not have any effect on total lipids of egg yolk. Marion and Edwards (1962) found that egg lipids of hens fed 10 percent corn oil remained unchanged from the control. Chung, Rogler and Stadelman (1965) observed that total yolk lipids of eggs from pullets fed corn oil, lard or hydrogenated coconut Oil fed at a level of 10 percent were not significantly different t0 the control. Total yolk cholesterol.--Fisher and Leveille (1957) rePOIrted that the cholesterol content of egg lipids was not Significantly affected by feeding diets containing either 30 Percent safflower oil or 20 percent linseed oil. Simi- larly. Wheeler _£_§l, (1959) found that the cholesterol content of eggs from hens fed diets containing either safflower Oil or linseed oil at levels as high as 30 percent did not differ significantly from values obtained with eggs from hens fed the control diet. t al, (1960) found no change in yolk choles- Daghir terol content of eggs from pullets fed 12 percent of either soybean oil or white grease compared to the control. Combs and Helbacka (1960) observed no increase in the cholesterol content of eggs from hens fed 10 percent tallow compared to that of the control. They also reported that hens fed 10 percent corn Oil produced eggs which contained increased amounts of cholesterol. Edwards §£_§l, (1962) reported that yolk cholesterol content of eggs from White Leghorn chickens fed corn oil, tallow and lard was not significantly differ- ent from that of the control. Chung _§_gl, (1965) noted that amount of egg yolk cholesterol of eggs from hens fed 10 percent of either corn oil, lard or hydrogenated corn oil was not sifnificantly different from that of the control. Xglk fattygacids.--The fact that the distribution of fatty acids in egg yolk varies considerably with the dietary fat appears to be well established. Cruickshank (1934) reported variation in fatty acids of egg yolks from hens fed high.levels (28 percent) of various fats. The total fatty acids of eggs from hens fed either a highly saturated fat, palm kernel oil, or a highly unsaturated fat, hemp oil, consisted of 16.1 and 47.7 percent linoleic acid respec- tively. Reiser (1951) found that either a fat-free diet or the presence in the diet Of a highly saturated fat resulted in reduction of the dienoic acid (Cruickshank, 1934; Reiser, 1951; Fiegenbaum and Fisher, 1959) but oleic acid levels were not influenced by feeding high levels of unsaturated fats. Fisher and Leveille (1957) studied the linoleic and linolenic acid levels in egg yolk of hens fed 20 percent fat in the diet. Yolk fatty acids were proportional to the level in the diet. A more recent study (Fiegenbaum and Fisher, 1959) indicated that when various oils were fed as 10 percent of the diet, the composition of the egg yolk fat was influenced only by the dietary polyunsaturated fatty acids, whereas the composition of the body fat was influ- enced by either saturated or unsaturated fatty acids in the diet. Wheeler, Peterson and Michaels (1959) found, on all diets they tested, that the principal change accompanying an increase in linoleic acid was a corresponding decrease in oleic and palmitoleic acids. No change occurred in the level of stearic acid in the yolk. Botino (1965) reported a large increase in the level of linoleic acid was accompa- nied by a decrease in the level of oleic and palmitoleic acids in the egg yolk of pullets fed soybean oil meal. Sell, ChOO and Kondra (1968) found that feeding soy- bean oil altered the relative distribution Of nearly all the 10 fatty acids of egg yolk. There were significant decreases in the proportions of myristic, palmitic, palmitoleic and oleic acids. There was an appreciable increase in the linoleic acid concentration of egg yolk. MATERIALS AND METHODS Part I Brooding and rearinq.--Three hundred one-day-Old commercial S. C. W. Leghorn (Hy-Line) pullets hatched and shipped air freight from California to Honolulu, Hawaii were brooded in electrically heated all-wire Oakes battery brooders from 3 through 8 weeks and then moved to alldwire develOper pens from 8 through 18 weeks of age. The birds were fed a standard starter mash ration from 1 day through 6 weeks and a standard grower mash ration from 6 through 18 weeks of age. Feed and water were provided ad libitum. The chicks were vaccinated with an attenuated fowl pox vaccine at 3 weeks and a live virus New Castle Disease vaccine at 7 and 17 weeks. Experimental design.-2At 18 weeks, the birds were housed in a 731.52 cm x 1219.20 cm building with Open sides enclosed with 1.27 cm x 1.27 cm wire mesh cloth. Electric lights in the building were turned on and off, with the use of a time switch at 5:00 A.M. and 8.A.M., respectively, dur- ing the duration of the experiment to provide the birds with a minimum of 14 hours of light daily. 11 12 Each bird occupied an all-wire 25.40 cm x 45.72 cm laying cage in the laying house during the adjustment period (18-20 weeks), pre-test period (20-22 weeks) and test period (22-74 weeks). The pullets were fed a standard mash layer ration during the adjustment period, whereas they were fed the test diets shown in Table 1 during the pre-test and test periods. At 20 weeks, 250 pullets were selected for general vigor and apparent sexual maturity as manifested by good comb develOpment. The birds were distributed at random into 25 cage groups, each consisting of ten individually caged birds. At this time each bird was weighed. They were fed the test diets allocated in a 5 x 5 Latin square design shown in Table 2. Each diet was fed to only one group of birds in each column and in each row. Data were Obtained on body weight, feed consumption, egg production, egg weight, sexual maturity and mortality. Part II Total plasma lipids.-2After the pullets were weighed at 74 weeks of age, at 4:00 o'clock P.M., feed was removed; however, the birds were allowed access to drinking water. On the following morning at 9:00 o'clock, four birds from each group, 20 birds per treatment, were killed by cutting the jugular vein, blood collected into heparinized centri- fuge tubes, centrifuged for five minutes, 5 ml plasma pipetted into test tubes, stOppered, identified, refriger- ated and then analyzed for total plasma lipids (TPL). 12 Each bird occupied an all-wire 25.40 cm x 45.72 cm laying cage in the laying house during the adjustment period (18-20 weeks), pre-test period (20-22 weeks) and test period (22-74 weeks). The pullets were fed a standard mash layer ration during the adjustment period, whereas they were fed the test diets shown in Table 1 during the pre-test and test periods. At 20 weeks, 250 pullets were selected for general vigor and apparent sexual maturity as manifested by good The birds were distributed at random into comb development. 25 cage groups, each consisting of ten individually caged birds. At this time each bird was weighed. They were fed the test diets allocated in a 5 x 5 Latin square design shown in Table 2. Each diet was fed to only one group of birds in each column and in each row. Data were Obtained on body weight, feed consumption, egg production, egg weight, sexual maturity and mortality. Part II Total plasma lipids.-2After the pullets were weighed art 74 weeks of age, at 4:00 O'clock P.M., feed was removed: huowever, the birds were allowed access to drinking water. (Dri the following morning at 9:00 o'clock, four birds from each group, 20 birds per treatment, were killed by cutting tlle jugular vein, blood collected into heparinized centri- fuge tubes, centrifuged for five minutes, 5 ml plasma Pipetted into test tubes, stOppered, identified, refriger- ated and then analyzed for total plasma lipids (TPL) . 13 Table 1. Composition of experimental diets Diet NO. l 2 3 4 5 Unit % % % % % Cellulose 7.13 5.63 4.13 2.63 1.13 Prime tallow .... 1.50 3.00 4.50 6.00 Corn meal 59.93 59.93 59.93 59.93 59.93 Soybean meal (44%) 22.32 22.32 22.32 22.32 22.32 Alfalfa meal (17%) 3.00 3.00 3.00 3.00 3.00 Tricalcium phosphate 2.30 2.30 2.30 2.30 2.30 Limestone 4.25 4.25 4.25 4.25 4.25 Salt 1 0.50 0.50 0.50 0.50 0.50 Premix MS 0.36 0.36 0.36 0.36 0.36 DLdMethionine 0.21 0.21 0.21 0.21 0.21 Total 100.00 100.00 100.00 100.00 100.00 Calculated Analysis: Kcal M.E./kgz 2576 2682 2788 28 94 3000 Protein, % 16 16 16 16 16 Energy:Protein ratio 161 168 174 181 188 1Provided the following per kg diet: 7900 I.U.; vitamin D3, 2378 I.C.U.; vitamin E, 1.58 I.U.: riboflavin, 6.3 mg; d-calcium pantothenate, 8.7 mg; niacin, 29 mg; choline chloride, 317 mg; vitamin B12, 0.009 mg; 179 mg; menadione, ethoxyquin, 0.59 mg; B.H.T., 29 mg; manganese, 86 mg; mg: and zinc, 2 of diet. iron, 39.6 mg. copper, 3Based on kcal M.E./kg diet. 29 mg; Vitamin A, 1.59 mg; cobalt, 0.28 Kilocalories of metabolizable energy per kilogram 13 Table 1. Composition of experimental diets Diet NO. l 2 3 4 5 Unit % % % % % Cellulose 7.13 5.63 4.13 2.63 1.13 Prime tallow .... 1.50 3.00 4.50 6.00 Corn meal 59.93 59.93 59.93 59.93 59.93 Soybean meal (44%) 22.32 22.32 22.32 22.32 22.32 Alfalfa meal (17%) 3.00 3.00 3.00 3.00 3.00 Tricalcium phosphate 2.30 2.30 2.30 2.30 2.30 Limestone 4.25 4.25 4.25 4.25 4.25 Salt 1 0.50 0.50 0.50 0.50 0.50 Premix MS 0.36 0.36 0.36 0.36 0.36 DLeMethionine 0.21 0.21 0.21 0.21 0.21 Total 100.00 100.00 100.00 100.00 100.00 Calculated Analysis: Kcal M.E./’kg2 2576 2682 2788 2894 3000 Protein, %. 16 16 16 16 16 Energy:Protein ratio 161 168 174 181 188 1Provided the following per kg diet: 7900 I.U.; vitamin D3, 2378 I.C.U.; vitamin E, 1.58 I.U.; riboflavin, 6.3 mg; d-calcium pantothenate, 8.7 mg; niacin, 29 mg; choline chloride, 317 mg; vitamin B12, 0.009 mg: 179 mg; menadione, ethoxyquin, 0.59 mg; B.H.T., 29 mg; manganese, 86 mg: mg: and zinc, iron, 39.6 mg. COPPer: 29 mg; Vitamin A, 1.59 mg; cobalt, 0.28 2Kilocalories of metabolizable energy per kilogram of diet. 3Based on kcal M.E./kg diet. 14 Table 2. Experimental design and diet allocation in the 5 x 5 Latin square Experimental Design: Source of Variation Number Degrees of Freedom Total 25 24 Diets 5 4 Columns 5 4 Rows 5 4 2 Error 1 Diet Allocation: A B C D E 1* 2 4 5 3 5 3 1 2 4 2 4 5 3 1 3 1 2 4 5 4 5 3 l 2 *Indicates experimental diets. 15 Extraction Of TPL was conducted according to the method reported by Folch §£_§l, (1957). Twenty ml of cold chloroform:methanol (2:1, v/v) were used for each ml of plasma, mixed thoroughly, let stand for two hours with Occasional mixing and then filtered through a fat-free filter paper. The clear filtrate was washed with 0.2 of its volume with distilled water in a 250 ml separatory funnel, let stand for four hours at 50 C during which time a biphasic system was Obtained. The lower phase containing the lipids, was drawn Off into a 200 m1 volumetric flask and then made to volume with chloroform:methanol. To get the weight of the total lipids an aliquot was pipetted into a tared moisture dish and then dried to constant weight at 500 C in a convection oven. Liver fat scores.-2After the birds were killed, they were scalded in hot water (ITT°<:), defeathered with the use of a feather picking machine, cooled in a tank of tap water and then examined for gross lesions of the liver and develOp- ment of the ovary to identify laying and non-laying birds. Livers were excised, identified, placed in cellophane bags, refrigerated at 8°C until the next morning when they were fat scored from one through five. A liver which looked normal and mahogany brown in color was assigned a score of 1, whereas a score of 5 denoted a yellow friable liver (Barton, 1967). 16 Part III Total yolk lipids.-~At 65 weeks of age, six eggs laid on the same day were collected from each of the 25 groups of pullets. The six yolks from each group were pooled, mixed and two lO-gram samples were weighed for extraction of total yolk lipids (TYL) according to the t al, (1957). To get the weight method reported by Folch of the total yolk lipids, an aliquot of the extract was pipetted into a tared moisture dish and then dried to con- stant weight at 500 C in a convection oven. Total yolk cholesterol.--The total yolk cholesterol (TYC) content of the eggs was analyzed according to the direct method reported by Zlatkis _Ehal. (1953) as modified by Weiss _E__l, (1964). Yolk fatty acids.--Twenty ml of yolk lipid extract were pipetted into 120 ml boiling flasks, evaporated in a 500 C water bath under a stream of air under the hood. Esterification of the fatty acids was accomplished according to the method of Dronawat _£._l, (1966). The methyl esters of the fatty acids were pipetted into screw capped vials and kept under refrigeration at 00 C until analyzed. One microliter of petrolem ether containing the methyl esters of the fatty acids was injected into an Aero- graph.Model W-600 C unit containing a five feet by one-eighth inch stainless steel column packed with 20 percent diethylene— glycol succinate, 5 percent isothalic acid on a 60/80 l7 hexamethyl-disilazane-treated Chromosorb W. Peak areas for myristic, palmitic, palmitoleic, stearic, oleic and linoleic acids were obtained using a disc chart integrator. Chroma- tographic runs were made using authentic samples of methyl esters of fatty acids. Retention on the column was the criterion used for identifying the fatty acid components of the yolk lipids. The data were statistically analyzed according to Duncan's multiple range test (1955) and Snedecor and Cochran's analysis of variance, correlation and regression (1967). RESULTS AND DISCUSSION Part I Body weight.--The data Obtained on the effect of dietary energy level on mean body weight may be seen in Table 3. Initial weights at 20 weeks were not significantly different indicating that the pullets were effectively dis- tributed at random into the 25 groups. At 22 weeks, two 1 weeks after the test diets were fed, pullet weight tended to increase with increase in dietary energy concentration. Dietary energy level significantly affected mean body weights at 26, 42, 58 and 74 weeks of age. At 26 weeks, pullets fed the 2894 kcal M.E./kg diet were significantly heavier than those fed the diet containing 2682 kcal M.E./kg. The mean body weights of the pullets fed diets containing 2576, 2682, 2788 and 3000 kcal M.E./kg were not significantly different . At 42, 58 and 74 weeks Of age, the pullets fed the 2894 kcal M.E./kg diet were significantly heavier than those fed diets containing 2576, 2682 and 2788 M.E./kg. The pul- lets fed the diets containing 2576, 2682, 2788 and 3000 kcal M.E./kg were similar in weight at these ages. 18 19 “30.0 v me ms.v .ml .Aao Hmmcaa .m.© .amo.o v ac me.m "unmaoammooo :Oammoumou yamoamacmam .AQV ceammonmma 80am COauma>on N .muaaanmnoum mo ao>oa usooaoe m can um ucoaomwap maucmuamacmam mam aouuoa Deaaomumom ucouommap m meaumon Osaa amucoNauon oEmm map so memoza 0.8 0.8 o.~ o.m o.oa x_.mamoosma on was saaamunoz 0.0a o.ma o.m o.ea 0.8a a .mxmma vanmm 0.8a 0.8a o.m o.~a o.oa x_.mxmmz venom o.~ o.m o.o o.o o.¢ a..mxmms omnmm ”momsmo Ham 0» map auaamuuoz o.m~a o.sva a.maa ¢.moa o.ooa a .camm m>aamamm mmm oov vom mam man 8 .mxmms esuom .aamo ¢~.m oa.aa amoooa Qma: momma mecca mamma m .mxmms vs ammmma G.amea moema momma mmmma m .mxmms mm nmvvma Q.oama macma moama mmmva m .mxmms we ammama ammma nmomva apnea hammea m .mxmms on mmva amea maea moea mama m .mxmms mm «mma mama amma moma mama .m .mxmmz om "unmams saom mma ama sea moa aoa oaumu camuoamusmumcm O a ma ea Oa Oa ma x..camuoum 000m vmmm mmsm «mom mama mx\.m.s anus mamamcm m e m m a Oman Oman co unmauammmoo COammmHmmm amuaamuuoe paw unmam3 upon so mmamso mumuoao mo uomwmm .m manna 19 “$06 v mo mm.e .ml .Aav Hmocaq .m.e .amo.o v me mv.m .AQV cOammmumOH Eoum sOauma>mQ "ucoaoammooo GOammoummH ucmuamaamam N .muaaanmnoum mo HO>OH ucmouom m mnu um usmummmao waucmoamacmam mum Houuoa umauomumom usouommap m meanmmn mead amuconaaon OEmm map so memoza o.v o.v o.~ o.m o.oa a .mamoosma on mac muaamuaos o.ma o.ma o.m 0.8a o.ea x .mxmms enumm 0.8a o.ma o.m o.~a o.oa .x .mxmms «atom o.m o.m 0.8 0.0 o.e x_.mxmmz omumm "momsmo Ham Ou TOO muaamuuoz o.mma o.a8a a.~aa «.moa o.ooa .s .camm m>aumamm mmm oov vom mmm mmm m .mxmmz venom .camo v~.m oa.aa Ogamma amasa mmmma mvoma mamma m .mxmms 8m ammmma namma mmvma mmmma mmmma m .mxmmz mm nmvvma nomma mmoma moama mmmva m .mxmmz Ne ammama nmmma nmmmea msmva nmmmma m .mxmms mm mmva amea mama moea mmma m .mxmms mm vmma mama amma moma mama .m .mxmmz om "unmawz moom mma ama «ma mma ama oaumu camuoumummumcm a ma ma ma ma ma _x .camuoam ooom vmmm mmmm mmmm mmmm mx\.m.z.amox mamamam m 8 m m a Dean Dean :0 unmaoammmoo :Oammonmmm wuaamuHOE new unmam3 moon so monosm humumap mo uommwm .m manna H 20 The preceding Observations are in agreement with those of Hill a£_al, (1956) and Jackson, Kirkpatrick and Fulton (1969). They found that the body weight of laying pullets was maintained at somewhat higher levels by rations high in energy concentration. weight gain during the exper- iment tended to increase with an increase in energy in the diet. They attributed the increase in weight gain to a considerable excess of energy above the requirement for maintenance. In the present experiment, mean body weight of pul- lets at 74 weeks Of age increased as dietary energy level increased from 2576 to 2894 kcal M.E./kg. Mean body weight of pullets fed the 3000 kcal M.E./kg diet increased less than that Of pullets fed the 2894 kcal M.E./kg diet. These observations are at variance with those of Jackson, Kirk- patrick and Fulton (1969) who reported that there was a decrease in weight of hens fed a diet containing 4150 kcal M.E./kg compared to the weight of hens fed a diet containing 3530 kcal M.E./kg. They reported successive increases in the body weight of laying White Leghorn chickens fed up to 3530 kcal M.E./kg diets. Regression analysis was made to describe the rela- tionship of pullet body weight at 74 weeks and dietary energy level. The regression coefficient of the two vari- ates was significant indicating that pullet body weight increased linearly with increase in dietary energy level (Table 3). The F-ratio for deviation from the regression 21 line (D) was not significant, indicating that the straight line was an adequate fit. The preceding observations reveal that there is an upper limit of dietary energy level to which pullets con- tinue to gain in body weight. Beyond the upper limit the birds decline in weight. The reason for the decline may be partly due to decreased feed consumption. Because of the high concentration of energy in the diet the birds consumed feed to meet their energy requirement but other nutrients are not necessarily met for Optimum efficiency. Also the preceding observations reveal that the upper limit at which dietary energy level in the diet that is conducive to increased gain in body weight is influenced by the weather conditions at which the birds are being raised. Under the sub-trOpical conditions of this experi- ment, the upper limit of dietary energy level was 2894 kcal M.E./kg, whereas in the temperate weather conditions of Jackson _£_al, (1969), the upper limit at which body weight increased was 3550 kcal M.E./kg diet. Chickens require more 22-62 weeks, 93 55.6ab 55.3a 56.3a 56.5ab 56.9 Egg weight gain: 22-62 weeks, 9 21.0 19.5a 23.6 21.3ab 21.5ab 1Means on the same horizontal line bearing the same postscript letter are not significantly different at the 5 percent level of probability. 2All eggs except crack and soft shell eggs were individually weighed. 3Egg weights every 4th week were averaged. 24 M.E./kg diet. Diets containing 2576, 2788, 2894 and 3000 kcal M.E./kg were not significantly different. Egg weight increased with age of the pullets. A graphical representation of egg weights obtained every four weeks from 22 through 62 weeks of age may be seen in Figure 1. It may be seen that eggs from pullets fed the diets contain- ing 2576 and 2682 kcal M.E./kg weighed less than those from pullets fed the diets containing 2788, 2894 and 3000 kcal M.E./kg at each of the respective dates. It was noteworthy that the average egg weight from 22 through 62 weeks of age ranged from 55.3 to 56.9 grams and that egg weight increased with increase in dietary energy level. The regression analysis of egg weight on dietary energy level revealed a significant F-ratio indicat— ing a linear relationship between the two variates (Table 4). The foregoing Observations suggest an apparent advantage in the use of high energy diets for laying chickens to improve egg size. The preceding data agree with those of Hocreich a; a1, (1958), Treat _£_al, (1960), Blamberg _£_al. (1964) and Jackson a£_al, (1969) who reported that the addition of fat to laying rations increased egg size but are at variance with MacIntyre and Aitken (1957) who found that high energy in the diet had no effect on egg weight. March and Bielay (1963) also found that the addition of 10 percent tallow significantly decreased egg weight compared with the effect of an isocaloric diet containing 0 to 5 percent tallow on 25 .mxoo3 No nmsonnu mm Eonw mxooz v mum>o Osmao3 mom .H madman Amxoo3v omm «mamm mmaem emaom omame meawe Newmm mmaem emaOm omdmm mmummI Id _ q d a q A U _ q ooom all; emmm I mmmm 811* Nmmm .uus mmmm III. 803 magma HNMVID Gammoq (smezfi) anTeM 663 26 this factor. They suggested that supplementary fat per se cannot be deduced to affect egg size but rather, feed intake appeared to be the causative factor. Birds fed the 10 per- cent tallow consumed less feed. It was not known if the reduced feed intake was due to poor palatability or induced satiety by the ration. Lillie and Denton (1965) also reported that dietary energy level did not significantly affect egg weight. qu productiaa,--The data on the effect of dietary energy on egg production are presented in Table 5. Dietary energy level did not significantly affect age at 50 percent egg production. The ages ranged from 163.9 to 166.1 days. No data have been reported on the effect of dietary energy level on age at sexual maturity but it is generally agreed that restricted feeding (Milby and Sherwood, 1953), declin- ing light during the growing period (Morris and Fox, 1960) and low dietary protein, provided protein was sufficiently low to avoid compensation by increasing appetite (Howes and Cottier, 1967), delay sexual maturity. Dietary energy level significantly affected egg pro— duction from the 30th to the 74th week of age. However, it did not significantly affect egg production during the 23rd, 30th, from the 22nd to the 30th and from the 70th to the 74th week of age. These observations suggest that energy concentration in the diet is more critical for egg produc— ‘tion from 30 through 70 weeks than from 22 through 30 weeks of age . 27 .Amo.o V mo mv.m .ADV Geauma>mn “30.0 V mo m>.v .AAV Hmmaaa "unmaoammmoo codmmmammn ucmoamacmam m .OOm oumoapca mxoo3m .muaaanmnoum mo Hm>oa ucwoaom m.onu um ucoaommap handmoamacmam mam aouuoa umaaomumom usmuommap m meaamon Ozaa amuconauon 08mm map so mdmmZa ma.e ea.mm ema.~m onmm.em ome.em noe.mm mme.mm amm.mm mom.om mom.om mme.am mom.~m Q.am.m. ammm.m nemm.m nmem.m mma.e mo.~m am.mm mm.mm nem.em mmam a.mm m.mm m.mm m.om e.mm mo.mm ne.mm ama.em ame.mm me.~m m.am m.mm m.mm m.om m.am m.~s m.am m.mm a.mm e.ms m.0m m.mm m.mm e.m~ e.mm H.moa m.m©H h.mma H.00H m.voa mx .mxwmz emumm ma .mxmms eRIOm ma .mxmmz omumm "com um COaumEOmsOO comm E .mxoo3 ehlmm R .mMOOB venom x .mxowz ehlom x .mxmmz cmumm x..x003 neon X .xooz puma “0mm um coduospoum mom mwmp .cOauOOOOHm Row um mom O a 000m vmmm mmhm mmom 05mm mx\.m.2 amox mmmwmam m e m m a weassz umao Oman co . usoaoammmoo GOammOHmom N.H GOAUQEOchO 600% new Goduospoae accuse: so hmaosm humumao mo uomumm .m manna 28 Weekly hen-day egg production from 22 through 30 weeks is graphically presented in Figure 2. Pullets fed diets containing 2576, 2682, 2894 and 3000 kcal M.E./kg reached their peak of egg production at 27 weeks of age, whereas peak production was reached at 28 weeks for those fed the diet containing 2788 kcal M.E./kg. All pullets fed the five diets peaked in egg production by the 28th week of age. Egg production of birds on the experimental diets ranged from 61.5 to 66.5 percent between treatments for the 52 weeks of egg production. It may be seen from the graphic presentation of egg production from 22 through 74 weeks of age (Figure 3) that the pullets fed the 3000 kcal M.E./kg diet laid at the low— est rate from 46 to 50 weeks of age, the period of lowest production after the pullets reached their peak of egg pro- duction in six out of 13 four week periods during the laying year. These observations probably partly explains the decreased egg production of the pullets fed the 3000 kcal M.E./kg diet compared to those fed the diet containing 2894 kcal M.E./kg. The foregoing data disagree with those of MacIntyre and Aitken (1957) and Anderson t al, (1957) who reported that increasing the metabolizable energy of layer diets had no effect on the rate of egg production. These workers did not report on the relationship of feed, energy and protein consumption on egg production. Percent Hen-Day Egg Production 29 80 -— 70.4.— 60... 50... 40-— 30-— 20-— Legend M.E./kg Diet h——o .._.. 2576 l __ *_" 2682 2 10 H 2788 3 H 2894 4 3000 5 I L I l I l l l T I ‘ I I r I r 21 22 23 22 25 26 2g» 28 25 30 Age (weeks) Figure 2. weekly hen-day egg production from 22 through 30 weeks. .mxomz vb nmsounu mm anm :Oauooooum moo hmOtcom .m ousmam Amxoo3v woe ebIOn oeuoo monmo NOIwm mmIVm emuom omlov ovlmv Nvlmm mmlem vmtom onion omlmm bl - P F P r b . _ IF IL L L b» ooom I em 8 I mmmm all: HNMQ‘I!) Nmom 911‘ mhmm flll . a . . Dean 939: . a\ 30 \ ov om om on om uorqonpoza 663 Kea-uaH quaozea 31 The results presented in this study agree with those of Skinner _£._L- (1951), Singsen _E__1, (1952) and Hill ag a1, (1956). The latter workers reported that an increase in energy level in the diet increased egg weight only during the winter months. Jackson, Kirkpatrick and Fulton (1969) obtained the most satisfactory egg production from pullets fed 3.5 percent tallow in one experiment and 7.5 percent tallow in the second when compared with the control diet. Total feed consumption.-—Dietary energy level sig- nificantly affected total feed consumption from 22 through 30 weeks, 30 through 74 weeks and 22 through 74 weeks of age (Table 5). From 22 through 30 weeks, average feed consump- tion per bird ranged from 3.81 to 4.12 kilogram. Pullets fed the diets containing 2576 kcal M.E./kg consumed signif- icantly more feed than those fed the diet containing 3000 kcal M.E./kg, whereas those fed diets containing 2576, 2682, 2788 and 2894 kcal M.E./kg consumed similar amounts of feed. From 30 through 74 weeks, pullets fed the diets con— taining 3000 kcal M.E./kg consumed significantly less feed than those fed diets containing less metabolizable energy. Pullets fed all other diets consumed similar amounts of feed. From 22 through 74 weeks Of age, average total feed consumption per bird ranged from 32.16 to 36.72 kilograms. Pullets fed the 3000 kcal M.E./kg diet consumed signifi— cantly less feed than those fed diets containing less kilo— calories of metabolizable energy per kilogram of feed. 32 Diets containing 2788 and 2894 kcal M.E./kg were not signif- icantly different. Likewise diets which contained 2682 and 2894 kcal M.E./kg were similar for total feed consumption. Pullets fed the diet containing the least energy (2576 kcal M.E./kg) consumed significantly more feed than those fed diets that contained more energy. Total feed consumption decreased with increase in dietary energy level. The regression analysis of total feed consumption from 22 through 74 weeks of age on dietary energy level revealed a significant F-ratio (Table 5) indi- cating a linear relationship between the two variates. The analysis also revealed a significant F-ratio for deviation due to regression indicating that the regression is curvi- linear. The preceding data agree with those of Peterson a; a1, (1960) who found that the most prominent effect of in— creasing dietary energy concentration on laying pullets was to decrease feed consumption.' Average daily feed consumption.--The data on average daily feed consumption are presented in Table 6. Dietary energy level significantly affected average daily feed con- sumption from 22 through 30 weeks, 30 through 74 weeks and 22 through 74 weeks of age. From 22 through 30 weeks, aver- age daily feed consumption per bird ranged from 68.1 to 73.5 grams. Pullets fed the 2576 kcal M.E./kg diet consumed sig- nificantly more feed than those fed the 3000 kcal M.E./kg diet. Diets which contained 2576, 2682, 2788 and 2894 kcal 33 mv.m .AQV Goduma>mm “30.0 v mo ms.e .aav amenaq “memaoammmoo memoamaemam .amo.o v my a .muaaanmnoum mo HO>OH ucooaom m on» um ucmnoumao manom0amac Imam mam wouuoa peawomumom ucmuommao m mcaumon Ocaa amucoNaHOE 08mm one so mcmoza mm.m me.mm om.mm 0m.~m n~.e~ ha.e~ mm.mm m “mammz enumm gm.mm am.m~ na.mm am.em me.m~ m mammz emuom a.ma a.ma a.ma m.ma a.ma m .mxmmz omumm "mmo\caOuOHm mm.e mo.o mm.m~e na.moe amm.ame no.moe amm.m~e amok .mxmms emnmm mm.mee ame.m~e am.mme nm.mae mm.oee amux .mxmmz emuom a.mmm m.0mm m.~mm e.aam o.mom amox .mxmmz omumm - "mmm\.m.2 No.0 mm.mm no.mea na.mea am.ama am.oma mm.mma m .mxmms esumm am.sea n~.mea amm.mma nma.mma m~.asa m .mxmmz venom a.maa m.oaa e.maa a.maa m.maa m .mxmmz omumm «mmm\ooom mm.e mm.mm 0a.ea am.ma aa.ma nm.ma ma.ma m .mxmmz emnmm 0m.ea am.ma am.ma pm.ma mm.ma m .mxmmz emnom hm.oa amm.aa nm~.aa nmm.aa mm.aa m .mxmmz cmumm "mmO\caouOHm om.e mm.m ma.mm~ am.mm~ mm.em~ mm.om~ mo.om~ amux .mxmmz emumm nma.mmm am.mmm amo.ma~ amm.mam mm.~m~ amux .mxmmz emuom am.eom na.eo~ amm.mma mm.mma mm.mma amux .mxmmz omumm "mmo\.m.z m~.e em.m oe.mm n~.mm - am.em n~.mm mm.ooa m .mxmmz emumm 0s.mm hm.mm am.mm pa.~oa mm.moa m .mxmmz venom a.mm m.os m.mm e.om m.mm .mxmms omumm e m... m... m... m .smmxmmmm uwxmo3 .mm« a a 000m emmm mmmm mmmm mmmm mk\.m.z amox Noumea Oman m e m N a HOQEOZ Oman :0 .mmou .mmm cam samuOHm pew mmuocm acOaumnaaaus.CaouOHm ocm aoaocm .OOOM mo mocmaoammo .owmm mo abaumadmcoo xaamo so amumcm mumuoao mo vacuum .0 manna 34 M.E./kg were consumed in similar amounts. Moreover, the birds fed the diets which contained 2682, 2788, 2894 and 3000 kcal M.E./kg consumed amounts of feed which were not significantly different. From 30 through 74 weeks, average daily feed consump- tion of pullets fed the five diets ranged from 92.7 to 105.9 grams per bird. Pullets fed the diet which contained the least energy (2576 kcal M.E./kg) consumed significantly more feed than those fed diets which contained 2682, 2788, 2894 and 3000 kcal M.E./kg. Pullets fed diets which contained 2682, 2788 and 2894 kcal M.E./kg consumed similar amounts of feed, but significantly more than the feed consumed by pul- lets fed the 3000 kcal M.E./kg. From 22 through 74 weeks, average daily feed consump— tion per bird ranged from 88.4 to 100.9 grams. Pullets fed the 2576 kcal M.E./kg diet consumed the most feed. Their feed consumption was significantly more than that of pullets fed diets containing 2682, 2788 and 2894 kcal M.E./kg which were not significantly different. The pullets which were fed the 3000 kcal M.E./kg diet consumed significantly less feed than those fed diets containing 2576 up to 2894 kcal M.E./kg during the 52-week test period. Average daily feed consumption decreased with in- crease in dietary energy level. Regression analysis re- vealed significant F—ratios for regression and deviation from regression indicating a curvilinear relationship between feed comsumption and dietary energy level. 35 The foregoing data are in agreement with NRC (1966) and Jackson, Kirkpatrick and Fulton (1969) who reported that White Leghorn pullets laying approximately 200 eggs per year consumed from 94 to 105 grams of feed daily. Average daily energy consumption.--Dietary energy concentration significantly affected average daily energy consumption per bird from 22 through 30 weeks, 30 through 74 weeks and from 22 through 74 weeks of age. Average daily metabolizable energy consumption from 22 through 30 weeks ranged from 188.8 to 20412 kilocalories per bird. Pullets fed the 2576 and 2682 kcal M.E./kg diets consumed signifi- cantly less energy than those fed the diets containing 2894 and 3000 kcal M.E./kg which were similar. Pullets which were fed diets containing 2576, 2682 and 2788 kcal M.E./kg were not significantly different in the amount of feed consumed. From 30 through 74 weeks, the average daily metab- olizable energy consumption ranged from 272.9 to 288.3 kilocalories. Pullets fed the 2576 kcal M.E./kg diet con- sumed significantly less energy daily than those fed the 2894 kcal M.E./kg diet. Those fed diets which contained 2682, 2788, 2894 and 3000 kcal M.E./kg consumed similar amounts of feed. From 22 through 74 weeks, the average daily metab- olizable energy consumption ranged from 260.0 to 275.5 kilo- calories. The pullets fed the diet containing 2894 kcal M.E./kg consumed significantly more energy daily than those 36 fed the diets which contained 2576, 2682, 2788 and 3000 kcal M.E./kg. It was noteworthy that the pullets fed the 3000 kcal M.E./kg diet consumed significantly less energy daily than those fed the 2894 kcal M.E./kg diet. Average daily energy consumption tended to increase with increase in dietary energy level. Regression analysis revealed significant F-ratiOs for regression and deviation from regression indicating that the relationship of daily energy consumption and dietary energy level is curvilinear. The average daily energy consumption data presented in this study agree with Jackson, Kirkpatrick and Fulton (1969) who reported that daily metabolizable energy intake increased with increasing dietary energy concentration, but are contrary to the suggestion of Hill (1962) that the highly productive laying hen adjusts her level of intake on diets of widely varying energy concentrations, consuming approximately 350 kcal of metabolizable energy per day. Average daily protein consumpEipa,--The data on the effect of dietary energy level on dietary protein consump- tion are presented in Table 6. Dietary energy concentration significantly affected average daily protein consumption. From 22 through 30 weeks, average daily protein consumption ranged from 10.0 to 11.8 grams, whereas from 30 through 74 weeks the range was from 14.8 to 16.9 grams and from 22 through 74 weeks the range was from 14.1 to 16.1 grams. 37 From 22 through 30 weeks, pullets fed the diet con- taining 3000 kcal M.E./kg consumed significantly less pro- tein daily than those fed the diet containing 2576 kcal M.E./kg. However, average daily protein consumption by birds fed diets which contained 2682, 2788, 2894 and 3000 kcal M.E./kg was not significantly different. This was also true for birds fed the diets which contained 2576, 2682, 2788 and 2894 kcal M.E./kg. From 30 through 74 weeks, pullets fed the 3000 kcal M.E./kg diet consumed significantly less protein daily than those fed the other diets. On the other hand, pullets fed diets containing 2682, 2788 and 2894 kcal M.E./kg consumed similar amounts of protein daily, but consumed significantly less protein daily than those fed the diet which contained 2576 kcal M.E./kg. From 22 through 74 weeks, pullets fed the 3000 kcal M.E./kg diet consumed significantly less protein daily than the pullets fed all other diets. Pullets fed diets which contained 2682, 2788 and 2894 kcal M.E./kg consumed shnilar amounts of protein daily, but consumed significantly less protein daily than those fed the diet which contained 2576 kcal M.E./kg. Average daily prOtein consumption decreased with increase in dietary energy level. Regression analysis revealed significant F-ratios for regression and deviation from regression, indicating that the regression of daily protein consumption and dietary energy level is curvilinear. 38 The foregoing data are comparable with published information. NRC (1966) reported that S. C. W. Leghorn pullets laying at a rate of 60 percent and weighing 1800 grams require 16.0 grams of protein daily. The birds used in this study weighed from 1591 to 1718 grams at 74 weeks of age. Because of smaller body size and difference in egg production, they consumed only 14.8 to 16.9 grams of protein daily. Scott a£_al, (1969) found that the protein require- ment of S. C. White Leghorn pullets raised under warm envi- ronmental conditions is 16.0 grams per day when the metabo- lizable energy of the diet is 2800 kcal M.E./kg. Average dailypfeed cOnsumpann per egq.--The data on the effect of dietary energy level on average daily feed con- sumption per egg produced may be seen in Table 6. Dietary energy concentration did not significantly affect the amount Of feed consumed daily per egg produced from 22 through 30 weeks. However, it significantly affected the daily feed consumption per egg from 30 through 74 weeks of age. The average daily feed consumption per egg from 22 through 30 weeks ranged from 110.8 to 119.6 grams, whereas the daily feed consumption per egg ranged from 147.8 to 171.2 grams from 30 through 74 weeks and the range was from 143.0 to 168.5 grams of feed per egg produced from 22 through 74 weeks of age. A From 30 through 74 weeks, pullets fed diets contain- ing 2894 and 3000 kcal M.E./kg consumed significantly less feed daily per egg produced than did those fed the diet 39 containing 2576 kcal M.E./kg. On the other hand, pullets fed the diets containing 2682, 2788, 2894 and 3000 kcal M.E./kg consumed daily amounts of feed per egg which were not significantly different. Those fed diets containing 2576, 2682 and 2788 kcal MLE./kg consumed daily amounts of feed per egg which were not significantly different. From 22 through 74 weeks, pullets fed the 2682, 2788, 2894 and 3000 kcal M.E./kg diets consumed similar amounts of feed daily per egg produced but consumed significantly less feed daily per egg than those fed the 2576 kcal M.E./kg diet. Average daily feed consumption per egg produced decreased with increase in dietary energy level. Regression analysis revealed a significant F-ratio for regression but a non-significant F-ratio for deviation from regression indi- cating that the regression of feed consumption per egg pro- duced on dietary energy level is linear. The foregoing observations agree with those of Singsen a£_al, (1952), Griminger and Scott (1954), Hill (1956) and Anderson _£__l, (1957). They reported that diets containing low concentrations of energy are less efficient than those which contain high concentrations of energy. Averaga daily energy conaamptionper egg.--Dietary energy level did not significantly affect average daily metabolizable energy conSumption per egg produced from 22 through 30 weeks. However, it did from 30 through 74 weeks and from 22 through 74 weeks. The average daily metaboliz- able energy consumption per egg produced from 22 through 30 40 weeks ranged from 308.0 to 336.4 kilocalories, whereas it ranged from 415.9 to 443.3 kcal from 30 through 74 weeks and from 405.1 to 428.9 kilocalories from 22 through 74 weeks. Those fed diets containing 2682, 2788 and 2894 kcal M.E./kg diet consumed similar amounts of energy per egg produced. From 22 through 74 weeks, pullets fed the 3000 kcal M.E./kg diet consumed significantly more energy daily per egg produced than those fed the 2682 and 2894 kcal M.E./kg diets. Pullets fed the diets containing 2576, 2682, 2788 and 2894 kcal M.E./kg consumed similar amounts of energy daily per egg produced. Pullets fed the 2682 and 2894 kcal M.E./kg diets produced at the highest rate of egg production and consumed significantly less energy per egg produced than those fed the 3000 kcal MIE./kg diet. Regression analysis of daily energy consumption per egg produced on dietary energy level revealed that the two variates were not linearly related. Average daily protein consumption per egg.--Dietary energy level did not significantly affect average daily pro- tein consumption per egg produced from 22 through 30 weeks. However, it significantly affected the daily protein consump— tion per egg from 30 through 74 weeks and from 22 through 74 weeks of age. The range of daily protein consumption per egg from 22 through 30 weeks was from 17.7 to 19.1 grams, whereas the range was from 23.6 to 27.4 grams from 30 ‘41 through 74 weeks and from 22.9 to 26.3 grams from 22 through 74 weeks of age. From 30 through 74 weeks, pullets fed the diets which contained 2682, 2788, 2894 or 3000 kcal M.E./kg con- sumed significantly less protein daily than those fed the diets which contained 2576 kcal M.E./kg. There were no significant differences in the amounts of protein consumed daily per egg produced by the pullets fed the diets which contained 2682, 2788, 2894 and 3000 kcal M.E./kg. Average daily protein consumption per egg produced decreased with increase in dietary energy level. Regression analysis revealed significant F—ratios for regression and deviation from regression, indicating that the regression of daily protein consumption per egg produced and dietary energy level is curvilinear. Part II Liver fat scores.-+The data on the effect of dietary energy level on liver fat scores are presented in Table 7. Dietary energy level significantly affected the fat scores of livers from 74-week Old pullets. The range Of liver fat scores within treatments (20 livers per treatment) was from one to five each of the five dietary energy levels. However, the range of liver fat scores among treatments was from 2.02 to 2.85. Livers of pullets fed the 2894 kcal M.E./kg diet had fat scores which were significantly higher than those of pullets fed the 2576 kcal M.E./kg diet. Livers from pullets 42 .amo.o v mo me.m .Anc scauma>on “Amo.o v my mh.¢ .AAV undead "OaumHIm ceammmammn ucmoamacmamm .muaaanmnoam mo ao>oa unmouom m Ono um ucoaommao xaucmoamacmam mum aouuma peaaomumoe ucoaommao m msaumon osaa amudOnaaon 08mm onu co msmoza as ooa\ms mama osea eama eema mama .mmamaa ammoo mammam . . . . - . . . ouoom m uo>a so o om 4 Eco N omm m amom m nmma m mmo m a w .a O a m as m m a 38:52 umao NWUHTCM umao co memaoamwmoo sawmmoumom amoflmaa mammam pom Hm>aa muumm so ao>oa mmHOcO mumOan mo uommmm .h manna 42 aOaDma>oo hamoo v my mm.v .aac wmmcaa “Oaumulm scammoumma unmoamasmam .amo.o v mo me.m .aoc N .muaaanmnoum mo am>ma ucmoumm m can um ucmuommao mausmoamacmam mam Houuoa peanomumom usmuommao m mcaamon Ocaa anaconaaon 08mm on» so mcmoza as ooa\ma mama omma eama vema mnma .mOamaa HmuOu mammam no.0 om.e noo.m nmm.m amom.m Qmma.m mmo.m ouoom umm Ho>aa Q .a m o m m a Honasz Dean NWUHmcm uoaa so ucmaoammooo ceammoumom annamaa mammam pom Hm>aa muumm do Hm>ma mmamco mnmumao mo uommmm .h magma 42 sOauma>oo “Amo.o V my ma.v .Aav “mosaq "Oaumaum ceammoumma unmoamacmam .amo.o v 8 mom .2: m .muaaanmnoum mo ao>oa unmouom m Onu um ucouommao waucmoamacmam mum aouuoa umauomumom ucmuommao m mcaumon mafia HmucoNHHon 08mm map so mcmOZH as ooa\ms mama oaaa eama eema mama .moamaa ammo» mammao . . . . , . . . onoom m Ho>a am o om a gem m nmm m nmom m omma m mmo m u m .a a a m e m m a woossz mmao Nwmuwcm moan so usmaoammmoo GOammmnmom HmOamaa mammam ocm Ho>aa muumm so ao>oa monoco mumuoao mo uommmm .a canoe 43 fed the 2682, 2788, 2894 and 3000 kcal M.E./kg diets had fat scores which were not significantly different. Fat scores of livers from pullets fed diets contain- ing 2576 up to 2894 kcal M.E./kg increased with dietary energy level. Those of livers from pullets fed the 3000 kcal M.E./kg diet scored slightly lower than those from pullets fed the 2894 kcal M.E./kg diet. Regression analysis of liver fat score and dietary energy level revealed a significant F-ratio for regression but a non-significant F-ratio for deviation from regression indicating that the regression of liver fat score on dietary energy level is linear. The preceding observations are in agreement with those of Barton, Flegal and Schaible (1966) who reported that in one Of their experiments with laying chickens, a low-energy, high fiber ration prevented fatty liver from develOping while fatty livers developed in birds on the high energy ration. The data reported by Quisenberry, YOung and .Murthy (1967) that dietary energy level had no effect on fatty liver of laying chickens and that fatty liver symptoms were neither caused nor prevented by dietary energy level are at variance with the data Obtained in the present study. The dissimilarity of the results of Quisenberry aEDal, (1967) and those Obtained in the present experiment may be explained in part by the energy to protein ratio used. Quisenberry and co-workers used diets with different dietary energy and pro- tein levels, but maintained increasing concentrations of 44 energy and protein so that the energy to protein ratio remained the same. Liver fat score increased with dietary energy level in the present study, whereas Quisenberry a£_al. (1967) did not find any increase in liver fat scores with an increase in dietary energy level. The energy to protein ratio may be an important factor in the assessment of fatty liver in laying chickens. Total plasma lipids.--Dietary energy level did not significantly affect the concentration of total lipids in the plasma. The concentration of total plasma lipids (TPL) ranged from 1214 to 1770 mg/100 ml. These observations are comparable to those of Lorenz _£_al, (1938) and Walker _a._l. (1951) who reported that the level of dietary fat had little effect on the level of total plasma lipids. In the present experiment, there was no indication of increasing concentra- tions of total plasma lipids with increasing dietary energy concentrations. Interrelationships: Correlation analysis was used to describe the relationship of liver fat score (LFS), total plasma lipids (TPL) and/or number of eggs (NE) produced dur- ing the last four weeks of production (70-74 weeks of age). The data may be seen in Table 8. Correlation coefficients of liver fat scores ranged from -0.762 to 0.479. The corre- lation coefficients of LFS on NE of birds fed diet 1 which contained 2576 kcal M.E./kg was negative and significant (-0.762) indicating that eggproduction decreased with increase in liver fat score. .- 45 Table 8. Correlation coefficients Of certain traitsl Liver Fat Total Plasma Diet Score Lipids 1. Egg number (70-74 weeks) -0.762 0.050 2. Egg number (70-74 weeks) -0.579 -0.441 3. Egg number (70-74 weeks) 0.479 0.173 4. Egg number (70-74 weeks) 0.374 0.487 5. Egg number (70-74 weeks) 0.257 0.218 1Significant correlation coefficient is 0.632 at the 5 percent level of probability (10 pairs of Observation, 8 degrees of freedom). On the other hand, the coefficient of correlation of LFS on NE of birds fed the diet containing 2682 kcal M.E./kg (diet 2) was -0.579, whereas the coefficients of correlation Of LFS on NE of pullets fed the 2788 (diet 3), 2894 (diet 4) and 3000 (diet 5) kcal M.E./kg diets were not significant. The correlation coefficients of egg number on liver fat score from the diets containing 0 and 1.5 percent tallow (diets l and 2) were negative, whereas the coefficients of correlation Of the two variates were positive when egg num- bers and liver fat score of the liver were correlated. The significance Of this observation is not clearly evident. The total plasma lipids and number of eggs laid from 70 to 74 weeks of age were also analyzed. The correlation coefficients ranged from -0.441 to 0.487. The tabular value for significance at the 5 percent level of probability (8 degrees Of freedom) is 0.632 (Snedecor and Cochran, 1967). 46 Total plasma level and liver fat score were not signifi- cantly correlated. Part III Total yolk lipid_,--Dietary energy level did not significantly affect the concentration of total lipids in egg yolk (Table 9). The treatment means of total yolk lipids ranged from 33.72 to 34.84 percent (wet basis). These observations agree with those of Reiser t al. (1951), Marion and Edwards (1962) and Chung _E._L- (1965) and Palafox (1968). They reported that the energy level in layer diets did not significantly affect total yolk lipid concentration. Total yolk cholesterol.--Dietary energy level did not significantly affect total yolk cholesterol (Table 9). The treatment means ranged from 13.22 to 13.96 milligrams per gram of fresh yolk. Similar observations have been reported by Daghir _£__l, (1960) who reported that the cholesterol content of egg yolk from hens fed 12 percent white grease did not differ significantly from that of con— trol. Combs and Helbacka (1960) and Edwards a§_al,(l962) reported that the total yOlk cholesterol of eggs from White Leghorn pullets fed tallow was similar to that of eggs from birds fed the diets without tallow. Yolk satugated fatty acids.--Dietary energy level significantly affected the concentration of myristic, palmitic and total saturated fatty acids (myristic, palmitic 47 .aoc coauma>mo uamoo v my ma.e .aac smocaa "ucOaOHMMOOO scammoumou unmoamacmam .Amo.o v mo me.m m .amaaanmnone mo am>ma msmuwmm m mm» mm msmhmmmam samemoamas Imam mam Houuoa “manomumoe powwommao m mcmumon Ocaa amucouawon mamm Ono so msmoza oom.mm ameo.mm ammm.am amme.mm mom.em x .amooa oa.o me.mm oom.ma nom.ea moa.aa mom.aa mem.ma a .aummaoc mamaoeaa ao.o mo.am ooa.ae moom.me onmm.me omem.ae mmm.mm w. anamaoc oamao oo.a om.m om.m om.m om.m x_.au aoc oamaomasamm "modem wuumm Umumuoummcb nomnam ammmnmm amemumm ammmuem momnmm . ma a_.amuoa oo m ma m ma m mm m ea m a a aOc oawmmmm omm.em mamm.mm ooem.mm meo.mm ommm.am a .am Oc mamasamm nmm.o amm.o ammm.o mmm.o mom.o a .aeaoc mammawaz ”meaom muumm omumusumm m\mE mm.ma mm.ma mm.ma om.ma mm.ma .aowmmmmaoeo xaoa ammoa mm.em em.sm mo.em oa.em ma.mm a .moaoaa xaom ammoa o a ooOm emmm mmam mmmm mamm mx\.w.z amos monocm m v m m a Honesz uoan GHQ GO msmaoawwmoo sOammOHmmm ampaom muumm pom aoamumoaono .mOamaa xaom so ao>oa mmuoso mumuoao mo uoommm .m manna 48 and stearic) 0% egg yolk (Table 8). However, the level of energy in the diet did not significantly affect the concen- tration of stearic acid. Yolk myristic acid concentration ranged from 0.60 to 0.96 percent. YOlk of eggs from pullets fed diets contain- ing 2894 and 3000 kcal M.E./kg contained significantly more myristic acid than those from birds fed 2576 and 2682 kcal M.E./kg diets. Pullets fed diets containing 2576, 2682 and 2788 kcal M.E./kg were not significantly different in yolk myristic acid concentration} This was also true with egg yolks of pullets fed diets containing 2788, 2894, and 3000 kcal M.E./kg. The yolks contained similar amounts of myristic acid. Palmitic acid concentration in egg yolk ranged from 24.86 to 28.04 percent. Egg yolks from pullets fed the 3000 kcal M.E./kg diet contained significantly less palmitic acid than those from pullets fed 2576 and 2682 kcal M.E./kg diets. YOlks from eggs of pullets fed diets containing 2788, 2894 and 3000 kcal M.E./kg were not significantly different in palmitic acid concentration. Total saturated fatty acids in egg yolk ranged from 31.80 to 35.20 percent in this eXperiment. Egg yolks from pullets fed the 3000 kcal M.E./kg diet contained signifi- cantly less saturated fatty acids than those from pullets fed the diet containing 2576, 2682, 2788 and 2894 kcal M.E./kg. Egg yolks from pullets fed from 2576 to 2894 kcal 49 M.E./kg diets contained similar amounts of unsaturated fatty acids. These observations are in agreement with those of Cruickshank (1934) who reported that when she fed high levels (28 percent) of various fats, she found variations in fatty acids of egg yolk. Wheeler, Peterson and Michaels (1959) found no change in the level of stearic acid in egg yolk Of pullets fed different diets. YOlk unsaturated fatty aciQ§,--Dietary energy level significantly affected the concentration of Oleic, linoleic and total unsaturated fatty acids (palmitoleic, Oleic and linoleic) in egg yolk. However, the level of energy in the diet did not significantly affect the concentration of palmitoleic acid. YOlk oleic acid concentration ranged from 39.58 to 47.70 percent. Egg yolks from pullets fed the 3000 kcal M.E./kg diet contained significantly more oleic acid than those from pullets fed the 2576, 2682 and 2788 kcal M.E./kg diets. Oleic acid content of egg yolks of pullets fed 2576 and 2682 kcal M.E./kg was not significantly different. Pullets fed 2782 and 2788 kcal M.E./kg laid eggs which con- tained similar concentrations of Oleic acid in their egg yolks. Likewise pullets fed diets containing 2788 and 2894 kcal M.E./kg were not significantly different in their egg yolk oleic acid content. 50 Yolk linoleic acid level ranged from 13.5 to 18.94 percent. Egg yolks from pullets fed the 2894 and 3000 kcal M.E./kg diets contained significantly less linoleic acid than those from pullets fed diets containing 2576, 2682 and 2788 kcal M.E./kg. Pullets fed diets containing 2894 and 3000 kcal M.E./kg laid eggs which contained similar concen- trations of linoleic acids in their yolk lipids. Regression analysis revealed that the regression of yolk Oleic acid concentration on dietary energy level was positive and significant indicating that yolk Oleic acid concentration increased linearly with increase in dietary energy level. The F-ratio of deviation from regression was not significant indicating the linearity of the regression of the two variates. Linoleic acid concentration decreased linearly with increase in dietary energy level as indicated by the signif- icant F-ratio of the regression of the two variates and the non-significance of the F-ratio of the deviation from regression. The Observation that the linoleic acid content of egg yolk decreased with increasing concentration Of metab- olizable energy with the addition of tallow is in agreement with the data reported by Cruickshank (1934). When she fed 28 percent palm kernel oil, a highly saturated fat, to lay— ing hens, their egg yolks contained 16.1 percnet of the total fatty acids as linoleic acid, but when she fed a 51 highly unsaturated fat, hemp oil, the linoleic acid content of the yolk was 41.1 percent. Also Reiser (1951) reported that the presence of a highly saturated fat (bayberry tallow) in the diet of laying chickens resulted in the reduction of the dienoic acid content of the egg yolk to very low levels. Machlin _£._l, (1962) found that fatty composition of egg yolks reflect the fatty acid composition of the diet. SUMMARY A 5 x 5 Latin Square experiment was conducted with 250 S. C. White Leghorn (Hy-Line) pullets raised under sub- trOpical conditions to study the effect of 16 percent pro- tein layer rations containing increasing concentrations of metabolizable energy (2576, 2682, 2788, 2894 and 3000 kcal M.E./kg) from 22 through 74 weeks of age with the addition of tallow. Criteria measured were efficiency of egg pro- duction, fatty liver, total lipids of plasma and egg yolk, yolk cholesterol and yolk fatty acids. Dietary energy leVel did not significantly affect (l) mortality, (2) egg weight from 22 through 28 weeks, (3) age at 50 percent egg production, (4) egg production from 22 through 30 weeks and (5) daily feed, energy and protein consumption per egg produced from 22 through 30 weeks of age. However, dietary energy level significantly affected (1) egg weight from 22 through 62 weeks and (2) egg produc- tion, total feed, daily feed, energy and protein consumption and daily feed, energy and protein consumption per egg pro- duced from 22 through 74 weeks of age. 52 53 Pullet body weight increased and feed per egg pro- duced decreased linearly with increase in dietary energy level. Daily feed consumption of feed, protein and protein consumption per egg produced decreased with increase in the concentration of energy in the diet. Dietary energy level significantly affected liver fat score. Liver fat score increased linearly with increase in dietary energy level. Total plasma lipid concentration was not significantly affected by the level of energy in the diet. The number of eggs produced from 70 through 74 weeks of age and liver fat score of pullets fed the control diet were significantly and negatively correlated. Dietary energy level significantly affected the level of myristic acid in egg yolk. The concentration Of myristic acid in egg yolk increased with increase in the level of dietary energy. The concentration of energy in the diet significantly affected oleic and linoleic acid content of egg yolk. Yolk oleic acid level increased linearly, whereas yolk linoleic acid decreased linearly with increase in the level of energy in the diet . The results of this experiment indicate that addi- tional research is needed to determine Optimum energy and protein concentrations in the diet of laying chickens housed in temperature controlled environmental conditions. REFERENCES REFERENCES Anderson, G. J., C. F. Petersen, A. C. Wiese and C. E. Lampman, 1957. The effect of high vitamin supplementa- tion of high and low energy rations on egg production and egg shell quality. Poultry Sci. 36:1369-1376. Barton, T. L., 1967. Fatty liver studies in laying hens. Ph.D. Thesis, Michigan State University, East Lansing, Michigan. ‘ Barton, T. L., C. J. Flegal and P. J. Schaible, 1966. Fatty liver syndrome in laying hens as influenced by protein- energy rations. Poultry Sci. 45:1068. Berg, L. R. and G. E. Bearse, 1957. The effect of protein and energy content of the diet on the performance of laying hens. Poultry Sci. 36:1105. Blamberg, D. L., E. H. Bossard and G. F. Combs, 1964. Influence of energy intake on egg weight with diets varying in fat content and physical form. Poultry Sci. 43:1304. Botino, N. R., R. E. Anderson and R. Reiser, 1965. Dietary fatty acids: Their metabolic fate and influence on fatty acid biosynthesis. J. Amer. Oil. Chem. Soc. 42:1124-1129. Brown, W. P., 1964. High energy diets for poultry. London, Tech. Pub. U.S. Feed Grain Council and U.S.D.A. Foreign Agr. Service. Brown, W. O., J. J. Waring and E. Squance, 1965. A study of the effect of variation in the calorie-protein ratio of a medium energy diet and a high energy diet containing sucrose of the efficiency of egg production in caged layers. Br. Poultry Sci. 6:59-66. Chung, R. A., J. C. Rogler and W. J. Stadelman, 1965. The effect of dietary cholesterol and different dietary fats on cholesterol and lipid composition of egg yolk and various body tissues. Poultry Sci. 44:221-228. 54 55 Combs, G. F. and N. V. Helbacka, 1960. 1. Effect of dietary fat, protein levels and other variables in practical rations. Poultry Sci. 39:271-279. Couch, J. R., 1956. Fatty livers in laying hens-sA condi- tion which may occur as a result of increased stress. Feedstuffs 28:(47)46-54. Cruickshank, E. M., 1934. Studies in fat metabolism in the fowl. l. The composition of egg fat and depot fat of the fowl as affected by ingestion of large amounts of different fats. Biochem. J. 28:967-977. Daghir, N. J., W; w. Marion and S. L. Balloun, 1960. Influence of dietary fat and choline on serum and egg yolk cholesterol in the laying chicken. Poultry Sci. 39:1459-1466. Donaldson, w. E. and C. D. Gordon, 1960. The effect of three percent added animal fat on laying hen performance. Poultry Sci. 39:583-587. Dronawat, N. S., R. W. Stanley, E. Cobb and K. Morita, 1966. Effect of feeding limited roughage and a comparison between loose and pelleted pineapple hay and milk pro- duction, milk constituents and fatty acid composition of milk fat. J} Animal SCi. 49:28-31. Duke, M. J., R. K1 Ringer and J. H. Wolford, 1968. Failure of plasma protein level to indicate develOping fatty liver in chickens. Poultry Sci. 47:1098-1100. Duncan, D. B., 1955. Multiple range and multiple F. tests. Biometrics 11:1-42. Edwards, H. M., Jr., J. E. Marion and J. D. Driggers, 1962. Serum and egg cholesterol levels in the mature hen as influenced by dietary protein and fat changes. Poultry Sci. 41:713-717. Fiegenbaum, A. S., and H. Fisher, 1959. The influence of dietary fat on the incorporation of fatty acids into body and egg fat of the hen. Arch. Biochem. BioPhys° 79:302-306. Fisher, H. and G. A. Leveille, 1957. Observations on the cholesterol, linoleic acid and linolenic acid content of eggs as influenced by dietary fats. J. Nutrition 63:119-129. Folch, J., M. Lees and G. H. S. Stanley, 1957. A simple method for the isolation and purification of total lipids from animal tissues. J. Biol. Chem. 226:497-509. 56 Greenberg, D. N., C. E. Larson, P. B. Pearson and B. Burmester, 1936. The state and partition of the calcium and inorganic phosphorus in the serum of the fowl: Effect of growth and ovulation. Poultry Sci. 15:483-489. Griminger, P. and H. M. Scott, 1954. The effect of differ- ent cereals on feed efficiency, egg quality and shell thickness. Poultry Sci. 33:1217-1219. Hill, F. W., 1956. Studies of the energy requirements of chickens. 4. Evidence for a linear relationship between dietary productive energy level and the effi- ciency of egg production. Poultry Sci. 35:59-63. Hill, F. W., 1962. Some aspects of the physiology Of food intake and digestion in chickens. Nutrition in Pigs and Poultry. Edit. Morgan, J. T., and D. Lewis. London, Butterworth. Hill, F. W., D. L. Anderson and L. M. Dansky, 1956. Studies Of the energy requirements of chickens. 3. The effect of dietary energy level on the rate and tross efficiency of egg production. Poultry Sci. 37:949-953. Hocreich, H. J., C. R. Douglas, I. H. Kidd and R. H. Harms, 1958. The effect of dietary protein and energy levels upon production of Single Comb White Leghorn hens. Poultry Sci. 37:949-953. Howes, J. R. and G. J. Cottier, 1967. Further studies comparing methods of delaying maturity in heavy breeder pullets. Poultry Sci. 46:1273. Jackson, N., H. R. Kirkpatrick and R. B. Fulton, 1969. An experimental study of the utilization, by the laying hen, of dietary energy partially supplied as animal fat. Br. Poultry Sci. 10:115-126. Lillie, R. J. and C. A. Denton, 1965. Protein and energy interrelationships for laying hens. Poultry Sci. 44: 753-761. Lillie, R. J., J. R. Sizemore, J. L. Milligan and H. R. Bird, 1952. Therprotein and fat in laying hens. Poultry Sci. 31:1037-1042. Lorenz, F. W., C. Entenman and I. L. Chaikoff, 1938. The influence of age, sex and ovarian activity on the blood lipids of the domestic fowl. J. Biol. Chem. 122:619. 57 Machlin, L. J., R. S. Gordon, J3 Marr and C. W. Pope, 1962. Effect of dietary fat on the fatty acid composition of eggs and tissues of the hen. Poultry Sci. 41:1340-1343. MacIntyre, T. M. and J. R. Aitken, 1957. The effect of high levels of dietary energy and protein on the performance of laying hens. Poultry Sci. 36:1211-1216. March, B. E. and J. Bieley, 1963. The effects of dietary fat and energy levels on the performance of caged laying birds. Poultry Sci. 42:20-24. Marion, J. E., and H. M. Edwards, Jr. 1962. The influence of various oils in the diet on lipid metabolism of fat deficient laying hens. Poultry Sci. 41:1662. Morris, T. R. and S. Fox, 1960. The use of lights to delay sexual maturity in pullets. Br. Poultry Sci. 1:25-35. Milby, T. T. and D. H. Sherwood, 1953. The effect of restricted feeding on growth and subsequent production of pullets. Poultry Sci. 32:916. National Research Council, 1966. Nutrient requirements of poultry. National Academy of Sciences. Publication 1345. Palafox, A. L., 1968. Effect of age, energy source and concentration of yolk lipids and cholesterol. Poultry Sci. 47:1705. ' Petersen, C. F., E. A. Sauter, D. H. Conrad and C. E. Lampman, 1960. Effect of energy level and laying house temperature on the performance of white leghorn pullets. Poultry Sci. 39:1010-1018. Reiser, R., B. Gibson, J. J. Carr and B. G. Lamp, 1951. The synthesis and interconversion of polyunsaturated fatty acids by the laying hen. J. Nutrition 44:159-176. Quisneberry, J. H., L. A. Ybung and P. V. L. N} Murthy, 1967. The fatty liver syndrome in commercial layers. Poultry Sci. 46:1308-1309. Scott, H. M., L. D. Matterson and E. P. Singsen, 1947. Nutritional factors influencing growth and efficiency of feed utilization. 1. The effect of source of carbohydrate. Poultry Sci. 26:554. Scott, M. L., M. C. Nesheim and R. J. Young, 1969. Nutrition of the Chicken. M. L. Scott and Associates, Ithaca, N.Y. 58 Sell, J. L., S. H. Choo and P. A. Kondra, 1968. Fatty acid composition of egg yolk and adipose tissue as influenced by dietary fat and strain of hen. Poultry Sci. 47:1296- 1302. Skinner, J. L., J. H. Quisenberry and J. R. Couch, 1951. High efficiency and APF concentrates in the ration of the laying fowl. Poultry Sci. 30:319-324. Singsen, E. P., L. D. Matterson and A. Kozeff, 1952. A high efficiency ration for laying and breeding hens. Storrs (Connecticut) Agr. Exp. St. Bul. 286. Snedecor, G. W. and W. G. Cochran, 1967. Statistical Methods, 6th Ed., Iowa State University Press, Ames, Iowa, 593 pp. Treat, C. M., B. L. Reid, R. E. Davies and J. R. Couch, 1960. The effect of animal fat and mixtures of animal fatty acids on performance of cage layers. Poultry Sci. 39: 1550-1555. Walker, A. E., M. W. Taylor and W. C. Russell, 1951. The level and interrelationship of the plasma lipids of the laying hen. Poultry Sci. 30:525-530. Waring, J. J., R. F. Addison and W. 0. Brown, 1968. A com- parative study of energy utilization by the laying hen from diets containing a high proportion of fat and diets made up mainly from carbohydrate source. Br. Poultry Sci. 9:79-86. Weiss, H. S. and H. Fisher, 1957. Plasma lipid and organ changes associated with the feeding of animal fat to laying chickens. J. Nutrition 61:267-280. Weiss, J. P., E. C. Naber and R. M. Johnson, 1964. Effect of dietary fat and other factors on egg yolk cholesterol. 1. The "cholesterol" content of egg yolk as influenced by dietary unsaturated fat and the method of determina- tion. Arch. Biochem. and BiOphys. 105:521-526. Wheeler, P., D. W. Peterson and G. D. Michaels, 1959. Fatty acid distribution in egg yolk as influenced by type and level of dietary fat. J. Nutrition 69:253-260. Zlatkis, A., B. Zak and A. J. Boyle, 1953. A new method for the direct determination of serum cholesterol. J. Lab. & Clin. Med., 41:486-492. ll‘lWlllMIllWlWUlHllHlWll '