107 452 .THS_ um mu m H! 171mm”! ”MW -' L m I, 3 1293 Michigan Sta-:33 University I'Hi‘a rs This is to certify that the thesis entitled The Effects of High Dietary Energy and Different Light Regimes on the Performance of Broilers Raised at High Temperature presented by Abubaker Abed El-Oraiby has been accepted towards fulfillment of the requirements for 14.8. _dpgreein Poultry Science éflo H. We * Major professor Date [7/151/77 0-7639 OVERDUE FINES ARE 25¢ pER DAY PER ITEM Return to book drop to remove this checkout from your record. l 1.54:1; 'n' z')- o‘ {'"o e pWo—w.‘ / J ' “ O} ' THE EFFECTS OF HIGH DIETARY ENERGY AND DIFFERENT LIGHT REGIMES ON THE PERFORMANCE OF BROILERS RAISED AT HIGH TEMPERATURE By Abubaker Abed El-Oraiby A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Poultry Science 1979 ABSTRACT THE EFFECTS OF HIGH DIETARY ENERGY AND DIFFERENT LIGHT REGIMES ON THE PERFORMANCE OF BROILERS RAISED AT HIGH TEMPERATURE By Abubaker Abed El-Oraiby An experiment was conducted to study the effects of high energy level diets on the performance of commercial broiler type birds raised in a high temperature environment. Included were two test diets which contained 3410 or 3080 kcal. M.E./kg metabolizable energy, two temperature treatments either normal (20°C) or high (31°C), and two light regimes, continuous or intermittent light (14L and 10D). The experimental treatments were started when the birds reached 3 weeks of age and lasted for 10 weeks. Data were col- lected on 8 week and 10 week old birds. The high energy diet significantly (P5.Ol) increased the body weight gain and feed efficiency of birds from 3 to 10 weeks of age. The dif- ferent light treatments had no significant effect on the body weight gain of birds from 3 to 10 weeks of age. Chickens raised in intermit- tent light had significantly better feed efficiency than those raised in continuous light from 3 to 10 weeks of age. Abubaker Abed El-Oraiby The mortality of birds after the 10 week study was not great; but there was a significantly greater (P5.05) mortality in the group of birds that received the high energy diet. DEDICATION To my family, my wife Nadia and my son Osama, for their patience and understanding during the course of this work. ACKNOWLEDGEMENTS The author is deeply grateful to Dr. T.H. Coleman, Professor of Poultry Science, for his guidance of the research project and for his constructive criticism of this dissertation. He has proven himself to be an ideal adviser, constantly suggesting and leading, but never insisting. Sincere appreciation is expressed to Dr. Cal J. Flegal for his continuous help in this research and for his critical review of this manuscript. The author is indepted to Dr. J.L. Gill and Dr. R.R. Neitzel for the statistical and computer work; Dr. L.E. Dawson and Dr. L.R. Dugan, Department of Food Science and Human Nutrition, for their interest and assistance. The author also wishes to express his appreciation to Dr. H.C. Zindel, Chairman of the Department of Poultry Science, for making available Poultry Science Department laboratory and farm facilities for the conduct of this research. The graduate students in the Department of Poultry Science for their help. Sincere appreciation to Manfred L. Schwarz for editing this manuscript. The Libian Society for their financial support. ii TABLE OF CONTENTS Page INTRODUCTION . . . . . . . . . . . . . . . . . 1 LITERATURE REVIEW . . . . . . . . . . . . . . . 3 MATERIALS AND METHODS . . . . . . . . . . . . . . 13 Statistical Procedure . . . . . . . . . . . . 19 RESULTS AND DISCUSSION . . . . . . . . . . . . . 20 Body weight . . . . . . . . . . . . . . . 20 Feed Consumption . . . . . . . . . . . . . . 29 Feed Efficiency . . . . . . . . . . . . . . 38 Mortality O O O O O O O O O I O O O O O O 47 SUMMARY . . . . . . . . . . . . . . . . . . 50 RANCIDITY TEST . . . . . . . . . . . . . . . . 52 Introduction . . . . . . . . . . . . . . . 52 Literature Review . . . . . . . . . . . . . 52 Materials and Methods . . . . . . . . . . . . 53 Results and Discussion . . . . . . . . . . . . 53 Conclusion . . . . . . . . . . . . . . . . 55 LITERATURE CITED . . . . . . . . . . . . . . . 56 iii Table 10 11 12 13 14 15 16 LIST OF TABLES Composition of Starter Diet . . . . . . . . Experimental Design and Allocation . . . . . . . Composition of Experimental Diets . . . . . . . Michigan State Starter-Grower Vitamin Premix No. 5003 (with Ethoxyquin) . . . . . . . Average Body Weight Gain in Grams of Birds From 3 to 8 Weeks of Age . . . . . . . Analysis of Variance of Bird weight Gain From 3 to 8 weeks of Age . . . . . . . Average Body weight Gain in Grams of Birds From 3 to 10 weeks of Age . . . . . . . . . . Analysis of Variance of Bird Weight Gain From 3 to 10 Weeks of Age . . . . . . . . Average Daily Feed, Protein and Calorie Consumption of Birds From 3 to 8 Weeks of Age . . . . . Analysis of Variance of Food Consumption by Birds From 3 to 8 weeks of Age . . . . . . . . Average Daily Feed, Protein and Calorie Consumption of Birds From 3 to 10 Weeks of Age . . . . Analysis of Variance of Food Consumption by Birds From 3 to 10 Weeks of Age . . . . . . . . Feed Efficiency of Birds From 3 to 8 Weeks of Age . Analysis of Variance of Feed Efficiency in Birds From 3 to 8 Weeks of Age . . . . . . . . . . Feed Efficiency of Birds from 3 to 10 weeks of Age Analysis of Variance of Feed Efficiency in Birds From 3 to 10 Weeks of Age . . . . . . . . . . iv Page 14 16 17 18 22 24 25 27 30 31 34 37 39 42 43 45 Table 17 18 Page Mortality during the Experimental Period (3 to 10 weeks of Age . . . . . . . . . . . . 48 Peroxide Level of Feed Kept at High Temperature for 28 Days . . . Figure II III IV VI LIST OF FIGURES Average body weight gain of birds in kilograms from 3 to 8 weeks of age Average body weight gain of birds in kilograms from 3 to 10 weeks of age . . . . . . Average daily feed consumption of birds from 3 to 8 weeks of age Average daily feed consumption of birds from 3 to 10 weeks of age . . . . . Feed efficiency in grams gain for birds from 3 to Feed efficiency in grams gain for birds from 3 to feed/grams weight 8 weeks of age . feed/grams weight 10 weeks of age . vi Page 21 . 26 32 . 35 44 _' i INTRODUCTION In 1947, Scott et al. demonstrated that high levels of energy are desirable in broiler rations. Since that discovery, an extensive amount of research has been conducted with poultry to determine the influence of high energy feed on growth rate, feed efficiency and the relation- ship between added fats in the feed and other nutrients. That is true if the chickens are raised under normal temperature and normal light regimes. However, formulas for broiler feeds must be changed as tempera- ture changes. These formula changes are based on the assumption that the amount of feed consumed by the broiler is determined by their need for energy. During cold weather, extra energy is needed to maintain body temperature; therefore, chickens increase feed intake to meet this re- quirement. Nutritionists change the nutrient content of feed in an attempt to compensate for differential intakes during summer and winter. When these changes are made, it is assumed that the feed is balanced to meet the need of the chickens. Some poultry researchers report that chickens do not regulate feed consumption to the extent needed for proper energy intake. They conclude that chickens adjust feed intake only to meet their appetite, not to meet their energy requirements. During extremely hot weather the chickens' appetite decreases, therefore the chicken does not consume enough feed to support maximum performance. At moderate temperatures the chickens' feed intake is better adjusted to meet their energy needs for optimum perfor- mance . The objectives of this study was to determine whether a high energy diet and different light treatments are able to improve the weight gain, feed consumption, and mortality rate of chickens raised in a high mortality rate of chickens raised in a high temperature environment. LITERATURE REVIEW Fats and oils are practically all substances that are ether- extractable from feeds or tissue. Fats are those glycerol esters which are solids, while oils are liquids at ordinary temperatures. From a nutritional point of view, only linoleic acid is an essential fatty acid. The importance of linoleic acid for bird growth and hatchability, egg size and maximum egg production have been reported by many researchers (Thomasson, 1962; Menge st aZ., 1965; and Menge, 1968). Lipids are added to the poultry diet primarily as a source of energy. They contain fat soluble vitamins and also help in their absorption. Fats act as a lubri- cant to facilitate the passage of feed; they reduce dustiness of feed and increase the palatability of the feed. It has been known for many years that an increase in the energy content of poultry diets results in a decreased feed intake and improved performance in broilers (Donaldson at aZ., 1956; and Waldroup et aZ., 1976) and in laying hens (Jones et aZ., 1976). Fraps (1928, 1944) and Scott et al. (1947) were among the first nutritionists to evaluate dif- ferent feed as to their ability to support growth in chickens as a func- tion of protein and fat deposition in the carcasses. They indicated that growth rate and efficiency of feed utilization were improved by feeding diets high in digestibility and energy concentration. Siedler et a1. (1955) showed that addition of vegetable oil (not beef tallow) to the chicken diet will improve the efficiency of feed utilization. These results are similar to those of Renner and Hill (1960) and Matterson et al. (1965), who indicated in their evaluation studies that, in general, vegetable oil was characterized by higher absorbability and higher metabolizable energy (M.E.) values than was animal fat. Scott at al. (1976) indicated that fats included in the diet in- creased the utilization of feed as compared with that of a low fat diet. This improvement in energy efficiency can be attributed to a lowered heat increment with the diets that contained fat. This phenomenon has t been called "associative dynamic action of fats". It has been recognized that poultry do not regulate feed intake to the extent needed for proper energy intake, and do not eat to meet their energy requirements, but to meet their appetite. Gutteridge (1946) re- ported that the addition of 57. of animal fat to a poultry ration increased the rate of gain and improved the quality of the carcass. Slinger et al. (1952) found that the addition of soybean oil to the chickens ration in- creased growth slightly and improved the feed efficiency. Yacowitz (1953) and Sunde (1954b) have also shown that fat added to broiler rations at levels up to 5% improved the performance of the birds. Siedler et a1. (1953) added 2, 4, 6 and 8% stabilized white grease, respectively, to a practical basal ration fed to growing birds. The rate of gain when fat was added was equal to or slightly higher than when the basal ration was fed. Feed efficiency increased with the in- crease in the level of fat. Sunde (1954a) fed white grease, prime tallow, or soybean oil at levels of 2.2 and 5% to birds and poults. No consistent increase in the rate of gain was observed with birds, but a slight improvement was noted when prime tallow was fed to turkey poults. Feed efficiency was increased with both birds and turkey poults. Jackson et al. (1969) fed diets with up to 28.25% added tallow at constant calorie:protein ratios. Feed conversion decreased with increased dietary fat. However, the efficiency of metabolizable energy utilization decreased with added tallow. The average daily M.E. consumption of birds fed the high tallow diet was 354 kcal. in comparison with 250 kcal. for those birds fed a comparable diet with- out added fat but with equivalent egg production and average egg weight. Scott et a1. (1947) demonstrated that both growth rate and feed effi- ciency utilization were improved by feeding diets high in digestibility and energy concentration. Siedler et al. (1955) showed improved effi- ciency of feed utilization with the addition of beef tallow or vege- table oils to the diet of birds. This was also reported by Sunde (1954a), Aitkem et al. (1954), and Matterson et a2. (1955). Waldroup at al. (1976) found that as the nutrient density level of the diet in- creased, bird body weights were increased. Total feed consumption tended to decrease with increasing nutrient density levels and the total energy consumption increased as the nutrient density level of the diet increased; gain:feed ratios were improved as the nutrient density levels of the diet increased. Sell and Thompson (1965) found that feeding low fat rations in the form of pellets or ground pellets in- creased weight gain, feed consumption and improved efficiency of food utilization. However, 10% fat in the ration increased weight gain only slightly and failed to increase feed consumption or to improve effi- ciency of food utilization. Further studies involving high fat rations for chickens were conducted by Combs et al. (1958); they found that marked differences were obtained in the value of various fats when compared with starch as a source of energy. They found that 10 and 18% supplemental fat may be used successfully in practical feeds. The addition of 10% fat slightly improved eight week weight in broilers re- ceiving all mash but not in those receiving pelleted feeds. Feed con- version improved in proportion to the increased energy potency of the rations. Reiser and Pearson (1949) used lard and hydrogenated vegetable oils in bird starter rations and the addition of these fats resulted in no deleterious effects on the growth of birds. Siedler et a2. (1953) re- ported that the performance of birds fed added levels of fat was equal to, or better than, that of birds fed a ration without added fat. Fuller and Rendon (1976) conducted two experiments to determine the energy efficiency of diets containing different feed grade fats for the growth of broiler birds during the finishing period. They found that energy and nutrient intake were higher for all diets containing fats, indicating that feed intake was influenced by the heat increment (H.I.) of the diet as well as by energy level. Daghin (1973) reported on three experiments conducted in Egypt, employing diets ranging from 2.28 to 2.92 kcal. M.E./g. These studies indicated improvement of feed conversion and reduced feed intake with higher performance of hens during warm weather. Douglas and Harms (1977) found that the addition of 2% animal fat and 1/2 lb. of methionine per ton resulted in an increase in feed intake. They also reported (1976b) that a certain change in the diet of laying hens and pullets would im- prove the performance of hens during hot weather. According to Harms at al. (1978), low temperature resulted in an increase in the birds' intake of energy, more than necessary for optimum performance. They found that at moderate temperature, the chickens eat to meet energy for optimum performance, but in hot temperature do not eat to support maximum performance. Reid and Weber (1975) found that temperature had an effect on in- creased M.E. consumption in the presence of dietary fat. They found that birds housed in a conventional cage house significantly increased M.E. consumption with increasing levels of supplemental fat, while the birds in the evaporated cooled house did not. They concluded that the energy intake regulatory mechanisms are not adequately operative under high temperature conditions; or, more likely, that the effects of heat increments were magnified by high temperature and can be offset by high fat levels. Their finding was in agreement with the work by Jackson et al. (1969) in which daily M.E. consumption was increased from 250 to 354 kcal. per day with the feeding of 28.25% added tallow. Jackson et a1. (1969) indicated that in a climate where a cooled housing is not commonly used, supplemental fat in a diet could be expected to result in improved performance during periods of high temperature. Jones and Barnett (1974), in five experiments, determined that turkey hens in egg production required one to eight days to adjust feed consumption in 4.50C environmental temperature and eight to fourteen days in 35°C temperature. There was no significant difference in feed consumption due to dietary energy level after the hens were acclimatized to the environmental temperature. However, Guenthner et a1. (1972) re- ported that increasing the dietary energy fed to S.C. White Leghorn hens significantly decreased feed consumption, improved feed conversion and increased feed cost per dozen eggs; whereas, the rate of egg production was not affected. Jones et al. (1976) reported that there was no significant difference in feed consumption among hens housed at cool (4.5 i 1°C) or moderate (21 i 1°C) temperature. However, hens housed in a hot temperature (35 i 10C) ate significantly less feed than hens housed at a cool temperature. Egg production was significantly less for hens in high environmental temperature when compared to hens confined in the low temperature environment. The hens housed at a control temperature of 21 i 1°C produced at the same rate as the hens housed in both the higher and lower temperature. Hens in the 35 1 10C environment did not consume enough feed to maintain body weight. They lost significantly more weight than hens in the other treatment groups. Miller and Sunde (1975) and deAndrade et al. (1976) reported that mild heat stress improved feed efficiency while reducing egg production and quality. deAndrade et al. (1976) found that feed conversion was im— proved with high temperature and the best conversion was noted in the 310C environment. A high nutrient density diet (HND) (25% more of all nutrients except energy which was increased 10%) increased egg production only at high temperatures and egg production of hens fed the HND diet at an elevated temperature approached normal egg production. Food consump- tion was decreased and feed efficiency was improved. Huston and Edwards (1961) designed an experiment to determine the influence of protein and energy levels upon growth and feed efficiency of immature fowl held at different environmental temperatures. They found that the body weights were lower at the high environmental tempera- ture than at either of the other temperatures. Less feed was required per pound of gain at the high temperature. The ration with the higher protein and energy values produced heavier birds in all environments. Lillie et al. (1976) reported that the best overall performance in Leghorn pullets was obtained with a temperature of either 130C or 21.50C and with a dietary energy level of 2648 kcal. M.E./kg. Feed intake per hen per day was equivalent at 13°C and 21.50C and significantly greater at these temperatures than at 29.50C. The fact that feed intake de- creases at high temperatures is well documented, as shown by warren and Schnepel (1940) with a temperature of 15.20C versus 34.50C, Ahmed et al. (1974) with 230C versus 300C, deAndrade et a2. (1974) with 21°C versus 32th and Jones et a1. (1976) with 210C versus 350C. Thomason et a2. (1976) studied the effects of environmental factors on the reproductive performance of young turkey hens. They found that a constant temperature of 29.40C reduced egg production and lowered body and egg weight. They also reported that feed consumption decreased with increasing pen temperature. They suggested that Optimum reproductive performance can be obtained with breeder turkeys when environmental temperatures are maintained between 12.80C and 21.10C. Thomason et al. (1972) reported that the maintenance of young turkey hens in a constant temperature environment of 29.40C caused lower egg and body weights and reduced feed consumption when compared with females maintained at a temperature of 12.80C and 21.10C. Casey at al. (1974) found that the incidence of encephalomalacia in commercial broilers appeared to be associated with extended storage of starter feed at high temperature. The results suggested that field storage of feed at high temperature may affect performance of broilers. Deaton and Reece (1970) found that a light-temperature interaction existed for broiler body weight gain. They found that broilers attained greater body weight gains at high varying temperature when given the opportunity to consume feed and water in the lower portion of the tem- perature cycle than when they had the opportunity to consume feed and water in the high portion of the temperature cycle through six weeks of 10 age. Birds receiving light in the high portion of temperature cycle consumed practically the same amount of feed as birds receiving light in the lower portion of the temperature cycle. Skoglund at al. (1964) found that birds consumed more feed when given a longer light period. They reported that this did not neces- sarily mean they would weigh significantly more than those on a shorter light period. When the light period was uninterrupted, then the normal day length of 12 hours was sufficient for maximum broiler growth. Buckland et al. (1973) found that broilers, exposed to light regimen of one hour light to three hours dark (1L:3D), were heavier at eight weeks of age than comparable birds given continuous light. Similar results were reported by Proudfood (1975) while Beane and Siegle (1965) found that Optimum growth and feed conversion were attained with birds kept on continuous light as compared to light regimes of less than 24 hours of light per day. Moore (1957) has reported that chicken broilers grew best under continuous, or near continuous light to 4 weeks of age, and thereafter required less light to market age (8 to 10 weeks). Shutze at al. (1959) found that chicken broilers grew equally well under con- tinuous light or six cycles of intermittent 2L:2D per 24 hours. Similar results were reported by Cherry and Barwick (1962) who found that under commercial broiler conditions, optimum weight and feed conversion were obtained with near continuous lighting, or with patterns involving 2 hours darkness or less per cycle. Buckland and Hill (1970) reported that birds on intermittent light were slightly heavier than those on continuous light; however, Buckland at al. (1971) reported that the use of continuous light generally resulted in larger birds at two weeks than did intermittent light. 11 They concluded that birds under intermittent light did not have suffi- cient time to consume adequate quantities of feed, especially on low density ration. Barrett and Pringle (1951), Clegg and Sanford (1951), Marr et al. (1971), McDaniel (1972), Cain (1973), Hooppaw and Goodman (1976), and McDaniel et a1. (1977) found that birds grew better under intermittent light as compared to birds under continuous light. Weaver and Siegel (1969) reported that male broilers grown under continuous lighting were significantly heavier at 56 days of age than males exposed to periods of darkness. Feed efficiency was nonsignificantly different among light regimens in their study. According to Foshee et a1. (1970), the primary factor affecting the growth rate of broilers was the uniform distribution of activity periods throughout the 24 hour day. Gore et al. (1969) reported that an adequate dark period following feeding plays the dominant role in broiler growth. Dorminey (1971) found that body weight and feed conversion of broilers grown in varying light periods and intensities compared satis- factorily with broilers grown in continuous light of normal intensity if the lights-on period was at least one hour and the lights-off period did not exceed two hours. The effect of environmental conditions such as light and temperature on the performance of broiler chickens is still unclear and needs more investigation. Many different systems of lighting are used in commer- cial broiler houses at the present time. Light schedules may be con- tinuous or interrupted. The effect of different light intensity, color and light regime on the performance of broiler chickens have been re- ported (Cherry and Barwick, 1962). However, other investigator results 12 were inconclusive. Barrott and Pringle (1951) indicated that growth rate in the first 18 days was slightly lower with light intensity greater than six foot candles. However, Skoglund (1959) and others showed no consistent difference in bird growth rate with 15 or 120 foot candles. It has been reported that a chicken eats to satisfy its energy re- quirements. However, at high temperature, it is not known whether a lower feed intake or some other physiological mechanisms caused the re- duced growth rate. Huston and Edwards (1961) indicated that factors other than energy intake are involved in growth inhibition of birds at high environmental temperature. However, Sturkie (1976) reported that energy intake is affected by the environmental temperature and showed that gross energy intake increased linearly with decreasing environmental temperature. Most investigators have found that the feed consumption of chickens decreased when the environmental temperature was increased. However, during hot temperature the broilers or laying hens will eat just to satisfy their appetite, which is usually not enough to support their growth and production. 80 it is necessary to adjust the nutrient content of the diet according to the change of environmental condition to support a maximum performance in broilers. MATERIALS AND METHODS Six hundred day-old commercially hatched broiler type birds (approximately 300 of each sex) were wing banded and maintained with sexes separated in floor pen units with wood shaving litter. Gas heated brooders were used, and for the first two weeks flat type feeders and jar-waterers were employed, then replaced by hanging feeders and mechanical waterers. The birds were fed a standard starter ration from day one through three weeks of age. Feed and water were provided ad libitum. The composition and analysis of the starter diet used in this experiment is shown in Table 1. At three weeks of age, the birds were sorted according to body weight categories (in grams) into the following groupings: Female 378-422, 423-447, 448-472, 473-500; Male 450-475, 476—500, 501-525, 526-550. Birds outside this range were discarded. Then selected birds were distributed into groups of nearly the same average weight. The birds were then divided into 16 experimental groups of 10 males and 10 females in each group and individual weights were recorded. There were 20 birds/group x 8 treatments x 2 replications for a total of 320 birds. The experiment lasted for 10 weeks. The temperature was the same in 8 of the pens (normal temperature about 20°C); and the other 8 pens had a high temperature (about 31°C). The birds received two different light regimes, intermittent and continuous light. Eight pens received intermittent light and the other eight pens received continuous light. The intermittent light was controlled by the use of 13 14 TABLE 1 Composition of Starter Diet Diet Unit % Cornmeal 52.00 Soybean meal (49%) 33.60 Animal fat 5.10 Fishmeal 4.00 Alfalfa meal (17%) 2.50 Limestone 0.90 Dicalcium phosphate 1.10 Salt 0.42 DL-Methionine 0.13 Vitamin premix3 0.25 TOTAL 100.00 Calculated Analysis: kcal. M.E./kgl 3190.00 crude fiber 3.10 total fat 7.70 xanthophyll 7.10 crude protein 24.07 energy:protein ratio2 132.50 1kilocalories of metabolizable energy per kilogram of diet. 2based on kcal. M.E./kg diet. 3see Table 4. 15 a time switch which turned off at 6:00 p.m. and on at 4:00 a.m., during the duration of the experiment to provide the birds with 14 hours of light and 10 hours of dark daily. Experimental design and allocation were as shown in Table 2. Birds in one-half the pens were given a low energy diet A, that contained a total metabolizable energy (M.E.) of 3080 kcal. M.E./kg. The birds in the other pens received a high energy diet B, that con- tained a M.E. of 3410 kcal. M.E./kg (see Table 2). Birds in pens number 1, 3, 5, and 7 received diet A; while the birds housed in pens number 2, 4, 6, and 8 received diet B. The composition and analysis of the experimental diets are shown in Table 3. Feed was mixed at the Michigan State University Poultry Science Research and Teaching Center, and weighed at the beginning and at the end of each experimental period. Feed consumption was measured and mortality was recorded throughout the experiment and computed for the periods 3 to 8 and 3 to 10 weeks of age. During the fourth week of age, swollen hocks and lameness were observed in birds in a number of pens. Some of the birds died from starvation because they could not reach the food and water. Some of the birds that had swollen hocks and lameness were sent to the M.S.U. Animal Health Diagnostic Laboratory, but no cause for the condition could be determined. To alleviate any possibility of a borderline vitamin deficiency, the remaining feed was collected and more vitamin premix was added to it. Thus, from four to ten weeks of age, the diet used contained 0.5% vitamin premix. The formula for Michigan State starter-grower vitamin premix No. 5003, which was the one used in these diets, is shown in Table 4. 16 TABLE 2 Experimental Design and Allocation l 1 NC 2 2 3 3 NI 4 4 5 5 HC 6 6 7 7 HI 8 8 NC = Normal temperature, continuous light NI = Normal temperature, intermittent light HC = Hot temperature, continuous light HI = Hot temperature, intermittent light A = Diet No. A (3080 kcal./kg) B = Diet No. B (3410 kcal./kg) 17 TABLE 3 Composition of Experimental Diets 1 Diet No. A B Unit 1 % Cornmeal 63.50 48.00 Soybean meal (49%) 25.70 33.10 Animal fat 1.60 9.20 Fish meal 4.00 4.00 Alfalfa meal (17%) 2.50 2.50 Limestone 0.40 1.00 Dicalcium phosphate 1.00 1.30 Salt 0.40 0.50 DL-Methionine 0.20 0.21 Vitamin premix1 0.50 0.50 TOTAL 100.00 100.00 Calculated Analysis: kcal. M.E./kg2 3080.00 3410.00 crude fiber (%) 3.10 2.90 total fat (%) 4.70 11.70 xanthophyll, mg/kg 3.80 3.05 crude protein (%) 21.24 23.60 energy:protein ratio3 145.00 144.74 1see Table 4. 2kilocalories of metabolizable energy per kilogram of diet. 3based on kcal. M.E./kg diet. 18 TABLE 4 Michigan State Starter-Grower Vitamin Premix No. 5003 (with Ethoxyquin) Micronutrients Per Kilogram of Starter—Grower Vitamin A, U.S.P. units Vitamin D3, I.C. units Riboflavin, mg Pantothenic Acid, mg Niacin, mg Choline Chloride, mg Vitamin B12, mg , Menadione Sodium Bisulfite, mg Vitamin E, I.U. Manganese, mg Iodine, mg Copper, mg Cobalt, mg Zinc, mg Iron, mg 8250 2750 24 550 2 80 5 312 61 .00 .00 5. 8. 10 30 .80 .00 12. 40 .10 2. 10 .00 1. 30 .00 .00 .50 31. 20 19 The body weight, feed consumption, and mortality of birds were recorded. The average weight gain, average feed consumption, and feed conversion were calculated for each group. There were 16 groups of birds composed of duplicate combinations of high and low energy diet, continuous and intermittent light, normal and high environmental temperature. Each group was analyzed separately for birds 3 to 8 weeks and 3 to 10 weeks of age. Statistical Procedure Significance of variation in growth, feed consumption and feed efficiency were tested by analysis of variance using a M.S.U. Hustler computer. The 0.01 or 0.05 levels of probability provide the basis for all statements concerning statistically significant difference. RESULTS AND DISCUSSION Body Weight The body weight gain of birds from 3 to 8 weeks of age are shown in Table 5. From Table 5, it is evident that the birds in the lot fed the high energy diet and raised under normal temperature and continuous light gained more weight (1827 g) than did birds in other lots. This result would be expected by examination of Figure I. As illus- trated in Figure I, the factors of high energy, normal temperature, and continuous light produced the greatest body weight gain. The birds in this treatment group would be expected to have the greatest weight gain. Using similar reasoning, the group with the lowest body weight gain would be expected from the birds receiving the treatments with the least body weight gain (low energy, high temperature, intermittent light) from Figure I. From Table 5, the lowest weight gain of 1537 g was from this group. A high energy diet was responsible for the largest body weight gain as compared with all other variables tested. The difference in the body weight gain of the high and low energy diet was statistically significant (P < .01). Normal environmental temperature significantly increased (P < .05) the body weight gain when compared to a high temperature environment. In three out of the four possible comparisons in Table 5, the birds raised in continuous light had a greater body weight gain than those raised in intermittent light. Also, in Figure I there is a difference 20 21 1.8 H - Z '1 ”Ha-3% __5 ‘1 6% =5 1. 3 '— E E] 3 1.! (I) 5 u: 53 >‘ 0.6 0.2 ENERGY" TEMPERATURE' LIGHT HIGH-Low 20°C-310C CONT-INTER CONT = CONTINUOUS INTER = INTERMITTENT SIGNIFICANCE: *P 5.0.05 ‘*P 5.0.01 FIGURE I AVERAGE BODY WEIGHT GAIN 0F BIRDS IN KILO- GRAMS FROM 3 TO 8 WEEKS OF AGE. 22 TABLE 5 Average Body Weight Gain in Grams of Birds from 3 to 8 Weeks of Age1 “ _ Temperature Treatment Average Gain for Period LC 1622a 0 LI 1627a 20 C HC 1827b HI 1649a LC 15708 0 LI 1537a 31 C HC 16423 HI 16418 L = low energy (3080 kcal. M.E./kg) H = high energy (3410 kcal. M.E./kg) C = continuous light I = intermittent light 1 Means with different postscripts differ significantly (P < .05) 23 of 3% between the two variables. Although birds raised under continuous light appear to have a greater body weight gain no statistically signifi— cant difference was found. Analysis of variance was used to study the effect of each variable and its interaction with the other variables on body weight gain of birds from 3 to 8 weeks of age. As shown in Table 6, there was no interaction between the three variables of energy, temperature, and light. Energy and temperature were the only significant factors affecting the body weight gain. The light regime had no significant effect. Table 7 shows the body weight gain for birds in 8 treatments from 3 to 10 weeks of age. The greatest body weight gain of 2458 g was in the group of birds that received the high energy diet, raised at high temperature and continuous light. The high energy diet was again re- sponsible for the greatest body weight gain as illustrated in Figure II. The 7% difference between high and low energy diets of birds from 3 to 10 weeks of age was slightly greater than the 6% difference in the body weight gain of birds from 3 to 8 weeks of age due to diet. The 1% and 3% difference in the body weight gain of birds raised in normal versus high temperature and continuous versus intermittent light were not statistically significant. Again, as with birds from 3 to 8 weeks of age, there was no statistically significant interaction between the 3 factors: energy, temperature, and light as seen in the analysis of variance, Table 8. Energy was the only significant factor affecting the body weight gain of birds from 3 to 10 weeks. Temperature and light had no significant effect. The literature consistently supports our finding that a high energy diet increased body weight gain. Siedler et al. (1953) reported that 24 TABLE 6 Analysis of Variance of Bird Weight Gain from 3 to 8 Weeks of Age Source of Variance Sum of Squares Degree Of Mean F Value Freedom Square Energy 40768.66 1 40768.66 l3.84** Light 10781.19 1 10781.19 3.66 Temperature 28092.27 1 28092.27 9.54* Energy & Light 5712.71 1 5712.71 1.94 Energy & Temperature 644.52 1 644.52 .22 Light & Temperature 4742.73 1 4742.73 1.61 Energy & Light & Temperature 11682.91 1 11682.91 3.97 Error 23565.32 8 2945.66 TOTAL 125990.32 15 Significance: *P S 0.05 **P 5 0.01 25 TABLE 7 Average Body Weight Gain in Grams of Birds from 3 to 10 Weeks of Age1 Temperature Treatment Average Gain for Period LC 22148: 0 LI 2238a 20 C HC 24343b HI 2305ab LC 21763b 0 LI 2189a 31 C HC 2458b HI 2240ab L = low energy (3080 kcal. M.E./kg) H = high energy (3410 kcal. M.E./kg) C = continuous light I = intermittent light 1Means with different postscripts differ significantly (P < .05) 26 T—_ _7% re :11 "'11__3% 2.| Z 3 g 1. E] 3 E g; 1.! $2 0.‘ ENERGY" TEMPERATURE LIGHT HIGH-LOW 20°C-310C CONT-INTER CONT = CONTINUOUS INTER = INTERMITTENT SIGNIFICANCE: **P :.0.01 FIGURE II AVERAGE BODY WEIGHT GAIN 0F BIRDS IN KILO' GRAMS FROM 3 TO 10 WEEKS OF AGE. 27 TABLE 8 Analysis of Variance of Bird weight Gain from 3 to 10 Weeks of Age w Source of Variance Sum of Squares Degree Of Mean F Value Freedom Square Energy 95920.28 1 95920.28 13.l7** Light 23938.28 1 23938.28 3.29 Temperature 4158.96 1 4158.96 .57 Energy & Light 27167.98 1 27167.98 5.10* Energy & Temperature 503.10 1 503.10 .07 Light & Temperature 2467.11 1 2467.11 .34 Energy & Light & Temperature 1524.90 1 1524.90 .21 Error 58274.87 8 7284.90 TOTAL 223955.49 15 Significance: *P < .05 **P < .01 28 body weight gain of birds fed added levels of fat was equal to or better than that of birds fed rations without added fat up to 9 weeks of age. waldroup et a1. (1976) reported that as the energy level of the diet was increased, bird body weights were increased. Experiments by Huston and Edwards (1961) indicated that the body weight gains in birds were increased with high energy diets at both 190C and 310C environmental temperature. From our results, birds raised at 20°C gained more weight than those raised at 310C from 3 to 8 weeks; whereas no significant difference was found from 3 to 10 weeks. Huston and Edwards (1961) re- ported body weight gains were lower at a high environmental temperature (310C) than at a lower temperature (19°C). This supports our findings in birds from 3 to 8 weeks of age. Similarly, Thomasson et a1. (1976) found that a high temperature of 29.40C reduced the body weight of turkeys in 8 weeks. An explanation of these findings was given by Harms et al. (1978) who states that in extremely hot weather birds do not consume enough feed to support maximum performance. Continuous and intermittent light patterns had no significant effect on body weight gain in our study. This result was supported by the work of Cherry and Barwick (1962), who found that different lighting patterns had no important effect on the body weight of broilers at 10 weeks of age. Moore (1957) found that chickens kept in continuous light grew faster than those given periods of darkness. This result was suggested by our data from Figure I and II where birds from 3 to 8 and 3 to 10 weeks of age had a 3% and 1% increase in weight respectively; although this in- crease was not statistically significant. 29 Feed Consumption The data on the average daily feed consumption in grams/bird/day from 3 to 8 weeks of age are presented in Table 9. The different dietary energy, environmental temperature, and light treatments had a highly significant (P < .01) effect on feed consumption (Table 10). The dietary energy level of the feed appeared to have a greater effect on feed consumption than did either temperature or light treat- ment (Figure III). Chickens consumed approximately 21% more low energy feed (3080 kcal. M.E./kg) than high energy feed (3410 kcal. M.E./kg). This increase may be explained in part by the fact that more low energy feed is required to supply the same amount of calories as that supplied by the high energy feed. Although this probably accounts for much of the increased consumption of the lower energy feed, it does not seem to account for the entire increase. The high energy feed contains about 10% more calories than the low energy feed. Therefore, the birds on the low energy diet would have to consume only 10% more feed to obtain the same amount of calories as those on the high energy feed, but they consumed 21% more feed. This leave about one-half of the increased feed consumption of the birds on a low energy diet unexplained. Feed consumption was decreased about 12% at the higher temperature and 10% with intermittent light (Figure III). This is probably because the birds at the lower temperature (20°C) had to use more energy to maintain their body temperature of 410C. Chickens are more active in continuous rather than intermittent light conditions; therefore, it would be expected that more feed would be consumed by chickens raised in continuous light. Using the results 30 TABLE 9 Average Daily Feed, Protein and Calorie Consumption of Birds from 3 to 8 Weeks of Age Temperature Treatment Feed gm1 Protein % Calories kcal./g LC 110.08 23.4 330 200C LI 98.2d 20.9 302 HC 86.9c 20.5 396 HI 77.8b 18.3 265 LC 96.5d 20.5 297 0 LI 98.5c 19.0 276 31 C HC 77.3b 18.2 264 HI 66.93 15.8 228 L = low energy (3080 kcal. M.E./kg) H = high energy (3410 kcal. M.E./kg) C = continuous light I = intermittent light 1Means with different postscripts differ significantly (P < .05) 31 TABLE 10 Analysis of Variance of Food Consumption by Birds from 3 to 8 Weeks of Age Source of Variance Sum of Squares Degree Of Mean F Value Freedom Square Energy 1819.96 1 1819.96 252.75** Light 369.24 1 369.24 51.29** Temperature 455.84 1 455.84 63.32** Energy & Light .09 l .09 0.01 Energy & Temperature 1.02 1 1.02 0.14 Light & Temperature 3.18 l 3.18 0.44 Energy 8 Light & Temperature 9.60 1 9.60 1.13 Error 57.61 8 7.20 TOTAL 2716.53 15 Significance: **P S 0.01 32 10' 21% 12% 10% 8| '1 - 6: Lu GRAMS/BIRD/DAY 20 ENERGYfl TEMPERATURE** LIGHTfl HIGH-Low 20°C-31°C CONT-INTER CONT = CONTINUOUS INTER = INTERMITTENT SIGNIFICANCE: **P 0.01 FIGURE III AVERAGE DAILY FEED CONSUMPTION OF BIRDS FROM 3 TO 8 WEEKS OF AGE. 33 in Figure III, one would expect the greatest amount of feed consumption from those birds in the group that received the low energy diet and raised at 200C in continuous light. From Table 9 the greatest con- sumption of 110 grams/bird/day was found in this group. Conversely, the lowest feed consumption would be expected from the birds in the group that received a high energy diet and were raised at 31°C in intermittent light. This was confirmed in Table 9 with the lowest consumption of 67 grams/bird/day from this group. When the effect on feed consumption of the different variables, energy, temperature and light were tested against each other; no statistically significant interaction was found (Table 10). Therefore, it appears that each variable acts independently of the others. The difference between the 3 factors of energy, temperature, and light were highly significant (P < .001). The data on the average daily feed consumption by birds from 3 to 10 weeks are presented in Table 11. Again, as in the 3 to 8 week group the greatest feed consumption (120 grams/bird/day) was found in the group of birds receiving the low energy diet, raised at normal tempera- tures and continuous light. Conversely, the lowest feed consumption of 87 grams/bird/day was found in the group of birds that received a high energy diet, raised at high temperature and intermittent light. The 15% greater consumption of low rather than high energy diets by birds from 3 to 10 weeks of age was less than the 21% difference in consump- tion from 3 to 8 weeks of age (Figure IV). There was a 6% difference in the feed consumption of birds raised in normal versus high temperature and in continuous versus intermittent light. This 6% difference was not statistically significant. 34 TABLE 11 Average Daily Feed, Protein and Calorie Consumption Of Birds from 3 to 10 Weeks of Age Average Daily Consumption Temperature Treatment Feed gm1 Protein % Calories kcal./g LC 119.8b 25.4 369 200C LI 107.0ab 22.7 329 HC 102.4ab 24.1 349 HI 94.6a 22.3 323 LC 108.7ab 23.1 335 3100 L1 108.6ab 23.1 334 HC 92.6a 21.8 316 HI 86.9a 20.5 296 L = low energy (3080 kcal. M.E./kg) H = high energy (3410 kcal. M.E./kg) C = continuous light I = intermittent light 1Means with different postscripts differ significantly (P < .05) 35 1'7 -. _. fl 7 IT 6% 100 152 H _ez 1 _ 80 2 E as 60 a E 40 20 L 5% ENERGY" TEMPERATURE LIGHT HIGH-LON 20°C-3l°C CONT-INTER CONT = CONTINUOUS INTER = INTERMITTENT SIGNIFICANCE: *‘P 5.0.01 FIGURE IV AvERAGE DAILY FEED CONSUMPTION OF BIRDS FROM 3 T0 10 WEEKS OF AGE. 36 Again, as with birds from 3 to 8 weeks of age, there was no statistically significant interaction between the 3 factors; energy, temperature, and light (Table 12). Energy was the only factor which significantly (P < .01) affected feed consumption of birds from 3 to 10 weeks of age. This is different from the results Obtained in birds from 3 to 8 weeks of age where all three factors (energy, temperature, and light) were significant. deAndrade et al. (1976), Fuller and Randon (1976), and Reid and Weber (1975) agreed with our findings that a high energy diet signifi- cantly reduced feed consumption. Using the data of Waldroup et al. (1976), feed consumption of broiler birds from 0 to 56 days drOpped about 6% when diets of 3080 kcal. M.E./kg (low energy diet) were com- pared to those of 3410 kcal. M.E./kg (high energy diet). Jones et a1. (1976) found no difference in feed consumption with different dietary energy levels of 2671, 2853, and 2992 kcal. M.E./kg. This may be because these energy levels are substantually lower than those of 3080 and 3410 kcal. M.E./kg used in this study. Thomasson at al. (1976) reported decreased feed consumption in turkeys with increasing temperature from 12.8 to 21.1 to 29.40C. This differential response to feed consumption was attributed to the different requirements of feed for body maintenance at the different temperatures. These results were the same as our findings of a significant effect of temperature on feed consumption in chickens from 3 to 8 weeks of age. Jones et a1. (1976) also found that at high temperatures of 35°C hens consumed significantly less feed than those at the control temperature of 21°C. These results are further supported by deAndrade et al. (1976) who used temperatures of 210C and 310C. 37 TABLE 12 Analysis of Variance of Food Consumption by Birds from 3 to 10 Weeks of Age Source of Variance Sum of Squares Degree 0 Mean F Value Freedom Square Energy 1130.98 1 1130.98 21.91** Light 179.41 1 179.41 3.48 Temperature 185.49 1 185.49 3.59 Energy & Light .02 1 .02 .01 Energy & Temperature 14.44 1 14.44 .28 Light & Temperature 52.77 1 52.77 1.02 Energy & Light & Temperature 27.01 1 27.01 .52 Error 412.93 8 51.61 TOTAL 2003.04 15 Significance: **P < 0.01 38 In this study, the results for chickens from 3 to 8 weeks of age were in agreement with those of Skoglund at al. (1964) who found that birds given a longer light period consumed more feed. The effect of light on feed consumption of birds from 3 to 10 weeks of age was not significant. The decreased importance of light on the feed consumption of older birds was described by Cherry and Barwick (1962). They found that as the age of the birds increased from 2 to 6 weeks the effect of light on feed consumption decreased. Feed Efficiency The feed efficiency of chickens from 3 to 8 weeks of age was best for the group of birds that received the high energy diet and raised at high temperature with intermittent light (1.43 grams feed/gram gain) (Table 13). This is more easily seen in Figure V, where it is shown that these same factors resulted in the greatest feed efficiency. Again, the opposing treatments of low energy, normal temperature, and continuous light resulted in the poorest feed efficiency in Figure V as well as in the group of birds raised under these three treatments (2.38 grams feed/ gram gain) (Table 13). Dietary energy levels produced the greatest difference in feed efficiency (26%). The birds receiving the high energy diet had the best feed efficiency (1.59 grams feed/gram gain) and those on the low energy diet had the least efficiency (2.16 grams feed/gram gain) Of the six variables (see Figure V). The differences between normal versus high temperature and continu- ous versus intermittent light of 7% and 8%, respectively, were only about 1/3 as great as that of dietary energy but they were still stignificant (P < .01). 39 TABLE 13 Feed Efficiency of Birds from 3 to 8 weeks of Age1 W Feed Efficiency Temperature Treatment gm feed/gm gain LC 2.38d 0 LI 2.11c 2° C HC 1.66b HI 1.65b LC 2.15c 0 LI 2.04C 31 C HC 1.65b HI 1.43a L = low energy (3080 kcal. M.E./kg) H = high energy (3410 kcal. M.E./kg) C = continuous light I = intermittent light 1Means with different postscripts differ significantly (P < .05) 40 2.0 _ _82 z 3 $2 1.5 8 E ‘9 1.0 0.5 _ ENERGY” TEMPERATURE" LIGHT** HIGH-Low 20°C-31°C CONT-INTER CONT = CONTINUOUS INTER = INTERMITTENT SIGNIFICANCE: **P 5 0.01 FIGURE V FEED EFFICIENCY IN GRAMS FEED/GRAMS WEIGHT GAIN FOR BIRDS FROM 3 TO 8 NEEKS OF AGE. 41 The analysis of variance (Table 14) showed a significant interaction between the three factors of energy, light, and temperature (P < .05) for birds from 3 to 8 weeks of age. Also shown in Table 14 is the signifi- cant difference in feed efficiency of each of the three variables tested (P S .01). The feed efficiency for birds from 3 to 10 weeks of age was similar to that of the 3 to 8 week group (Table 15). Again, the best feed effi- ciency of the 8 treatment groups was found in those that received a high energy diet, raised at high temperature, and with intermittent light (1.90 grams feed/gram gain), and the best in those birds that received the low energy, normal temperature, and continuous light (2.65 grams feed/gram gain) treatment. Although the dietary energy level again had the greatest effect on feed efficiency in birds from 3 to 10 weeks of age; the difference of 19% (Figure VI) was not as great as the 26% difference found in 3 to 8 week old birds. The difference in feed efficiency due to environmental temperature was much less from 3 to 10 weeks of age than from 3 to 8 weeks of age. This 3% difference was not statistically significant. Birds raised in intermittent light had a 6% greater feed efficiency than those raised in continuous light. This was slightly less than the 8% difference in feed efficiency due to light treatment found in the 3 to 8 week old group; although it was still statistically significant (P < .05). The analysis of variance of feed efficiency of birds from 3 to 10 weeks of age was different from that of the 3 to 8 week group. This time no interaction was found among the three variables (Table 16). Also, only the different energy and light treatment had a significant 42 TABLE 14 Analysis of Variance of Feed Efficiency in Birds from 3 to 8 Weeks of Age Source of Variance Sum of Squares Freedom Square Energy 1.31 1 1.31 267.68** Light .09 1 .09 l9.01** Temperature .07 l .07 14.95** Energy & Light .01 l .01 1.12 Energy & Temperature .01 l .01 .22 Light & Temperature .01 l .01 .14 Energy & Light & Temperature .03 1 .03 6.77* Error .04 8 .01 TOTAL 1.56 15 Significance: *P < 0.05 **P < 0.01 43 TABLE 15 Feed Efficiency of Birds from 3 to 10 Weeks of Age1 Feed Efficiency Temperature Treatment gm feed/gm gain LC 2.65: 0 LI 2.34 C 20 C HC 2.06ab HI 2.01a LC 2.4scg 0 LI 2.42C 31 C HC 2.04a HI 1.908 L = low energy (3080 kcal. M.E./kg) H = high energy (3410 kcal. M.E./kg) C = continuous light I = intermittent light 1Means with different postscripts differ significantly (P < .05) 44 G FEED/G GAIN ENERGYu TEMPERATURE LIGHT' HIGH-Low 20°C-31°C CONT-INTER CONT = CONTINUOUS INTER = INTERMITTENT SIGNIFICANCE: *P 5.0.01 **P 5.0.05 FIGURE VI FEED EFFICIENCY IN GRAMS FEED/GRAMS NEIGHT wGAIN FOR BIRDS FROM 3 TO 10 WEEKS OF AGE. 45 TABLE 16 Analysis of Variance of Feed Efficiency in Birds from 3 to 10 weeks of Age Source of Variance Sum of Squares Degree Of Mean F Value Freedom Square Energy .86 1 .86 91.66** Light .07 l .07 7.33* Temperature .02 l .02 1.77 Energy & Light .01 1 .01 .61 Energy & Temperature .00 1 .00 .00 Light & Temperature .01 1 .01 1.07 Energy & Light & Temperature .04 l .04 3.72 Error .08 8 .01 TOTAL 1.07 15 Significance: *P < .05 **P < .01 46 effect on feed efficiency of P 5 .01 and P 5 .05, respectively. Normal and high temperature had no significant effect on feed efficiency. The improved feed efficiency with increased dietary energy seems to be a consistent finding among researchers. Deaton et a1. (1973) found that the amount of feed required per unit of gain increased as dietary energy decreased. When Aitken et al. (1954) added 10% fat to the diet of birds from 0 to 10 weeks of age, the efficiency increased by 8%. waldroup et a2. (1976) used energy levels identical to those in this study. Using their data it was found that birds from 0 to 8 weeks of age receiving the high energy diet had a 9% increase in feed efficiency when compared to the low energy diet. This was significant to the 95% confidence level. Our results showed a much greater feed efficiency with a high energy diet than that found in the literature. This may be because the experimental period in this study did not include the period of 0 to 3 weeks of age, while the data in the literature included this period. Huston and Edwards (1961) reported that less feed was required per unit weight gain at the high environmental temperature of 31°C. A significantly better feed efficiency in birds from 3 to 8 weeks of age was found by Harris et al. (1975) as the temperature was increased from 26.700 to 350C. deAndrade et a2. (1976) found that feed conversion was improved with high temperature and that the best conversion was noted in the 310C environment. These results are similar to our find- ings in birds from 3 to 8 weeks of age. Birds from 0 to 8 weeks of age raised in intermittent light were found to have a 9% better feed efficiency by Buckland et al. (1973) compared to those receiving continuous light. Proudfoot (1975) also 47 reported that intermittent light treatment resulted in better feed con- version than continuous light treatment. He suggested that the larger rest period afforded by an intermittent light treatment may have con- tributed to this improvement in feed conversion. Cherry and Barwick (1962) did not find a significant effect of lighting patterns on feed efficiency. In our study, intermittent light improved feed efficiency in birds from 3 to 8 and 3 to 10 weeks of age. Mortality The percent mortality was calculated from the number of birds that died during the 3 to 10 weeks of age trial period. Data on the percent mortality of birds for the 3 to 10 weeks with varied light, temperature, and diet are shown in Table 17. The percent mortality for birds fed low energy diets (3080 kcal. M.E./kg) and raised under high temperature (31°C) was increased compared to low environmental temperature (20°C) and high energy diet (3410 kcal. M.E./kg) birds. The lighting scheme, either continuous or intermittent, had absolutely no effect on the mortality. The normal and high environ- mental temperatures had no significant (P > .05) effect on mortality. There appears to be an increase in mortality at high temperature and low energy diet versus normal temperatures and low energy diet. This difference of 2 dead birds at normal temperatures compared to 6 dead birds at high temperatures was not statistically significant (P > .05). The mortality of birds raised on a high energy diet was significantly greater (P < .05) than those on a low energy diet. Even though there was greater mortality for birds fed the high fat diet, their mortality was still only 11%. 48 TABLE 17 Mortality during the Experimental Period (3 to 10 Weeks of Age) W T - Number of Dead Birds Energy Levels (kcal. M.E./kg)* Treatment 3410 3080 NC 4 1 NI 5 1 HC 5 3 HI 4 3 TOTAL 18 8 NC = normal temperature and continuous light NI = normal temperature and intermittent light HC = high temperature and continuous light HI = high temperature and intermittent light *One hundred sixty birds started at each treatment level 49 An increase in mortality with high fat diet was described by Jackson et al. (1969), who noted that, in two experiments, there was a very high mortality rate (average 41%) of birds fed a diet that contained 28.5% fat (3980 kcal. M.E./kg). This was in comparison to mortality rates of 1% to 16% with birds on lower fat diets (1900 to 3060 kcal. M.E./kg). These results were in contrast to those of Reiser and Pearson (1949), who used lard and hydrogenated vegetable oils in bird starter rations and reported that addition of these fats produced no deleterious effects on the birds. The exact cause of the higher mortality of the birds fed the high energy diet is not known. The major cause of death in all groups of birds was diagnosed as leg abnormality by the M.S.U. Animal Health Diagnostic Laboratory. These results were similar to those re- ported by Scott (1978) on tibial dyschrondroplasia. Tibial dyschrondro- plasia is most severe in rapidly growing broilers being raised under hot weather conditions and is not prevented by any of the known nutrients. These observations agree with our findings. First, our highest mortality rate was for birds receiving a high energy diet. This was also the most rapidly growing group. Second, the addition of more vitamin premix to the feed did not prevent the occurrence of the leg abnormalities. Although the real cause Of the leg abnormalities is not clear, these abnormalities may be the result of genetic factors en- hanced by the high stress environment. SUMMARY An experiment was conducted to evaluate the effects of the addi- tion of fat in broiler chicken's diet in different environmental con- ditions and comparisons were made between low energy diet (low fat) and high energy diet (high fat). Test diets were also fed under different environmental temperature and light regimes as a basis for evaluating the comparative practical use of these two diets for birds. Body weight, feed consumption and feed efficiency were used as the criteria for making the comparisons. Commercial broiler type chickens were selected according to weight at three weeks of age. The selected birds were randomized into treat— ment groups with two replications per treatment. Each of the two repli- cations had twenty birds (ten of each sex). The total number of birds in the experiment was 320. The growth trial lasted for 10 weeks. Both diets were formulated to be isonitrogenous, but with one diet containing more added fat. Birds which were fed the high energy diet performed significantly better than those fed the low energy diet to 10 weeks of age under all environmental conditions; at which time the differences in average body weight gain, feed consumption and feed efficiency were significant at P 5 0.01. There was no significant difference in the body weight gain of birds from 3 to 10 weeks of age raised in continuous or intermittent light. Feed efficiency was significantly improved in chickens raised in intermittent light (P < .01 for birds from 3 to 8 weeks of age and P < .05 for birds from 3 to 10 weeks of age). 50 51 The mortality of birds raised on a high energy diet was signifi- cantly greater (P < .05) than those on a low energy diet. Although there was a greater mortality for chicks fed the high fat diet, their mortality was still only 11%. APPENDIX RANCIDITY TEST Introduction It is well known that poultry and other animals may suffer harmful effects from rancid fats in feed. Rancid fats tend to destroy carotene, Vitamin A, and other fat-soluble and water- soluble vitamins in feed as well as having direct toxic effects on the animal. Since fat rancidity is deleterious to poultry it should be kept to a minimum. Literature Review Fats and oils which have developed an objectionable odor and taste upon storage are said to be rancid. Rancidity is usually the result of chemical changes brought about by oxidation or hydrolysis. Hydrolytic rancidity is caused by simple hydrolysis of fat or oil into fatty acids, diglycerides, monoglycerides and glycerols by microorganisms. However, it has been shown that hydrolytic rancidity does not interfere with the nutritional value of the diet or the fat. Oxidative or peroxidation rancidity, which affects the unsaturated fats or oils, can lead to tremendous loss of their dietary energy value (Privett, 1959). Oxida- tive rancidity is enhanced by light, heat and the presence of some minerals such as copper, zinc, etc. which act as catalysts. Many essential dietary components are highly susceptible to oxida- tion. Oxidized feeds may have substandard nutritional value, which re- sults in low feed efficiency and less monetary return to the producer. Dugan (1961) reported that oxidative rancidity in food has been traced to the lipid portions, in which both the simple triglycerides and the 52 53 more complex phospholipids and lip0proteins may be involved. Scott et a1. (1976) reported that there are many factors other than the fatty acid composition of the fat which influence the oxidation process of fat in poultry diets. These include moisture, enzyme activity, pigment, nature of protein, acidity, nature of carbohydrate and trace minerals. Kraybill and Dugan (1954) mention that rancidity is not confined to food of high fat content. It may occur in cereals and other foods of relatively low fat content. Dugan (1961) reported that low temperature storage protects against or reduces the rate of oxidation. Materials and Methods At the start of this experiment two samples of each diet were stored in a paper bag for subsequent peroxide level determination. The samples were divided into two parts, each weighing approximately 500 grams. One portion was kept at 27°C and the other at 38°C. The samples were stored in two incubators to maintain these temperatures for the twenty-eight day holding period. All samples were treated similarly and after the twenty-eight day incubation were sent to the laboratory for testing. Results and Discussion Samples of the chicken's feed at the beginning of the experimental period were used to study the development of rancidity at high tempera- tures. The results obtained are shown in Table 18. The peroxide level varied with the amount of fat in the diet and the storage temperature. The results for the samples stored through 28 days indicated that the peroxide level (rancidity) increased as the fat in the diet and/or storage temperature increased. The peroxide 54 TABLE 18 Peroxide level of feed kept at high temperature for 28 days. Peroxide Levela Temperature Low Fatb High Fatc 27°C 33.7 35.0 38°C 63.7 69.6 aM.E./kg peroxide values above 10 indicate rancidity. b3080 kcal. M.E./kg. c3410 kcal. M.E./kg. 55 level (rancidity) appeared to be higher at 38°C than at 27°C. A higher storage temperature resulted in higher peroxide level in those samples which contained a greater amount of fat. This demon- strates the effect of storage temperature on fat oxidation. The fact that the low fat feed became very rancid, agrees with the findings of Kraybill and Dugan (1954), who indicated that rancidity is not confined to food of high fat content. The results of this study indicated that the storage of chicken feed under high temperature greatly increases the rancidity of fat. Since rancidity indicates deterioration and loss of the nutritional value of the feed, storage of feed at high temperatures should be avoided. Conclusion The rancidity of high and low energy feed increased greatly when stored at 38°C versus that stored at 27°C for 28 days. LITERATURE CITED LITERATURE CITED Ahmed, M.M., F.B. Mather and E.W. Gleaves. 1974. Feed intake response to change in environmental temperature and dietary energy in roasters. Poultry Sci. 53: 1043-1052. Aitken, J.R., G.S. Lindbald and W.G. Hunsaker. 1954. Beef tallow as a source of energy in broiler rations. Poultry Sci. 33: 1038. Barrott, H.G. and E.M. Pringle. 1951. Effect of environment on growth and feed and water consumption of chickens. IV. The effect of light and early growth. J. Nutrition 45: 265-274. Beane, W.L. and F.B. Siegel. 1965. Light environment as a factor in growth and feed efficiency of meat type chickens. Poultry Sci. T 44: 1009-1012. Buckland, R.B. and A.T. Hill. 1970. 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