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Threonine is generally considered the third limiting amino acid after methionine and lysine in broiler production. Less information is available on the quantitative requirement of threonine for older broilers than for birds during the starter phase. The experiments reported here suggest that the threonine requirement for male broilers from 3 to 6 wk of age fed a 20% protein diet containing 3200 kcal ME/kg is no higher than 0.70%. The requirement for females is less. These requirement estimates are lower than those given in the 1994 National Research Council report.

Arbor Acres broiler breeder hens, 21 to 61 wk of age, were given the daily ME level recommended by the primary breeder for their age and level of production (100% AA) or were given 94 or 88% of that amount. The reduction in daily energy allotment had no effect on age at 50% or age at peak production, but there was a highly significant linear decrease in the eggs per hen from 165 +/- 2.8 in hens given 100% AA to 149 +/- 3.2 and 141 +/- 3.8 in hens given 94 and 88% AA. The percentage of nonlaying hens between 44 and 60 wk of age was substantially increased as daily energy allotment was reduced. The percentage settable eggs was significantly lower in the 100% AA group, but no differences in fertility or hatchability were seen. Chicks per hen fell from 123 +/- 2.4 to 116 +/- 2.4 to 102 +/- 2.6 as energy allotment was progressively reduced. Dietary energy allotment had no effect on egg weight, shell weight, shell characteristics, or proportion of albumen and yolk. Chick weight was unaffected but chicks' liver weight increased with increasing dam energy intake. Percentage lipid in hens' carcasses increased with increasing energy intake and percentage protein and percentage ash decreased.

The effect of high-protein barley flour (HPBF), cholesterol, and α-tocotrienol on tissue and egg cholesterol homeostasis of laying hens was investigated. Laying hens (eight per treatment) were fed a basal diet with 0, 5, or 10% HPBF in the presence or absence of 1% cholesterol for 8 wk. In a second experiment, laying hens were fed diets with 0, 10, or 20% added HPBF (± 1% cholesterol). In a final experiment, α-tocotrienol was incorporated into a basal diet at 0, 20, or 200 ppm and fed to laying hens for 6 wk. In all experiments, plasma and egg cholesterol concentrations were determined biweekly and upon termination of the experiment, liver and breast tissue samples were removed for cholesterol analysis. Inclusion of HPBF in laying hen diets did not significantly influence plasma or egg cholesterol concentrations. However, when fed in the presence of 1% cholesterol, HPBF significantly (P

Experiments were conducted to determine whether a diet with added dichloroacetate (DCA), an inhibitor of cholesterol biosynthesis, would influence plasma and egg cholesterol concentrations when fed to laying hens. In the first experiment, 62-wk-old laying hens (10 hens per treatment) were fed a control diet containing 0, 350, 700, or 1,400 ppm DCA for an 8-wk period. Egg production and size, feed intake, weight gain, and plasma and egg cholesterol were determined at biweekly intervals. In a second experiment, 36-wk-old laying hens (eight hens per treatment) received diets with 0, 3,000, or 6,000 ppm added DCA for a period of 6 wk. Production parameters and cholesterol measurements were conducted as in Experiment 1. Egg production and feed intake were significantly decreased with increasing levels of DCA in Experiment 1. In the second experiment, 6,000 ppm DCA sharply reduced feed intake, body weight, and egg production. Yolk weight and percentage yolk were significantly decreased by the higher levels of DCA used in Experiment 2. Total plasma cholesterol was not affected by dichloroacetate in either of the experiments. In contrast, egg cholesterol concentration increased by 10 and 37% in Experiments 1 and 2, respectively, in response to diets with added DCA when compared with the unsupplemented controls. Total egg cholesterol increased in response to dietary DCA in Experiment 1, but not consistently in Experiment 2 due to the decreased yolk size of the hens fed DCA. The results of these studies indicate that dietary DCA was not effective in reducing egg cholesterol concentrations.

Experiments were conducted to determine the effect of sorbose on feed consumption, egg production and size, and cholesterol metabolism of laying hens. In Experiment 1, 87-wk-old laying hens (10 per treatment) were fed diets containing 0, 10, or 20% sorbose for 4 wk. In a second experiment, 108-wk-old laying hens (eight per treatment) were fed a control diet, a diet with 10% added sorbose, or the control diet with intake restricted to the level of sorbose-treated hens for 4 wk. Feed consumption and egg production were recorded daily. Plasma and egg cholesterol levels were determined at 0, 2, and 4 wk. Plasma and egg very low density lipoprotein (VLDL) concentrations were determined after 4 wk. Egg production, feed intake, and body weight gain were significantly reduced by dietary sorbose. Egg and yolk weight and percentage yolk decreased in response to sorbose. Sorbose significantly reduced plasma cholesterol and VLDL by approximately 50%, compared with the hens fed a control diet. Egg cholesterol concentration (milligrams per gram of yolk) was significantly increased, although the reduction in yolk size resulted in similar total egg cholesterol (milligrams per egg). Restricting feed intake of laying hens significantly lowered plasma cholesterol, but not to levels comparable to that of sorbose-treated hens. The data indicate that substantial reduction of plasma cholesterol and VLDL by dietary sorbose was not accompanied by reduced egg cholesterol.

Dietary alpha-ketoisocaproic acid (KIC) was studied for effects on growth, feed efficiency, tissue cholesterol (TC) content, and immune response to a Newcastle disease virus (NDV) vaccination in broilers. In two experiments, broiler chicks were fed diets supplemented with graded levels of KIC to .54% of the diet. Feed efficiency, fat deposition, BW gain, and plasma cholesterol levels were determined at 3 wk. In a third experiment, broilers were fed diets supplemented with 0, .1, .2, and .4% KIC throughout the starter (0 to 3 wk), grower (3 to 6 wk), and finisher (6 to 7 wk) periods. Abdominal fat and plasma and breast TC were measured at 7 wk. In Experiment 4, levels of KIC to .6% were fed to broilers to determine TC content and to measure the immune response to NDV vaccination. Feed efficiency, BW gain, and percentage abdominal fat were not affected by KIC in any of the broiler experiments. The addition of KIC to broiler diets resulted in a significant reduction in breast (Pectoralis major) TC. Biceps (Biceps femoralis) TC, adductor (Pubo-ishio-femoralis) TC, and plasma cholesterol content was not affected by KIC. Geometric mean titers to NDV were not improved by KIC. The data indicate that KIC has no effect on growth or abdominal fat deposition, but may have a role in TC homeostasis.

Taurine, an amino acid synthesized from Met, primarily functions in bile acid conjugation. Four experiments were conducted to determine whether Tau supplementation of broiler cockerels and female turkey poults to 3 wk of age would influence performance and fat retention at different levels of dietary fat. In these experiments, Tau was added at 0 or .8% to a corn and soybean meal basal diet with dietary poultry fat added at 0, 5, or 10%. Taurine did not affect BW gain of broiler cockerels; however, in one experiment feed efficiency was improved (P less than .01) during the 1st wk and fat retention was improved (P less than .06) at 7 days of age. In experiments with turkey poults, dietary Tau did not affect weight gain but improved feed efficiency (P less than .01) during the 1st wk and decreased overall feed efficiency (P less than .01) in one experiment. Improvement of fat retention by Tau at 14 days was significant (P less than .02) in one experiment and approached significance (P less than .07) in the other experiment. Fat supplementation of both the broiler and turkey diets significantly (P less than .05) improved weight gain, feed efficiency, and fat retention. Supplementary Tau appears to have little effect on performance of broilers and turkeys.

Experiments were conducted to determine whether age of hen, weight of the egg, and sex of the chick affected fat retention and growth of the broiler chick. Chicks were fed a corn and soybean meal diet containing 5% supplemental poultry fat. In the first study, eggs from two ages of hens were compared (30 and 52 wk) with six egg weight classes per age. The second experiment consisted of three hen ages (31, 37, and 47 wk) with three egg weight classes per age. The results indicated that as hen age and egg weight increased, BW gain of the chicks increased but feed efficiency and fat retention were not affected. Females had improved fat retention when compared with males. When analyzed within each egg weight class, there was no age effect on fat retention, BW gain, or feed efficiency.

Feeding a 13% CP diet based on corn and soybean meal and supplemented with methionine to laying hens results in reduced egg weight in comparison with hens fed a corn and soybean meal methionine-supplemented diet containing 16% CP. An experiment was conducted to determine whether the egg weight reduction could be eliminated by supplementing the low-protein diet with additional lysine, methionine, and tryptophan or by adding glycine and glutamic acid to increase the amino nitrogen to a level equivalent to 16% CP. The influence of the dietary treatments on the weight of the major egg components was also determined. In a second experiment, the influence of time of day of feeding the 13 or 16% CP diets on egg weight and egg components was determined. Adding additional amino nitrogen in the form of glycine and glutamic acid or increasing the levels of lysine, methionine, or tryptophan individually or in combination failed to prevent the depression in egg weight of hens fed the lower protein diet. Measurement of egg components demonstrated that the reduction in egg weight was primarily associated with a reduction in albumen content of the egg. Feeding a high-protein diet from 1400 to 0800 h and a low-protein diet from 0800 to 1400 h resulted in egg weight equivalent to that from hens continuously fed the high-protein diet. The lower weight of the albumen in eggs from hens fed a 13% CP diet may be due to a lower availability of amino acids for protein synthesis during the 3- to 4-h period when the ovum is in the magnum.

In view of the relatively minor changes in the type of feed ingredients used by the poultry industry during the last 10 to 15 yr, it is unlikely that there will be any major changes during the next decade. There are developments, however, that could result in either minor or major changes in feed ingredient usage by this industry. Successful commercialization of certain cultivars of cereal grains with nutritional changes beneficial for use in poultry feeds could result in less use of conventional corn. The demand for certain specific human foods such as oils high in Omega-3 fatty acids will make some change in the availability of feed ingredients such as canola meal, and may result in the use of other feed ingredients to increase the content of these fatty acids in poultry products. Concerns with environmental contamination by waste products from poultry production may eventually dictate changes in poultry feed formulation to increase the efficiency of dry matter utilization of the diet. This could result in the use of phytase to improve phosphorus utilization, lower protein diets with higher levels of synthetic amino acids to lower nitrogen excretion, and possibly change processing of soybean meals to lower undigestible carbohydrate content. Increased alcohol production for fuel may lead to greater quantities of fermented grain by-products for poultry feeding.

Two experiments were conducted with White Leghorn laying hens to determine the influence of the dietary CP concentration on the requirement for TSAA. Supplements of 0, .05, .1, or .15% of DL-methionine (Experiment 1) and 0, .025, .05, .075, .1, or .125% of DL-methionine (Experiment 2) were each added to corn-soybean meal diet with 13,16, or 19% CP. Experiment 1 was conducted for 4 wk (four groups of 10 hens, 32 wk of age per treatment). Experiment 2 was conducted for 5 wk (three groups of 9 hens, 59 wk of age per treatment). Methionine supplementation significantly improved egg production in Experiment 2, and in Experiment 1, the increase in egg production approached significance (P = .077). Egg production was highly significiantly improved by increasing the protein level in both experiments. Egg weight was increased by methionine supplementation at all protein levels. For Experiments 1 and 2, respectively, the estimated requirement for TSAA in order to achieve maximum egg mass (grams of egg per day) was .61 and .54% for 13% CP, .61 and .65% for 16% CP, and .68 and .73% for 19% CP. The methionine requirement for maximum egg mass in Experiment 2 was .29%, .36 and .41% for 13, 16, and 19% CP, respectively, but was not unproved in Experiment 1 by increasing the concentration of protein. Feed per gram of egg, but not feed per dozen eggs, was improved by methionine supplementation at all CP levels. Body weight gain generally increased along with the CP levels and with methionine supplementation, but the methionine requirement for maximum body weight did not appear to increase along with the increase in protein concentration. The results of the present study show that the concentration of dietary protein should be considered when determining the requirement of laying hens for TSAA.

Experiments were conducted to determine the effect of supplemental α-ketoisocaproic acid (KIC) or Leu on layer performance and plasma and egg cholesterol levels. In the first experiment, 0, .09, or .27% KIC and .09 or .27% Leu were fed to 62-wk-old laying hens. In a second experiment, the same levels plus another level of .54% KIC and .54% Leu were fed to 32-wk-old hens for an 8-wk period. The basal diet or the basal diet supplemented with .27% KIC or .27% Leu were continued for 20 wk to determine the long-term effects of these supplements. In a third experiment, hens were fed 0, .1, .2, or .4% KIC for 8 wk. The addition of KIC and Leu to the hen diets did not affect percentage egg production, egg weight, shell thickness, or Haugh units. In Experiment 1, .27% KIC and .09% Leu significantly increased BW gain. Neither KIC or Leu significantly affected BW gain in Experiment 2 when measured at 8 or 28 wk. In the third experiment, diets supplemented with KIC increased significantly BW gain. In Experiment 1, .09% KIC and .09% Leu significantly reduced egg cholesterol at 4 wk. After 8 wk, .27% KIC reduced egg cholesterol significantly below the controls. No effect on plasma or egg cholesterol was observed in Experiments 2 and 3.

Three experiments were conducted to determine the effects of dietary orotic acid (OA) on laying hen performance, liver lipid content, and plasma and egg cholesterol levels. Laying hens were fed a basal diet supplemented with 0, .5, 1.0, and 2.0% OA for 8 wk. Performance of the hens and cholesterol levels were measured at biweekly intervals. In all three experiments, OA decreased (P less than .05) BW in a linear manner. In two experiments, OA caused a linear decrease in total liver lipid (P less than .05), and in a third experiment OA resulted in a quadratic effect (P less than .01) on liver lipid content. There were no effects observed by OA supplementation on egg weight, yolk weight, percentage yolk, or egg production. Orotic acid failed to influence egg cholesterol content in any of the biweekly measurements of the three experiments. In two experiments, total plasma cholesterol content was not influenced by OA supplementation. Orotic acid significantly reduced (P less than .05) free and total plasma cholesterol in a third experiment when measured at Weeks 4, 6, and 8 of the experiment. The data indicate that OA is an ineffective dietary supplement for reducing egg cholesterol levels in laying hens.

Four experiments were conducted with White Leghorn laying hens to estimate their requirement for tryptophan for optimal egg production and other parameters. In the first two experiments, the hens were fed a 14.5% protein diet supplemented with 0, .025, .05 and .075% L-tryptophan. The first experiment was conducted for 12 wk and the second for 55 wk. In the third and fourth experiments, the influence of protein concentration on tryptophan requirement was investigated. Diets formulated to contain 14, 16, and 18% protein were supplemented with 0, .02, .04, .06, or .08% L-tryptophan. Protein concentration in Experiment 3 was increased by increasing only soybean meal; in Experiment 4, it was increased by increasing all protein concentrates, resulting in the same ratio of tryptophan to protein. These experiments were conducted for 6 wk. Rate of egg production was significantly improved by tryptophan supplementation in Experiments 1 and 2, but production was inferior to that expected for commercial laying hens. The estimated tryptophan requirements were .137% of the diet and 123 mg/day per hen in Experiment 1 and .118% of the diet and 95 mg/day per hen in Experiment 2. Egg production was significantly increased by adding tryptophan to the 14% protein diet in Experiment 3 but not to the higher protein diets. The estimated requirement was .164% of the diet and 168 mg/day per hen. In Experiment 4, tryptophan supplementation significantly increased egg production at all protein percentages, and the requirement increased as the protein increased. Egg weight was not significantly affected by tryptophan supplementation in any of the four experiments. Hepatic lipid accumulation was generally not decreased by tryptophan supplementation.

Experiments were conducted to investigate the effect of feeding cimetidine (CIMET), ranging from 0 to 750 mg/kg, on vitamin D3 metabolism and eggshell calcification in laying hens fed two levels of vitamin D3 (500 and 2,000 ICU/kg). Final BW and feed intake were not significantly affected by either CIMET or vitamin D3 level. Feeding 500 and 750 mg of CIMET significantly decreased total egg production in hens fed either level of vitamin D3, but no differences were observed at lower CIMET levels. Tibia ash decreased significantly in hens fed 150 to 750 mg of CIMET, regardless of the vitamin D3 level. Plasma Ca and inorganic P concentrations were decreased in hens fed high CIMET levels (500 and 750 mg/kg) at Week 2, but no differences were observed at Week 4. Feeding CIMET (500 and 750 mg/kg) significantly decreased plasma 25-hydroxycholecalciferol (25-OHD3) levels at Week 2 in hens fed both vitamin D3 diets but not at Week 4. Eggshell breaking force, shell thickness, and percentage shell weight were decreased significantly by CIMET in all experiments; however, in one experiment, shell quality recovered by Week 8. These results suggest that the CIMET-induced reduction in bone mineralization, eggshell quality, and plasma 25-OHD3 levels could be due to interference of CIMET with vitamin D3 metabolism in vitamin D3-replete laying hens. Shell quality decreased in CIMET-treated hens fed the higher vitamin D diet even though 250-HD3 plasma levels were three times higher than in hens fed the lower vitamin D diet, suggesting that CIMET affected shell quality through some mechanism other than inhibition of 250-HD3 synthesis.

Performance of broiler chicks fed low protein diets supplemented with several essential amino acids (EAA) is generally inferior to that of birds fed a higher protein diet composed primarily of intact protein. Two experiments were conducted to determine whether lowering the minimum requirements of the EAA in proportion to the lowered protein concentration or equalizing the dietary amino nitrogen content by use of glutamic acid would prevent the reduction in performance. Chicks were fed the experimental diets from 7 to 21 days of age, and body weight gain, feed consumption, and feed efficiency were determined. In the first experiment, the chicks were fed diets with 23, 20, or 17% CP with minimum EAA set at 100% of the 1984 National Research Council (NRC) suggested requirements. Other groups were fed the 20% CP diet with EAA set at 93.5% or the 17% CP diet set at either 93.5 or 87.5% of the NRC requirements. In the second experiment, the 23% and 17% CP diets were fed, and glutamic acid was added at 3, 6, or 9% to provide the amino nitrogen equivalent of 23% protein with the minimum EAA set at 100% of 1984 NRC requirements. In the first experiment, body weight gain and feed efficiency, but not feed intake, were depressed by lowering CP content. Reducing the minimum EAA requirements in proportion to the reduction in CP failed to correct the difference in performance between the high and low CP diets. In Experiment 2, body weight gain and feed intake were reduced as intact CP decreased and glutamic acid increased, but feed efficiency was unaffected.(ABSTRACT TRUNCATED AT 250 WORDS)

Four experiments were conducted to investigate if the degree of activation of the microsomal mixed-function oxidase (MFO) system was related to the degree of growth depression associated with the addition of monensin to the diet. The experiments were conducted with broiler chicks in battery brooders in which the chicks were fed diets of various composition and containing monensin at 0 to 160 ppm. In all experiments, the activity of the MFO system was estimated by the change in the content of cytochrome P-450 in the hepatic microsomes. Activities of some microsomal enzymes were also measured in some of the experiments. Feeding a diet with 24% protein containing fish meal, alfalfa meal, and torula yeast significantly increased the activity of the MFO system in comparison with feeding an isonitrogenous and isoenergetic corn and soybean diet, but there was no difference between the diets in the toxicity of monensin as measured by growth rate. Supplementing a 16% protein but not a 24% protein diet with monensin significantly reduced growth rate. In none of the four experiments was there a statistically significant change in the hepatic content of cytochrome P-450 as a result of feeding monensin. Thus, variation in the magnitude of growth depression caused by monensin in diets of different protein concentration or ingredient composition does not appear to be explained on the relative degree of the activation of the MFO system.

Four experiments were conducted to investigate further the effects of V on hen performance and egg quality as well as on the ability of ascorbic acid and Cr to counteract the deleterious effects of V on interior egg quality. At 10 ppm, added V significantly reduced albumin quality as measured by Haugh units; and at 30 ppm and 100 ppm, respectively, significantly reduced rate of lay and feed consumption and also increased body weight loss. As measured by shell breaking strength or shell thickness, shell quality was not affected significantly by V (added to a maximum of 100 ppm). Ascorbic acid (100 to 5,000 ppm) effectively protected the hens from the reduction in albumen quality resulting from the addition of 10 ppm of V to the basal diet. Hen performance and egg quality were not significantly affected by adding 10 or 50 ppm of Cr to a diet with 10 ppm of added V, nor by adding 30 or 150 ppm of Cr to a diet with 30 ppm of added V. The added Cr failed to counteract the depressing effects of V on the Haugh units recorded, regardless of the composition of the basal diet.

SUMMARY. Copper sulfate was added to the diet of broiler chickens from 1 day to 3 weeks of age at the rate of 0.05% to 0.20% in order to evaluate its influence on the incidence of oral lesions. Both the incidence and severity of oral lesions showed a significant linear increase as the concentration of copper sulfate increased. Adding a level of sulfate equivalent to that produced by the highest level of copper sulfate failed to induce oral lesions. The severity of gizzard erosion also increased as the concentration of copper increased. Dietary copper sulfate supplementation should be considered a possible cause of oral lesions seen during the necropsy of avian species.

Three experiments were conducted with Single Comb White Leghorn laying hens kept in wire floored cages to determine the effect of supplementing practical rations with l -lysine. Wheat-based rations containing 20% distillers dried grains with solubles (DDG/S) depressed rate of egg production and egg weight below that obtained with rations containing no DDG/S. Adding l -lysine to the ration containing DDG/S corrected the depression in egg production and egg weight. A basal ration containing corn, 20% DDG/S and cottonseed meal was used to estimate the requirement of laying hens for lysine. The results indicate that a level between 666 and 788 mg. per hen per day is necessary for optimum performance. A summarization of recent published results suggests that the requirement for lysine is higher for hens fed rations containing wheat in contrast to corn. In either case, however, the requirement appears to be higher than that currently suggested by the National Research Council.

TWO experiments, of five weeks each, were designed to study the effect of protein source and level of dietary protein on hepatic and plasma lipids and incidence of liver hemorrhagein caged laying hens. Experiment 1 compared equicaloric (3.1 kcal/g) and isonitrogenous (12.5%) corn-fish meal and corn-soybean diets. An equicaloric 16.5% protein corn-soybean diet was included to assess the effect of dietary protein level. Fatty Iiver-hemorrhagic syndrome was induced under ad libitum feeding in birds fed the corn-soybean diet. The corn-fish meal diet reduced (P Influence of dietary protein source was reevaluated in Experiment 2 and the effect of adding selenium (0.3 mg/kg as Na2 SeO3) or a combination of trace elements (As, Br, Cr, F, Mo, Ni, Sn, V) to the corn-soybean diet on liver lipid accumulation examined. Results with respect to dietary protein source were similar to the previous experiment. Neither selenium nor the combination of trace elements had a significant effect on hepatic and plasma lipids. Adding selenium to the corn-soybean diet reduced incidence of liver hemorrhage to the same level as that observed with the corn-fish meal diet.

The effect of feed restriction of broiler chicks during the 2nd wk of age on subsequent feed consumption and body growth to 49 days of age was investigated in two studies. From 7 to 14 days of age, female and male (in parentheses) birds were allowed to consume feed providing 35(36) or 60(65) kcal/bird per day or ad libitum-fed diets containing either 1.5 or 3% glycolic acid. The period of restriction was followed by ad libitum feeding. A marked reduction in feed intake was achieved by both physical feed restriction and inclusion in feed of the chemical additive. Final body weights and feed:gain ratios (0 to 49 days) of the restricted birds were consistently less than for the unrestricted (control) birds. No significant differences were observed in abdominal fat or in breast muscle as a percentage of body weight. The results show that dietary glycolic acid can serve as an anorectic agent and replace the traditional physical feed restriction regimen.

Adding 900 p.p.m. silver (as silver nitrate) to a practical diet for chicks significantly depressed growth, increased wet and dry heart weight to body weight ratios and markedly increased mortality during a four-week experimental period. Blood packed cell volume was not affected. Supplementing the diet containing silver with 50 p.p.m. copper prevented cardiac enlargement and mortality, but only partially corrected the growth depression. Glycogen content of the heart was not affected, but aortic elastin content was significantly reduced by silver and restored to normal by supplemental copper. Dietary silver significantly reduced the copper content of blood, spleen, brain, liver, but except for the brain, the level of copper in these tissues was restored to normal by dietary copper supplementation. No significant differences in copper content of kidney tissue were observed among the treatments. Copper content of the excreta was not significantly increased by adding dietary silver, but was greatly increased by adding 50 p.p.m. copper to the diet containing silver. 9 references, 4 tables.

White Leghorn hens were fed a diet containing 0, 50, 100, or 200 p.p.m. of the anticoccidial drug monensin. A level of 200 p.p.m. reduced feed consumption, egg production, and egg weight, compared with birds receiving unmedicated feed. Weight loss was seen in hens receiving 100 and 200 p.p.m. monensin. Feed consumption decreased during the first week while the decrease in egg production was delayed until one week later. Levels of 50 and 100 p.p.m. monensin had no effect on egg production or feed consumption compared with unmedicated controls. No detectable effect was seen with any level of medication on Haugh units, egg shell thickness, or visible quality of eggs. A level of 100 p.p.m. monensin did not affect fertility and hatchability of eggs.

Three experiments were conducted to determine the nitrogen-corrected metabolizable energy (MEn) content of ground pearl millet [Pennisetum americanum (L.) Leeke]. On a dry matter basis, 40% ground pearl millet was substituted for an equivalent amount of glucose monohydrate (reference substance) to determine MEn using male broiler chicks. Food and excreta samples were analyzed for nitrogen, gross energy, chromic oxide, and dry matter. On a dry matter basis, the MEn content of the ground pearl millet ranged from 2.891 to 3.204 kcal/g, depending upon the pearl millet cultivar used. These results suggest that previously reported MEn values for pearl millet may be underestimated by up to 21%.

Four experiments were conducted using broiler chicks to study the effects of feeding a semipurified diet on coccidial infection. Chickens fed a semipurified diet and inoculated with E. tenella had a very mild infection with little or no mortality and no effect on body weight gain, feed intake, feed conversion ratio, and blood cell loss as judged by hematocrit. At necropsy the infected chickens had light cecal lesions. However, no difference in response was observed between chickens fed either the corn-soybean meal or the semipurified diet and inoculated with a mixture of E. acervulina, E. maxima, and E. brunetti. Chickens fed a diet composed of 25% of the corn-soybean meal diet plus 75% of the semipurified diet and inoculated with E. tenella had the same mortality as chickens fed the corn-soybean meal diet. Feeding chickens the semipurified diet as early as 6 days before inoculation did not affect the severity of E. tenella infection. No difference was observed in the intestinal or cecal pH or food passage time of noninfected chickens fed either the corn-soybean meal or the semipurified diet. No differences were found in the number of oocysts discharged between 2 and 9 hr after inoculation expressed as a percentage of the infective dose. The results of these studies show that a semipurified diet ameliorates infection of chickens with the cecal parasite E. tenella but not coccidial infections of the small intestine.

Four hundred and eighty sexed broiler chicks were fed corn-soy-oats-poultry oil-based diets of 2.9, 3.1, or 3.3 kcal/g in each of two trials in battery brooders. Diets were fed in either mash or crumbled form. Increasing dietary density increased chick gain, feed efficiency, and percent abdominal fat. Significant interactions were found between dietary density and diet form, indicating the slopes of the regression lines depicting the relationship between dietary density and gain, consumption, and percent abdominal fat are different for mash and crumbled diets. The interaction was most striking for percent abdominal fat: crumbling the low density diet increased percent fat by 23%, crumbling the high density diet decreased percent fat by 1%. Responses to dietary density cannot be assumed to be the same for mash and crumble or pellet-fed broilers.

The influence of dietary cereal on hepatic lipid metabolism was studied in adult Japanese quail and mature female chickens fed isoenergetic and isonitrogenous corn-soy and wheat-soy diets ad libitum. Hepatic lipid accumulation and rate of biosynthesis were significantly higher in birds fed the corn-soy diet. The differential response to the cereals was seen in ovipositing females but not in mature male quail. There were no significant concomitant changes in body composition, egg production, egg weight, body weight, feed, and energy intake. Results of sequential changes in hepatic lipid metabolism showed that reduction in liver fat was significant 2 to 3 weeks after feeding the wheat diet and was due to a significant reduction in rate of lipogenesis and the amount of triacylglycerols deposited. Plasma levels of free fatty acids and glucose were not significantly altered by the dietary regimes in laying hens. In Japanese quail fed the corn-soy diet, plasma glucose was elevated and there was evidence of impaired glucose tolerance. In vitro rate of oxidation of labeled palmitate was significantly higher in liver homogenates from birds fed the corn-soy diet. Addition of carnitine to the incubation mixtures resulted in an increase of equivalent magnitude for both treatments. Liver hemorrhages were observed in laying hens but not in Japanese quail. Addition of myo-inositol to the corn diet for Japanese quail failed to significantly alter hepatic lipid accumulation. These studies show that differences in liver lipid accumulation due to corn and wheat diets are related to changes in rate of lipogenesis.

Two experiments were conducted with cage layer hens to determine the effect of various levels of dietary brewers dried grains on liver fat accumulation and performance. The first experiment was conducted from September to February and the second from May to August. Liver fat per unit of body weight was significantly reduced by including 20% brewers dried grains in both pelleted and unpelleted diets below that observed with the corresponding basal diets in the summer experiment, but not in the winter experiment. An intermediate response was obtained with 10% brewers dried grains in the summer experiment. Adding 20% brewers dried grains significantly improved interior egg quality as measured by Haugh units in both experiments. Smaller increases in Haugh units were observed with lower levels of brewers dried grains. Egg production was not significantly different among the dietary treatments in the summer experiment, but was significantly lower with 20% brewers dried grains in the winter experiment. Adding lysine to the diet with the 20% brewers dried grains slightly improved rate of production, but not significantly (P > 0.05). Differences in egg weight, body weight change, fertility, hatchability of fertile eggs, egg shell quality, and feed consumption per hen per day were not significantly different among the dietary treatments in either experiment. Daily intake of calculated metabolizable energy calories per hen was reduced with 10% or more brewers dried grains in both experiments. The results indicate that economic evaluation of brewers dried grains for layer diets based solely on metabolizable energy content (1760 kcal./kg.) underestimates its value.

Two experiments were conducted to determine if differences in response of livers to estradiol administration in male broiler chicks would be observed if fed isonitrogenous and isocaloric diets of different composition. A polymethylsiloxane tube filled with estradiol dipropionate was implanted under the neck skin to ensure a constant release of hormone. Different tube sizes were implanted in two- to three-week-old chicks fed a basal corn-soybean meal (CS) diet or a diet containing fish meal, alfalfa meal, and torula yeast (FAY) o distiller's dried grains with solubles (DDGS). Body weight gains were significantly reduced by the highest level of estradiol in chicks fed the CS diet but not chicks fed FAY or DDGS. Liver weight, deposition of lipid in liver and plasma lipid were markedly increased in proportion to the size of estradiol tube in chicks fed all diets. Increase of liver weight and lipid deposition by the highest level of estradiol in chicks fed the CS diet was significantly greater than that in chicks fed the FAY diet. Liver weight and the liver lipid response to estradiol in chicks fed the CS diet were significantly greater than that in chicks fed the FAY diet when dose response equations were compared among diets. These data show that the response on deposition of lipid in liver to estrogen administration was modified by the type of ingredients included in diets with similar energy and nutrient profiles.

Including 120 to 250 mg./kg. additional copper in practical broiler rations significantly affected the cecal appearance. The ceca were distended and the contents were darker in color and more pasty in consistency, compared to controls. Adding monensin sodium, gentian violet, or ferrous sulfate alone or in combination with copper to the ration did not significantly change the appearance of the ceca. Copper concentrations in the cecal contents reached levels above 5000 mg./kg., suggesting that the mechanism of action of copper in changing the appearance of the ceca may be related to an inhibition of normal fermentation that occurs in this part of the gastrointestinal tract. Sulfate, chloride and carbonate forms of copper all significantly changed cecal appearance, but the oxide did not, nor did a non-copper containing sulfate source. Macroscopic appearance of the gizzard lining and the proventriculus was also significantly changed by adding 240 mg./kg. copper to the diet, and liver weight and lipid content of liver dry matter were significantly increased. 3 references, 5 tables.

A severe muscular dystrophy developed in broiler breeder hens involved in environmental studies at the University of Georgia. Necropsy of birds at approximately 27 weeks of age that had died or were paralyzed revealed severe myopathy of leg, cardiac, and pectoral muscles. The hens had been fed practical diets ad lib., containing supplements of vitamin E, ethoxyquin, and D, L methionine. Birds were kept in three environmental chambers in cages at different temperatures (2 to 13, 13 to 24 and 24 to 35 C). Those kept in the highest temperature had the highest mortality. At approximately 30 weeks of age, one-half the surviving hens in each temperature room were kept on the same practical breeder ration, and the other half was fed the same ration supplemented with .5 mg selenium, 55 IU vitamin E, and 1 g D,L methionine per kg of diet. After 8 weeks, mortality for control hens was 0, 27, and 71% respectively, for the three temperature ranges, and for the treated hens, 4, 7, and 32%. Plasma glutamic oxaloacetic transaminase activity was elevated at all temperatures initially but lowered in both the treated and control groups after 8 weeks. Plasma glutathione peroxidase activity was relatively high initially for birds in all temperatures and was higher for the treated hens at all temperatures at the end of the experiment. Gross lesion scores for myopathy of two hens for each treatment at the end of the experiment were higher for hens fed the unsupplemented diets and increased as environmental temperature increased.

A survey of the cholesterol content of eggs obtained from commercial sources in Georgia was conducted. Data on flock age, egg-production rate, strain, molting status, as well as dietary protein, fat, ME, and the content of animal by-products were obtained from producers via a questionnaire. Mean egg cholesterol level, determined by an HPLC procedure, was 195 mg/egg, which is substantially lower than that commonly included in tables of egg composition. The total cholesterol content correlated positively with egg weight and yolk weight and negatively with egg production and dietary protein levels, but no significant (P

Two experiments were conducted with Large White male turkeys to investigate the lysine requirement from 12 to 22 weeks of age. Six pens of 20 turkeys were fed each of the experimental diets. In experiment 1, a basal diet containing wheat, meat meal, cottonseed meal and distillers dried grains with solubles was supplemented with four levels of l -lysine. Lysine at 4.27% of protein and 2.31 g./mcal. of metabolizable energy from 16 to 20 weeks of age, and 1.83 g. from 20 to 22 weeks of age was inadequate for optimum growth and feed efficiency (16–22 weeks). Supplementing the diet with lysine from soybean meal gave performance equivalent to synthetic lysine, indicating that it was fully available. Performance of turkeys fed a diet containing 88% triticale from 16 to 20 weeks of age, and 72% from 20 to 22 weeks of age was equivalent to that of turkeys fed a more complex ration with an equivalent level of lysine. In experiment 2, Large White male turkeys were fed a basal diet composed largely of triticale and soybean meal from 12 to 20 weeks of age with different levels of added lysine. From 12 to 16 weeks of age, 3.11 g. lysine/mcal. of M.E. (4.9% of protein) was adequate for optimum growth and feed efficiency. From 16–20 weeks of age 2.36 g. lysine/mcal. of M.E. (4.3% of protein) was adequate for optimum performance. Although the estimated requirement from 16 to 20 weeks of age based on the two experiments differs (perhaps because of differences in lysine availability), the results suggest that the current N.R.C. recommendation may be higher than necessary.

Six experiments were conducted with male broiler chicks kept in battery brooders to investigate the effects of feeding diets high in copper on the integrity of the gizzard lining. Conventional and corn starch-soy basal diets were used. Slight improvements in body weight gain and/or feed efficiency were observed when the diets were supplemented with 250 p.p.m. copper as as CuSO4-5HSO, but higher levels (500 to 1000 p.p.m.) depressed growth and decreased feed efficiency. Little or no gizzard erosion was seen in birds fed the practical ration without added copper. Gizzard erosion was observed with 250 p.p.m. copper and the severity of the condition increased with higher levels. With the same level of copper supplementation, severity of gizzard erosion was greater when chicks were fed the corn starch-soy diet than when fed the practical diet. Adding 0.5 p.p.m. selenium to the practical diet containing 1000 p.p.m. copper slightly improved the appearance of the gizzard lining, although the subjective scoring index was significantly (P less than 0.05) lower in only one of two experiments. The addition of zinc, vitamin E, and vitamin B12 did not prevent the gizzard damage caused by high copper levels. Severity of gizzard erosion was significantly reduced by adding 0.35% cholic acid to the semipurified diet with 500 p.p.m. copper, but not to the practical diet with 100 p.p.m. copper. There was no correlation between acidity of the gizzard contents and severity of the erosion.

Studies were conducted to determine the effects of high levels of dietary silver nitrate and copper sulfate on the response of chicks to toxic levels of dietary selenium. Adding 5 ppm or more selenium to a basal stock diet significantly reduced growth rate, and 40 ppm or higher significantly increased mortality during the 2-week experiments. Dietary silver or copper (1,000 ppm) counteracted the growth depression and prevented mortality at the higher levels of selenium. Hepatic selenium reached a maximum in chicks fed the basal diet with 10 ppm dietary selenium. Hepatic selenium of chicks fed silver was less than that of the control chicks when diets containing 10 ppm or less selenium were fed. Adding copper to the diet resulted in considerable accumulation of selenium in the liver, which was evident even at the lower levels of added selenium. Results of an experiment to determine the effects of dietary silver and copper on the distribution of /sup 75/Se administered either orally or intramuscularly showed that silver interfered with absorption of selenium. The results of these experiments suggest that silver modified selenium toxicity both by interfering with selenium absorption and by causing the accumulation of a nondeleterious selenium compound in themore » tissues. Copper modifies selenium toxicity primarily by causing the accumulation of a nondeleterious compound in the tissues.« less

Three experiments determined if the methionine requirement of broiler chicks was affected by coccidial infection. Chicks were fed a corn-soy or a corn-soy-pea basal diet containing 0.73% and 0.62% total sulfur amino acids (TSAA), respectively. Levels of 0 to 0.45% DL-methionine were added, with and without 0.01% monensin sodium. In two experiments, the chicks were inoculated at two weeks of age with a mixture of oocysts of E. acervulina, E. maxima, E. tenella, E. necatrix and E. brunetti. Lesion scores on the intestines and ceca, and blood carotenoid levels were determined at three weeks. The experiments were terminated at four weeks. A level of methionine greater than 0.47% and of TSAA greater than 0.83% was necessary to obtain maximum growth rate in uninoculated chicks. No evidence of dermatitis was observed. Growth rate and feed efficiency of chicks infected with coccidiosis were more severly depressed when the diet was not supplemented with methionine. Infections of coccidia and low levels of methionine, which in themselves did not produce any significant change in weight gain, did give a significant weight depression in combination. Adding monensin to the diet prevented a reduction in growth rate and feed efficiency of inoculated chicks fed adequate methionine. Monensin did not completely prevent the adverse effects of a coccidial infection, based on feed efficiency, when chicks were fed diets inadequate in methionine. Blood carotenoid levels were not affected by methionine level, but were significantly lowered by coccidial infection in the absence of monensin. Intestinal and cecal lesions in inoculated chicks were significantly reduced by including monesin in the diet. Although the coccidial infection more severly affected the performance of chicks fed diets deficient in methionine, satistical analysis of pooled data indicated no difference in the quantitative requirement of chicks for methionine. Therefore, a level of methionine and cystine adequate for optimum growth under the coccidial-free conditions should be adequate for chicks when infected with coccidia.

Two experiments were conducted with Single Comb White Leghorn laying hens to determine the effect of dietary additions of selenium, choline, inositol, vitamin B12 and vitamin E on liver fat accumulation and other criteria. In Experiment 1, adding 1 p.p.m. selenium to corn-soybean meal rations, with and without added fat, significantly reduced total fat accumulation per liver. Adding a combination of choline, inositol, vitamin B12 and vitamin E to the corn-soy diet without added fat significantly reduced liver fat accumulation and percent fat of the liver. On the other hand, a wheat-pea-fat basal containing about half the selenium content of the corn-soy diets resulted in a liver fat accumulation significantly lower than that observed with the corn-soy basal diets. Adding selenium or the lipotropic mix to this diet failed to significantly affect fat accumulation. None of the dietary treatments significantly affected egg production, egg weight, and body weight changes. In the second experiment, individually supplementing a corn-soy-fat basal ration with vitamin E, inositol, vitamin B12, choline and selenium or combinations of these nutritional factors failed to significantly affect liver fat accumulation or other criteria measured. The fat accumulation tended to be lower with choline supplementation, but the effects were not statistically significant (P > .05).

Phosphorus from ammonium polyphosphate was equivalent in availability to that of other phosphate sources commonly used in broiler rations, and it was more available than that from reagent-grade tricalcium phosphate. Two three-week experiments conducted with broiler chickens showed that growth rate, feed efficiency, viability, and bone calcification were improved to a similar extent by adding an equivalent increment of phosphorus from dicalcium phosphate, defluorinated phosphate, or ammonium polyphosphate. The results of these experiments suggest that ammonium polyphosphate may be a useful phosphorus supplement for practical poultry rations.

Estimates of the N-corrected metabolizable energy (MEn) of meat and bone meal (MBM) were made using different methods of bioassay and different levels of dietary substitution. In general, significantly higher MEn values were obtained with 20% than with 40% substitution. Experiments were conducted in an attempt to determine the reason for the lower MEn values at higher dietary MBM levels. The MEn of a simulated MBM consisting of isolated soybean protein, tallow, and minerals with a proximate analysis similar to that of MBM was not lowered by increasing the level of substitution. The MEn of hexane-extracted MBM still was significantly lower at 40% than at 20% substitution. Synergism between types of fatty acids appears to play an insignificant role in the energy differences. In nitrogen metabolism studies, no evidence was obtained that reduced protein digestibility accounted for the lowered MEn values at higher levels of MBM. The average MEn value of MBM determined by the dietary substitution method at 40% was 2.029 kcal/g on an “as is” basis [similar to that of the table value of the National Research Council (1984)]. An MEn value between 2.3 and 2.5 kcal/g appears more appropriate when MBM is used at practical levels in balanced poultry diets.

The purpose of this study was to determine if length of time of feed withdrawal of broilers prior to slaughter could affect the lipid content of their livers. Seven-week-old male broilers were allocated to three treatments: 1) no feed and water, 2) no feed, and 3) feed and water ad libitum. Those in the first treatment were held in plastic coops and those in the latter two treatments were kept in floor pens. Eight birds were randomly sampled initially and eight birds from each treatment at 4, 8, 12, 16, and 24 hr after the start of the study. The birds were weighed, killed, and the livers removed and analyzed for lipid content. The regression slopes of the two treatments without feed for body weight, liver weight, liver weight per unit body weight, and liver fat per unit body weight were significantly different from the control treatment. The slopes for liver fat were not significantly different among treatments. No obvious differences in the gross appearance of the livers were detected. The occasional problems with fatty livers in commercial broilers apparently cannot be accounted for by the length of time of feed withdrawal before slaughter.

Injecting White Leghorn chicks every other day with 20 mg ascorbic acid significantly reduced the increase in liver weight and lipids caused by feeding a diet with 0.1% dienestrol diacetate. In chicks fed two different basal diets containing 0.1% dienestrol diacetate, injecting chicks every other day with 20 mg alpha-tocopherol did not significantly reduce liver weight or lipids while the ascorbic acid injections did. Injecting meat-type chicks implanted with estradiol with 10 mg ascorbic acid daily significantly reduced liver weight, liver lipids, and plasma estradiol, but injecting with 8 mg alpha-tocopherol daily had no significant effect.

Three experiments were conducted to determine effects of dietary CP level and essential amino acid (EAA) content upon female broiler performance during the grower period (21 to 42 days). In each experiment, the design included a diet containing a conventional CP level (17.8 to 19.0%) and a low CP diet (15.9 to 16.7%) supplemented with several EAA. Regardless of CP content, all diets were formulated to meet National Research Council requirements in 1984 of EAA and to be isocaloric. As additional treatments, modifications of the low CP diet were made in an attempt to improve broiler performance. In Experiments 1 and 2, body weight gain (BWG) and feed efficiency (FE) were significantly impaired by feeding the low CP diet despite various combinations of increased levels of methionine, lysine, arginine, threonine, isoleucine, and tryptophan. In Experiment 3, BWG and FE were not significantly influenced by dietary CP level. Feed intake was unaffected by treatment except when a high level of glutamic acid (GLU) was added; this lowered the intake. The low CP diets increased abdominal fat deposition, which was prevented by 5% GLU supplementation. Breast yield was not affected by diet composition. Plasma free amino acids responded, in some cases, to changes in dietary EAA content.

The metabolizable energy (ME) value of meat and bone meal (MBM) appears to be underestimated in the 1984 National Research Council (NRC) table of composition. Two experiments were conducted with broiler chickens from 3 to 7 wk of age to study their response to diets formulated with MBM assigned different ME values. Broiler grower (3 to 6 wk) and withdrawal (6 to 7 wk) diets containing 10% MBM were formulated using ME values of 1,960 (1984 NRC table), 2,250, or 2,500 kcal/kg for this ingredient. Corn-soy grower and withdrawal diets containing no MBM were also fed. No significant differences in body weight (7 wk) were observed in either males or females fed the diets. Feed:gain ratios were not different among males but in one experiment ratios for females fed the MBM diet formulated on the 2,500 kcal/kg ME basis were nonsignificantly higher than ratios for those fed the corn-soy diet. Abdominal fat as a percentage of body weight of males fed the diets containing MBM calculated on the 1,960 or 2,250 but not the 2,500 ME basis was significantly higher than that of males fed the diet without MBM. No significant differences in abdominal fat content were observed in females fed the different diets. The results show that an ME value higher than that given in the NRC table should be used for MBM in practical diets and that females are less sensitive than males to the influence of calorie:protein ratio on abdominal fat deposition.

Three experiments were conducted to determine the effects of dietary CP, essential amino acid (EAA), and K content upon male broiler performance during starting and growing periods (7 to 21 and 21 to 42 days, respectively). In Experiment 1, five grower diets formulated to be equal in K content and containing the following analyzed CP contents were used: 21.9, 19.1, and 16.2% with and without L-glutamic acid (GLU) supplementation or 10% increased levels of arginine (ARG), threonine (THR), isoleucine (ILE), and tryptophan (TRP). Seven diets containing the following analyzed CP contents were fed in Experiment 2: 21.5%, 19.6% with and without K supplementation, and 16.0% with and without K supplementation and/or 10% increased levels of ARG, THR, ILE, and TRP. In Experiment 3, four starter diets containing the following CP contents were fed: 24.5%, and 17.8% without and with added K. In all three experiments feed efficiency (FE) was lower and in Experiments 1 and 2, abdominal fat deposition (AFD) was higher with lower levels of dietary CP. Lower body weight gains (BWG) occurred with lower levels of dietary CP in Experiments 2 and 3, but not in Experiment 1. Adding extra ARG, THR, ILE, and TRP to the lowest CP diet sometimes improved FE, but had no effect on BWG or AFD. Supplementation with GLU or K failed to influence BWG or FE. However, addition of GLU was associated with lower AFD. Maximal performance generally was not obtained with the low CP, amino acid-fortified diets.

A series of experiments was undertaken to further investigate the influence of diet composition on chick response to monensin supplementation. Experiments were conducted to determine the effect of monensin on growth rate and hepatic Rb and K content as affected by dietary content of V, K, or protein. A factorial experiment involving V levels of 0, 5, 10, or 20 ppm and monensin levels of 0, 120, or 160 ppm was conducted with broiler chicks to 4 weeks of age. Growth rate was significantly depressed by 10 or 20 ppm V but not by monensin. Hepatic K content was not affected by dietary treatments. In another factorial experiment, effects of levels of 0 and 120 ppm monensin and 0 and 5 ppm V were compared. Growth rate was significantly depressed by both V and monensin but with no significant interaction. Neither hepatic Rb or K content was significantly altered by the supplements. A third factorial experiment involved monensin levels of 0, 120, or 160 ppm, added K levels of 0 or .3%, and dietary protein levels of 16 or 24%. Body weight at 3 weeks of age was significantly depressed by 160 ppm monensin in the high protein diet and by 120 or 160 ppm in the low protein diet. Added K did not counteract the growth depression. Hepatic Rb content was increased by monensin and significantly reduced by K supplementation. Hepatic K content was not increased by K supplementation. Chicks fed the low protein diet had significantly lower concentrations of hepatic Rb and K than those fed the high protein diet.

The interrelationships among dietary composition, environmental temperature, and level of estradiol (E2) administration on hepatic lipid deposition in chicks were studied. Two levels of E2 were injected at three intervals over a 4-day period, in 3-week-old male Leghorn chicks fed either a corn-soybean meal (CS) diet or a diet containing fish meal (FM) after 2 days fasting. The chicks were subjected to temperature ranges of 15 to 24 C (low) or 24 to 35 C (high) at 2 weeks of age. The E2 (in silastic tubes) was also implanted subcutaneously in 3-week-old broiler chicks fed either the CS diet or a diet containing fish meal, alfalfa meal, and torula yeast (FAY) from day of age to 6 weeks. They were subjected to the high and low temperature ranges at 3 weeks. Liver lipid deposition markedly increased with E2 administration among chicks fed all diets within both temperature ranges. Liver lipid was significantly greater at 24 to 35 C than at 15 to 24 C among estrogenized chicks. Feeding the FM or the FAY diet decreased hepatic lipid accumulation as compared to feeding the CS diet, but the ameliorative effect of the FM diet on hepatic lipid deposition was not observed at the low temperature or at the lower level of implantation. It was concluded that a range for estrogen administration exists wherein dietary effects are expressed. These data indicate that environmental temperature, dietary composition, estrogen level, and their interactions influence hepatic lipid deposition and also suggest that high temperature augments liver response to estrogen.