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Two experiments were conducted with laying hens fed a corn-soy basal diet or diets containing fish meal, distillers dried grains with solubles (DDGS) or torula yeast formulated to be isocaloric and isonitrogenous with the basal diet. One half of the hens were kept at a temperature range of 13-24 degrees and the other half at 24-35 degrees for 49 days in experiment 2. Liver lipid content was significantly lower in hens fed DDGS (experiment 1) and DDGS or fish meal (experiment 2) than in hens fed the corn-soy basal diet, but it was not influenced by environmental temperature. Feeding DDGS or fish meal reduced lipoprotein lipase activity in adipose tissue. High temperature reduced plasma estradiol level but not thyroid hormone levels. Plasma estradiol in the hens fed DDGS or fish meal (experiment 1) and DDGS, fish meal or torula yeast (experiment 2) an plasma thyroxine and triiodothyronine in hens fed the DDGS or fish meal at 24-35 degrees in experiment 2 were significantly lower than that of hens fed the corn-soy basal diet. Significant correlations were observed between liver lipid content and plasma estradiol or thyroxine concentrations. These findings show that plasma estrogen and thyroxine levels were influenced by diet composition and that these hormones have a close relation to induction of fatty livers in laying hens.

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)

Six experiments were conducted using broiler chickens to study the effect of selenium (Se) or vitamin E supplementation of a corn-soybean meal diet on the immune response to coccidiosis. Immunized chickens fed diets supplemented with .25 ppm Se or 100 IU vitamin E/kg of diet had increased body weight gain and feed intake and a tendency for lower feed conversion ratio than chickens fed unsupplemented diet after a challenge with 150,000 oocysts of Eimeria tenella. In two experiments, chickens fed .25 and .50 ppm of Se and immunized against E. tenella had higher body weight gain and a tendency for higher feed intake and lower feed conversion ratio than unsupplemented chickens when challenged with 150,000 oocysts of E. tenella. Except for a reduction on cecal lesion scores and blood packed cell volume in Experiments 1 and 4, respectively, no dietary effect was observed on cecal lesion score or blood packed cell volume of immunized chickens. Dietary supplementation with selenium or vitamin E reduced mortality and increased body weight gain of nonimmunized chickens infected with E. tenella in three of four experiments. These studies suggest that immunization of chickens against coccidiosis is enhanced by Se or vitamin E supplementation.