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Blood glucose levels and skeletal muscle glycogen concentrations were observed in 160 male chicks. Observations were made in four age groups and two diets. Carbohydrate diets resulted in higher blood glucose levels and glycogen concentrations than did fat diets. Age was found to significantly influence glycogen concentration in both diets. The linear regression of skeletal glycogen on blood glucose levels was significant in carbohydrate fed chicks.

Two experiments were conducted to investigate the relationship of energy source, age and glucose-6-phosphatase activity in the chick. In the first experiment liver glycogen and glucose-6-phosphatase were assayed in chicks of four age groups being fed either a high-fat or high-carbohydrate diet. It was observed that the feeding of the high-fat diet resulted in higher glucose-6-phosphatase activity and lower glycogen levels than did the feeding of the carbohydrate diet. Age was found to significantly influence enzyme activity. Both glucose-6-phosphatase and liver glycogen were found to be negatively correlated in the fat fed chicks. In the second experiment chicks were fed either a high-fat or high-carbohydrate diet for 28 days. Liver glucose-6-phosphatase activity was determined in representative samples of chicks from each group to establish basal levels. The diets were then reversed for a three-day period, after which the chicks were returned to their initial diets. Glucose-6-phosphatase was analysed at each step. Variation in enzyme activity in the chicks initially fed the high-fat diet could be attributed to differences in body weight. However, those chicks originally fed the carbohydrate diet did exhibit a true metabolic adaption when fed the high-fat diet.

Muscle hexokinase was ascertained in the gastrocnemius muscles of 160 male chicks. Observations were made in four age groups and two diets. No differences in enzyme activity were observed which could be attributed to the feeding of either the high-carbohydrate or high-fat diet. Hexokinase activity declined significantly between 6 and 12 days of age in the chicks fed the respective diets.

Two experiments were conducted to investigate the response of two populations of chickens, divergently selected for high and low oxygen consumption, to varying protein levels. Protein levels used for Experiments 1 and 2 were 16, 18, 20, and 22% and 20, 22, 24, and 26%, respectively. The birds were weighed initially and weekly to 4 weeks of age. Feed consumption was ad libitum with amounts consumed recorded weekly. Gross feed efficiency was computed per pen as the difference between initial and weight at 4 weeks divided by feed consumed adjusted for spillage. The results from these experiments indicate that at low protein levels both lines were equally efficient, but, as the level of protein was increased, the low line was increasingly more efficient while the high line became less efficient. Gain for the low O2 birds was greater than the high O2 birds in all cases with both lines increasing in gains equally with increased protein levels.

Two experiments were conducted to investigate the effects of varying levels of pantothenic acid on the efficiency of energy utilization and changes in body composition of the growing chick. The results indicate that a pantothenic acid deficiency does not interfere with the chick's ability to obtain metabolizable energy from the diet. The data do show that the efficiency of energy utilization and body composition were markedly affected when chicks were fed diets deficient in pantothenic acid. In both experiments, protein, fat and energy stores were significantly reduced when pantothenic acid-deficient diets were fed. Increased estimates of heat increment per gram of diet were observed when levels of pantothenic acid below the N.R.C. (1971) recommended level of 10 mg. per kg of diet were fed.

This experiment involving 288 Coturnix quail was conducted to determine the effects of various fiber sources (alfalfa, wheat bran, dried brewer's grain, cellulose, and pectin) on serum, liver and egg yolk cholesterol, and egg production. The fiber sources were added at a rate to provide 6.25% fiber to a corn-soybean meal diet and fed for a 28-day experimental period. Serum, liver, and egg cholesterol levels were measured as pen composite samples at the end of the experimental period. No difference was exhibited in egg yolk cholesterol among any of the groups (P greater than .10). Liver and serum cholesterol levels were elevated in the birds fed the pectin and wheat brain diets as compared with that in birds fed the other fiber source; also, metabolizable energy intakes and eggs per hen day (EHD) were decreased for both groups. When data were adjusted for EHD by covariance analysis, the treatment differences no longer appeared (P greater than .05). These results indicate that 1) there is a basal quantity of cholesterol deposited in the egg on which fiber intake, energy consumed, or egg production have very little effect and that 2) there is an inverse relationship between serum and tissue cholesterol levels and the total quantity of cholesterol excreted via the egg.