Dietary energy and fat content as factors in the nutrition of developing egg strain pullets and young hens. 4. Effect on growth, hepatic lipogenic enzyme activity and body chemical composition of White Leghorn pullets from hatch to 20 weeks of age.

Nine starting and rearing diets (three energy levels each with three fat levels) were fed to commercial White Leghorn chicks from hatch to 20 weeks of age. As noted in the earlier papers of this series, pullets fed the high energy rearing diets showed significant (P = 0.05) reductions in feed intake, however, average daily caloric intake was greater (P = 0.05) for pullets consuming the low energy rearing diets. Fat content of the diet had not influence on either daily feed (g.) or caloric (kcal.) intake. Energy content of the diets failed (P = 0.05) to affect parameters related to body growth and development, hepatic citrate-cleavage and "malic" enzyme activity and liver or body composition. Fat content of the diet depressed hepatic enzyme activity while no effect was noted on body weight, liver weight or body composition. The onset of sexual maturity altered lipid metabolism in the developing pullets. Significant (P = 0.05) energy level by fat level interactions were noted in only two of the 20 parameters studied in this experiment. In vitro assay of hepatic citrate-cleavage and "malic" enzyme activity proved to be of little value in predicting hepatic lipogenic activity and subsequent effects on liver and total body composition.