Dietary Energy and Fat Content as Factors in the Nutrition of Developing Egg Strain Pullets and Young Hens

Abstract

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.

Níveis de lisina digestível para poedeiras Hy-Line W-36 em produção

“…Os resultados obtidos neste experimento estão de acordo com os valores de referência de Swenson (1996): glicose (130-270 mg/dL); ácido úrico (1-2 mg/dL); creatinina (1-2 mg/dL); albumina (1,6 a 2 g/dL); e proteína total (4-5 g/dL). Os níveis de proteína e de glicose no sangue (Tabela 7) foram diferentes dos reportados por Cunningham & Morrison (1977), de 3,9 e 252 mg/100 mL de proteína e glicose no plasma sanguíneo de poedeiras de 20 semanas de idade.…”

Body weight and/or fatness as potential determinants of the onset of egg production in broiler breeder hens

“…The latter is greatly increased at the onset of sexual maturity (see Introduction), but there appear to be limits to lipogenic capacity. Among the potential causes of this constraint might be mentioned dietary lipids (Lorenz et al, 1938;Balnave and Pearce, 1969;Cunningham and Morrison, 1977) and differential genetic improvement in rate of lipogenesis and intensity of egg production, but not necessarily restricted feeding (Pearce and Jackson, 1976). On the other hand, the storing of lipids in preparation for the laying process is exemplified by the storing of linoleic acid and subsequent depletion to satisfy egg production requirements (Balnave, 1971).…”