RESUMEN
We examined the effect of dietary conjugated linoleic acid (CLA) on growth performance and liver composition in broiler chickens. Day-old male broiler chicks were assigned to receive a diet supplemented with corn oil (5%; n = 48) or CLA (5%; n = 48) for 21 d. Broilers fed CLA weighed less and grew at slower rates than broilers fed corn oil. Feed intake and feed conversion were higher for the corn-oil group than for the CLA dietary group. Hepatic lipid and triacylglycerol concentrations were significantly reduced by dietary CLA. The proportions of saturated fatty acids (SFA) in liver lipids increased, whereas those of monounsaturated fatty acids (MUFA) decreased with CLA supplementation. Although the total concentration of polyunsaturated fatty acids (PUFA) did not change with dietary treatment, the concentration of linoleic acid as a percentage of total methylated fatty acids decreased, and that of linolenic add increased in broilers fed CLA. The concentration of CLA isomers in liver lipids increased substantially with CLA feeding. The relative proportion of the c9,t11 CLA isomer in hepatic lipids was much higher than that of the t10,c12 or t9,t11 CLA isomers. These studies provide evidence that feeding CLA to broilers results in substantial reduction in liver fat accumulation and promotes CLA incorporation into hepatic lipid pools.
Asunto(s)
Pollos/fisiología , Dieta , Ácidos Grasos/análisis , Ácido Linoleico/administración & dosificación , Lípidos/análisis , Hígado/efectos de los fármacos , Fenómenos Fisiológicos Nutricionales de los Animales , Animales , Ingestión de Alimentos/efectos de los fármacos , Ácido Linoleico/análisis , Hígado/anatomía & histología , Hígado/química , Masculino , Tamaño de los Órganos/efectos de los fármacos , Triglicéridos/análisis , Aumento de Peso/efectos de los fármacosRESUMEN
Eight lactating Holstein dairy cows (80 d in milk) were used to examine the effects of exogenous bovine somatotropin (bST) on hepatic contents of mRNA encoding pyruvate carboxylase (PC), phosphoenolpyruvate carboxykinase (PEPCK), and microsomal triglyceride transfer protein (MTP). Concentrations of bST in plasma were higher and milk production increased 20% in bST-treated cows. Liver samples from cows treated with bST had significantly higher total lipid contents than those from control cows. Although there were small numerical tendencies, neither triglyceride concentrations in liver nor nonesterified fatty acids (NEFA), beta-hydroxybutyrate (BHBA), or glucose in plasma differed significantly between bST-treated and control cows. Short-term bST treatment had no detectable effects on contents of PC, PEPCK, and MTP mRNA in the liver. In summary, exogenous bST stimulation of milk production is not mediated through enhanced liver gluconeogenesis, but may involve partitioning of glucose and fatty acids for preferential use by the mammary gland.