The changes in some blood metabolites associated with the physiological responses in sheep

Abstract

This study was undertaken to evaluate the changes in the pattern of prolactin hormone associated with milk yield and milk composition in ewes. Moreover, the relationships of thyroxin, glucose, cholesterol and total protein with growth performance of lambs were investigated under southern Egypt local environmental conditions. Both ewes and lambs were of four genotypes namely, Ossimi (O), Saidi (S), Fl Chios-Ossimi (CO) and Fl Chios×Saidi (CS). Average daily milk yield, total milk yield and lactation period length were significantly ( P<0.05) higher in ewes with Chios genetics than the local breeds. Moreover, CS ewes were superior in this respect compared with CO ewes. However, none of the milk constituents (fat, total solids, solids non-fat and lactose) was affected by genotype. Genotype of ewes had a significant ( P <0.01) effect on prolactin hormone concentration being higher in crossbred ewes (CS and CO) than local ones (O or S). Across genotype, milk production was found to be positively correlated with plasma prolactin hormone concentration ( r=0.667, P<0.05). Body weight of lambs (O, S, CO and CS) at birth, at weaning (2 months) and at 4-months-old significantly ( P<0.01) differed among the various genotypes studied. CO lambs recorded the heaviest ( P<0.05) birth and weaning weights. Plasma thyroxin (T 4), glucose, cholesterol and total protein at birth, weaning and 4 months of age were significantly ( P<0.05) higher in the Chios crossbred lambs. Plasma T 4 hormone concentration was found to be negatively associated with age changes across genotypes r=−0.841, P<0.01).