Predection of Litter Size, Lamb Birth Weight, Mammary Gland Growth Indices and Milk Yield in Relation to Weaning Weight Based on Hormonal and Blood Metabolite Profiles During Pregnancy in Sheep (Ovis aries)

Abstract

Forty five Javanese Thin-tail ewes (20, 19, and 6 ewes carrying 1, 2-3, and 0 fetuses, respectively) were used to measure hormonal (progesterone, est radial, three iodothyronine [T3], cort is01 ) and metabolite (beta-hydroxy butyric acid [BHBA], blood urea nitrogen [BUN]) profiles during pregnancy to predict litter size, lamb birth weight, mammary gland growth and development, milk production, mammary gland involution, and lamb weaning weight. Eighteen ewes (9, 6, and 3 ewes carrying 1, 2-3, and 0 fetuses, respectively) were sacrificed at parturition to determine mammary gland growth at the beginning of lactation. The others (11, 13, and 3 ewes carrying 1, 2-3, and 0 fetuses, respectively) were maintained during lactation and supplemented with 500 or 1000 g concent rate per ewes daily, t o determine milk product ion and mammary gland involution. Ewes with higher litter size had higher maternal serum progesterone, est radiol, T3, cortis0l, BHBA, and BUN during pregnancy. Ewes with higher litter size had higher increase in maternal serum progesterone and estradiol concentrations during the second half of pregnancy until 4 months of gestation age. Ewes with higher maternal serum progesterone and estradiol concent rations during the second half of pregnancy had heavier lambs at parturition.