Abstract
•Supplementing the diet of Barki sheep with calcium soaps rich in Palmitic and Oleic fatty acids increased the female: male sex ratio of their lambs.•Calcium salts of fatty acids rich in palmitic and oleic fatty acids increased serum estrogen and size of corpora lutea not progesterone secretion.
The effect of a flushing diet supplemented with calcium salts of fatty acids (CSFA) high in palmitic (37%) and oleic (33.6%) fatty acids on reproductive performance was studied using 30 Barki ewes with a mean weight of 40.0±0.2kg (mean±SD). The control group (n=15) received the basic diet of 1kg/h/d concentrate plus Egyptian clover (Trifolium alexandrinum) hay ad lib and the CSFA group received the basic diet plus 50g/h/d CFSA. The diets were offered for 60 days, prior to (30 d) and subsequent (30 d) to mating. Estrus was synchronized using a single injection of PGF2α prior to the introduction of rams. CSFA-fed ewes had non-significantly different twinning (20.0 vs. 7.1%), prolificacy (1.2±0.1 vs. 1.0±0.1) and female: male lamb sex ratio (72.2 vs. 50.0%) compared to controls; also, pregnancy, embryo survival and lambing rates were not affected by diet. Feeding CSFA resulted in a higher (P=0.06) total number of follicles and number of large follicles; however, the number of small follicles, and diameters of small and large follicles were not significantly different. Serum concentrations of estrogen at estrus were higher (P=0.06) 3days after PGF2α administration in CSFA (52.3±4.2pg/ml) compared to for control (41.6±3.8pg/ml) ewes. There were no significant differences in total number of corpora lutea (CL) or serum concentrations of progesterone during the luteal phase. Diameters of nascent CL were increased (P<0.05) by CSFA treatment (13.0±0.7mm) compared to control (11.2±0.2mm). Serum concentrations of lipid metabolites (TG, CHOL, HDL and LDL) were significantly (P<0.01) elevated relative to controls in the CSFA treatment. Serum TP, G and liver enzymes (ALT and AST) were not significantly affected by treatment. It was concluded that including CSFA in a flushing diet for Barki ewes resulted in increased serum concentrations of lipid metabolites, and improved twinning and prolificacy rates, and female/male lamb sex ratios.