Effect of Calcium and Magnesium Supplementation of Ewes during Pre‐ and Post‐Mating on Lamb Sex Ratio.

The aim of this study was to investigate the effect of calcium (Ca) and magnesium (Mg) injection around mating on skewing lamb sex ratio in ewes. Thirty cycling multiparous Kurdish × Romanov ewes were divided into two groups (15 per group) based on age and body weight (BW). Animals were received either 20 mL of solution (CaMg) or 20 mL of sterile water (Control) subcutaneously every 7 days from 28 days preto 7 days post-mating. Each mL of CaMg solution contained 400 mg of Ca borogluconate and 22 mg of Mg hypophosphate, which provided 30.4 mg of Ca and 2.04 mg of Mg. Ewes in CaMg group tended to had lower body condition score (BCD) at the day of controlled internal drug release (CIDR) removal (2.79 vs. 2.69; P=0.09) and its change from beginning of experiment to CIDR removal (0.21 vs. 0.04; P=0.06) than control group. The CaMg injection increased plasma insulin (13.2 vs. 11.33 μIU/mL), Ca (9.13 vs. 8.30 mg/dL), Mg (3.66 vs. 3.33 mg/dL), Na (188.83 vs. 175.73 mEq/L) and glucose (56.94 vs. 50.07) concentrations at the day of CIDR removal and Ca (8.87 vs. 8.03 mg/dL) at the day of estrous and mating compared to control group (P<0.05). Lower estradiol (E₂) + testosterone to progesterone (P4) ratio at the day of estrous and mating (102.87 vs. 135.67) was observed in ewes received CaMg injection compared to other group (P<0.05). Injection of CaMg solution had no significant effect on lamb sex ratio (P>0.05), although proportion of female lambs (68.18 vs. 56.52%) was numerically higher in ewes of the CaMg group than control group. These results indicated that there was a potential for skewing the sex ratio of lambs toward females when CaMg solution was injected subcutaneously during mating. [ABSTRACT FROM AUTHOR]