Maternal resources mediate fetal growth and development. This study analyzes the association between maternal cortisol and testosterone levels in late pregnancy and litter size in sheep. Concentrations of cortisol and testosterone in the plasma and wool were determined by enzyme-linked immunosorbent assay (ELISA) kits in Afec-Assaf ewes with one to four fetuses. Concentrations of cortisol in the plasma at 130 days of gestation, and in wool grown in the last 2 months of gestation were greater (P < 0.05) in ewes lambing two or more lambs, compared to ewes producing a single lamb. Whereas there was no association between litter size and plasma concentration of testosterone at 130 days of gestation (P > 0.05), testosterone concentration in the wool was significantly associated with litter size (P < 0.05). We suggest that elevated cortisol and testosterone levels in ewes with multiple fetuses may serve as a mechanism to lower fetal weight, thereby decreasing fetus-related metabolic load in prolific sheep.

产妇资源可调节胎儿的生长发育。这项研究分析了孕晚期孕妇皮质醇和睾丸激素水平与绵羊产仔数之间的关系。血浆和羊毛中皮质醇和睾丸激素的浓度通过酶联免疫吸附测定（ELISA）试剂盒测定Afec-Assaf母羊中一到四个胎儿的浓度。与产单只羔羊的母羊相比，在怀胎两个或更多羔羊的母羊中，妊娠130天时血浆和妊娠最后两个月内生长的羊毛中皮质醇的浓度更高（P <0.05）。妊娠130天时的产仔数与血浆睾丸激素浓度没有关联（P> 0.05），羊毛中的睾丸激素浓度与窝产仔数显着相关（P <0.05）。我们建议多胎胎儿母羊中皮质醇和睾丸激素水平升高可能是降低胎儿体重的机制，从而降低了多产绵羊中胎儿相关的代谢负荷。