Steroid hormonal endpoints in goats carrying single or twin fetuses reared in semi-extensive systems.

Abstract

The study provides baseline data regarding 17- $\beta$ -estradiol (E ${}_2$ ), progesterone (P ${}_4$ ), and cortisol profile of 30 Nicastrese goats during different physiological periods. Animals were evaluated monthly from the pre-mating period (non-pregnant), during pregnancy, and from 30 to 105 d of lactation. The effects of single or twin births and the kid's sex were also considered. Serum E ${}_2$ , P ${}_4$ , and cortisol concentrations were measured using immunoenzymatic assay kits. The highest concentrations of E ${}_2$ and P ${}_4$ ( $P<0.0001$ ) were found during pregnancy and their lowest values ( $P<0.0001$ ) in the non-pregnant period. E ${}_2$ was negatively correlated with P ${}_4$ ( $r=-0.41$ ; $P<0.01$ ) during lactation. The mothers with twin kids showed the highest concentration of P ${}_4$ ( $P<0.04$ ) at $>$  95-115 d of gestation and the lowest of E ${}_2$ ( $P<0.04$ ) at $>$  50-70 d of lactation. Pregnant goats carrying male kid(s) presented the highest E ${}_2$ concentrations ( $P<0.02$ ) at $>$  130-150 d of gestation. Different physiological conditions induced a temporal relationship with the endocrine profile in Nicastrese goats. Understanding the effects of single or twin fetuses on the gestation and lactation will also be helpful to improve the managemental approach for the health of mothers and their kids.