Effect of social rank upon estrus induction and some reproductive outcomes in anestrus goats treated with progesterone + ecg

Abstract

We evaluated the possible role of the social rank [R] (i.e., low—LSR, middle—MSR, or high—HSR) in anestrus goats exposed to a P4 + eCG [D] (i.e., 100 or 350 IU) estrus induction protocol (EIP). Adult, multiparous (two to three lactations), multiracial, dairy-type goats (Alpine–Saanen–Nubian x Criollo goats (n = 70; 25◦510 North) managed under stall-fed conditions were all ultrasound evaluated to confirm anestrus status while the R was determined 30 d prior to the EIP. The variables of estrus induction (EI, %), estrus latency (LAT, h), estrus duration (DUR, h), ovulation (OVU, %), ovulation rate (OR, n), corpus luteum size (CLS, cm), pregnancy (PREG, %), kidding(KIDD,%),andlittersize(LS,n)asaffectedbyR,D,andtheR×Dinteraction,wereevaluated. While OVU and CLS favored (p < 0.05) HSR (96% and + 1.04±0.07 cm), an increased (p < 0.05) LS occurred in D350 vs. D100 (2.06±0.2 vs. 1.36±0.2); neither R nor D affected (p > 0.05; 38.5%) KIDD. However, EI, LAT, DUR, OR, and PREG were affected by the R×D interaction. The HSR group had the largest (p < 0.05) EI % and DUR h, irrespective of D. The shortest (p < 0.05) LAT occurred in D350, irrespective of R. While the largest (p < 0.05) OR occurred in HSR and MSR within D350, the HSR + D350 group had the largest PREG (p < 0.05). These research outcomes are central to defining out-of-season reproductive strategies designed to attenuate seasonal reproduction in goats.