Reproductive parameters of dairy goats after receiving two doses of d-cloprostenol at different intervals

Abstract

This study evaluated the efficiency of two d-cloprostenol injections at different intervals on the reproductive parameters of dairy goats. Trial 1 comprised 54 goats allocated to receive two 37.5μg d-cloprostenol doses at intervals of seven (T₇, n=19), 10 (T₁₀, n=18), and 11.5 (T_11.5, n=17) days. Trial 2 comprised 62 goats allocated to receive injections at T₇ (n=30) and T_11.5 (n=32). Ultrasonography was done and blood was collected just before d-cloprostenol injections. After the second dose, goats were artificially inseminated (AI) with frozen-thawed semen at 18-24h (Trial 1) or at 10-24h (adjusted according to the time of estrus onset in Trial 2) after estrus detection. Estrus response rate did not differ (P>0.05) among groups in Trials 1 (T₇=94.7%; T₁₀₌88.9%; T_11.5=88.2%) and 2 (T₇=90.0%; T_11.5=96.9). All females showed progesterone concentrations >1ng/mL before both d-cloprostenol injections. The largest follicle diameter present on ovaries was similar (P>0.05) among treatments at the first and second dose. The second largest follicle diameter was superior (P<0.05) to T₇ than to T₁₀ and T_11.5 goats at first dose only. This possibly resulted in lower interval to estrus (P<0.05) in T₇-treated goats than other treated goats in both trials. The conception rate was similar among treatment groups in Trials 1 (T₇=55.6%; T₁₀=18.8%; T_11.5=26.7%) and 2 (T₇=85.2%; T_11.5=93.6%). The three treatments efficiently synchronized estrus. T₇ and T_11.5 protocols resulted in high estrus synchrony and conception rates when adjusting the AI time according to interval of estrus.

Keywords: AI; Caprine; PGF2α analog; Prostaglandin; Reproductive performance.