Pregnancy rate in dry and lactating goats after estrus synchronisation with artificial insemination and natural breeding (a field study)

Abstract

The objective of this study was to determine the pregnancy rate in dry and lactating goats after estrus synchronisation with artificial insemination and natural breeding of unconceived animals. The investigation was conducted with 75 dry (group I) and 32 lactating (group II) local goats in breeding season. All animals were submitted to estrus synchronisation by intravaginal sponges for 12 days, PMSG injection on day of sponge removal and two artificial inseminations (AI) with fresh semen – 48 and 56 hours after sponge withdrawal. Two weeks after the AI, daily test for goats which had not conceived after the AI was performed by teaser and the detected animals in estrus were naturally mated with a fertile buck. Ultrasonographic pregnancy examination was carried out at 20-day intervals until day 100 after the AI. The pregnancy rate in artificially inseminated and naturally bred animals and the interestrus intervals were calculated. The pregnancy rate between both synchronised groups differed significantly (P<0.05), while the values in the groups with natural breeding were comparable. Different pregnancy rates between artificially inseminated and naturally bred goats in group I (72% vs. 42.9%) and group II (19% vs. 73%) were registered (P<0.05). Additionally, considerable differences (P<0.05) between the values after first natural breeding (9.6% and 46.6%) were detected. The total pregnancy rate (84%) in dry goats was higher (P<0.05) than that (54%) in lactating animals. The interestrus intervals were similar (P=0.2). In conclusion, the current data could be used for optimisation of the pregnancy rate and the reproductive efficiency in local goat breeds.