Optimal timing of artificial insemination and changes in vaginal mucous characteristics relative to the onset of standing estrus in Beetal goats

Abstract

The current study was conducted to determine the optimal timing of artificial insemination and vaginal mucous characteristics relative to the onset of estrus in goats. Does (n = 257) were estrous synchronized using hormonal treatments. Intracervical inseminations with fresh semen were performed at 0, 12, 24 and 36 h after the onset of estrus. Characteristics of vaginal mucus (i.e., color, consistency, and volume) were observed and graded at the time of AI to calculate cumulative mucous score. The vaginal electrical resistance (VER) was recorded (Draminski® detector) at the time of AI. Pregnancy rate was less (P < 0.05) when inseminations occurred at 0 h (28.6%) compared with 12 (58.3%) and 24 h (56.4%) after the onset of estrus; however, pregnancy rate at 36 h (54.5%) did not differ (P> 0.05) compared with inseminations at 0, 12 or 24 h after estrous onset. Relative odds for pregnancy rate at 12, 24 and 36 h were 5.24, 5.20 and 3.29 times greater compared with 0 h. Cumulative mucous score varied (P < 0.05) relative to the onset of estrus and correlated well (P < 0.05) with the color and consistency than volume of the mucus. The VER was less (P < 0.05) at 12 than 0 and 36 h after estrous onset. In conclusion, goats can be inseminated between 12–36 h after the onset of estrus; however, the chances of pregnancy are greater with inseminations at the 12 or 24 h time periods.