Temporal Changes in Physical Signs of Estrus and Validation of Fetal Parameters for Estimation of Gestational Stage through B-mode Ultrasonography in Beetal goats

Abstract

The current study evaluates changes in the physical signs of estrus (vulvar hyperemia, edema and mucous discharge) from their onset until ovulation, and validates fetal parameters for the estimation of gestational stage in Beetal goats. In experiment 1, temporal changes in estrus signs were monitored subjectively after the administration of two injections of PGF2α at 10-days interval and a cumulative behavioural index (BI) was calculated in goats that showed estrus response (n=7). Ovulation occurred after 18.8±2.3 h relative to peak vulvar hyperemia and edema; ovulation coincided with maximum mucous discharge (0±2.4 h). Maximum BI was observed between 7 to 31 h after the onset of estrus and was highly correlated with vulvar hyperemia (r=0.94), followed by vulvar edema (r=0.90) and mucous discharge (r=0.85). In experiment 2, fetal parameters were monitored in pregnant goats (n=7) via ultrasonography for estimation of gestational stage, and for validation in a separate set of goats (n=20; experiment 3). Gestational stage correlated significantly (P<0.05) with the uterine diameter (UD), crown-rump length (CRL), trunk diameter (TD), intercostal space (ICS); diameter of amniotic vesicle (AV), biparietal diameter (BPD), placentome diameter (PD) and umbilical cord (UC) diameter. Validation revealed the difference between the actual and estimated day of gestation was less for TD than BPD (4.1±0.6 vs 6.8±1.0 days; P<0.05). In conclusion, vulvar hyperemia, edema, and mucous discharge are highly correlated with BI. Fetal parameters are strongly associated with the gestational stage, and the estimation of the actual gestational stage is less variable through TD than BPD in Beetal goats