Temporal Changes in Endogenous Estrogens and Expressionof Behaviors Associated with Estrus during the Periovulatory Period in Doublesynch Treated Murrah Buffaloes (<i>Bubalus bubalis</i>)

Abstract

The aims of this study were (a) to establish the occurrence, duration and intensity of behavioral estrus symptoms, and (b) to determine the relationship between behavioral estrus symptoms with the total estrogen profiles in cycling Murrah buffaloes (n=10) subjected to Doublesynch protocol (0 PGF_2α, 2 GnRH, 9 PGF_2α and 11 GnRH). After both GnRH injections, estrus and its behavioral signs were detected at hourly intervals using visual observations, transrectal examination of genitalia, and bull parading twice a day for 30 min each. Frequent urination (100%) and excitement (100%) were the best indicators of estrus followed by swollen vulva (90%) and bellowing (85%). The longest duration of estrus signs viz. swollen vulva, was observed up to 8.9 ± 0.5 h and 11.1 ± 0.3 post first and second GnRH administrations, respectively. The mean intervals between the onset of estrus symptoms appearance and ovulation were 13.8 ± 0.9 h and 13.4 ± 1.0 h post first and second GnRH inactions, respectively. The mean total estrogen concentrations at the time of both GnRH injections were above the basal level (8.4±1.9 pg/mL; range 2.9-18.4 and 7.9±1.9 pg/mL; range 2.9-17.6 at the time of the first and second GnRH injections, respectively), temporarily increased post GnRH treatments and then gradually declined to its basal level during ovulation time window. Frequent urination, excitement and swollen vulva appeared to be the most notable estrus symptoms after GnRH injections. Our findings also suggest that the AI can be done at a fixed time (once 20 to 24 h posts second GnRH) in buffaloes treated with Doublesynch protocol.