The achievement of early cyclicity after calving is of vital importance in
maintaining a dairy industry. Post-partum anoestrous in buffalo is a major cause of
long calving interval and infertility resulting in economic loss to buffalo breeders.
For sustainable breeding program it is necessary to identify an oestrous
synchronization treatment that is more reliable for successful pregnancy after
artificial insemination (AI) with frozen semen. Two experiments were carried out to
evaluate the efficacy of an Ovsynch protocol (GnRH + PGF 2α + GnRH) for oestrous
synchronization and subsequent AI fertility in water buffaloes of two countries (Italy
and Bangladesh). The aim of the first experiment was to evaluate the efficacy of an
Ovsynch protocol with two GnRH analogues (Buserelin and Gonadorelin acetate)
and at two times of administration (AM and PM) for synchronization of ovulation
and fixed–timed AI using sexed frozen semen in Italian Mediterranean buffalo cows.
Thirty-two Mediterranean postpartum buffaloes cows were used for this study. All
animals were inseminated by AI with 2.5 million live (4million total) sex-sorted
frozen thawed spermatozoa (X-chromosome bearing spermatozoa) within 18 to 21
hours after using of 2nd GnRH. Vaginal electrical impedance (VEI), vulvar and
perivulvar temperatures were recorded at different stages of synchronization
protocol to asses oestrous. Pregnancy was confirmed by transrectal ultrasonography
after 42 days of AI. The pregnancy rate was 37.50 % when Buserelin was used for
synchronization, whereas the pregnancy rate was 50% when hormones were
administered at morning. Vaginal Electric Impedance decreased and vulvar
temperature, recorded with thermocamera, increased during administration of
second dose of GnRH, when buffaloes were supposed to be in oestrous. However,
the first study served as a basis for further study on time and type of treatment with
GnRH on synchronization of estrus and ovulation to improve pregnancy rate as well
as reproductive quality in Mediterranean buffalo cows.
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In second experiment, a total of 114 lactating Bangladeshi Indigenous buffalo cows were used to study the efficiency of Ovsynch protocol for oestrous and fertility after AI with frozen semen of Italian Mediterranean buffaloes. The effect of some factors such as follicles and corpus luteum numbers, postpartum period on the fertility of synchronized Bangladeshi water buffaloes was also studied. Buffaloes were selected from two different areas in Bangladesh and were divided into three groups. Buffaloes of each group were subdivided as AM and PM according to time of administration of hormones of synchronization protocols. Among three groups, higher pregnancy rate (78% in AM) was observed in buffaloes of Group-3 where Ovsynch protocol was combined with a third GnRH injection at the time of AI. Similar to first experiment, we observed higher pregnancy rate (74 %) in buffaloes received induction treatment and insemination at AM time than that of PM counterpart (63%). Regarding the post–partum days, pregnancy rate was higher (77%) in buffaloes received induction treatment at 90 to 180 days between calving to ovulation induction than that of more than 180 days (66%). We did not observe any significant difference in pregnancy rate in buffaloes with (59%) or without (57.1%) CL at the time of synchronization. In addition, this study did not show any significant in regards to follicles and CL numbers in both pregnant and non-pregnant buffaloes. This study results that time of day should considered during administration of hormones for Ovsynch protocols. The findings of the study suggests that Ovsynch protocol can be successfully used for selective breeding program of Bangladeshi Water buffaloes and a third injection of GnRH during AI could help to improve pregnancy rate of water buffaloes when inseminated with frozen-thawed semen. The genetic improvement resulting from AI with frozen-thawed semen in synchronized buffaloes could bring a significant economic gain for farmers of dairy industr
