Reproduction in Domestic Animals

Reproduction Augmentation in Yak and Mithun 221Application of Ovsynch protocol in yaks and mithunsThe Ovsynch protocol (Pursley et al. 1995) was developedas a breeding strategy to eliminate the need foroestrus detection. This method of oestrus synchronizationwas based on control of both ovulation andfollicular growth (Pursley et al. 1995). The protocol iscomposed of an injection of GnRH at random stages ofoestrous cycle to synchronize a new follicle waveemergence. Seven days later PGF 2a is given to regressthe original and the newly formed corpora lutea (CL),followed by a second GnRH injection 48 h later toinduce a synchronous ovulation 24–32 h later thatallows for fixed time artificial insemination 12–16 hafter the second GnRH injection.We tested the efficacy of ovulation synchronization inyaks (Sarkar and Prakash 2005b) and mithuns (unpublisheddata) using the Ovsynch protocol. Ovulation wasdetected by rectal palpation at 2 h intervals from theinitial signs of oestrus till ovulation. Ovsynch protocolfor synchronization of ovulation produced a response of87.5% and 100% in yak and mithun, respectively.Ovulation time and LH characteristics followingovsynch protocol in mithun is presented in Table 2.The LH peak values among individual yaks rangedfrom 10.2 to 40 ng ⁄ ml (n = 8) with a mean of22.8 ± 5.1 ng ⁄ ml. LH concentration (mean ± SEM)increased steeply from 0.98 ± 0.66 ng ⁄ ml at the time ofsecond GnRH injection to peak value of16.04 ± 4.30 ng ⁄ ml 2 h post-GnRH administrationdropping sharply thereafter to basal levels of£0.31 ng ⁄ ml. The duration of LH peak (mean ±SEM) was 4.69 ± 0.36 h with a range of 2.75 to 5.75 h.In seven yaks, the circulatory levels of plasmaprogesterone were basal (£0.2 ng ⁄ ml) at the time ofsecond GnRH administration, and remained basal tillovulation. It was concluded that the Ovsynch protocolcould be applied successfully for fixed time AI in yakand mithun.Application of Heatsynch protocol in yaksHeatsynch is a newly developed synchronization protocolthat uses the less expensive hormone oestradiolcypionate (ECP) in place of the second GnRH injectionin Ovsynch protocol (Lopes et al. 2000).We tested the efficacy of induction of oestrus,synchronization of ovulation and timed artificial inseminationin anoestrous yaks using the Heatsynch protocol(Sarkar et al. 2007e). All the animals responded toHeatsynch treatment for induction of oestrus andsynchronization of ovulation. The high degree ofTable 2. Plasma LH characteristics and timing of ovulation inmithuns (n = 23) subjected to Ovsynch protocolParameters Mean ± SEM RangeHighest LH peak concentration (ng ⁄ ml) 12.23 ± 0.66 9.03–17.22Duration of LH surge (h) 8.25 ± 1.38 6–12Time from:Onset of LH surge after second1.90 ± 0.44 1.25–2.75GnRH injection (h)Ovulation after second GnRH injection (h) 26.75 ± 2.02 19–33Ovulation after end of LH surge (h) 18.62 ± 1.69 15–27ovulation synchronization could be attributed to thehighly synchronized LH peaks in the treated animals. Inanoestrous yaks treated with the Heatsynch protocoland subjected to TAI 40% pregnancy rates wererecorded. Heatsynch protocol could therefore be successfullyutilized for improving fertility in anoestrusyaks too.Superovulation and embryo transferSuperovulatory treatments are widely used in embryotransfer programs to increase the supply of embryosfrom animals of superior genetic merit. In a trial byZagdsuren et al. (1997) three female yaks were superovulatedusing progesterone and FSH. Oestrus wasdetected by a teaser male and the females were inseminated24–36 h after the last FSH injection. Numbers ofCL and ovarian follicles detected by rectal palpationand laparoscopy averaged 5.0 ± 0.6 and 1.3 ± 0.9respectively, but embryo recovery was not reported.Davaa et al. (2000) used FSH and PMSG to inducesuperovulation in yak cows. Oestrus was detected34.1 ± 0.52 h after the prostaglandin treatment. Theaverage number of ovarian follicles was 5.4 ± 0.65, ofwhich 4.5 ± 0.43 ovulated.Sarkar et al. (2006a) used four yaks for superovulationfollowing Ovsynch program. On day 20 after thefirst GnRH injection, females received a total dose of200 mg Folltropin, twice daily, equal doses, over 4 daysperiod in association with two injections of prostaglandinanalogues on 48 and 60 h after initiation ofsuperovulation. The females were mated and the numberof CL was recorded on day 7 after the last injectionof FSH. Only one animal was flushed non-surgically forembryo recovery 7 days after mating. The averagenumber of palpable CL was 2 ± 0.71. A total of threeembryos were recovered on non-surgical flushing from asingle animal. One embryo was transferred to a recipientyak cow, which produced one female yak calf after258 days. This is the first yak calf reported throughembryo transfer technology. In another trial cyclic yaks(n = 10) were synchronized using Ovsynch protocol.On day 10 after expected oestrus, animals received atotal of 200 mg Folltropin, twice daily over 4 days.From 9 yaks, 27 ovulations were detected and 16embryos were recovered (Sarkar et al. 2007a). Plasmaprogesterone profiles from individual yaks suggestedthat a poor superovulatory response in terms of embryorecovery in some animals was caused by the lysis of CLbefore flushing which was carried out 7 days aftersuperovulatory ooestrus. It was suggested that flushing5 days post-superovulatory oestrus could improve thesuperovulatory response in this species.ConclusionsWe have presented here our major research efforts onsome aspects of reproduction in mithuns and yaks. Ourinitial efforts on developing hormone assay procedureshave helped us to successfully extend recent endocrinetechniques for fertility improvement in these species.The results of these studies hold promise for undertakingthese techniques on a larger scale.Ó 2008 The Authors. Journal compilation Ó 2008 Blackwell Verlag