Calves Born from Anestrus Yaks (Poephagus grunniens L.) Subjected to Ovsynch and Superovulation Treatment

Abstract

An attempt was made to induce estrus and ovulation in eight anestrus yaks by use of the Ovsynch protocol. Six out of eight yaks were successfully induced into estrus, and ovulation occurred in all the responding yaks 1-2 days after the second GnRH administration. Out of the six animals that responded to the treatment, two mated naturally with yak bulls, and calves were obtained from them. The other four animals were further administered a superovulatory regimen of Folltropin (FSH-P). Following Folltropin and Ilerin (a PGF(2alpha) analog) treatment, the animals were subjected to natural insemination. Only one animal in which natural mating occurred was flushed non-surgically for embryo recovery 7 days post-insemination. Thereafter, all the donor animals were administered with Ilerin. After 48-72 h, they came into heat and mated naturally with yak bulls, and calves were obtained from them after expiration of the normal gestation period. Following superovulation, the average numbers of palpable corpora lutea in the right and left ovaries were 2.25+/-0.6 and 1.75 +/-0.3, respectively. Three embryos were recovered by non-surgical flushing from a single animal. One embryo was transferred to a recipient yak, who produced one female calf after 258 days. This is the first report of production of a yak calf through embryo transfer-technology.

An Update on Reproduction in Yak and Mithun

“…2006a). In the same study, plasma total oestrogen and oestradiol‐17 β concentrations were high at oestrus and then declined to basal level on day 2 of the cycle and another small elevation was found between days 8 and 12 of the cycle (Sarkar et al. 2006a).…”

“…However, cyclic changes in plasma progesterone were seen in three yaks while the plasma progesterone level stayed high throughout the sampling period in one animal. There were clear indications of cyclic luteal activity in a large proportion of animals even during the non‐breeding season, although oestrus symptoms were not exhibited (Sarkar et al. 2006a).…”