Accurate oestrus detection can be a challenge in buffaloes. Swelling of the vulva, increased frequency of urination, restlessness and repeated vocalization are suggestive though not reliable indicators of oestrus. Mounting behaviour among females is uncommon and there is little mucous discharge. The most reliable sign of oestrus is acceptance of the male.
If natural service is used, the donors should be exposed to the male starting just prior to the time of the last scheduled FSH injection (day-1, p.m.) and continued at eight-hour intervals for 10 minutes until they are no longer receptive (see Table 1).
With artificial insemination the donors may be teased by checking with an intact male without permitting it to breed. A vasectomized buffalo fitted with a chinball marking device may be used as an aid in oestrus detection (Jainudeen, 1986).
Alternatively, an androgenized female buffalo can be used (Drost, Cripe and Richter, 1985). The use of such a teaser animal can greatly facilitate oestrus detection in groups of buffaloes being used as recipients. Close synchronization of oestrus and ovulation between donors and recipients is very important for embryo survival.
It is possible to monitor oestrus and ovulation by frequent palpation of the uterus and ovaries per rectum, by monitoring follicular development by ultrasonography (Pierson and Ginther, 1988) or by frequent determinations of the concentration of progesterone in milk or in plasma.
In the presence of hormonally stimulated ovulations, fresh semen gives higher fertilization rates than frozen semen. This probably reflects the number of viable spermatozoa in the inseminating dose. Donors should be artificially inseminated twice with a 10–12 hour interval beginning 8–10 hours after the onset of oestrus, to cover the range of time over which the ovulations may occur. Depending on the quality of the frozen semen, a double inseminating dose may be used at each insemination (Schiewe et al., 1984).