Patterns of oestrus, time of LH release and ovulation and effects of time of artificial insemination in Mediterranean buffalo cows.

Thirty-two post-partum Mediterranean river buffalo cows were continuously observed for signs of oestrus from September to December with the aid of two vasectomized bulls. Symptoms of oestrus among female Mediterranean buffaloes are weak, therefore oestrus was assessed based on bull behaviour (following and licking a cow and trying to mount her). Oestrus was divided into three phases based on the bull behaviour assessment. Status of the uterus and ovarian follicles were checked rectally every day for each cow which was detected by a teaser bull to be in oestrus. All cows in oestrus were bred twice by artificial insemination (AI), the first at ovulation and the second (using a different bull) 22 h later. The average duration of interest shown by the bull towards a cow (from the very first to the last sign of interest) was 68 h and the average length of the three phases was: phase I = 21 (s.d. 29) h, phase II = 32 (s.d. 24) h and phase III = 15 (s.d. 15) h. Fifteen buffaloes were bled during oestrus, and LH profiles were determined. No differences were evident among oestruses followed by pregnancy (no. = 18) and the others (no. = 26) for the variables describing behavioural events. Neither intensity of the bull courtship, presence or clarity of mucous discharge, or housing system affected the success of AI. The only differences between pregnant and non-pregnant cows were in the timing between the LH peak and the end of phase II (2·4 v. 14·7 h, P 0·05) and ovulation (25 v. 46 h, P < 0·05). Successful pregnancies occurred 34 (s.d. 14) h after the end of phase II. The endocrinology and behavioural patterns of buffalo reproduction need further research to clarify the reasons for non-optimal pregnancy rates after AI