Estrous behavior and the estrus-to-ovulation interval in Nelore cattle (Bos indicus) with natural estrus or estrus induced with prostaglandin F2alpha or norgestomet and estradiol valerate.

摘要

15 heifers and 28 cows were treated with prostaglandin F2alpha (2 injections, 11 days apart); only 6 heifers and 13 cows showed oestrous behaviour despite the presence of a functional corpus luteum, as indicated by progesterone concentrations >6.0 ng/ml. Treatment with norgestomet + oestradiol valerate induced high sexual receptivity in cows (10/11), but only 66% ovulated. The duration of behavioural oestrus in cows having natural or induced oestrus was 10.9±1.4 h, and ovulation occurred 26.6±0.44h after the onset of oestrus. The percentage of cows in which oestrus started during the day and night was 46.1 and 53.8 respectively, and the percentage in which oestrus ended at day and night was 46.1 and 53.8. 30.7% of oestruses started and ended during the night while only 23% of oestruses started and ended during the day.