Behavioural and ovarian changes during the oestrous cycle in the boran (Bos indicus)

Ten Boran ( Bos indicus ) cows were studied over 64 oestrous cycles. Alterations in sexual behaviour and of the ovaries palpated per rectum were related to the plasma progesterone profiles detemined using an extracted double antibody radioimmunoassay. The mean cycle length in the cows was 23 ± 0 · 4 days. Oestrus detection efficiency using standing to be mounted, was 27 percent. Restlessness, where observed, reliably indicated that a cow was in the period of basal progesterone concentration. Mounting, sniffing, head-butting, being sniffed, being mounted with avoidance behaviour, although shown by 50 percent of cows during the basal progesterone period were not confined solely to this part of the cycle. Use of Kamar heat-mount detectors in conjunction with standing to be mounted identified 44 percent of oestrous animals. However, the occurrence of false positives during the rest of the cycle precluded their use as sole indicators of oestrus. Accuracy of palpation of corpora lutea was 61 percent during periods of elevated and 98 percent in periods of basal progesterone concentrations.