Oestrus detection by mounts received in Friesian × Bunaji and Bunaji heifers

Abstract

SUMMARYBehavioural oestrus was studied using 32 Friesian × Bunaji and 29 Bunaji heifers standing for mounts by either vasectomized bulls or heifer herdmates. The study was conducted from 06.00 to 12.00 h and from 13.00 to 18.00 h local time for 96 days. All the 61 heifers showedoestrus. The mounts received by the heifers ranged from 68 to 170, being few between the first 24 days but increasing later. A total of 171 oestrous cycles were recorded, 85·4% of which had a mean oestrous cycle length (± S.E.) of 22·6 ± 0·9 days, while the average duration of oestrus (± S.E.) was 5·9 ± 0·2 h. Results showed significant differences between the mounts made by the teasers as well as mounts received by the heifer groups (both P = 0·01), but the teaser x heifer group interaction was not significant (P > 0·05). As all the heifers showed oestrus at least once, observation for oestrus between 06.00 and 18.00 hwould be reliable for supporting an artificial insemination scheme in the Guinea Savannah of Nigeria.