Oestrus Behaviour and Hormonal Characterization of the Oestrous Cycle in Nigerian Jennies

Abstract

This study was carried out to evaluate the onset of oestrus, duration of oestrus, oestrus behaviour and the hormonal profiles (Progesterone and oestrogen) of Nigerian indigenous jennies. Four (4) cycling Jennies were used in this study, cyclicity was determined based on two rectal palpations (30 days apart), ultrasound scans done twice and two blood samples were also obtained twice (30 days apart) to confirm cyclicity. Five (5) ml of blood was obtained from the jennies via jugular veni-puncture on the day the experiment commenced, then twice weekly for 8 weeks, to determine the progesterone and oestradiol using the principle of Enzyme-Linked Immunosorbent Assays (ELISA). Jennies were observed for behavioural oestrus three times daily (8-10 am, 12-2 pm and 4-8 pm) for two oestrous cycles. Parameters observed include; lowered head with neck extended forward, opening and closing of the mouth, ears back against the neck, standing to be mounted, tail raised from the perineum, vulva winking, mucous discharge and presentation of the perineum toward the jack. In addition, Jennies were exposed to a jack to aid oestrus detection. The following oestrus behaviour and characteristics were recorded: duration of oestrus, onset of oestrus, oestrus response rate, intensity of synchronization and physical manifestation of oestrus. It was established that the time to onset of oestrus in this study was 2.3 hours, the duration of oestrus was 48 hours. Tail raising, opening and closing of mouth (mouth clapping), flehmen with winking of the vulva were the most consistently observed signs of oestrus in jennies. Oestrus period was 8 days and the oestrous cycle length was 25 days in Nigerian indigenous jennies. In conclusion, it was established that the time to onset of oestrus was 2.3 hours, the duration of oestrus was 48 hours, oestrus response rate and intensity of synchronization were 50%, respectively. The characteristic oestrus behaviours were; head lowering, ears backward, standing to be mounted, vulva winking, mucous discharge, presentation of perineum, tail raising from the perineum, opening and closing of mouth (mouth clapping), flehmen with winking of the vulva.

Key words: Nigerian jennies, oestrus characteristics, oestrus behaviours, oestrous cycle.