Zebu cows in oestrus may hasten sexual behaviour and ovulation in herd mates

Abstract

The influence of behavioural oestrus on the manifestation of oestrus and ovulation of herd mates was studied by ultrasonogrophical examination (US) of ovarian activity. Ten non-pregnant animals divided into two groups (A and B) were treated with a 9-day implant of Synchromate B (SMB) with nine days of difference between treated groups. Seven pregnant cows (Group Q remained within the herd to keep the social structure intact. Animals were observed continuously for 100 h after implant withdrawal. Three sexually active groups (SAG) on three different dates were recorded

each formed by cows from groups A, B and even C. Sixty percent (3/5) ovulated in the 2nd SAG and 83% (5/6) in the 3rd. It may be concluded that: 1) Cows may display mounting behaviour without apparent follicular support even with a SMB implant in place and 2) Cows induced into oestrus may hasten behavioural activity and ovulation in non-treated herd mates.