Oestrous cycles were synchronised by two intramuscular injections of 50 g of the
prostaglandin F2 analogue, Cloprostenol (Estrumate; Schering-Plough Animal Health
Welwyn Garden City, UK) administered 12 days apart. Oestrus (day 0) was identified
by twice daily monitoring and the use of KAMAR heat detectors (KAMAR HeatmountTM,
Streamboat Springs, Colorado, USA). Following oestrous detection, cows were inseminated
at 9 a.m. with high fertility beef bull semen.