Reproductive Behaviour in Cattle

In dairy farms, cows calve year-round in order to produce a steady supply of milk for human consumption. Female cows are usually 9 months of age at first oestrus and each oestrous cycle lasts 21 days. The duration of the receptive phases of oestrus, where the cow will stand to be mounted, lasts approximately 12 h. Receptive females ('on heat') will stand to be mounted by bulls, but cattle also show female–female mounting. In addition to visual stimuli, bulls apply olfactory sense to detect whether a cow is receptive. Bulls will sniff the genital region and urine of cows and may display a flehmen response. The flehmen response assists pheromones and scent molecules in reaching the vomeronasal organ in the roof of the mouth. Successful Artificial Insemination requires that humans detect the receptive phase of oestrus. There are various ways to detect oestrus in cattle, and behaviour plays a key role in each method. Cows may be observed for female female mounting to detect oestrus. Alternatively, the tail head of the cow is painted and this paint is 'read' for signs of rubbing. If the paint wears away, this indicates that the cow has stood to be mounted and is ready to be bred. Cows also show restless behaviour during the receptive phase of oestrus. Automated measures of movement, such as a sensor on a collar or a pedometer attached to the leg, are used to record behaviour and detect the increase in activity associated with oestrus.