Insemination

 

Behaviour in Oestrus

Oestrus or ‘heat’ begins at the start of puberty. It occurs at regular intervals (usually every 21 days) and is a sign of readiness to mate in the female bovine. There is a temporal and functional link with ovulation. A cow in heat is restless and bellows frequently. She mounts other cows at the head or tail and stand stills herself when mounted from behind. This is called the ‘standing reflex’ or a ‘standing heat’. If you press on her lumbar area she arches her back downwards without resisting (the cow ‘stands’). Animals in heat usually produce slightly less milk. The vulva appears swollen and a clear vaginal discharge can be observed. Ovulation takes place at the end of the main phase of oestrus or in early post-oestrus. The egg (ovum) is capable of being fertilised for 12 to 24 hours.

The ‘morning-evening’ rule is very useful for insemination: if the cow ‘stands’ in the morning, she can be inseminated in the afternoon. If she ‘stands’ in the afternoon or evening, she can be inseminated the following morning.
The cow is therefore inseminated in the second half of the main oestrus phase, or even at the beginning of the post-oestrus phase (metoestrus or post-oestrus).