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Pat and Sean Kelly - Cows with different milk sub-indexes and Heat Behaviour

Pat and Sean Kelly - Cows with different milk sub-indexes and Heat Behaviour

The breeding focus for today is on cows with different milk sub-index and what this means in terms of income. Dairy Specialist George Ramsbottom gives more information. Heat behaviour and time of AI is the topic covered by Stuart Childs Dairy Specialist.

Cows with different milk sub-indexes

Small differences in genetic merit for different traits can have a big impact long-term on a farm. On the Kelly farm, we look at two similar cows with different milk sub-indexes. While similar for fertility sub-index, one cow has a milk sub index of -€12 and the second has a milk sub-index of €56.The higher milk sub index cow has delivered milk worth at least €3,000 more over the first seven lactations than her contemporary.

Heat behaviour

Onset of standing heat takes place approximately 30 hours before the egg ovulates. After ovulation, the egg remains viable for only 8-10 hours. Cows can be successfully inseminated over a wide time period with conventional semen. The reason for this is that the sperm remain viable for a period in excess of 24 hours after insemination takes place.

Sexed semen

Sexed semen however is more fragile because of the sex sorting process that has taken place. Research shows that insemination with sexed semen should take place closer to the time of ovulation – ideally between 14 and 20 hours after onset of standing heat. At this stage the cow or heifer is no longer in standing heat. If heat onset occurred overnight and the animal is still standing, we recommend that you use conventional semen instead.