Advice for dairy farmers: Consider fixed time AI for some late calvers

The average calving interval has dropped from 402 days in 2011 to about 390 days.

According to Teagasc, this is worth tens of millions of euros to farmers. But the ideal target is 365 days, so there is room for improvement.

The average six-week calving rate is 58%, while the ideal target is 80-90%, which only a minority of farmers achieve.

Pregnancy rates to first service are 52% while the target is 68%. Calves per cow per year are at 0.9; the top 5% achieve 1.02.

It is not easy to achieve the targets. We know that some farmers are getting there, but it is difficult where existing calving patterns are very scattered.

It can be achieved by batch calving heifers at the start of the calving season, and adhering to best breeding practices.

Breeding of late calvers and non-cycling cows should be brought forward, using fixed time AI with CIDRs.

The breeding performance achieved by our best farmers is as good if not better than, for example, New Zealand and Australia, where over half of the cows have a strong Jersey and cross bred influence, with Jersey genes increasing every year. Yet, their fertility is deteriorating.

Here, ICBF (the Irish Cattle Breeding Federation) has found a very close relationship between the fertility index in their EBI, and fertility performance.

Most farmers are now using bulls with very high fertility indices.

Late calvers

Late calvers are very often a neglected part of the herd. This may be due to a poor understanding of the intake and energy requirement of these animals, making it difficult to get late calvers back in calf.

For a few weeks before calving and for the first 10 weeks of lactation, the intake of cows is significantly reduced, and there is a severe risk that these animals going into negative energy balance.

Their peak milk yield usually occurs at six weeks after calving, while peak intake does not usually occur until 10 to12 weeks after calving.

Therefore these cows need extra concentrates to avoid a negative energy balance which delays them going back in calf.

The problem is worse with over fat cows.

Even on good quality grass, the intake of late calvers will be about 20% less than early calvers for the first six weeks, and they need extra supplementation. 

Almost one third of our cows calve after late March, and they are in a vulnerable position now. Some of these should get fixed time AI to short gestation bulls, which has been very successful in tightening up the calving season on some farms, and reduces the necessity of culling due to late calving.

Most late calvers do not get any special treatment and they calve later and later, until they are eventually culled.

This is a huge loss to the herdowner, who should take all the necessary steps to reduce the problem.

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