Synchronising Your Herd

Anoestrus Cows & Synchronising your herd.

At present there is a review occurring as to the future of Induction of calving in cows. The rules regarding this are unlikely to be relaxed and there is a possibility that the procedure will be banned, except in animal welfare cases.

This makes it more important to get your cows cycling and in calf, in a reasonable time, and there are a couple of procedures available.

The first of these is the use of Prostaglandins (OG) but this only works on cows that have already cycled, and can only really be done at the start of mating. Beaically this drug is given at least 7 days after the cow’s last heat and will bring her onto heat again in 3-5 days. So if a cow comes on heat 7 days before the planned start of mating (PSM) she would normally be first mated on about day 14 of mating. However if she was injected with a PG on day O (PSM) she would come on heat on day 3-5. This can advance calving date by a maximum of 11 days. Mating is on observed heat.

The conception rate with this method is very good and another advantage is that it may allow cows to have an extra round of AI.

How frequently you inject is up to you. You could safely inject cows that have a heat of 9 or more days before the PSM or day 2 and expect them to be on heat in the first few days of mating.

However if the cow has had a heat 2 or more weeks before the PSM then there are marginal benefits as she would come on heat in the first week of mating anyway.

The major benefits arise from injecting those cows that come on heat in the week before mating starts.

A variation of this plan is to give 2 injections of PG, 11 days apart. The cows have to be cycling and the second injection is given just before the PSM. This obviously doubles the cost but reduces the organisational work. Mating is still done on observed heat.

Some farmers have used the single shot PG method here, generally not on all of their cows and have been very satisfied with the results. In fact the major complaint is at the other end where they have to be prepared for a lot of cows calving early in the season.

The PG method is ineffective on anoestrus cows and is probably not advisable if premating heat date recording is not a part of your management.

For anoestrus cows, and for heifer synchronization and even cow synchronization there is the Ovsynch progress.

This consists of 3 injections, with 9 days before the first and third injection and fixed time insemination 16-20 hours after the third injection.

Using a CIDR does significantly improves the conception rate and also you can give a Chorionic Gonadolsophin which also improves the conception rate.

The CIDR can also be reinserted into these anoestrus cows on day 14 to day 20 and returning cows mated on observed heat.

If you require any further information, please contact us at the clinic.