Factsheets - Sheep & Beef
The following fact sheets have been prepared by Anexa FVC Veterinarians as a guide to topics of interest. For specific information please contact your local vet.

Mating Strategies Planned?

Mating Strategies Planned?
By Fiona McLeod, Veterinarian, Anexa Vets Te Kauwhata

With calving upon us, it is time to start planning our mating strategies before it is too late to make any changes. Good mating policies lead to a compact calving period, more calves weaned and even better results next year.

The end goal is a calving rate of 90% over all ages with 60% calving in the first three weeks. Unfortunately it’s not just getting them pregnant that is important but getting them pregnant early. A compact calving makes for easier feed allocation, an even line of weaners to sell, an even line of heifer replacements, increased average weaning weights and more cows pregnant early next year. For mature cows, the average mating length is nine weeks or three cycles.

Breeding heifers at 15 months old to calve at 2 years old is an important tool to speed up genetic progress and increase the efficiency of each cow’s breeding life. It is important that they are grown well before mating starts, reaching 300kg for Angus and Hereford or 320 kg for later maturing breeds. Heifers are usually only mated for six weeks or two cycles. This is based on the average cow which has a 21 day cycle. However, this is just an average and means that the heifer that has a 22 or 23 day cycle will only get one chance to get in calf. Consider extending this period to seven weeks to give these girls a second chance. It is important to cull the drys from this mob as this is a good predictor for their future breeding potential.

Bull failure is another important cause of dry cows. There should be at least one bull per 50 cows, or one yearling bull per 30 cows. Yearling bulls must have reached puberty and be well grown, aim for 350kg before mating starts. It is recommended that the bulls are fertility tested to check for any duds but a good on farm indicator is scrotal size. We recommend a minimum of 32cm for yearling bulls and 34cm for 2 year olds. Of the bulls we test, we find about 10% that are subfertile which will be contributing to a decreased calving rate and later calving pattern.

Bulls aren’t the only option of course. Many studs are using AI on their best cows to speed up the genetic gain. Usually CIDRs are used to stop the cow’s cycle and start them again so that we can inseminate on a set day. This reduces the number of AB visits and the need to heat detect. CIDRs need to be inserted 10 days prior to the AB date so speak to your vet if you think this might be an option for you.

The final stage is to check how well we did. Pregnancy scanning is best done six weeks after the bull has come out. Knowing the drys early gives a chance to cull them or allocate feed appropriately. It also allows us to plan for the calving period in terms of calving spread and labour and helps us to begin planning for next year!





Date Added: Wednesday, 9th October 2019


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