Non-cyclers

With the end of calving drawing closer and days getting longer, now is the time to start thinking about mating. Maximising reproductive performance not only sets you up for success in the coming season, but the impacts of a good (or bad) mating season are felt for years to come.

Non-cycling is the most common cause of infertility in New Zealand herds.

Non-cycling cows fit into two categories:

• Cows that have cycled but have not had a detected heat i.e. a “silent heat”
• Cows that have not started cycling since calving – true non-cyclers.

These cows reduce submission rates; in turn impacting the 6-week in-calf rate, the number of AB calves, and days in milk for the following season. 

What Causes Non-Cyclers?

A number of factors can contribute to a cow becoming a non-cycler

• Calving date – cows need adequate time to resume cycling following calving (around 42d for cows and 50d for heifers)
• Low BCS
• Assisted or difficult calvings
• Uterine infections
• Poor heat detection (missed heats)

How do I Identify Non-Cyclers?

Pre-mating heat detection (through the use of tail paint or heat mount detectors) is crucial to identify non-cyclers early on. Starting 5 weeks out from planned start of mating (PSM) gives you adequate time to identify whether you have a problem. To reach the target 3-week submission rate of 90%, more than 85% of the herd should have cycled by 10 days before PSM.

How Can We Help?

The only effective option this close to mating is hormonal intervention. Your vet will be able to tailor a plan that is cost-effective and works for your specific situation, but in general, non-cycler treatments are more profitable the earlier you treat. This is because it:

• Generates earlier AB calves
• Results in more days in milk
• Produces a tighter calving spread so cows have more time to recover prior to mating next season
• Reduces bull power demand later on in calving

Now is the time to act, if you think (or know) you have a problem, do not hesitate in getting in touch!

Dr Steph Reid, Farm Vet, Kopu.