Non-cycling, or anoestrous, cows are a challenge. Cows are in a race against time to recover from calving and begin cycling again in time for mating.
We want cows cycling as early as possible to improve their chances of getting in calf early in the mating period, DairyNZ developer and InCalf programme manager Samantha Tennent explains.
Doing pre-mating heat detection provides early warning you have non-cyclers, and time to do something if required.
Short-term measures to treat non-cycling cows include treating them with hormones. However, there are no right or wrongs, and no one-size-fits-all approach. Each farm needs to assess their non-cycler situation individually and formulate a plan.
Farmers may question whether treatment is cost-effective – and whether to treat before or after mating starts. If they wait until after mating begins, some cows may have started cycling meaning fewer may require treatment. But for some cows, a delay until treatment may affect conception.
Both queries have been addressed in New Zealand research.
The financial benefits of hormone treatment were explored in 2010 research. The results were conclusive. Treating cows was more cost-effective than doing nothing, and this was valid over a wide range of milk payments and responses to treatment. This confirms that investing in the treatment of non-cycling cows provides worthwhile returns to farmers.
A clinical trial in the late 1990s assessed whether hormone treatment before the start of mating or leaving treatment until 16 days after mating began, would achieve better results.
The outcomes showed that treatment eight days before the planned start of mating increased the number of cows that conceived in the first three weeks. It also reduced the time from the start of mating to conception by 7.5 days.
Positively, the conception rate of cows mated following treatment was the same as cows mated at their first spontaneous cycle after calving.
The trial found that identifying and treating non-cycling cows before mating significantly improved the reproductive performance of seasonally calving dairy herds.
Both studies build the case that treating non-cycling cows is more cost-effective than not treating. They also confirm that if you’re going to spend money on treatment, starting early will allow you to reap the full treatment benefits and return on investment.
There are many reasons why cows may not cycle. If your herd is experiencing large numbers of non-cycling cows, there is likely an underlying issue that needs to be addressed with your vet and adviser.
New Zealand’s dairy sector can be commended for their 2019/20 seasonal efforts, with the national average ‘six-week in-calf rate’ hitting 67.8 percent, an increase on a 67.5 percent result for the previous season.
Another exciting milestone is achieving the lowest relative not-in-calf rate of 15.6 percent for the shortest average mating length recorded so far, 10.7 weeks.
DairyNZ has been working to support farmers to improve their results and is attributing the positive figures to continuous work by farmers, breeding companies and DairyNZ’s InCalf programme.
The data is drawn from detailed DairyNZ InCalf Fertility Focus Reports. The number of herds analysed has increased over time and was 4,430 for the latest season, as more farmers make use of this data.
Further information can be found at dairynz.co.nz/reproduction
Article supplied by DairyNZ