To treat or not to treat, that is the question

17 August 2020

By Samantha Tennent, DairyNZ developer and In-Calf programme manager

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 – when we want cows cycling as early as possible to improve their chances of getting in calf early in the mating period.

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. 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 and fewer may require treatment. But for some cows, a delay until treatment may affect conception. Both queries have been addressed in New Zealand research.

Research into the benefits of treatment

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 sixteen 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 their reproductive performance in seasonally calving dairy herds.

Treatment is cost-effective

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 each season there is likely an underlying issue that needs to be addressed with your vet and adviser.

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