22 March 1996

Hormone jab lifts cow pregnancies

This weeks British Society of Animal Science annual winter meeting at Scarborough, Yorks, presented the latest in livestock research.

Harry Hope reports

INJECTION of the gonado-trophin hormone buserelin 10 to 12 days after service has reduced embryo mortality and increased pregnancy rates to AI from 53.4 to 65.4% in dairy cows which are breeding normally.

But its use with known problem cows is unlikely to be beneficial.

This verdict was reported by Duncan Pullar, ADAS High Mowthorpe and Tony Wrathall, Central Veterinary Laboratory, in a paper at the BSAS meeting.

The trial involved 78 Hereford Friesians, of which 40 were reproductively normal, while 38 suffered breeding disorders and had not calved in the previous 15 months.

All cows were synchronised for heat and 15 of the suspect cows had to be rejected because they lost their "PRID" or could not be inseminated. All remaining cows were AId three times after PRID removal. Half of the cows in each group were injected with buserelin (2.5ml Receptal/ Hoechst Animal Health), 11 days after the first AI.

Pregnancy rates in normal untreated cows were considerably below herd average, possibly due to synchronisation treatment and hot weather over the trial.

Despite the high level of observed heats in suspect cows, pregnancy rates were very low. This implied that the breeding disorders could not be overcome by the use of buserelin.

Pregnancy rates to AIin dairy cow breeding can normally be improved by injecting the hormone buserelin 10 to 12 days post-service.