30 November 2001

How to improve B&Ws fertility

MANAGING body condition losses around first service and selecting easy calving bulls are key factors for improving dairy cow fertility, according to recent Irish research.

Pregnancy rates to first service have fallen by 12% since the mid-1980s and empty cow rates now exceed 15%, says Teagasc Moorepark researcher Frank Buckley. "This equates to a £70/cow increase in production costs from poorer fertility over this period."

To address this decline in fertility, a trial involving 73 Irish herds aims to identify management factors reducing herd fertility and provide practical solutions.

Early results from the trial identifies managing body condition losses between calving and first service as a key factor. A condition score loss of more than 0.5 resulted in conception rates falling by 31%, compared with a loss of 0.25. The optimum body condition at first service is 2.75.

"To achieve this, aim for a score of 3-3.5 at calving and limit condition losses to less than 0.5. This will maximise both milk production and fertility."

Calving difficulty is also important with conception rates reduced by up to 17% following assisted calvings in the trial.

Select bulls known for their calving ease to maximise herd fertility, says Dr Buckley.

"Increasing herd size also reduces herd fertility, with conception rates 6% lower for units with more than 150 cows compared with units with less than 75 cows." &#42