28 June 2002

Control energy deficit

REDUCING the frequency of milking during the first four weeks of lactation has been claimed to reduce negative energy balance of cows, but Irish research has failed to confirm this effect.

Declining dairy cow fertility is a major issue in Ireland, so nutrition research is investigating practical ways to reduce negative energy during early lactation, says Teagasc nutrition researcher John Murphy.

"Reducing milking frequency to once daily was thought to reduce the energy deficit, allowing cows to return into positive energy balance more rapidly. This was tested in a study comparing groups of cows milked either once, twice or three times daily."

Cows milked three times daily had an energy deficit 75% higher than cows milked once daily. This reflected a 7.3 litre difference in milk yields with cows being milked three times daily averaging at 31.4kg/day.

But body condition loss was only 0.28 units for the three times daily milked cows, well within the recommended maximum loss of 0.5 units for maintaining fertility from previous work, says Dr Murphy.

"Conception rates were at 69% across all three groups, suggesting energy deficit was insufficient to cause any problems. All cows reached positive energy balance by week six of lactation." &#42