14 February 1997

Irish and Scots beg to differ on benefits of DUP

Feeding extra protein to dairy cows pre-calving may not improve milk protein percentages. Jessica Buss reports on research results

FEEDING cows concentrates high in undegradeable protein in the month before calving fails to increase milk protein content or milk yields.

That is according to researcher John Murphy of Teagascs Moorepark Dairying Research Institute, Cork Ireland. His two-year findings are contrary to those of the Scottish Agricultural College and ADAS, where studies have shown a response to feeding extra protein pre-calving.

In the Irish studies cows were fed sources of undegradeable protein (DUP) with ad lib grass silage, or with restricted silage and straw diets. A control group of cows was fed unsupplemented grass silage.

The DUP concentrates fed with the silage in the first year of the studies were 0.5kg of fishmeal with 0.5kg of unmolassed sugar beet pulp, or 0.75kg of soya with 0.25kg of beet pulp.

"These diets provided the same protein intake but had different digestibility," says Dr Murphy.

He found no differences in the performance of cows fed unsupplemented silage or silage supplemented with protein.

In year two, three diets were fed: Silage, restricted silage with straw, and lastly restricted silage with straw plus 1kg of concentrate made up of half fishmeal and half beet pulp.

"We were using fish, as it is a good source of undegradeable protein," he says. "But there was no response in this study either."

He concludes that increasing milk protein is not as simple as feeding undegradeable protein pre-calving. He admits that the mineral balance of cows is important pre-calving, but notes that there has never been milk fever at Moorepark, indicating adequate mineral levels in cows pre-calving.

The milk proteins of the unsupplemented control cows were higher at Moorepark, at 3.2%, compared with milk protein of 2.89-3.07% for the control cows in previous SAC studies.

Moorepark trials (yr 1)




Milk (litres)24.123.524.1

Fat %3.593.653.58

Protein %