28 July 1995

DUPfor dry cows boosts milk

COWS fed a protein supplement in the dry period produce more milk than those fed silage alone, according to Tim Harrington of ADAS Bridgets.

Speaking at the Elite herd sponsors open day, he said it was the quantity of protein fed rather than the source which was important in increasing milk yields.

This was the result of a study which compared high and low rates of digestible undegradable protein (DUP) fed as either fishmeal or protected soya (SoyPass) with a silage only diet in the four weeks up to calving.

Cows on the study were fed an ad-lib silage diet only, or were supplemented with fishmeal at 0.3kg a day or 0.6kg a day, or protected soya at 0.45kg a day or 0.9kg a day.

Silage intakes in the four weeks up to calving did not differ significantly between treatments but there was a trend for protein supplemented cows to eat more silage.

"The greatest difference occurred two weeks pre-calving, where cows fed a protein supplement consumed 10.62kg silage DM a head a day whereas cows fed the silage only diet ate 9.25kg DM a head a day," said Mr Harrington.

Milk protein percentages differed between the diets with cows fed the protected soya DUP source recording 3.30% milk protein over the whole lactation while cows fed with fishmeal recorded 3.18% protein.

"But when we compared the total yields of protein for the whole lactation we could not establish a difference between the diets," said Mr Harrington.

Protected soya supplemented diets also increased fat percentages at certain stages throughout lactation. Up to month seven, cows fed protected soya averaged 4.03% fat compared with the fishmeal supplemented and silage-only fed cows which averaged 3.80% fat.

"Once again when we compared total yields of fat there were no differences across the diets," he said.

Over the course of the study the cows fed the high level of DUP in the dry period had significantly higher milk yields. Both the silage only group and the low DUP groups had average daily yields of 22.4kg whereas the high DUP groups had an average daily yield of 24.7kg.

Work this summer will examine dry cow feeding in more detail.

"This study provided further evidence that DUP in the dry period can give a response in terms of milk production. It is not clear whether the effect is due to the DUP level, or indirectly due to increased energy intake further work this summer at ADAS Bridgets is looking at these factors in more detail," said Mr Harrington.


ELITE HERD FACTS


&#8226 Herd size: 56

lAverage milk yield: (kg a cow) 10205

lFat (%): 3.53

lProtein (%): 3.16

lMilk price (p/litre): 21.82

lMargin over all purchased feed (p/litre): 15.06

lMargin over concentrates (£/cow): 1564

lMargin over all purchased feed (£/cow): 1537

ADASresearch consultant Tim Harrington… cows fed high DUPlevels produced more milk.

next lactation than those fed fishmeal.