15 August 1997

DM intake after calving key to yield

INDIVIDUAL dry matter intakes have a direct impact on cow performance, according to initial monitoring of the Elite herd at ADAS Bridgets using newly installed electronic feed boxes.

Freshly calved cows and heifers in this herd have produced 2.6kg of milk for every kg of dry matter eaten this June.

The first months intake data shows a strong relationship between individual dry matter intake and milk yield, and could influence subsequent lactation yield, says researcher Rosemary Mansbridge.

December and January calving cows also showed a direct relationship between dry matter intake and milk yield, producing 1.9kg of milk/kg of DM.

"But these cows and heifers showed a steady increase in liveweight and growth. Dry matter here is being used not only for milk production but also for liveweight gain," says Ms Mans-bridge.

"Intake data of individual cows from calving shows that cows with steadily increasing intakes over the first five days produce more milk by day 21. Heifers which ate less produced less milk." This highlights the need for better control of factors affecting dry matter intake, which may include pre-calving diets and improved management immediately post-calving.

Heifer intakes and yields increased more slowly than those of cows; in the first 21 days after calving, heifer intakes rose gradually to about 15kg DM, whereas cows ate more quickly, often reaching 20kg DM three to five days after calving.

Data also shows that in the first days after calving cows ate on average 7.3 meals a day, each averaging 1.5kg DM; five days after calving, while the number of feeds a day remained unchanged, average meal size had increased to 2.2kg DM.