31 March 2000

Low yielding cows get lift from sodium input

APPLYING sodium to grass will boost milk yields from low yielding cows and will also prolong lactation persistence in high yielding cows.

Research work at the University of Cambridge showed that the best milk yield response from applying sodium to grass came from low yielding cows. This result surprised researcher Clive Phillips who had thought previously that there would be a more marked response in high yielding cows.

"This may be because high yielding cows are already performing to their potential," he told delegates.

This was not the case when high yielding cows were fed grass with extra sodium as their liveweight increased, and this may be why these cows produced milk for longer than usual, said Dr Phillips.

Roles are reversed for low yielding cows, which might produce more milk because they require a nutrient boost, said Dr Phillips. "Sodium increases nutrient availability and stimulates grass intakes and it seems that low-yielding cows are in the best position to respond to this."

Additional sodium was applied to pasture as ammonium and sodium nitrate compound fertiliser, at a rate of 32kg/ha/year and a cost premium over typical ammonium nitrate fertiliser of £10-20/t. &#42