28 March 1997

Lambs face less risk from copper

THE addition of 4ppm molybdenum to the diet of intensively reared lambs reduced the concentration of copper in the liver and the risk of copper poisoning.

This was despite the short duration of an 11-week trial and a low level of copper in the diet.

Work on the effect of dietary molybdenum content and also the floor type on the liver copper concentration at slaughter and the growth rate on early-weaned lambs, was done by M OHara, J V ODoherty, P J Quinn, J J Callan and T F Crosby at the University College Dublin, Ireland.

Lambs bedded with straw accumulated less liver copper than those on expanded metal floors. For lambs on the metal floor, increasing the level of added molybdenum from 4ppm to 8ppm reduced the liver copper concentration further.

For lambs on straw bedding, an increase in dietary molybdenum from 4ppm to 8ppm had no effect.

A greater production of sulphide in the rumen of straw fed lambs results in a lower efficiency of dietary copper absorption and a resulting lower accumulation of liver copper.

It was concluded that, for intensively fed lambs, the risk of copper poisoning may be reduced without loss of performance, by housing lambs on straw bedding instead of metal floors.n