23 February 1996

Lamb feed roots check

SHEEP producers relying on roots to finish lambs are urged to check the crop for frost damage.

Low dry matter varieties (under 10%) are likely to be affected badly where temperatures went below -5C, according to Dr John Vipond of the Scottish Agricultural College. Christmas frosts did most damage unless crops were protected by snow or weeds, he says.

Frozen roots turn a brighter orange and will rot more quickly – some lower dry matter varieties will fail to last longer than two to three weeks after a severe frost, he reports in the latest edition of Signets Sheep and Beef Notes. When the root becomes "soup-like" the sheep will eventually reject it, he says.

Producers offering roots early in the year should consider sowing high DM varieties to reduce the risk of frost damage – typically one-third should be of such varieties, for example Melfort and Angus. Crops to be grazed in late autumn/early winter can comprise more of the lower DM varieties which tend to be high yielding.

He suggests that where frost damage has occurred and lambs are nearly finished it may pay to increase concentrate feeding to push the lambs on quicker. This could be as trough feeding of cereals plus soya, or straights or a commercial compound. Up to 1.2kg/head/day can be offered in this way as two feeds. Ad lib feeding would demand a low starch (10-20 ME) concentrate to avoid acidosis. This could be a proprietary compound or a blend of beet pulp/maize gluten/cereals.

He also advises against sending lambs to abattoirs with dirty fleeces. Where possible put them onto grass plus concentrates a week before they are sent off.