Supplementation of finishing lambs fed swedes in situ has been traditionally achieved with cereals or 14% CP compound feeds. Crowing of winter cereals has reduced the availability of protein-rich grass runbacks and on most farms where lambs are consuming mainly swede bulbs there is likely to be a daily deficit of RDP of around 16 g RDP/day (0.15 of total requirement). Recent MLURI work (Milne pers comm) indicates that the normal RDP:ME ratio of ruminant diets of 7.8:1 may be inadequate in the unusual conditions of high rumen turnover rates and rapid fermentation associated with root feeding. Rowett feed evaluation work indicates higher ME values for swedes than previous estimates increasing energy:protein imbalance.
This trial had two objectives; to study response to supplementation of swedes with soya bean meal compared to barley and to study whether holding lambs for 3 months inside on a straw based diet prior to finishing was an effective alternative to holding lambs on autumn grass outside. The potential advantages of this alternative are reduced competition for autumn grass between breeding ewes and finishing stock and better utilisation of sheep housing and arable by-products.