[The nitrogen retention of early weaned lambs]

At 30-to-60-day-old lambs reared without mothers 23 different feed mixtures were tested in N-balance experiments. The following results were achieved: The concentration of digestible crude protein and energy as well as the relation between them (PEQ) have no significant influence on the lambs' nitrogen retention. The energy intake and the intake of digestible crude protein have an intensive, significant influence on nitrogen retention. Rising energy and N-intake within the limits on which the investigation is based increased nitrogen retention. Of the protein feedstuffs tested, a 6 ... 7% higher nitrogen retention was realised from soybean oil meal as the sole source of proteins with 35% retained nitrogen related to the nitrogen intake in comparison to the combinations soybean oil meal/dried skim milk resp. fish meal. Increasing dried yeast portions (greater than 5%--20%) in the feed mixture diminished nitrogen retention. On the basis of the existing results the following recommendations for the use of the tested protein feedstuffs in rearing feed for lambs can be formulated: Soybean oil meal can be used as the sole source of protein in rearing lambs. The use of up to 5% dried yeast in the rearing feed as protein source and for vitaminisation is possible; 20% however diminish nitrogen retention. Because of the positive effect on feed intake it appears suitable to use fishmeal in the rearing feed for lambs.