The effect of steroid hormones on the rate of gain and feed utilization in lambs

In Tennessee, approximately 80 per cent of the income from sheep comes from the sale of fat spring lambs. These lambs are usually marketed during the period from April through June at a weight of 80 to 100 pounds. Light weight and/or under finished lambs usually sell at marked discount. During the latter part of the season a considerable number of such lambs are marketed. During the 1953 marketing season, approximately 16 per cent of 17,350 lambs, sold through organized lamb pools in the state, graded utility or lower. The prime, choice and good lambs returned an average of $13.21, $10.88 and $6.41, respectively, more per hundred pounds than the utility lambs.

Late lambing, poor milking ewes and parasites are probably the primary factors preventing these lambs from meeting desired market requirements. If some method could be found to salvage such lambs, the returns to the farmer could be increased considerably. A few farmers have developed a satisfactory program for handling those lambs. As a rule, they are wormed, pastured through the summer and fed for a limited time during the fall. Then they are marketed during the late fall early winter.

Subcutaneous implantation of stilbestrol, a synthetic female-like sex hormone, has shown considerable promise of increasing rate of gain and efficiency of feed utilization in fattening lambs. However, previous work at this Station has shown that one possible disadvantage to the use of this hormone in fattening lambs has been the frequent occurrence of rectogenital prolapse, particularly in the stilbestrol treated ewe lambs. If this difficulty could be overcome, the use of these sex hormones possibly offers a method of increasing the returns from these utility and cull lambs to the farmer.