Date of Award
Master of Science
Charles S. Hobbs
Harold J. Smith, R. L. Murphree, J. M. Lain
Reproduction is one of the most important phenomena of the sheep industry. Regular early reproduction is one of the chief factors involved in improving income from sheep. This is particularly true of spring lamb production, where approximately 85 per cent of the total sheep income is received from the sale of lambs.
Sheep production in Tennessee is chiefly devoted to the raising of spring lambs. Such lambs are born during the months of December through early March. These milk-fattened lambs, at weight of 70 to 105 pounds, are marketed from April through June.
Observations have shown that lambs sold during the early part of the marketing season have produced much greater returns than those sold later. To produce early lambs, ewes must be bred early and uniformly during the late summer and early fall. This has been a problem in Tennessee, because many ewes fail to conceive at this time. High temperatures, characteristic of this season, may account for a part of the lowered breeding performance of sheep.
Many attempts have been made to induce ewes to breed early. Recent Australian studies of teasing ewes with vasectomised rams prior to joining fertile rams apparently show considerable promise for increasing conception rate in the ewe. However, more experimental work is needed before this practice can be recommended.
Another important problem in keeping Tennessee flocks on a high level of lambing production is the culling of non-productive ewes. In this area, flock replacement ewes are generally purchased rather than raised. This leaves the sheepman with no records or basis for culling these purchased ewes, short of performance testing. To solve this problem, an accurate method of selecting ewes for future performance is needed. A possible answer might be the use of a yearling ewe's first lambing record as an index of subsequent lashing performance.
Ioset, Robert Murray, "A study of some factors affecting reproduction of sheep. " Master's Thesis, University of Tennessee, 1956.