The efficiency of lamb production can be improved by overcoming the major reproductive problems of sheep: (a) low lambing rate; (b) restricted breeding season; (c) low fertility during the early postpartum period; (d) late puberty; and (e) perinatal lamb losses.

Lambing rate is being improved impressively by increasing the ovulation rate through crossbreeding., selection, and improved management. Little progress has been made in reducing embryonic and fetal mortality, a problem especially prevalent during the early part of the breeding season and in hot environments. Some progress is being made toward reducing the restrictions to lamb production efficiency caused by the short breeding season. The breeding season is being eliminated, lengthened, or modified through breeding and selection hormone therapy and controlling exposure to light. Much more needs to be done to permit lambing at any time of year and to shorten lambing intervals to less than one year.

Little progress has been made in improving fertility during the early postpartum interval. This an important area for future investigation in order to shorten lambing intervals. Age at puberty has been reduced and fertility improved in ewe lambs through crossbreeding, selection, improved nutrition, and management. The breeding of ewe lams is commonly practiced throughout the United States with increasing success every year. New research data in management and disease control suggest success each year. New research data in management and disease control suggest way to markedly reduce losses of perinatal lambs. Further progress may come through the development of new vaccines for the prevention of losses caused by enzootic abortion in ewes and scours in lambs.