Frequent lambing systems.

Summary Five frequent lambing schedules are discussed and compared to a normal once-a-year lambing system. These include a twice a year, three lambings in 2 years, four lambings in 3 years and the CAMAL and STAR systems. The CAMAL (Cornell alternate Month accelerated Lambing) system allows ewes the maximum opportunity to lamb at intervals of less than 12 months but is more difficult to manage than the STAR system. The STAR system is based on the fact that a calendar year (365 days) contains exactly five, 73 day periods each of which is exactly half of a sheep pregnancy (146 days). By expressing the calendar in circular fashion with each 73 day period marked off and connecting alternate points a perfect star is formed, hence the name STAR. Ewes are managed to breed at every third point thus allowing 73 days for lambing, lactation and weaning and 146 days for pregnancy. Optimally, ewes can lamb five times in 3 years. The system fits into sheep biology and the calendar year, and because lambing and breeding dates are exactly coincident management of the sheep is easier than most systems. After working on frequent lambing systems for approximately 15 years at Cornell, the author considers the STAR system the frequent lambing sheep production system of choice.