Association of Certain Variables with the Performance of Spring VS. Fall-Born Lambs

Abstract

WITH the current interest in maximizing total lamb production by the use of some type of multiple lambing scheme, some lambs would be produced in the spring and fed during warm seasons and some produced in the fall and fed during cool seasons. The performanace of spring-born and fall-born lambs in the Southern Great Plains area has been studied extensively on a within season basis. However, little information is available directly comparing the performance of spring and fall-born lambs produced under similar management conditions. Blackwell and Henderson (1955) reported that spring-born lambs from Dorset dams were heavier at birth and at weaning than fall-born lambs. However, it has not been established how growth rates compare for lambs fed during warm seasons as opposed to lambs fed during cool seasons. Also, it is not known if sources of variation associated with birth weight and subsequent growth are related in the same manner to lamb performance for both spring and fall-born lambs.