Group breeding schemes and simplified recording in sheep improvement

Summary Group breeding schemes have been developed to enable several small-scale breeders to combine into an effective breeding operation, involving the screening of large numbers of females for use in a nucleus flock. Developments associated with the University College of North Wales are described and some detail given of the operation of the Lleyn group breeding scheme. The scheme operates on a total group membership of approximately 1200 ewes, associated with an open nucleus of 150 breeding females. Emphasis in selection is placed on prolificacy and milk yield and the results indicate a level of performance of two lambs weaned per mature ewe over a 5 year period at a mean 56 day weight of 17.3 kg for twins. Computer simulation studies indicate that the structure of the scheme, involving the use of 7 month old rams only as the nucleus sires, is in the main appropriate for the type of breed and flock structure involved. The use of simplified recording, particularly for screening extensively managed flocks, is an important aspect; it is concluded from the work of Fadel (1986, personal communication) that systems that involve no individual identification and only one visit, shortly post-weaning, is a most efficient way of ranking ewes, on the basis of milk yield, in dairy ewes of the Awassi breed. Similar applications are also noted for Welsh Mountain sheep in temperate conditions (Phillips, 1986).