Blood Groups and Their Associations with Production and Reproduction in Sheep.

ALLELES at eight autosomal loci are known to affect blood groups in sheep, as recently reviewed by RASMUSEN ( 1962). As in studies of blood groups in cattle, chickens, rabbits and other domestic species, the question has arisen whether balance mechanisms may be involved in maintaining heterozygosity at any or all of these blood-group loci. To that end we have examined the blood groups of several populations of sheep in different environments to determine whether selection for production traits may indeed favor survival of heterozygotes. We have also made statistical comparisons between those sheep with a given blood factor (as A) and those sheep lacking that factor, in order to determine whether selection for various production traits favors one or the other class. The results of these studies are summarized in this paper; details of procedure have been given by STANSFIELD (1963).