Detection of milk protein genetic polymorphisms in order to improve dairy traits in sheep and goats: A review

The polymorphism detected in the DNA region containing milk protein genes in sheep and goats, alpha-s1 and alpha-s2 casein, beta-casein, kappa-casein, beta-lactoglobulin and alpha-lactalbumin are described, and the current knowledge of their effects on manufacturing properties of cheese and milk production traits. Other genes showing polymorphisms related to milk production performance are also examined. Sheep genome research and the usefulness of other polymorphic loci, such as microsatellites, for mapping and marker-assisted selection, are also discussed. Current exploitation of the detected polymorphisms in sheep and goats involves the early identification of the animal carriers of the non-wanted alleles, exclusion from mating, as well as parentage verification, which is highly desirable in sheep-and goat-breeding systems. Future exploitation will consider the possibility for the genetic modification of milli composition, fulfilling nutritional requirements and manufacturing properties. (C) 1998 Elsevier Science B.V.