Frequency Distribution of Genetic Markers in Guernsey Cattle

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Abstract
Ten polymorphic systems of blood antigens and blood proteins were analyzed in 6802 Guernsey cows from 77 herds and 11 states. The numbers of alleles identified with frequencies > 1% in the A, B, C, F, J, L, M, S and Z blood antigen systems and the alkaline phosphatase system were 3, 17, 11, 2, 2, 2, 1, 3, 2 and 2. Gene frequencies were determined by maximum likelihood, allocation and square root methods for the dominant systems and by the gene counting method for the codominant system. Distributions varied greatly in the different systems. Comparisons among these and other blood and milk genetic marker systems revealed lack of independence of J and alkaline phosphatase phenotypes, J and milk prtein .beta.-lactoglobulin phenotypes, and of combined phenotypes of the 3 systems. More cows than expected were J-negative when alkaline phosphatase A was present or when .beta.-lactoglobulin B was present. Phenotypes of blood antigen system A and Hb were also different from independent assortment. More Hb B cows had blood antigen system A phenotype A than the other phenotypes. The blood antigen locus F had more heterozygous cows than were expected for Hardy-Weinberg equilibrium.