Abstract
Ten stations have cooperated to utilize genetic markers to permit selection of animals at an early age. Data from 47 Holstein herds from 1960 to 1973 included 22,000 lactations, genetic markers on 8600 cows, 4,800 first lactations with associated marker data, and 30,000 services with marker information on both the cow and service sire. Genetic markers were 10 loci for blood groups (A, B, C, FV, J, L, M, S, Z, and R′ S′), one locus for serum protein (transferrin), and four loci for milk protein (β-lactoglobulin, αs1-casein, β-casein, and κ-casein). Production variables were milk yield and percentages of fat, solids-not-fat, and protein. Reproduction data included dates of service, service sire, and a conception code. Linkage among caseins was extremely close. Phenotypic frequencies of combinations of J and β-lactoglobulin differed significantly from expected, and there was evidence of other nonrandom frequencies within and between systems. Preliminary analysis of relationships between markers and production in first lactation indicated that evaluation of effects should be on models containing several markers and interactions to determine additivity of effects. Preliminary results suggest the probability that some effects will have economic importance. Analysis of reproduction data has been started.
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