Animal Science Department
Date of this Version
Original data consisted of 31,777 records of progeny of 1442 sires for calvings between 1975 and 1983. Unadjusted means for milk yield (kg), days in milk, days dry, calving interval, days carried calf, and age at calving were 4281, 267, 88, 421, 145, and 36.6. Estimated total variance for first lactation milk yield by Henderson's method 3 was 1,385,436 kg 2 with sire and error variances accounting for 1.8 and 98.2%. Heritabilities for milk yield, lactation length, age at calving, and days carried calf were .07, .06, 2.59, and .01. High estimate for age was attributed to confounding of sires with season of calving. Genetic and phenotypic correlations between traits were milk and lactation length, .76 and .72; milk and age at calving, .17 and -.04; milk and days carried calf, -2.11 and .13; lactation length and age at calving, -.13 and -.06; lactation length and days carried calf, .87 and 16.; age at calving and days carried calf, -.60 and -.03. Sires with at least 10 daughters were evaluated by best linear unbiased prediction procedures. First lactation sire values for milk ranged from 359 to -340 kg with an average difference between sires of 12 kg. Sire values using all lactations ranged from 505 to -286 kg with an average difference between sires of 13 kg. Rank correlation between all and first lactation evaluations was .77.
Published in J Dairy Sci1986, 69:1081-1086. Copyright © 1986 The American Dairy Science Association. Used by permission.