Heritability estimates and selection indices in Hereford from Rio Grande do Sul

Abstract

A total of 8,064 records from weaning weights and conformation scores traits of calves nearly seven month-old were studied. The study included animals from 22 herds from state of Rio Grande do Sul, borned from 1973 to 1985 which were raised on pastures. The weaning weight adjusted to 205-day weight and fat deposition and the relation size-length of body were scored subjetively in a scale from zero to ten. The dates 205-day weight, fat deposition and relation size-length of body were 137.00±0.20 kg; 6.38±0.01 and 6.77±0.01 grades, respectively. The heritability estimates were 0.25±0.03, 0.38±0.04 and 0.37±0.04, respectively. The selection index was more efficient than direct phenotypic selection and this study also indicates that general selection index is not adequated to use it in all farms, and it is not necessary to have accurate economic values. The most important parameters to get good selection are reliable estimates of genetic and phenotypic variances and covariances.