Heritability estimates derived from threshold analyses for reproduction and stayability traits in a beef cattle herd

The object of this study was to estimate heritabilities and sire breeding v alues for stayability and reproductive traits in a composite multibreed bee f cattle herd using a threshold model. A GFCAT set of programmes was used t o analyse reproductive data. Heritabilities and product-moment correlations between predicted breeding values for stayability at 36, 48, 60, 72 and 84 months of age, calving success and longevity were estimated. The estimated heritabilities on the underlying scale for these traits were 0.06, 0.10, 0 .06, 0.03, 0.11, 0.03 and 0.08 respectively. Product-moment correlations be tween breeding values for stayability traits were low. The highest correlat ion of 0.22 was obtained between the ages of 36 and 48 months. Heritability estimates and correlations between traits appear to be of such a low magni tude that selection for these characteristics would result in limited genet ic improvement, and also indicate that sires had little influence on the st ayability, longevity or calving success of their daughters.