Calving interval of canchim cows

Abstract

The 1.095 calving intervals of 224 5/8 Charolais.3/8 Zebu cows and 318 intervals of 170 Canchim cows were studied. Month of the beginning of the interval affected (P<0.01) the intervals from both genetic groups, while year (P<0.01) and interval number (P<0.05) affected only the intervals of the 5/8 Charolais -3/8 Zebu cows. The intervals were, in general, shorter when the first calving of the interval occurred during the dry season (April to October). The first interval was the longest, and there was a tendency to shorten up to the last interval studied. Sex of calf and age at first calving had no effect on calving interval. The least squares means were, 405.2 days for the Canchim and 407 days for the 5/8 Charolais - 3/8 Zebu cows. Heritability estimates of, in the same order, 0.045 ± 0.100 and 0.041 ± 0.142, suggest that there is no scope for improving calving interval through selection. Repeatability estimates of 0.171 ± 0.080 for the Canchim and of 0.203 ± 0.031 for the 5/8 Charolais- 3/8 Zebu cows, indicate, however, that there is some permanent effect, hereditary or environmental, responsible for permanent differences among cows.