Factors that affect birth and weaning weights of Canchim calves

Abstract

Birth and weaning weights of 1404 Canchim calves (5/8 Charolais-3/8 Zebu) sired by 29 bulls and born during the period of 1971 to 1979 were studied. Weaning weights were adjusted to 270 days, by means of the average daily gain from birth to weaning and regression of weaning weight on weaning age. Year and month of birth and sex of calf significantly (P<0.01) affected birth and 270-day weights; age of cow affected (P<0.01) only 270-day weights. Sire of calf did not affect significantly (P>0.05) the traits studied. The heritability estimates, obtained by the paternal half-sib method, were 0.038 ± 0.036, 0.039 ± 0.036 and 0.033 ± 0.034, respectively, for birth weight, 270-day weight adjusted by the average daily gain. and 270-day weight adjusted by the regression equation. The low heritabilities suggest that selection for these traits would result in very small or none genetic progress. Least square means were, in the same order, 38.05 kg, 204.87 kg and 211.46 kg. Very similar results were obtained for the two methods of adjustment for 270-day weight, suggesting that both methods can be used for this particular herd of Canchim cattle.