Authors : A.P. Marquez and H. Gonzalez-Garcia
Abstract: Crossbred dams when mated at different ages and in different years by natural service to Charolais (n = 415) bulls were compared for calf birth weight BW, weaning weight WW, calving difficulty CD measured categorically and calving ease CE measured binomially and calf survival CS. Crossbred cows were from Angus, Hereford, Pinzgauer, Brahman, Sahiwal and Tarentaise crosses. The analytical model included: dam line (breed combination of dam) age of dam, sex and year as fixed effects, whereas julian birth day was a covariate. For analyses with back cross dams, covariates were included in the model for fractions of inheritance from each breed and fraction of complete heterosis of dams due to Bos taurus x Bos taurus, Bos indicus x Bos indicus and Bos taurus x Bos indicus crosses instead of breed combination of dam. Differences among crossbred dam groups were observed for birth and weaning weights and calving difficulty. Birth and weaning weights were less in female calves than bull calves. Crosses involving Brhaman and Sahiwal cows had least calving difficulty. Heifer calves had less calving difficulty than bull calves. There were few differences among dam breeds for survival at weaning, at 3 d or at birth.
A.P. Marquez and H. Gonzalez-Garcia , 2008. Comparison of Crossbred Cows Mated by Natural Service to Unidentified Charolais Sires to Calve at 4-9 Years of Age. Journal of Animal and Veterinary Advances, 7: 478-481.