Authors : A.P. Marquez and H. Gonzalez-Garcia
Abstract: Crossbred dams when mated at different at different ages and in different years by natural service to sires Longhorn and Red Poll (n = 81 and 86, respectively) 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�Bos taurus, Bos indicus Bos indicus and Bos taurus�Bos indicus crosses instead of breed combination of dam. Red Poll sired calves had more calving difficulty than bull calves, but were heavier at birth and weaning than Longhorn sired calves. Variance due to dam within dam breed effects was important for growth traits and as a fraction of phenotypic variance ranged from 0.47 to 0.48 for birth weight, and weaning weight, respectively. Phenotypic variances due to individual effects of dams whithin crossbred groups mated to Red Poll and Longhorn bulls were 109 and 3528 for birth weight and weaning weight, respectively.
A.P. Marquez and H. Gonzalez-Garcia , 2008. Comparison of the Performance of the Progeny of Crossbred Cows Mated Naturally to Calve at 2 and 3 Years of Age to Red Poll and Longhorn Sires. Journal of Animal and Veterinary Advances, 7: 482-484.