ARS | Publication request: Genetic parameters for weaning weight by age of dam for Brazilian Nellore

Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: March 12, 2007
Publication Date: June 20, 2007
Citation: Da Silva, L.O., De Souza, J.C., Gondo, A., Malhado, C.H., Freitas, J.A., Santos, I.W., Sereno, J.R., Weaber, R.L., Van Vleck, L.D., Lamberson, W.R. 2007. Genetic parameters for weaning weight by age of dam for Brazilian Nellore [abstract]. Journal of Animal Science. 85 (Supplement 1):258-259. (Abstract #T54)

Technical Abstract: The objective was to estimate genetic parameters by age of dam subclass for weaning weight of Nellore cattle raised on pasture in two regions of São Paulo State, Brazil, between 1975 and 2001. The data were from ABCZ / EMBRAPA and included 51,664 weights at 205 d (W205) from progeny of 24,996 cows. Records were grouped on the basis of age and number of calves of dams. Seven groups were established: G1 included all dams; G2 had dams with a minimum of 2 calvings, age of first calving greater than 60 mo, and calving between 280 and 1095 d; G3 had dams with one parturition (first) between 22 and 84 mo; G4 to G7 included dams calving between 35 and 60; 61 and 84; 85 and 120; 121 and 240 mo of age, respectively and all had at least two parturitions with no restriction for calving interval. Estimates of variances and covariates were obtained from single trait analyses using the MTDFREML set of programs. Fixed effects were contemporary group [season (dry or wet), year, sex and farm combination] with age of dam as linear and quadratic covariates. Random effects were direct and maternal genetic effects with covariance, and the uncorrelated maternal permanent environmental effect. Estimates of direct heritabilities ranged from 0.14 ± .02 to 0.19 ± 0.02 for all groups except G5 which had an estimate of 0.26 ± 0.06. Maternal heritabilities ranged from 0.02 ± 0.09 to 0.11 ± 0.11. Estimates of the direct-maternal genetic correlation were negative and increased from -0.14 ±.66 for G4 to -0.87 ± 0.20 for G6, although the estimate was near zero with a large standard error for G7. These results suggest that heritabilities remain relatively constant across age of dam groups for Nellore, but that the direct-maternal genetic correlation may become more negative for older dams.