Estimate of genetic parameters for probability of pregnancy at 14 months and hip height in Nelore beef cattle

Records of 24,703 Nelore cattle from six herds were used to estimate coefficients of heritability for probability of pregnancy at 14 months (PP14) and hip height (HH) traits. For PP14, the mathematical model included as fixed effects the contemporary groups (181 groups) and dam age class at calving (7 classes) and for HH only contemporary groups (584 groups). Random effects included were genetic additive of sire and residual effects. Variance and covariance components were obtained by method R. Heritability estimates were 0.73 +/- 0.01 and 0.30 +/- 0.00 for PP14 and HH, respectively. Genetic correlation estimate between PP14 and HH was 0.10 +/- 0.01. Results reveal that PP14 is of high heritability and, therefore, it can be indicated for selection programs of bulls, with the objective of increasing the heifer fertility. The value of the genetic correlation suggests low genetic correlation between the two traits, indicating that selection for growth, measured by the HH, is not a so strong antagonism to the precocity of the heifers measured by PP14.