Efeitos não genéticos sobre as características reprodutivas de fêmeas da raça Nelore

Abstract

Reproductive performance of Nellore cattle herd, raised in pasture, without supplementation in dry season, in Baixada Litorânea region, Rio de Janeiro state, between 1980 and 2004, was analysed. The gestation length (GL) average was 293.30 + 0.13 days. The GL varied from 275 to 305 days, with a higher concentration (67.08%) between 287 and 299 days. The GL was significantly influenced by year (P<0.05), month (P<0.01) and sex of calf (P<0.05), although the parturition order was not significant (P>0.05) influenced by this characteristic. The age at first calving (AFC) average was 1256.05 + 7.33 days (41.87 months). The AFC was significantly (P<0.01) influenced by year and month of birth. The calving interval (CI) average was 461.80 + 1.964 days (15.39 months). The CI was significantly influenced (P<0.01) by year, month and parturition order, although the sex of calf was not significant (P>0.05) influenced by this characteristic. The average for GL is in the normalit limit for the species and breed. The AFC and CI were higher, that agree with the reality of the herd in the tropics region, in pasture, without supplementation in dry season. This was aggravate by the inefficient reproductive management. The improvement on nutrition and reproductive management can be a faster option for the reduction of AFC and CI in the study herd.