Abstract
ABSTRACT. Vieira D.H., Medeiros L.F.D., Barbosa C.G., Rodrigues V.C., Mello M.R.B. de & Oliveira J.P de. [Non Genetics effects on reproductive traits in Nellore female. II - Age at first calving and calving interval]. Efeitos não genéticos sobre as características reprodutivas de fêmeas da raça Nelore. II - Idade à primeira parição e intervalo de parto. Revista Brasileira de Medicina Veterinária, 32(2):79-88, 2010. Centro de Criação de Animais de Laboratório, Fundação Instituto Oswaldo Cruz, Avenida Brasil, 4365, Manguinhos. RJ 21040-360, Brasil. E-mail: deborahv@fiocruz.br Reproductive performance of Nellore cattle herd, raised in pasture, without supplementation in dry season, in the Baixada Litorânea region, State of Rio de Janeiro, between 1980 and 2004, was analyzed. 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 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 aggravated 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.