EFEITOS NÃO GENÉTICOS SOBRE AS CARACTERÍSTICAS REPRODUTIVAS DE FÊMEAS DA RAÇA NELORE. II - IDADE À PRIMEIRA PARIÇÃO E INTERVALO DE PARTO * NON GENETICS EFFECTS ON REPRODUCTIVE TRAITS IN NELLORE FEMALE. II - AGE AT FIRST CALVING AND CALVING INTERVAL

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 nao geneticos sobre as caracteristicas reprodutivas de femeas da raca Nelore. II - Idade a primeira paricao e intervalo de parto. Revista Brasileira de Medicina Veterinaria, 32(2):79-88, 2010. Centro de Criacao de Animais de Laboratorio, Fundacao 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 0.05) 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.