AVALIAÇÃO DO DESEMPENHO REPRODUTIVO DE VACAS NA REGIÃO DO PANTANAL SUL-MATO-GROSSENSE SUBMETIDAS A IATF Com Aplicação De GnRH

The technique of timed artificial insemination (TAI) is spreading in Brazil, as it contributes to the increase of productivity. The objective of this work was to evaluate the use of GnRH in TAI protocols of cows raised in the swamp of Mato Grosso do Sul. 531 Nelore breed calved cows participate in the survey, which were evaluated according to the body condition score (BCS), and then performed three types of TAI protocols (batch 1, 2 and 3). After 40 days of the insemination, a pregnancy diagnosis was made. The matrices that did not receive GnRH in batch 1 (apparent oestrus), batch 2 (partial oestrus) and batch 3 (no oestrus presentation) presented respectively 55.4%, 19.2% and 25.9% of pregnancy, while those receiving the drug showed 48.6%, 37.2% and 38.8%. Related to BCS, it can be observed that the highest pregnancy rate occurred in animals with BCS 3. Primiparous had a better pregnancy rate when receiving GnRH regardless of BCS. It was concluded that the use of GnRH was efficient to improve the pregnancy rate mainly in primiparous as well as animals that showed no oestrus or partial oestrus, and matrices with BCS 3 had better pregnancy rates than cows with lower scores.A Inseminação artificial em tempo fixo (IATF) está se difundindo no Brasil, pois contribui para o aumento da produtividade. O objetivo neste trabalho foi avaliar o uso do GnRH em protocolos de IATF de vacas criadas no pantanal Sul-mato-grossense. Participaram da pesquisa 531 vacas paridas da raça Nelore, que foram avaliadas de acordo com o escore de condição corporal (ECC), submetidas a três tipos de protocolos de IATF (lote 1, 2 e 3). Após 40 dias da inseminação artificial foi realizado diagnóstico de gestação. As matrizes que não receberam GnRH no lote 1 (estro aparente), lote 2 (estro parcial) e lote 3 (sem apresentação de estro) apresentaram, respectivamente 55,4%, 19,2% e 25,9% de prenhez, enquanto as que receberam o fármaco apresentaram 48,6%, 37,2% e 38,8%. Relacionado ao ECC, pode-se observar que a maior taxa de prenhez ocorreu em animais com ECC 3. Primíparas apresentaram melhor taxa de prenhez quando receberam GnRH independente do ECC. Concluiu-se que o uso de GnRH mostrou-se eficiente para melhoria da taxa de prenhez principalmente em primíparas, assim como nos animais que não apresentaram estro ou apresentaram estro parcial, e que matrizes com ECC 3 apresentaram melhores taxas de prenhez que vacas com escore inferior. Palavras-chave: bovino de corte; inseminação artificial em tempo fixo; produtividade; GnRH; Nelore. Evaluation of cow reproductive performance in the region of Mato Grosso do Sul swamp submitted to TAI with GnRH application ABSTRACT: The technique of timed artificial insemination (TAI) is spreading in Brazil, as it contributes to the increase of productivity. The objective of this work was to evaluate the use of GnRH in TAI protocols of cows raised in the swamp of Mato Grosso do Sul. 531 Nelore breed calved cows participate in the survey, which were evaluated according to the body condition score (BCS), and then performed three types of TAI protocols (batch 1, 2 and 3). After 40 days of the insemination, a pregnancy diagnosis was made. The matrices that did not receive GnRH in batch 1 (apparent oestrus), batch 2 (partial oestrus) and batch 3 (no oestrus presentation) presented respectively 55.4%, 19.2% and 25.9% of pregnancy, while those receiving the drug showed 48.6%, 37.2% and 38.8%. Related to BCS, it can be observed that the highest pregnancy rate occurred in animals with BCS 3. Primiparous had a better pregnancy rate when receiving GnRH regardless of BCS. It was concluded that the use of GnRH was efficient to improve the pregnancy rate mainly in primiparous as well as animals that showed no oestrus or partial oestrus, and matrices with BCS 3 had better pregnancy rates than cows with lower scores. Keywords: beef cattle; timed artificial insemination; productivity; GnRH; Nelore