Reproductive rates of Nellore herd at Nhumirim farm, Nhecolandia Pantanal/Indices reprodutivos do rebanho Nelore da fazenda Nhumirim, Pantanal da Nhecolandia

• Published in: Acta scientiarum. Animal sciences 2012-01, Vol.34 (1), p.71
• Main Authors: Batista, Dayanna Schiavi do Nascimento, de Abreu, Urbano Gomes Pinto, Filho, Paulo Bahiense Ferraz, Rosa, Antonio do Nascimento
• Format: Article
• Language: Spanish
• Subjects: Analysis; Beef cattle; Distribution (Probability theory); Pregnancy
• ISSN: 1806-2636
• DOI: 10.4025/actascianimsci.v34i1.12267

The pregnancy rates of nulliparous, primiparous and multiparous Nellore cows were evaluated from data from four insemination stations at a farm with extensive cow-calf system, based on native pastures typical of the Pantanal. Pregnancy probabilities were calculated by a model that included the effects of final weight, initial and final body condition scores, and average daily daily gain. The pregnancy rates were analyzed by chi-square test and statistical analyses were carried out through generalized linear models, using a binomial distribution function and the logistic regression function. The pregnancy rates were 35.28, 40.98, 74.14 and 52.00% for the 2005/2006, 2006/2007, 2007/2008 and 2008/2009 insemination stations, respectively. The nulliparous, primiparous and multiparous categories showed average pregnancy rates of 84, 43 and 47%, respectively. The effects of final weight, body condition score at the beginning of the insemination station, body condition score at the end of the insemination station and daily gain during the insemination station were significant. The probabilities of pregnancy are higher with higher final weight (except for nulliparous cows), with higher initial and final scores and higher average daily gain. Keywords: nulliparous, primiparous, multiparous, pregnancy rate, artificial insemination. Avaliaram-se taxas de prenhez de vacas da raca Nelore das categorias nuliparas, primiparas e multiparas, a partir de dados de quatro estacoes de inseminacoes de uma fazenda com sistema extensivo de cria, com pastagens nativas tipicas do Pantanal. As probabilidades de ocorrencia de prenhez foram calculadas por meio de um modelo que incluiu os efeitos de peso final, escore de condicao corporal inicial, escore de condicao corporal final e ganho medio diario. As taxas de prenhez foram analisadas pelo teste de qui-quadrado e as analises estatisticas foram realizadas por meio de modelos lineares generalizados, empregando-se a funcao de distribuicao binomial e a funcao de regressao logistica. As taxas de prenhez foram 35,29; 40,98; 74,14 e 52% para as estacoes de inseminacoes de 2005/2006, de 2006/2007, de 2007/2008 e de 2008/2009, respectivamente. As categorias nuliparas, primiparas e multiparas, apresentaram as medias das taxas de prenhez de 84, 43 e 47%, respectivamente. Os efeitos de peso final, escore de condicao corporal inicial, escore de condicao corporal final e ganho medio diario foram significativos. As probabilidades de prenhez sao ele