Efficiency of fixed-time artificial insemination in zebu females in the Southeastern Mesoregion of Pará, Brazil

• Autor(a) principal: Carvalho, Jeferson Silva
• Data de Publicação: 2019
• Outros Autores: Cavalcanti, Matheus Oliveira, Chaves, Maiana Silva, Rizzo, Huber
• Tipo de documento: Artigo
• Idioma: por
• Título da fonte: Revista de Ciências Agrárias (Belém. Online)
• Texto Completo: https://ajaes.ufra.edu.br/index.php/ajaes/article/view/2977
• topic: Bos taurus indicus; Reproductive efficiency; Reproductive management; Interval between deliveries; Inglês; Bos taurus indicus; Eficiência reprodutiva; Manejo reprodutivo; Intervalo entre partos; português

Fixed-time artificial insemination (FTAI) is considered a reproductive biotechnology capable of promoting the increase of reproductive indices, having a significant effect on the bioeconomic efficiency of the property. However, the success of FTAI depends on several factors that directly affect the pregnancy rate. This study aims to evaluate the effect of FTAI on the fertility of Nelore females of the Southeastern Mesoregion of Pará and to verify the influence of some factors that may compromise the pregnancy rate. Based on a field study, the information on the reproductive control records of 9,455 Nelore females belonging to nine farms was collected and submitted to the same insemination protocol. The variables considered were farm, animal category, reuse of the intravaginal progesterone device, body condition score, bull semen and inseminator. The pregnancy rate was 53.4% (5,052 out of 9,455), with an association between the farms (p<0.05), with results ranging from 46.8% to 63.1%. The animal category affected the pregnancy rate (p<0.05) of nulliparous, primiparous and multiparous (50.2, 47.2 and 56.0%, respectively) animals. There was no difference (p>0.05) regarding the reuse of the first, second, third and fourth use intravaginal progesterone device, with the respective rates of 54.3%, 53.1%, 53% and 51.2%. According to the body condition score (p<0.05), females with score of 3 and 3.25 presented higher pregnancy rates, with 59.8% and 54.8%, respectively. In relation to the bull variable, fourteen were responsible for a pregnancy rate above 50%; three with results above 60% and one bull with 38.3% (p<0.05). There was a difference between the pregnancy rate and the inseminator (p<0.05), with results ranging from 45.5% to 71.4%. Improvements in the management systems of each farm may significantly increase the pregnancy rate of the herds in the Southeastern region.