Influence of difficulty of insemination, temperament and plasma cortisol on conception rate of Nelore cows and heifers in timed AI

• Autor(a) principal: Oliveira, L. Z.
• Data de Publicação: 2019
• Outros Autores: Silva, A. G., Noronha, I. M. [UNESP], Oliveira, C. S., Monteiro, F. M., Peres, R. F. G. [UNESP], Graff, H. B., Rodrigues, A. L. R., Brandao, F. Z.
• Tipo de documento: Artigo
• Idioma: por
• Título da fonte: Repositório Institucional da UNESP
• Texto Completo: http://dx.doi.org/10.1590/1678-4162-10478; http://hdl.handle.net/11449/194936
• topic: bovine; fertility; for AI

The objective was to evaluate the influence of stress and difficulty of insemination (DifIA) on conception rate (CR) of Nellore cows (n = 93) and heifers (n = 72) in Timed-AI. On D9, temperament (NTe) and time for chute exit (TSB) were recorded for all animals, and blood samples were colected from heifers. On the day of Timed-AI (D11), NTe, TSB, DifIA and time for AI were recorded. For cows, CR was 36% and for heifers 46% (P > 0.05). No effect (P > 0.05) of NTe was observed on CR. However, a tendency (P < 0,10) for higher CR was observed in animals with no difficulty for insemination (DifIA1; CR=42%) compared to animals that presented moderate or high difficulty (DifIA2+DifIA3, CR=27%). Time required for AI was lower (P < 0.05) in animals DifIA1 (17:31 +/- 06:02sec) than in animals DifIA2-3 (30:10 +/- 15:45sec). Heifers with greater (P < 0.05) cortisol levels presented higher Nte (P < 0.05). However, CR (59%) of less reactive heifers (cortisol=4,12 +/- 1,12ng/mL; NTe=3,2 +/- 0,6) did not differ from CR (41%; P > 0.05) of stressed animals (cortisol=7,76 +/- 1,33ng/mL; NTe=3,82 +/- 0,79). It was concluded that assessments of temperament were related to stress level, although these parameters did not affect the CR of this study. However, the higher difficulty and/or time to complete AI showed to be a potential factor for reducing fertility after timed-AI.