Evaluation of stress in Nelore bulls (Bos taurus indicus) submitted to eletroejaculation

Abstract

The bovine cattle industry reached its current status mainly due to reproductive biotecniques. Artificial insemination is the most employed Brazilian biotecniques. The first step of semen processing is its collection made by artificial vagina (AV) or eletroejaculation (EEJ) procedures. Recentely the eletroejaculation has been considered a welfare problem by cientific comunity. Five Freedoms and the physiologic and behaviour indicators are the main methods of welfare assessment. The objective this work was to evaluate the stress effects to EEJ in Nelore bulls. Twenty Nelore bulls were divided in two groups. The Control (n=10) was displaced weekly for nine weeks to a stable for evaluation behavior indicators for five minutes. The animals were restrained in a trunk for evaluation of physiological indicators (respiratory and heart rates, and rectal temperature) and blood sample collection for measurement of cortisol and progesterone plasmatic. After that they remained restrained for five minutes, followed by another evaluation of the physilogical variables. They were released in a stable for five minutes for individual evaluation of the behavior indicators. The Stress group (n=10) was submitted to the same protocol except that the animals were submitted to a five minute session of transrectal eletric stimulation by EEJ device while they remained restrained. The animals of the Control group were also submitted to EEJ the nineth week of the study. Both before and after of the restrain period the animals of the Stress group showed greater frequence of lower head than those from Control group. The animals of the Stress group also had higher respiratory and heart rates and cortisol and progesterone plasma concetrations in the second evaluation of the restrain period than those from the Control group. Eletric stimulation modified the welfare behavior indicators in both groups after and during the restrain period. The respiratory frequence, heart rates, cortisol and progesterone plasmatic concentrations of the second evaluation of the restrain period were higher in the Stress group so the EEJ for five minutes should be considered a stress agent in Nelore bulls (Bos taurus indicus).