Relação da temperatura do escroto com a qualidade seminal em touros Nelore e Girolando

Abstract

The selection of bulls by the andrological examination is determinant for the improvement of the bovine herd. Bulls of zebu origin have better adaptability to high temperatures in relation to bulls of taurine origin, which may influence the temperature of the scrotum and seminal quality. The objective of this study was to compare the relation of infrared thermograms profiles of the scrotum and the quality of fresh and frozen semen in Nellore and Girolando bulls. Four Nellore and four Girolando bulls were used, kept in pickets with access to water and mineral mix; and supplementation with concentrate. Infrared thermographs of the scrotum, eyeball and mufla were performed twice a week with Flir® E40 thermal imager. For the scrotal thermograms, the temperatures of the spermatic cord, proximal and distal portion of the testes and tail of the epididymis were analyzed using Flir Tools software. Samples were collected with artificial vagina and the ejaculates were processed and frozen in liquid nitrogen and analyzed in post-thawing. The data passed the normality Anova test and Tukey test; and in the absence of normality by the Kruskall-Wallis test; and correlations classified according to Levine et al. (2012). Among breeds, differences (P <0.05) were observed in the temperatures of the ocular globe, spermatic cord and proximal portion of the scrotum. The Nellore bulls presented lower body temperature and regions of the scrotum, compared to Girolando bulls. Seminal characteristics varied between breeds (P <0.05), the Nellore breed had better quality semen. Significative correlations were observed between smaller spermatic defects (thin head, normal small head, giant head, short and flattened, normal head detached, prominent acrosome, abaxial insertion, distal droplet, folded or curled tail, and tail curled at the end) in Girolando bulls. Nellore bulls were less influenced by climatic variables with lower temperatures of areas of skin surface examined by infrared thermography in relation to Girolanda bulls. Nellore bulls presented superior fresh and thawed semen quality in relation to Girolanda bulls.