Infrared thermography as a noninvasive method to assess scrotal insulation on sperm production in beef bulls.

This study evaluated the thermoregulation and spermatogenic changes by scrotal temperature gradient using infrared thermography in testicular compromised bulls. Bulls were insulated (n = 6) for 72 hr and control animals (n = 3) remained without insulation during all the experimental period. Seminal evaluation was performed prior, at insult removal and once per week for 13 consecutive weeks. Mean temperature gradient in insulated animals was lower at the time of insulation removal compared to the week prior and after the insult (p < .05). Two weeks after insult, sperm motility was lower in insulated compared to control animals (p < .01) and spermatozoa total defects were higher in insulated compared to control animals (p < .05). Two and seven weeks after insult, the major defects were higher in insulated compared to control animals (p < .05). Scrotal temperature gradient showed a positive correlation with sperm mass motion (p < .01) and a negative correlation with ocular globe temperature (p < .01) in insulated animals. The infrared thermography can be used to evaluate ocular globe temperature in bulls; however, it is only effective to detect changes in scrotal temperature gradient at the insult removal.

Determinação da circunferência escrotal em touros de corte no Rio Grande do Sul / Measurement of scrotal circumference in beef bulls in Rio Grande do Sul

The variability of scrotal circumference and the effects of age and breed as well as the relationship between testicular weight (TW), scrotal circumference (SC), and live weight (BW) were investigated in bulls. Devon, Polled Hereford, and Red Angus breeds showed higher SC values than the other British, Continental, Synthetic, and Zebu studied breeds. The percentage of culled bulls because of low SC ranged from 7.01 to 24.25 percent. The increase of SC was proportional to the increase in TW and they were highly correlated (r²= 0.90). The results suggest that SC in young bulls is the best way to predict TW and, therefore, a useful tool for their selection.

A variabilidade da circunferência escrotal e os efeitos de idade e raça,assim como, as relações existentes entre o peso testicular (PT), a circunferência escrotal (CE) e o peso vivo (PV) foram investigados em touros. As raças Devon, Polled Hereford e Red Angus apresentaram valores de CE mais altos que as demais raças avaliadas, tanto inglesas, como continentais, sintéticas e zebuínas. O percentual descartado de touros devido à baixa CE variou de 7,0 a 24,2 por cento. O aumento da CE acompanhou o aumento do PT dos animais, e estes foram altamente relacionados, r² = 0,90. Os resultados sugerem que, em touros jovens, a CE é a melhor forma de predizer o PT e, portanto, uma ferramenta útil para selecionar touros.