Termografia digital por infravermelho no estudo de características reprodutivas de touros nelore (Bos taurus indicus)

Abstract

The objective was to study the surface temperature of the scrotum with digital infrared thermography before and after semen collection, and the correlation of these temperatures with semen quality in Nelore bulls bred extensively. 80 Nelore bulls, with an average age of 60 months, of which was collected semen by electroejaculation and digital infrared thermograms (E-40®, FLIR) of the scrotum, before and after collection of semen and measurement of rectal temperature. The data were subjected to analysis of variance and means compared by Tukey at 5% and the correlations were obtained by Pearson at 5%. There were differences (P>0.05) between the surface temperatures of the scrotum, before and after semen collection, between the anatomical points analyzed, where, spermatic cords temperature (T1), temperatures of dorsal, medial and ventral thirds of the testicles (T2, T3 and T4), and epididymal tail temperature. However, there was no difference (P>0.05) comparing times before and after semen collection between the temperatures of each anatomical point of the scrotum. There was decrease in scrotal surface temperature in the dorso-ventral axis, where the difference between spermatic cord temperature (T1) and epididymal tails temperature was 4.04ºC, resulting in a good quality semen. There was correlation between T2 x total defects (r=0,30; P<0,05); T3 x minor defects (r=0,35; P<0,05); T3 x major defects (r=0,30; P<0,05) and T3 x total defects (r=0,42; P<0,05); T4 x minor defects (r=0,30; P<0,05); T4 x major defects (r=0,28; P<0,05) and T4 x total defects (r=0,37; P<0,05); T5 x major defects (r=0,29; P<0,05) e T5 x total defects (r=0,28; P<0,05). There was correlation between rectal temperature RT x T1 (r=0,51; P<0,05); RT x T2 (r=0,43; P<0,05); RT x T3 (r=0,37; P<0,05); RT x T4 (r=0,33; P<0,05) and RT x T5 (r=0,32; P<0,05). The digital infrared thermography is a complementary exam of image with accuracy in the measurements of the scrotal surface temperature indicated before and after semen collection of the bulls bred extensively. Therefore, is recommended this technique as of the screening to detect the adequate scrotal thermoregulation in the breeding bulls selection.