Jp. Kastelic et al., SCROTAL SURFACE, SUBCUTANEOUS INTRATESTICULAR, AND INTRAEPIDIDYMAL TEMPERATURES IN BULLS, Theriogenology, 44(1), 1995, pp. 147-152
Sixteen 2-yr-old beef bulls were used in the study. Under caudal epidu
ral analgesia (xylazine HCl 40 mg), infrared thermography was used to
determine scrotal surface temperature (SST) and needle thermistors wer
e used to determine scrotal subcutaneous (SQT) and intratesticular (IT
T) temperatures at 3 locations on the posterior aspect of the scrotum:
3 cm from the top of the testis, 3 cm from the bottom of the testis,
and at the midpoint of the testis. Average temperatures (degrees C) at
the top, middle and bottom locations were 0.4+/-0.4, 29.8+/-0.6 and 2
8.8+/-0.8 (SST); 33.3+/-0.2, 33.0+/-0.2 and 32.9+/-0.3 (SQT); and 34.3
+/-0.1 1, 34.3+/-0.1 and 34.5+/-0.1 1 (ITT). Correlation coefficients
between SST and SQT were moderate to high, those between SQT and ITT w
ere low to moderate, and those between SST and ITT were low. Therefore
, caution must be exercised when making inferences about ITT based on
measurement of SST. The temperature gradient from top to bottom was mo
st pronounced for SST (1.6 degrees C), smaller for SQT (0.4 degrees C)
, and slightly negative (relative to the surface) for ITT (-0.1 degree
s C). These gradients may be due to the arrangement of the vasculature
; the scrotum is apparently vascularized from the dorsal pole of the t
estis to the ventral pole, while the testicular artery ramifies dorsal
ly from the bottom of the testis to the top. Intraepididymal temperatu
res (IET) of the head, body and tail of the epididymis averaged 35.6+/
-0.2, 34.6+/-0.1 and 33.1+/-0.3 degrees C. The head of the epididymis
was warmer than the testicular parenchyma, but the tail, an important
storage site for spermatozoa, was cooler.