Use of scrotal infrared thermography and ultrasonography to understand thermoregulation of testis and sperm quality in Karan Fries breeding bull

The present investigation was carried out to study the effect of testicular covering thickness, scrotal circumference and scrotal surface temperature gradient insert semen quality attributes of Karan Fries breeding bull. Six ejaculates were collected from each randomly selected bulls (n=15) and seminal quality attributes were evaluated during peak winter season. Same time scrotal surface temperature gradient (SSTG), the thickness of testicular covering (TTC) and scrotal circumference (SC) of individual bulls were recorded using DarviDTL007 infrared thermography camera, ultrasonography and measuring tape, respectively. Three groups were formed based on SSTG (Group I-# 4ºC, Group II-4.1 to 6.8ºC and Group III-#6.9ºC), two groups based on TTC (Group I-3.03 to 4.85 and Group II-4.86 to 7.03 mm) and SC (Group I-32 to 35 and Group II-36 to 41 cm). Ejaculate rejection rate (ERR) was significantly decreased with the increase of SSTG and SC. ERR was not affected with TTC. The increase of SSTG (from Group I to Group III), mass activity and non-eosinophilic sperm count weresignificantly increased, and sperm abnormalities were significantly (p<0.01)decreased. Similarly, with the increase of SSTG and abnormalities were significantly (p<0.01) increased among different groups. Ejaculate volume and non-eosinophilic sperm count were significantly (p<0.01) increased with SC group I and group II. It can be concluded that scrotal surface temperature gradient wasa better indicator ofsemen quality ascomparedto the thicknessof testicular covering and bulls having a higher scrotal surface temperature gradient, scrotal circumference and lower thickness of testicular covering produced better quality semen.