Measurement of bovine body and scrotal temperature using implanted temperature sensitive radio transmitters, data loggers and infrared thermography.
Synchronous and continuous measurement of body (BT) and scrotal temperature (ST) without adverse welfare or behavioural interference is essential for understanding thermoregulation of the bull testis. This study compared three technologies for their efficacy for long-term measurement of the relationship between BT and ST by means of (1) temperature sensitive radio transmitters (RT), (2) data loggers (DL) and (3) infrared imaging (IRI). After an initial pilot study on two bulls to establish a surgical protocol, RTs and DLs were implanted into the flank and mid-scrotum of six Wagyu bulls for between 29 and 49 days. RT frequencies were scanned every 15 min, whilst DLs logged every 30 min. Infrared imaging of the body (flank) and scrotum of each bull was recorded hourly for one 24-h period and compared to RT and DL data. After a series of subsequent heat stress studies, bulls were castrated and testicular tissue samples processed for evidence of histopathology. Radio transmitters were less reliable than DLs; RTs lost >11 % of data, whilst 11 of the 12 DLs had 0 % data loss. IRI was only interpretable in 35.8 % of images recorded. Pearson correlations between DL and RT were strong for both BT (r > 0.94, P < 0.001) and ST (r > 0.80, P < 0.001). Surgery produced temporary minor inflammation and scrotal hematoma in two animals post-surgery. Whilst scar tissue was observed at all surgical sutured sites when bulls were castrated, there was no evidence of testicular adhesion and normal active spermatogenesis was observed in six of the eight implanted testicles. There was no significant correlation of IRI with either DL or RT. We conclude that DLs provided to be a reliable continuous source of data for synchronous measurement of BT and ST.
School of Agriculture and Food Sciences, Animal Science Group, The University of Queensland, Gatton, QLD, 4343, Australia. a.wallage@uq.edu.au.
A L
AL
Wallage
School of Agriculture and Food Sciences, Animal Science Group, The University of Queensland, Gatton, QLD, 4343, Australia.
J B
JB
Gaughan
School of Agriculture and Food Sciences, Animal Science Group, The University of Queensland, Gatton, QLD, 4343, Australia.
A T
AT
Lisle
School of Biological Science, The University of Queensland, St. Lucia, 4072, Australia.
L
L
Beard
School of Veterinary Science, The University of Queensland, Gatton, 4343, Australia.
C W
CW
Collins
School of Agriculture and Food Sciences, Animal Science Group, The University of Queensland, Gatton, QLD, 4343, Australia.
S D
SD
Johnston
D000818:Animals; D001831:Body Temperature; D001833:Body Temperature Regulation / Q000502:physiology; D002417:Cattle; D007259:Infrared Rays; D008297:Male; D011846:Radio Waves; D012611:Scrotum / Q000502:physiology*; D013686:Telemetry / Q000379:methods; D013817:Thermography / Q000379:methods
Body temperature; Bulls; Heat stress; Radio transmitter; Scrotal temperature; Testicular thermoregulation; iButton data logger