title: Thermoregulation of the bovine scrotum 1: measurements of free-range animals in a paddock and pen.
abstract: The bull's scrotum and scrotal cord vasculature has traditionally been regarded as a thermoregulatory device for maintaining optimal testicular temperature for normal spermatogenesis. This assumption has mostly been derived from discrete measurements using thermocouples with limited data correlating continuous scrotal temperature (ST) to body temperature (BT). From mid-summer to early autumn, four Wagyu bulls (9-18 months) were surgically implanted with two data loggers (DL) logging at 30 min intervals: one on the right hand side flank and the other was attached to the visceral vaginal tunic of the mid-testis. Bulls were firstly housed in a paddock (PK) for 13 days and then moved to individual pens (IP), again for 13 days. Repeated measures analysis modelled the long-term and diurnal trends in BT and ST. While both day and time of day (TOD) were significant effects for ST at both housing locations (P < 0.005), only TOD showed significance for BT at both locations (P < 0.0001). Significant effects were seen between bulls with ST (F = 167.2, P < 0.001) but not BT (F = 0.03, P = 0.863), suggestive of variation in individual bull thermoregulatory capacity. Dual peaks were observed in ST at 0500 and 2130 h when housed in PK but not IP, suggesting ST may be influenced by external stimuli such as postural or behavioural changes. Reporting concurrent and continuous BT and ST will allow further investigation into factors influencing bovine ST and should be useful in selecting bulls with high degrees of thermoregulation capacity.
authors.affiliation: School of Agriculture and Food Sciences, Animal Science Group, The University of Queensland, Gatton, QLD, 4343, Australia. a.wallage@uq.edu.au.
authors.forename: Andrea L
authors.initials: AL
authors.lastname: Wallage
authors.affiliation: School of Agriculture and Food Sciences, Animal Science Group, The University of Queensland, Gatton, QLD, 4343, Australia.
authors.forename: S D
authors.initials: SD
authors.lastname: Johnston
authors.affiliation: School of Agriculture and Food Sciences, Animal Science Group, The University of Queensland, Gatton, QLD, 4343, Australia.
authors.forename: A T
authors.initials: AT
authors.lastname: Lisle
authors.affiliation: School of Agriculture and Food Sciences, Animal Science Group, The University of Queensland, Gatton, QLD, 4343, Australia.
authors.forename: L
authors.initials: L
authors.lastname: Beard
authors.affiliation: School of Agriculture and Food Sciences, Animal Science Group, The University of Queensland, Gatton, QLD, 4343, Australia.
authors.forename: A M
authors.initials: AM
authors.lastname: Lees
authors.affiliation: School of Veterinary Science, The University of Queensland, Brisbane, 4343, Australia.
authors.forename: C W
authors.initials: CW
authors.lastname: Collins
authors.affiliation: School of Agriculture and Food Sciences, Animal Science Group, The University of Queensland, Gatton, QLD, 4343, Australia.
authors.forename: J B
authors.initials: JB
authors.lastname: Gaughan
mesh_terms: D000822:Animal Husbandry; D000818:Animals; D001831:Body Temperature; D001833:Body Temperature Regulation; D002417:Cattle / Q000502:physiology; D006813:Humidity; D008297:Male; D012611:Scrotum / Q000502:physiology*; D013696:Temperature
keywords: Body temperature; Bovine; Scrotal temperature; Scrotum; Thermoregulation