Rectal temperature responses of pigs transported by road and administered with ascorbic acid during the hot-dry season

Abstract

Experiments were performed in order to determine the rectal temperature (RT) responses of pigs to eight-hour
road transportation and the effect of administration of ascorbic acid (AA) on the responses in transported pigs
during the hot -dry season. Twenty three experimental pigs were given AA orally and individually at 100 mg/kg
prior to the transportation, while thirteen control pigs were administered with 20 ml of drinking water. The RTs
of the pigs were measured by inserting a clinical thermometer (Hartman Company, England) into the rectum via
the anus. The ambient temperature (AT) and relative humidity (RH) were measured concurrently with the RT.
The AT and RH values ranged between 23.5 - 39.0°C and 43 - 97% respectively. The values were outside the
thermo-neutral zone for the pig, indicating that the season was thermally stressful. The AT values, which
fluctuated with the hour of the day and increased with the hour of the journey, were significantly (P < 0.001) and
positively correlated with RT values in both experimental (r = 0.941) and control pigs (r = 0.942). The overall
mean RT value of 39.8 ± 0.1°C recorded in the experimental pigs after 8 h road transportation did not differ (P >
0.05) with the corresponding value of 39.4 ± 0.3°C in control pigs, demonstrating that AA did not induce
hypothermia in experimental pigs. In conclusion, transportation of pigs by road for 8 h in the zone induces
hyperthermia and administration of AA in the experimental pigs did not induce hypothermia. Optimum duration
of road transportation of pigs is 6 h. This duration should be considered in the development of guidelines and
welfare for pigs, transported by road during the hot-dry season