Dietary supplementation with ascorbic acid has been reported
to lower the body temperature of chickens maintained at elevated
environmental temperatures (Kutlu and Forbes, 1993; Thornton,
1962; Attia, 1976). As body temperature is the result of the net
effects of heat production and heat loss, it is not known if the
reduction in body temperature observed with ascorbic acid is due
to its ability to lower heat production or increase heat loss. More
recently, using indirect calorimetry we reported that the heat
production of chickens exposed to an elevated environmental
temperature and provided 150 ppm ascorbic acid from day 9 to
17 post-hatch was not different compared to non-supplemented
birds (McKee et al., 1997). This finding suggests that earlier
reports of ascorbic acid lowering the body temperature of chickens
maintained at elevated environmental temperatures may be due
to its ability to promote heat loss. The objective of the present
study, therefore, was to determine if the provision of supplemental
ascorbic acid to chickens maintained at an elevated
temperature affects inferred heat loss as determined by simultaneous
measurement of body core temperature and heat production
using indirect calorimetry.