The provision of supplemental ascorbic acid has been reported to lower the body temperature of
chickens maintained at elevated environmental temperatures. Since body temperature is the net effect
of heat production and heat loss, it is not known if the reductions in body temperature were due to a
lower heat production or an increase in heat loss. The purpose of this work was to determine if
supplemental ascorbic acid facilitates heat loss in chickens exposed to an elevated temperature. On day
12 post-hatch broiler chickens were implanted intra-abdominally with a thermo-sensitive radio
transmitter. The following day, birds were placed inside an indirect calorimeter maintained at 34 C
for 24 h and provided water containing 0 or 400 ppm ascorbic acid. Oxygen consumption, carbon
dioxide production, heat production, respiratory exchange ratio, and body core temperature were
measured for 3 h; beginning 21 h after the birds were placed inside the calorimeter. No differences
were observed in heat production or body core temperature between birds provided or not and
400 ppm ascorbic acid. This suggests that ascorbic acid has no effect on heat loss. Birds provided
ascorbic acid did exhibit a significantly lower respiratory exchange ratio suggesting a greater utilization
of lipid for energy production. Although lipid has a lower heat increment compared with protein and
carbohydrate, the significance of this finding to birds exposed to elevated temperature is not known.
In conclusion, under the conditions of this study the provision of supplemental ascorbic acid to broiler
chickens maintained at an elevated temperature did not affect heat loss as inferred from measured heat
production and body core temperature.