The effect of α2-adrenoceptor stimulation with guanfacin on heat production of restricted fed steers kept at −9, 11 or 28°C and on ad libitum fed steers acclimated to −19 and 22°C

Abstract

1. Guanfacin, an α2-adrenergic agonist was used to examine the α2-adrenoceptor mediated thermogenic and metabolic effects in steers (Bos taurus) kept at either −9, 11 or 28°C and in ad libitum fed steers acclimated to −19 and 22°C.

2. Guanfacin reduced (P < 0.05) the heat production in steers kept in the −9°C and 11°C thermal environments by 23 and 20% respectively. At 28°C thermal environment the reduction (P < 0.1) in heat production was only 8%. 3.

3. The rectal temperature was lower (P < 0.05) at −9°C, unchanged at 11 but elevated (P < 0.05) at 28°C in response to guanfacin.

4. Guanfacin reduced (P < 0.05) the heat production in ad libitum fed steers by 12%.

5. In conclusion, cattle may have the potential to improve energy conservation by activating α2-adrenoceptor-mediated processes in response to thermal and nutritional stimuli. In addition, guanfacin may reduce maintenance energy requirements of steers by 12–20%.