Title: The effects of some physiological and nutritional factors on circulating concentrations of thyroxine and triiodothyronine in white-tailed deer.
Year: 1982
Abstract: Concentrations of circulating thyroid hormones (thyroxine; T4 and triiodothyronine; T3) have been suggested as possible indicators for energy intake in white-tailed deer. An ideal indicator of energy intake would be influenced only by energy and not other factors. Circulating concentrations of T4 and T3 were found to follow a circannual rhythm in male and female whitetailed deer. Restricting food intake significantly lowered (P>0.05) T3 concentrations and body weight in male deer and significantly lowered (P>0.05) T3 concentrations in female deer. Body weight in the female deer did not significantly differ (P>0.05) by restriction. Lactation did not significantly affect (P>0.05) circulating concentration of T3, T4, or body weight. Lactating deer ate significantly (Px0.05) more food than non-lactating deer. Pregnancy with 1 or 2 fawns compared to non-pregnant animals from January to parturition showed inconsistent results on concentrations of the 2 hormones. It may be possible to relate circulating concentrations of T3 to specific levels of energy use if time of the year is considered.
