EFFECTS OF TANNINS ON DIGESTION AND DETOXIFICATION ACTIVITY IN GRAY SQUIRRELS (SCIURUS-CAROLINENSIS)

Acorn tannins may affect food preferences and foraging strategies of s quirrels through effects on acorn palatability and digestibility and s quirrel physiology. Captive eastern gray squirrels (Sciurus carolinens is) were fed 100% red oak (Quercus rubra) or white oak (Quercus alba) acorn diets to determine effects on Intake, digestion, and detoxificat ion activity. Red oak acorns had higher phenol and tannin levels, whic h may explain the lower dry matter intakes and apparent protein digest ibilities and the higher glucuronidation activities observed in squirr els. Although the white oak acorn diet had lower apparent protein dige stibilities than the reference diet, it did not suppress dry matter in take for a prolonged period or stimulate glucaronidation. Negative phy siological effects of a 100% red oak acorn diet suggest gray squirrels may require other foods to dilute tannin intake and provide additiona l nutrients. To distinguish the roles of different tannin types in the observed effects of acorn diets on squirrels, squirrels were fed rat chow containing no tannins, 4% or 8% tannic acid (hydrolyzable tannin) , or 3% or 6% quebracho (condensed tannin). Apparent protein digestibi lities were reduced by tannic acid and quebracho diets, Only the 8% ta nnic acid diet tended to Increase glucuronidation. Specific effects of tannins may largely depend on tannin type, composition, and source an d on other nutritional and physiological factors.