EFFECTS OF ACOMASTYLIS-ROSSII TANNINS ON A MAMMALIAN HERBIVORE, THE NORTH-AMERICAN PIKA, OCHOTONA-PRINCEPS

I investigated the effects of tannin consumption, using plant tannins naturally occurring in the diet, on a herbivorous mammal, the North Am erican pika, Ochotona princeps. The objectives were to determine if a high-tannin diet influenced protein and dry matter apparent digestibil ity, fiber digestibility and production of detoxification by-products. Additionally, I examined the possibility that pikas produce salivary tannin-binding proteins, a potential mechanism for avoiding detrimenta l effects of tannins. My results demonstrate that although pikas const itutively produce salivary tannin-binding proteins, animals consuming a high-tannin diet of Acomastylis rossii exhibited lower dry matter, p rotein and fiber digestion and excreted higher concentrations of detox ification by-products. Thus, A. rossii tannins are potential toxins as well as digestibility reducers. I propose a hypothesis coupling detox ification to reduced fiber digestion that is applicable to pikas as we ll as other mammalian herbivores consuming phenolic-rich diets.