Application of Experimental Animals to Toxicological Study of Feed Poisoning in Livestock —a Preliminary Scrutiny of Diet—

摘要

As an initial step in the study of endophyte-infected diets of tall fescue and perennial ryegrass in mice as an experimental model of endophvte-induced toxicosis, it is first necessary to determine if mice can tolerate diets rich in tall fescue and perennial ryegrass. Therefore, mice were fed solid diet (pellet) added with endophyte-free seed powder at 30, 50, 80, 90 or 100 % for 14 days. The mice were determined for food intake, water intake, body weight and rectal temperature, and also examined forambulatory activity (open-field test) and rotarod performance. Pellets were prepared with a high-pressure press. No significant difference in water intake was found between groups fed standard mouse diet (MEQ) and pellets prepared with varying amounts of seed powder from endophyte-free tall fescue or perennial ryegrass, although there was more food intake in the latter groups than the former. However, there were no significant differences in body weight, rectal temperature, ambulatory activity in the open-field test, and muscle coordination and sense of balance as measured by rotarod performance among groups fed pure MEQ and pellets containing varying amounts of the seed powder. It is concluded that pellets containing up to 90 or 100 % of tall fescueor perennial ryegrass, respectively, can be used without causing negative effects. Mice can, therefore, possibly be used as an inexpensive model for studying livestock toxicosis in future experiments by feeding the mouse diets consisting of varying amounts of endophyte-infected tall fescue and perennial ryegrass without concern that the simple presence of tall fescue or perennial ryegrass will affect the overall well-being of the mice.