A model of fescue toxicosis: responses of rats to intake of endophyte-infected tall fescue.
A study was conducted to develop a model for fescue toxicosis using rats fed a diet containing endophyte-infected tall fescue seed (E+). Rats implanted with telemetric transmitters to continuously monitor core body temperature (Tc) and activity were housed at thermoneutrality (21 degrees C) and were fed a diet containing endophyte-free fescue seed (E-). After 2 wk, they were assigned to either E+ or E- diets and initially maintained at thermoneutrality (preheat) for 8 d. They were then exposed to heat stress (31 degrees C) for 22 d, followed by 1 wk of recovery at thermoneutrality (post-heat). Body weight and feed intake were measured daily. Rats receiving the E+ diet showed decreased feed intake (P = 0.001) and weight gains (P = 0.003) during the preheat period. The decrease in Tc from the pre-treatment level was greater in E+ than in E- rats during the preheat (P = 0.001) and postheat (P = 0.001) periods. With heat stress, both groups showed parallel decreases in feed intake. The increase in Tc from pre-heat to heat conditions was greater in E+ vs. E- rats (P = 0.001). Activity level was lower in E+ than in E-rats during heat stress (P = 0.009) and postheat (P = 0.037) periods. These results show that the rat model for fescue toxicosis is extremely useful because many of the observed responses to E+ diet are similar to those noted for cattle, and additional variables that are difficult to measure in cattle, such as activity, can be easily evaluated.
Spiers
D E
DE
University of Missouri, Columbia, 65211, USA. spiersd@missouri.edu
Eichen
P A
PA
Rottinghaus
G E
GE
D000821:Animal Feed / Q000032:analysis / Q000382:microbiology; D000818:Animals; D001831:Body Temperature / Q000187:drug effects*; D001835:Body Weight / Q000187:drug effects*; D004032:Diet / Q000662:veterinary; D004435:Eating / Q000187:drug effects*; D031751:Festuca / Q000382:microbiology; D006128:Growth / Q000187:drug effects; D018882:Heat Stress Disorders / Q000662:veterinary; D008297:Male; D023421:Models, Animal; D009043:Motor Activity / Q000187:drug effects; D009183:Mycotoxins / Q000494:pharmacology*; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors
D009183:Mycotoxins