PATHOPHYSIOLOGY OF FESCUE TOXICOSIS

The pathophysiology of fescue toxicosis is discussed relative to observed symptoms and the inhibition of animal production (average daily pin and decreased reproductive efficiency). Hyperthermia, vasoconstriction and perhaps increased activity of hepatic mixed-function oxidases are important effects. Perhaps secondarily intake is reduced by the above mechanisms and possibly by unpalatability factors. The decreased milk yield is considered a function of decreased intake and suppressed prolactin secretion. Evidence is discussed that corpora lutea in cattle are morphologically altered and consequently may not support a pregnancy. The effect of endophyte presence upon the outcome of pregnancy in the mare is considered a function of an alteration in placental function as a result of vasoconstriction.