Pathophysiology of Gastrointestinal Nematode Infections in the Ruminant

Recent advances in the understanding of the physiological and biochemical . consequences-of gastrointestinal nematode infections in ruminants are examined, particularly in relation to the nitrogen economy of the host and effects on animal productivity. Evidence is presented which suggests that, although there may be an apparent reduction in the net availability of nitrogen from the gut of infected animals, this is probably due to an increased secretion of endogenous nitrogen rather than decreased digestion and absorption of dietary nitrogen. Increased leakage of plasma proteins into the gut is a feature common to many nematode infections of ruminants and is considered an important source of increased endogenous nitrogen secretion. This leakage also results in an increased albumin turnover, which, in laboratory animals, is associated with an elevated hepatic protein synthesis. Together with inappetance, these changes are probably responsible for decreased synthesis of meat and wool protein through their influence on the availability of amino nitrogen at the tissue level.