The role of endoparasitism on host nutrition was reviewed and the opportunities for manipulation considered with emphasis on two specific nutrients for which information is becoming available-protein and copper. The major effect of parasitism on protein metabolism is to increase the protein requirement of the host as a result of increased endogenous loss of protein rather than malabsorption per se. Protein supplementation has been shown to increase liveweight gain of infected sheep and to reduce faecal egg counts and worm burdens probably reflecting enhanced immunological competence of the host. Such rates of protein supply could be achieved in practice on temperature pastures if protein losses across the rumen could be reduced. Liver copper levels have been shown to be depressed by parasitism in the abomosum. The effectiveness of oral copper supplements depends on their ability to increase soluble copper levels in abomasal digesta, which is reduced by nematode-induced increase in pH. Intake depression has by far the greatest effect on production loss due to endoparasitism. Evidence is emerging that the mechanism for this depression has a peripheral hormonal and central neural basis. It was concluded that specific nutrient manipulation in plants or via supplements may enable the host to cope better with the debilitating effects of endoparasitism.
Proceedings of the New Zealand Society of Animal Production, Volume 50, , 167-180, 1990
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