Ds. Wallace et al., THE INFLUENCE OF DIETARY SUPPLEMENTATION WITH UREA ON RESILIENCE AND RESISTANCE TO INFECTION WITH HAEMONCHUS-CONTORTUS, Parasitology, 116, 1998, pp. 67-72
Previous research has indicated that supplementing an apparently adequ
ate diet with additional protein improves both host resistance and res
ilience in lambs infected with Haemonchus contortus. The present study
tested the influence of supplementation with non-protein nitrogen (ur
ea). Helminth-naive Hampshire Down lambs were given an apparently adeq
uate basal diet or a diet supplemented with urea. The lambs were then
infected with Haemonchus contortus for 10 weeks. Supplementation with
urea had no discernible effect an resistance to infection; faecal egg
counts, worm burdens, worm lengths and mean number of eggs per adult f
emale worm did not differ between the 2 groups. However, lambs on the
supplemented diet showed better resilience; they had greater packed re
d cell volumes, higher plasma albumin concentrations and increased liv
eweight gain compared to lambs on the basal diet. The loss of appetite
following infection was less in lambs fed the urea-supplemented diet.
The observed effect of urea supplementation was seemingly due to grea
ter food consumption as well as the better diet.