Abstract:
Experiments were performed to determine the effect of parasitic gastroenteritis on copper levels in the blood and liver of Australian Illawarra Shorthorn dairy calves. In two trials with calves heavily infested with Haemonchus placeii (Place) Ransom, Bunostomum phlebotomum Railliet, Oesophagostomum radiatum (Rudolphi), and CooperiaA spp., severe anaemia and hypoproteinaemia resulted. Liver copper levels of the infested calves were depressed, n-hereas those of wormfree controls either rose or remained relatively constant. The degree of depression appeared to be related to the magnitude of infestations. While slight falls in liver copper levels of worm-free calves could be induced by daily withdrawal of large volumes of blood, these falls were not of the same magnitude as those produced by trichostrongyle parasites. In a third experiment calves were infested with B. phlebotomum only, and it was demonstrated that following the administration of a known amount of copper sulphate by ruminal injection, significantly less copper was taken up and stored in the liver by parasitized calves than by worm-free controls. Indications were obtained that whole blood and plasma copper levels mere depressed by infestations in which B. phlebotomum predominated, but plasma copper concentrations were unaffected by chronic phlebotomy or by heavy infestations in which H. placei predominated. It was found necessary to withdraw a total of 27.5 I. of blood over a period of 19 weeks from worm-free calves in order to produce changes in their haemoglobin levels similar to those shown by calves carrying heavy mixed infestations consisting of H. placei, B. phlebotomum, O. radiatum, and Cooperia spp.