Abstract

The effect of a Trichostrongylus colubriformis infections on ammonia and urea fluxes across the mesenteric-drained viscera (MDV), portal-drained viscera (PDV), and liver was investigated using an arterio-venous preparation in lambs fed fresh lucerne (Medicago sativa). The lambs were infected with 6000 T. colubriformis L3 larvae per day for 6 days (n=5) or kept as parasite free controls (n=5). On day 48 of the experiment, the lambs were infused continuously for 8 hours with r-aminohippuric acid (688 mg/h) into the mesenteric vein in order to measure plasma flow across the MDV, PDV and liver. Blood was continuously collected from the mesenteric artery and vena cava for consecutive two hour periods throughout the infusion period and plasma was harvested. Plasma concentrations of ammonia and urea were unaffected by the presence of intestinal parasites. Ammonia fluxes across the MDV, PDV, and liver were similar between treatment groups. Urea fluxes were also similar between treatment groups with the exception of the PDV, which showed a net release of urea in the parasite group and a net uptake by the control group (P=0.03). This suggests that the presence of a sub-clinical T. colubriformis infection does not increase the demand on the lamb for amino acids for ureagenesis.

EN, Bermingham, NC Roy, GW Reynolds, BR Sinclair, JS Peters, IA Sutherland, GC Waghorn, DK Revell, and WC McNabb

Proceedings of the New Zealand Society of Animal Production, Volume 62, Palmerston North, 77-80, 2002