Amino acid flux across the hind limbs in lambs fed fresh lucerne (Medicago sativa) with or without Trichostrongylus colubriformis infection

Abstract

The effect of parasite infections on amino acid (AA) flux across the hind limbs in lambs infected with or without Trichostrongylus colubriformis and fed fresh lucerne (Medicago sativa), was investigated using an arterio-venous preparation. 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 indocyanin green (14.7 mg h-1) into the abdominal aorta in order to measure plasma flow across the hind limbs. Blood was continuously collected from the mesenteric artery and vena cava for two hour periods throughout the infusion period and plasma was harvested. The concentration of AA in plasma from the mesenteric artery and vena cava, and plasma flow across the hind limbs were determined and the corresponding net AA flux was calculated. Parasite infection had no effect on the feed intake (777 g DM d-1 (SE 7.69); P>0.05) or plasma flow across the hind limbs(498 mL min-1 (SE 46.7); P>0.05). In most cases, the plasma concentration and the net flux of AA were not affected by the presence of an intestinal parasite infection (P>0.05). Due to a decrease in average daily gain in these lambs it is likely that there may be an alteration in the utilisation of AA in other tissues (e.g. gut and liver) of lambs infected with intestinal parasites.