Modelling endogenous leucine flows at the jejunum and ileum in lambs exposed to the intestinal parasite Trichostrongylus colubriformis
G. Holtrop 1  
,   F. Yu 2,   R. L. Coop 3,   L. A. Bruce 2,   G. E. Lobley 2,   J. C. MacRae 2
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Biomathematics and Statistics Scotland, Bucksburn, Aberdeen, AB21 9SB, UK
Rowett Research Institute, Bucksburn, Aberdeen, AB21 9SB, UK
Moredun Research Institute, Pentlands Science Park, Penicuik, Midlothian EH26 0PZ, UK
G. Holtrop   

Biomathematics and Statistics Scotland, Bucksburn, Aberdeen, AB21 9SB, UK
Publication date: 2004-10-25
J. Anim. Feed Sci. 2004;13(4):589–603
A mathematical model is presented that compartmentalizes endogenous secretions into the gastro-intestinal tract, according to site of origin. This model was applied to data from three growing lambs (initial liveweight 25-30 kg) given a daily dose of 2500 Trichostrongylus colubriformis larvae for 12 weeks. At weeks 0, 6 and 12 of infection, endogenous leucine flows were determined during an 8 d intra-jugular infusion of [1-13C]leucine, with samples taken from the jejunum, ileum and plasma. The infection had no effect on jejunal leucine flow (102.1 vs 105.5 mmol/d), but ileal leucine flow increased from 18.6 to 26.3 mmol/d (P=0.023). Endogenous leucine flow at the jejunum was unaffected by the infection (15.0 vs 18.9 mmol/d; P=0.116) but was doubled at the ileum (5.5 vs 10.4 mmol/d; P=0.025). Secretions into the small intestine contributed 58 (controls) to 65% (parasites) of ileal endogenous flow. The model also predicted that net portal drained viscera appearance was, at maximum, 79% of net appearance in the mesenteric vein.