Influence of genotype on tryptophan metabolism in pig
Influence du croisement génétique sur le métabolisme postprandial du tryptophane chez le porc
Résumé
Tryptophan (Trp), an indispensable amino acid, is involved in numerous metabolic pathways. Previous data showed that Trp conversion into kynurenine and nicotinamide may differ among studies and such differences cannot be explained by different dietary niacin supply. We hypothesized that pig genotype influences Trp metabolism and thus the conversion of Trp into metabolites. The objective of this study was to compare plasma appearance of Trp and related metabolites in 12 Duroc and 12 Piétrain crossbred growing pigs after a meal test. Pigs were fitted with a catheter in the jugular vein to perform frequent blood samplings. Within each genotype, 6 pigs were fed a limiting or non‐limiting Trp diet (15 and 22% Trp:Lys DIS, respectively). After an overnight fasting, 350 g of the experimental diets was offered to each pig and plasma concentrations of Trp, kynurenine, nicotinamide and serotonine were measured for 6 hours. The activities of Trp degrading enzymes were measured in different tissues collected after pig slaughtering. Our data showed an increase in plasma concentrations of Trp and its metabolites after the meal and with the Trp dietary content. However, plasma concentrations of Trp metabolites and enzyme activities were not significantly different between Duroc and Piétrain crossbred.
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