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This article in JAS

  1. Vol. 95 No. 4, p. 1606-1613
     
    Received: Nov 04, 2016
    Accepted: Feb 12, 2017
    Published: April 13, 2017


    2 Corresponding author(s): nathalie.lefloch@inra.fr
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doi:10.2527/jas.2016.1179

Comparison of plasma tryptophan-related metabolites in crossbred Piétrain and Duroc pigs1

  1. N. Le Floc’h 2*,
  2. A. Simongiovanni,
  3. E. Corrent and
  4. J. J. Matte
  1. * PEGASE, INRA, Agrocampus Ouest, F-35590 Saint-Gilles, France
     Ajinomoto Eurolysine S.A.S., F-75817 Paris Cedex 17, France
     Centre de R & D sur le Bovin Laitier et le Porc, Agriculture et Agroalimentaire Canada, Lennoxville, QC, J1M0C8 Canada

Abstract

Besides being incorporated into proteins, Trp, an indispensable AA, is involved in numerous metabolic pathways. Previous data showed that Trp conversion into kynurenine (Kyn) and nicotinamide (Nam) differs among studies, and such differences cannot be explained by different dietary niacin supplies. We hypothesized that pig genotype influences Trp metabolism and thus the conversion of Trp into its metabolites. The objective of this study was to compare plasma appearance of Trp and related metabolites in 12 Duroc and 12 Piétrain crossbred postweaning pigs fed 2 contrasting dietary Trp levels. Within each genotype, 6 pigs were fed a basal (B-Trp: 17% and 15% standardized ileal digestible [SID] Trp:Lys for starter and prestarter diets) or supplemented (S-Trp: 24% and 23% SID Trp:Lys for starter and prestarter diets) Trp diet. Growth was monitored, and plasma fasted concentrations were measured over 4 wk, and then pigs were fitted with a jugular catheter for frequent blood samplings. After overnight fasting, 350 g of the experimental diets were offered to each pig, and plasma concentrations of Trp, Kyn, Nam, and 5-hydroxytryptamine (5-HT) were measured for 6 h. The activities of Trp-degrading enzymes were measured in different tissues collected after pig slaughtering. Plasma Trp fasted concentrations did not differ between B-Trp and S-Trp diets and increased from weaning to 2 and 4 wk after weaning for Piétrain but not for Duroc crossbred pigs (time × genotype, P = 0.001). Plasma Kyn concentrations were greater 4 wk after weaning (P = 0.002) than at weaning and for Piétrain compared to Duroc genetics (P = 0.008). Plasma Nam concentrations were greater for pigs fed the S-Trp diet than for those fed the B-Trp diet (P = 0.0001) and for Duroc than for Piétrain genetic lines (P = 0.001); this difference tends to be greater at weaning than after (P = 0.055). Our data showed an increase in plasma concentrations of Trp, Kyn, Nam, and 5-HT according to time after a meal and to the dietary Trp content. However, postprandial plasma concentrations of Trp metabolites and enzyme activities were not significantly different between Duroc and Piétrain crossbred pigs. In conclusion, our results suggest that Nam endogenous synthesis capacity from Trp is greater in Duroc than in Piétrain crossbred pigs, but this was apparent only at weaning.

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