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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, = 0.001). Plasma Kyn concentrations were greater 4 wk after weaning ( = 0.002) than at weaning and for Piétrain compared to Duroc genetics ( = 0.008). Plasma Nam concentrations were greater for pigs fed the S-Trp diet than for those fed the B-Trp diet ( = 0.0001) and for Duroc than for Piétrain genetic lines ( = 0.001); this difference tends to be greater at weaning than after ( = 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.

The objective of the study was to estimate Leu requirement for weaned piglets to balance indispensable AA in reduced CP diets. A dose-response experiment was conducted to estimate the standardized ileal digestible (SID) Leu to Lys ratio required for the maximum growth of young pigs after weaning. In this study, 96 female pigs (initial BW of 8 kg) were allotted to 1 of 6 dietary treatments with 16 individually penned pigs per treatment. Graded levels of crystalline l-Leu were added to a basal diet to provide diets containing 0.70, 0.80, 0.90, 1.00, 1.10, and 1.20 SID Leu: Lys. Lysine was limiting and fulfilled 90% of the current recommendations. The ADFI, ADG, and G: F were determined during a 2 wk experimental period. Blood and urine samples were taken at the end of each wk. The ADFI increased linearly (P

Session 2 : Energy and Protein Interaction: Monogastrics; absent

International audience

A total of 144 pigs were divided into four dietary treatment groups with increasing tryptophan:lysine ratios (apparent ileal digestible (AID) Trp:Lys 0:14, 0:17, 0:20 and 0:23 and standardized ileal digestible (SID) Trp:Lys 0:15, 0:18, 0:21 and 0:24) for 6 weeks. There were 6 replicates with 6 animals per replicate in each treatment. It was shown that increasing dietary AID Trp:Lys from 0:14 to 0:20 significantly stimulated feed intake from 1.2 to 1.6 kg/day, liveweight gain from 509 to 752 g/day and body weight at the end of the experiment from 44.2 to 56.6 kg. Feed conversion ratio was reduced from 2.49 to 2.15. AID and SID Trp:Lys requirements for maximum liveweight gain were estimated at 0.19 and 0.22 and 0.20 and 0.23 using linear plateau and quadratic models, respectively.

National audience; L'effet de deux stratégies de restriction de l'ingestion (-25% de 35 à 63j d'âge), avec distribution unique ou fractionnée en 2 (1D vs 2D), a été analysé sur le comportement alimentaire du lapin, sa digestion et sa qualité de carcasse. L’étude a été réalisée dans un réseau de 5 stations d’expérimentation cunicole (groupe GEC) et sur un total de 2444 animaux élevés en cages collectives. Le fractionnement de la distribution ne modifie pas la quantité d'aliment ingérée (121g/j en moy., 35-63j.). Sept jours après l'application du rationnement (42j.), le profil quotidien d'ingestion est profondément modifié, avec une consommation du tiers de la ration quotidienne de 8h30 à 10h30, contrairement aux témoins qui en ingère moins de 10%. La distribution fractionnée accroit l'ingestion du matin chez les lapins restreints (>40%), en revanche cela accroît l'ingestion "nocturne" chez les animaux nourris à volonté (85-90%). Les animaux restreints du groupe "1D" ont en moyenne consommé 90% de la ration avant 16H30. La distribution fractionnée n'interagit pas avec le niveau alimentaire sur l'efficacité digestive, cette dernière étant améliorée avec une ingestion réduite de 25% (+3 unités pour l'énergie, +6 pour les protéines, et +4 pour le NDF, P

National audience; La croissance et la santé de lapereaux nourris à volonté, en une ou deux distributions quotidiennes, de 35 à 70jours d'âge, ont été comparées à celles de lapereaux dont l'ingestion a été restreinte de 25% de 35 à 63 jours puis remise à volonté jusqu'à 70 jours. L'étude a été réalisée dans un réseau de 5 stations d'expérimentation cunicole sur un total de 2444 animaux. La stratégie de rationnement a conduit à des réductions significatives, du taux de mortalité de 21,6% (lapins nourris à volonté) à 11,9%, du taux de morbidité de 18,7% à 14,0%, et de l'Index de risque sanitaire (IRS) de 40,3% à 25,9%. En parallèle, l'efficacité alimentaire des animaux rationnés a été améliorée de 10% (3,04 vs 3,31), tandis que leur poids final d'abattage a été réduit de 6% seulement (2,45 kg vs 2,61 kg à 70 jours). En revanche, la distribution de l'aliment en une ou deux fois n'a pas eu d'effet significatif sur ces paramètres.

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An important mechanism in regulating immunological and neurological responses is the catabolism of tryptophan (Trp). The pool of enzymes that break down Trp through the kynurenine pathway (so called from one of the final products) are found in numerous cell types, including cells of the immune system. Some of these enzymes are induced by some inflammatory signals. Thus, tissue inflammatory condition can cause depletion of tryptophan. This raises the hypothesis that intestinal infections could increase the requirement of Trp. Supplementary L-Trp limited the decrease of feed intake and growth in Enterotoxigenic E. coli K88 (ETEC) susceptible pigs, upon oral challenge with this pathogen (Trevisi et al., 2009). Our aim was to assess if genes involved in the intestinal barrier are changed by dietary Trp in healthy pigs susceptible or not to ETEC. Tryptophan favourably interacted to reduce the induction of lipopolysaccharide on genes involved in the intestinal barrier in ETEC susceptible pigs, but the causative mechanism needs to be established.