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International audience; The objective of the current study was to identify biomarkers of branched chain amino acids (BCAA) intake status that could be linked to the best animal growth perfonnance. Three dose-response studics were carried out to collect blood and urine samples from pigs fed diets with increasing levels of isoleucine (Ile), valine (Val), or leucine (Leu) followed by a non-targeted LC-MS approach to characterize the metabolic profile of plasma and urine, when the level of BCAA in the diet is optimum for the best animal growth performance. The LC-MS method could separate and identify the plasma and urine metabolites which were discriminating the pigs fed optimum dietary level of Ile, Val, and Leu. Among the discriminating plasma and urine metabolites, that correlated closely to the highest animal growth performance, were plasma glycocholic acid and taurocholic acid as biomarkers of the optimum Ile level in the diet, and plasma creatine and urinary 2-aminoadipic acid, ascorbic acid, and choline as biomarkers of optimum Leu level. No good biomarkers were identified in the Val study.

This study aimed at refining the response of piglets to different supplies of standardized ileal digestible (SID) isoleucine (Ile), valine (Val), and leucine (Leu). Three 2‐week experiments were carried out with piglets, initially weighing 7 kg and which were penned individually. One week after weaning, piglets (16 per treatment) were offered ad libitum the experimental diets. These diets were sub‐limiting in lysine (Lys) and supplied 6 equidistant levels of either Ile (42 to 62% SID Ile:Lys), Val (58 to 78% SID Val:Lys), or Leu (70 to 120% SID Leu:Lys). Feed intake, body weight gain, and feed efficiency were determined each week. Significant performance responses were observed in the three dose‐response studies. Increased Ile levels had an effect on feed intake and weight gain, while increased levels of Val and Leu affected all performance traits. The estimated requirement values (levels obtained by the curvilinear‐plateau model to reach the plateau) were 52% SID Ile:Lys, 70% SID Val:Lys, and 100% SID Leu:Lys, and similar to literature data. An amino acid supply 10% below the requirement values determined for average daily gain (ADG) resulted in the reduction by 3% for Ile, 6% for Val, and 5% for Leu of the ADG.

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 < 0.001) from 0.70 to 0.80 SID Leu:Lys and then remained constant from 0.90 to 1.20 SID Leu:Lys. The ADG showed a quadratic increase (P = 0.02), as the SID Leu:Lys level increased from 0.70 to 0.90 SID Leu:Lys and did not change further from 0.90 to 1.20 SID Leu:Lys. The G:F increased quadratically (P < 0.001) with increasing SID Leu:Lys level, and the greatest G:F was achieved with pigs receiving the diet with 0.80 SID Leu:Lys. Increasing the dietary SID Leu:Lys resulted in a linear increase in plasma Leu concentration (P < 0.001) and quadratic increases (P < 0.001) in plasma Cys concentration. The plasma concentration of most of the other AA was lowest in pigs receiving the diets with 0.90 to 1.00 SID Leu:Lys. The plasma urea nitrogen concentration tended (P = 0.08) to be lowest in pigs receiving 1.00 SID Leu:Lys, suggesting a more balanced AA profile at this level. Using a curvilinear-plateau model, the SID Leu:Lys requirement was estimated at 0.93 to maximize growth in female pigs weighing 8 to 12 kg.