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The standardized ileal digestible valine to lysine requirement ratio is at least 70% in post-weaned piglets

  • Van Milgen, Jacob
  • Bar, Roberto
  • Brossard, Ludovic
  • Le Floc’h, Nathalie
  • Melchior, D.
  • Primot, Y.
Publication Date
Mar 16, 2009
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Improving the balance between amino acids relative to the requirement implies that we need to have accurate knowledge of the requirement of individual amino acids. Although there is relatively little information available concerning the Val requirement in pigs, it is often considered to be a potentially limiting amino acid for growth. The purpose of this study was to determine the standardized ileal digestible (SID) Val requirement in post-weaned piglets using diets in which the Lys supply is second-limiting (1.0% SID Lys). Three experiments were carried out using individually-housed piglets. The ADFI, ADG, and G:F were used as response criteria during a 3 wk period (approximately 12 to 25 kg BW). The first experiment was conducted to evaluate the response of piglets to an increasing Val supply provided by 2 sources of L-Val differing in degree of purity. Increasing the Val supply from 58 to 66% SID Val:Lys resulted in a linear increase in both ADFI and ADG by 24 and 30%, respectively. No difference was observed between both sources of L-Val. Experiments 2 and 3 were dose-response studies using 5 levels of Val with SID Val:Lys levels ranging from 60 to 80%. The two experiments differed in the supply of branched-chain amino acids (BCAA) other than Val. The SID Ile:Lys and Leu:Lys ratios were respectively 55 and 113% in Exp. 2 and 65 and 166% in Exp. 3. In Exp. 2, the SID Val:Lys requirements for maximizing ADFI, ADG and G:F were respectively 74, 70, and 68% using a linear-plateau model. These values were approximately 5 percentage points higher when a curvilinear-plateau model was used. In Exp. 3, the SID Val:Lys requirements for maximizing ADFI and ADG were 69 and 69%. The F:G ratio was not affected by Val supply. Excess supply of Ile and Leu had a large impact on the depression of ADFI and ADG when Val supply was limiting. At a supply of 60% SID Val:Lys, ADFI and ADG were 88 and 82% of the plateau values in Exp. 2, but only 53 and 42% of the plateau values in Exp. 3. The results of these experiments indicate that the SID Val:Lys is at least 70%, which is slightly higher than the current NRC recommendation of 68%.

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