Détermination du besoin en isoleucine chez le porcelet
2012
Gloaguen, Mathieu | Le Floc'h, Nathalie | Primot, Yvan | Corrent, Etienne | Van Milgen, Jacob
The branched‐chain amino acids (BCAA: valine, leucine, isoleucine) are among the next‐limiting amino acids for growth in piglets after Lys, Thr, Met+Cys and Trp. To formulate low crude protein diets, a clear understanding of the BCAA requirement (e.g. Ile) is required. Most studies dealing with the Ile requirement use blood cells as a protein source, which has a very low Ile content and high or very high Leu and Val contents. However, the BCAA share the first two steps of their catabolism and an excess of one BCAA may affect the availability of the other BCAA. The objective of this study was to determine the Ile requirement with a diet morebalanced in BCAA. A dose‐response study was carried out with 14 blocks of 6‐week‐old piglets (11 kg initial body weight). Each piglet within a bloc was allotted to one of six levels of standardized ileal digestible (SID) Ile:Lys (40, 43, 46, 49, 52, 55%) and performance was monitored for three weeks. Requirement for maximum growth rate and feed conversion ratio were estimated, respectively, at 47 and 45% SID Ile:Lys using a linear‐plateau model and at 49 and 47% SID Ile:Lys using a curvilinear‐plateau model. For diets without an excess supply of BCAA, the Ile requirement may be as low as 49% SID Ile:Lys in post‐weaned piglets. With the currently available crystalline amino acids, this recommendation allows further reduction of the crude protein content in piglet diets.
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