Réponse des porcelets sevrés (8-21 kg) à la valine

A dose-response study was performed to estimate the valine (Val) requirement of weaned piglets. The 432 piglets (weaned at 28 days) were distributed among eight diets differing in their Val:lysine (Lys) ratio expressed on a standardized ileal digestible (SID) basis. Two diets low in crude protein (16.8%), one deficient in SID Val:Lys (58% SID Val:Lys) and the other with an expected ratio above the requirement (82.5% SID Val:Lys), were mixed in different proportions to obtain eight SID Val:Lys levels. The diets were formulated to be isocaloric (9.8 MJ net energy/kg) and with a sub-limiting level of SID Lys (1.05%), allowing estimation of the Val requirement relative to that of Lys. Average daily gain (ADG) and feed intake (ADFI) improved with increasing SID Val:Lys level, the best performance being obtained at 72.0% SID Val:Lys. ADG and ADFI improved by 16% and 15%, respectively, from 61.5-72.0% SID Val:Lys. Using ADG and ADFI as response criteria, the requirement was estimated to be 67.5% and 74.2% SID Val:Lys with curvilinearplateau and quadratic models, respectively. These results are in line with those in the literature and confirm that piglets react to Val deficiency by decreasing their ADFI, which decreases their ADG without affecting feed efficiency. Results of the present experiment highlight that the Val level has to be controlled in piglet diets to avoid decreasing ADG.