Influence of low protein diets supplemented with isoleucine and valine on the quality and functional properties of chicken eggs

The influence of isoleucine and valine supplementation in low protein diets having constant lysine, sulphur amino acids and tryptophan on the quality and functional properties of both fresh and cooked eggs was investigated in laying hens. A lower protein and albumen level reduced egg weight, but the dietary addition of isoleucine significantly increased this trait. Yolk weight and yolk index were unaffected by dietary treatment. The drainage of emulsion after 60 min decreased with the addition of valine. Differences among groups were small and sometimes inconsistent in relation to cake volume, dough density of cake and baking losses of meringue and Madeira cake. Cohesiveness of yolk gel was significantly higher in the control group. Hardness of yolk gel and albumen gel improved with valine supplementation. L'influence d'une supplementation en isoleucine et valine de regimes alimentaires pauvres en proteines et constants en lysine, acides amines soufres et tryptophane, sur la qualite et les proprietes fonctionnelles d'oeufs frais et cuits, est etudiee. Une faible teneur en proteine et en albumen reduit le poids de l'oeuf mais la supplementation en isoleucine diminue ce phenomene. Le drainage de l'emulsion apres 60mn est reduit et la durete des gels est augmentee avec une supplementation en valine.