Lupinus luteus, Vicia sativa and Lathyrus cicera as protein sources for piglets: ileal and total tract apparent digestibility of amino acids and antigenic effects

Twenty-four male piglets, weaned at 28 days of age, were used to measure th e total and ileal digestibility and serum immune responses to dietary legum inous seeds. The experimental diets consisted of a control starter (C) and three other diets prepared by replacing 30% of the crude protein content of the C diet by the protein of Lupinus luteus (LL), Vicia sativa (VS) or Lat hyrus cicera (LC). The total tract apparent digestibility (TTAD) of energy and crude protein (CP) was lowest (P < 0.001) for the LC diet. Similarly TT AD of lysine, methionine and threonine were also lowest for the LC diet. Th e apparent ileal digestibility (AID) of lysine, methionine and threonine we re lowest for the LC diet. AID of lysine and methionine was highest for the LL seeds (0.764 and 0.834, respectively) and lowest (P < 0.05) for the LC seeds (only 0.454 and 0.420, respectively). Immunoblots of individual pig s erum were made to detect both residual antigenic storage proteins of the se eds of each legume used and IgGs specific to those storage proteins. Antibo dies against beta -conglutin of L. luteus. vicilin of V. sativa and vicilin of L. cicera were detected 28 days after feeding the diet in the sera of p iglets fed on the LL, VS or LC diets, respectively. Conversely, no storage protein was found in the serum of any piglet fed either on LL, VS or LC die ts. The presence of antibodies against beta -conglutin of lupine, vicilin o f V. sativa and vicilin of L. cicera, respectively indicated an immune resp onse in weaned piglets. The absence of residual antigenic proteins may be d ue to the digestive adaptation of the piglet to the legume-based diets. How ever, no direct relation between the differences in digestibility coefficie nts among the legume seeds and their antigenicity was established. (C) 2001 Elsevier Science B.V All rights reserved.