Amino acid digestibility and metabolisable energy of spring and winter faba beans grown on two sites and effects of dehulling in caecectomised laying hens

Abstract

BACKGROUND: The variation in amino acid (AA) digestibility and metabolisable energy (MEN) in four spring and four winter faba bean genotypes differing in vicine/convicine (V/C) concentrations grown on two sites was investigated in caecectomised LSL-Classic laying hens. Effects of dehulling one faba bean genotype were also examined. Diets containing one out of 17 faba bean variants each and a basal diet were fed to ten caecectomised laying hens in a row-column design to achieve five replicates per diet. RESULTS: Ranges and levels of digestibility of the hulled variants differed widely among AA with the lowest and highest range determined for Arg (90–93%) and Cys (−12–65%), respectively. MEN ranged between 10.3 and 12.3 MJ kg−1 dry matter. Lower MEN and digestibility of Cys, Glx, Phe, Pro, Tyr, and Val (P < 0.050) was determined for the winter genotypes grown in Nimtitz compared to the other variants. Digestibility of Ser was lower for the spring than for the winter genotypes (P < 0.050). Negative correlations with AA digestibility were determined for phytate, but not for tannin and V/C concentrations (P < 0.050). Negative correlations between tannin fractions and MEN were weak (P = 0.082–0.099). Dehulling increased MEN by 1.8 MJ kg−1 dry matter and raised the digestibility of Pro, His, and Glx (P < 0.050). CONCLUSIONS: The results indicated that the digestible AA and MEN supply of laying hens was increased by using low phytate faba beans while breeding for low V/C genotypes did not affect AA digestibility or MEN. Dehulling increased MEN and the digestibility of some AA.