Refining the metabolisable energy value of field beans for turkeys.

1. This study examined the feeding value of ten UK grown field bean ( Vicia faba L. var. minor) cultivar samples from the same harvest year on nitrogen corrected apparent metabolisable energy (AMEn) and nutrient retention coefficients when fed to young female turkeys.2. A balancer feed (BF) was formulated to contain 12.39 MJ/kg ME and 269 g/kg crude protein. Ten nutritionally complete, mash diets were prepared by mixing 200 g/kg of each ground field bean cultivar with 800 g/kg of the BF, totalling eleven diets. Diets were fed to female BUT Premium turkeys from 40 to 50 d of age. Each diet was fed to eight raised floor pens, housing two birds, following randomisation. The AMEn was determined by the total collection technique over the last 4 d of the study. Relationships were examined between AMEn, chemical composition and quality variables of the field bean samples.3. The overall determined AMEn value of the beans ranged from 7.72 MJ/kg DM to 9.87 MJ/kg DM, giving an average AMEn of 8.80 MJ/kg DM (P<0.05). The soluble non-starch polysaccharide (NSP) content of the beans negatively correlated with their determined AMEn (r=-0.730; P<0.05). Bean flour lightness-darkness degree (L*) correlated positively with the AMEn (r=-0.643; P<0.05)4. A positive correlation was observed between the degree of yellowness-blueness of bean flour and condensed tannins content (r=0.696; P<0.05). Step-wise regression indicated that soluble NSP + L* of field beans provided explanatory variables suitable for estimating the AMEn value for turkeys (r 2 =0.737; P<0.05).