Efficiency of utilization of metabolizable energy for carcass energy retention in broiler chickens fed different wheat cultivars

Six different wheat cultivar grain samples were grown in both the 1993 and 1996 harvest years, and their concentrations of nitrogen-corrected, apparen t metabolizable energy (AMEn) were determined and carcass energy retentions compared when fed nutritionally complete diets for broiler chicks. The AME n protocol involved a 14 d feeding period with growing chickens, with all e xcreta collected for the final 96 h. The carcass energy retention protocol involved a comparative slaughter technique in which growing chickens were g iven a wheat sample in a nutritionally complete diet at 90% of ad libitum i ntake. There was a significant (P = 0.023) linear relationship between ener gy retention and AMEn, although an r(2) = 0.42 indicated that there was a s ubstantial amount of unexplained variation. The ratio of energy retained pe r kg of additional wheat (kcal kg(-1)) eaten to AMEn (kcal kg(-1)) intake r anged from 0.49 - 0.56 in the 12 wheat samples. There were no significant ( P > 0.05) relationships between the proximate nutrient or polysaccharide co mpositions of the wheat samples and the ratio of energy retained to AME int ake. However, there was a significant, (r(2) = 0.40; P = 0.028) negative, l inear relationship between the water extract viscosity of the wheat sample (log transformed) and this ratio.