Efficiency of utilisation of metabolisable 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, apparent metabolizable energy (AMEn) were determined and carcass energy retentions compared when fed nutritionally complete diets for broiler chicks. The AMEn protocol involved a 14 d feeding period with growing chickens, with all excreta collected for the final 96 h. The carcass energy retention protocol involved a comparative slaughter technique in which growing chickens were given a wheat sample in a nutritionally complete diet at 90% of ad libitum intake. There was a significant (P = 0.023) linear relationship between energy retention and AMEn, although an r2 = 0.42 indicated that there was a substantial amount of unexplained variation. The ratio of energy retained per kg of additional wheat (kcal kg–1) eaten to AMEn (kcal kg–1) intake ranged from 0.49 – 0.56 in the 12 wheat samples. There were no significant (P > 0.05) relationships between the proximate nutrient or polysaccharide compositions of the wheat samples and the ratio of energy retained to AME intake. However, there was a significant, (r2 =0.40; P = 0.028) negative, linear relationship between the water extract viscosity of the wheat sample (log transformed) and this ratio.