A BROILER CHICK BIOASSAY FOR MEASURING THE FEEDING VALUE OF WHEAT ANDBARLEY IN COMPLETE DIETS

Energy is an important component of poultry feed and is derived princi pally from cereal grains. Unfortunately, all of the chemical energy is not available to the bird, and biological assays must be used to dete rmine the digestible energy value of a cereal grain. The bioassay desc ribed uses four pens of six male broiler chicks, complete diets contai ning 80% of a test cereal grain (with or without an appropriate commer cial enzyme), and ad libitum feed intake. Apparent metabolizable energ y values (kilocalories per kilogram of cereal grain, DM basis) values are calculated from gross energy and acid insoluble ash measurements o f diet and excreta collected for 24 h at 16 d of age. To monitor varia tion between broiler chick assays, due to bird, environment, etc., com mon control samples of Hard Red Spring (HRS) and Canadian Prairie Spri ng (CPS) wheat were tested in each of 15 separate assays over 2 yr. Si milarly, for barley, control samples of hulled and hulless barley were repeatedly tested in five assays.Broiler performance in this study wa s lower than expected for commercial broilers, in part due to a high d ietary cereal grain component and the fine mash texture. However, AME values as determined were comparable to those reported in the literatu re for wheat and barley. The CV for AME measured among pens, represent ing the intra-assay CV, was between 1.2 and 3.4% and was lower with en zyme supplementation. The interassay CV was only slightly higher than the intraassay CV. This assay provides precise estimations of ME in ce real grains fed to young broilers that can be used for diet formulatio n or for verification of laboratory measures of feeding value of cerea l grains.