The effect of storage of cereal grain and enzyme supplementation on measurements of AME and broiler chick performance

Abstract

There is a concern that feeding newly harvested cereal grain results in poor performance in poultry. A broiler chick apparent metabolizable energy (AME) bioassay was used to measure changes in feeding value of wheat (n = 14), hulless (n = 10) and hulled (n = 14) barley with or without a commercial enzyme appropriate for wheat- or barley-based diets. In the broiler chick bioassay, four pens of six male broiler chicks were fed ad lib, from 4 to 17 d, diets containing 80% of a test cereal grain and a high-protein basal mixture containing 1% “celite” as an acid-insoluble ash marker. Each of the cereal-grain-based diets, with or without enzyme, was tested within 3 mo of harvest and again 6 mo later. With cereal grain storage there were consistent (P < 0.05) increases in feed intake (FI) between 4 and 17 d and body weight (BW) at 17 d of age with wheat-based diets fed wit h (12.5 and 16.9%, respectively, for FI and BW) or without (16.1 and 22.7%) enzyme. In hulless barley diets without enzyme, there was a significant improvement in BW (7.5%) with storage, while storage had a significant effect on FI and BW (2.9 and 6.3%, respectively) when fed with enzyme. For all other barley diets there was a positive effect of storage on FI and BW, but it was not significant. Feed conversion ratios decreased marginally (P > 0.05) with storage of cereal grain. AME of diets was improved within each period by enzyme supplementation. However, there were measurable decreases (P < 0.05) in AME with storage of cereal grains for the three cereal grains with enzyme supplementation (ranging from –3.2 to –8.2%). The r2 of the above measurements for the different sources of cereal grain between storage periods ranged from 0.65 to 0.94, indicating that the relative ranking of the cereal grains, with respect to feeding value, remained similar during storage. Increases in FI with storage were not significantly related to the attempts of the broiler chicks, to maintain metabolizable energy (ME) intake. Therefore, this increases our concerns that “factors” in newly harvested cereal grains may exist and that they may limit voluntary feed intake and/or growth. Key words: Cereal grain storage, AME, broiler performance, wheat, barley