The effect of ammoniation on the nutritive value of wheat, barley and oat straws. I. Changes in chemical composition in relation to digestibility in vitro and cell wall degradability

Abstract

Twenty-two cereal straws (wheat, barley and oat) comprising 12 winter or spring cultivars, were treated with ammonia by the oven method. Their chemical composition, digestibility in vitro (OMD) and cell wall degradability (cellulase) (CWD) were then compared with those of corresponding untreated materials. Less cell wall was isolated from ammoniated than from untreated straws, as the treatment caused loss of hemicellulose and a proportionately greater loss of ferulic than p-coumaric acid groups from the walls. The OMD of untreated and treated straws, respectively, was poorly correlated with CWD. The relationships between each of these parameters and the α-cellulose, hemicellulose and lignin contents of cell walls and various estimates of aromatics released by ammoniation also showed poor correlations. However, the ferulic acid content of cell walls clearly distinguished untreated from treated material and could possibly be used to identify sub-optimal treatments on the farm.