Many different chemicals have been used for upgrading poor quality crop residues (sodium hydroxide, Jackson, 1977: ammonia, Sundstøl et al., 1988: Magadi soda, Nangole et al., 1983: organic waste ash, Adebowale, 1985: alkaline hydrogen peroxide, Gould, 1985; Lewis et al., 1987). Upgrading of crop residues by chemical treatment is the result of disruption of the cell wall structure to a point where the bacterial and fungal enzymes of the rumen can hydrolyse component of polysaccharides previously not accessible. One important constituent of cell walls acting as a barrier to the enzymes is lignin. Alkaline hydrogen peroxide is known to degrade lignin via a sequence of free radical reactions which are optimal at a pH 11.5 (Gould and Freer, 1981; Gould, 1985). An associated problem of upgrading crop residues is the low nitrogen content of such feeds. To alleviate this deficiency both ammonia and urea are commonly used to raise nitrogen.levels. In this study, the effect of sodium hydroxide alone and sodium hydroxide plus hydrogen peroxide are compared. The effect of pretreating straw with hydrogen peroxide and subsequent treatment with anhydrous ammonia was also investigated.

Expt. 1. Solutions of hydrogen peroxide were adjusted to pH 11.5 by addition of NaOH and added to straw to give 1 g H2O2/100 g straw. In order to achieve this pH 0.5 g of NaOH was used/g H202. In the second treatment therefore the NaOH was added without the H2O2- For treatment 3 10 g H2O2 was added per kg of straw and in order to achieve a pH of 11.5 5.5 g NaOH had to be used. Consequently in treatment 4 5-5 g NaOH was added without the H2O2.