Rumen degradation in sacco in sheep of wheat straw treated with calcium oxide, sodium hydroxide and sodium hydroxide plus hydrogen peroxide

This split unit study involved two sheep, seven incubation times and four test straws to compare with untreated straw the effect, kg(-1) straw dry matter (DM), of CaO (160 g CaO plus 2 1 of water), NaOH (80 g NaOH in 3 1 of water) and alkaline hydrogen peroxide (NaOH plus 132 g H2O2 in 3 1 of water, AHP) treatments on composition and rumen degradation in sacco of wheat straw in sheep. After 14 days of storage, each straw was mixed with molasses, dried, ground, weighed into nylon bags and incubated ruminally for various hours in sheep fed daily 1 kg dried grass cubes. After removal, the residues within bags were washed together with unincubated samples (0 h) of straws, dried and analysed for DM, organic matter (OM) and neutral-detergent fibre (NDF) to estimate nutrient disappearance from straws. The data on nutrient disappearance were fitted exponentially to estimate quick- (a), slow (b) and predicted (P-0.025) degradable fractions and degradation rate (c) for b. NDF and hemicellulose were reduced in treated compared with untreated straw (p < 0.001). Disappearance of nutrients from treated straws was significantly greater than that from untreated straw at almost all incubations (p < 0.001). The a, b, c and P-0.025 estimates were significantly increased by all treatments (p < 0.001). AHP treatment increased straw degradation more than NaOH and CaO treatments. Although, CaO improved rumen degradation less than NaOH, its use to increase straw digestion even moderately may be more desirable because it is readily available, cheap and less dangerous for the users and the environment. (C) 2000 Published by Elsevier Science B.V. All rights reserved.