The upgrading of wheat straw by alkaline hydrogen peroxide treatment: The effect of NaOH and H 2O 2 on the site and extent of digestion in sheep

Abstract

A study was conducted to evaluate untreated, NaOH-treated and alkaline hydrogen peroxide (AHP) treated wheat straw using digestibility and energy flow measurements. Eighteen mature South African Mutton Merino wethers were randomly allocated to three diets. Diets contained 89% untreated, NaOH-treated or AHP-treated wheat straw. The digestibility of organic matter (OM), neutral detergent fibre (NDF), cellulose and hemicellulose increased significantly ( P < 0.05) by 17.4% and 19.8%, 29.6% and 37%, 21.8% and 21.6% and 59.6% and 60.8% on the NaOH- and AHP-treated wheat straw diets, respectively, compared with the untreated wheat straw diet. Differences between the NaOH- and AHP-treated diets were not significant. The intake of OM on the NaOH-treated diet was significantly ( P < 0.05) higher than on the other two diets and the retention time of OM in the rumen was significantly ( P < 0.05) shorter on the chemically treated wheat straw diets. Rumen ammonia levels in wethers fed the untreated, NaOH treated and AHP-treated wheat straw diets differed significantly and were 157.4 mg l −1, 32.5 mg l −1 and 74.2 mg l −1, respectively. Total non ammonia-nitrogen flow at the abomasum was significantly ( P < 0.05) higher on the NaOH-treated diet compared with the other two diets. Intake of metabolisable energy (ME) was higher on the chemically treated diets compared with the untreated wheat straw diet. Wethers fed the NaOH- and AHP-treated diets gained 111 g day −1 and 3 g day −1 while those fed the untreated wheat straw diet lost 95 g day −1 during the experimental period of 45 days. Chemical treatment of wheat straw with only NaOH resulted in similar increases in digestibility and higher intakes of ME compared with straw treated with NaOH and H 2O 2.