In vitro and in sacco digestibility of wheat straw treated with calcium oxide and sodium hydroxide alone or with hydrogen peroxide

A series of five factorial experiments examined the effects of sodium hydroxide (NaOH) and calcium oxide (CaO) alone or together with hydrogen peroxide (H₂O₂, 27.5% w/w) at pH of about 11.5 (AHP) on in vitro (IVDMD) and in sacco (ISDMD) dry matter digestibility of wheat straw. The effects of different temperatures (20°C, 40°C and 60°C), various times (2, 3, 4, 6 and 27 h), pre-soaking, filtration and washing on the efficacy of the above levels of chemicals in improving IVDMD and ISDMD were tested in separate experiments. AHP improved IVDMD (P<0.001) of straws when pH was regulated to around 11.5 using NaOH. In contrast, AHP was ineffective or depressive (P<0.001) when CaO was used to regulate pH to around 11.5. However, CaO alone increased IVDMD to a similar extent as did NaOH. Washing, filtration and temperature were ineffective in improving the IVDMD of CaO-treated straw. AHP was most effective when 130 g H₂O₂ was applied to each kg DM of straw after soaking it with 3 l solution containing 80 g NaOH for a period of 27 h. The nutritional value of low quality forages can be enhanced for ruminants by using alkalis provided conditions as described above are maintained during alkali treatments.