Effects of alkali treatment of wheat straw on intake and microbial protein synthesis in cattle

Effects of sodium hydroxide treatment on intake and digestion of straw organic matter (OM), and microbial protein synthesis were examined in comparison with untreated and treated straws. Intakes (kg dry matter (DM)/d) of untreated, NaOH- and sodium carbonate-treated straws were 5.21, 7.04 and 6.48 respectively and intakes (kg/d) of digestible organic matter (DOM) for the respective diets were 2.57, 3.73 and 2.98 respectively. NaOH-treated straw ranked higher than untreated straw in intakes of DM and DOM (P less than 0.01). The proportion of DOM intake that was apparently digested in the rumen was 0.74, 0.77 and 0.66 on untreated, NaOH- and Na2CO3-treated straws respectively. Although the amount of bacterial N leaving the abomasum was higher with NaOH-treated than with untreated straw (74.6 v. 56.8 g/d, P less than 0.01), efficiencies of bacterial N synthesis were not different between these treatments (28.6 v. 31.5 g bacterial N/kg OM apparently digested, P greater than 0.05). The live-weight gain which the NaOH-treated straw could support was predicted to be 350 g/d and it was concluded that a protein supplement would have provided further increase in production in diets based on NaOH-treated straw.