New process of maize stalk amination treatment by steam explosion

Amination treatment of straw proceeds slowly at the low environmental temperatures. Although the aqueous ammonia has a relatively good effect, it has high volatility and an irritant odor. Steam explosion has the advantage of short reaction time, but it cannot improve the nitrogen content of the straw for animal feed. A new process combined with the two methods for maize stalk pretreatment was studied to improve its nutritive value. The results showed that nitrogen sources coupled with steam explosion modified the treated materials. Except for urea, other nitrogen sources promoted the degradation of hemicellulose and the increase of the soluble sugars content. Decrease of hemicellulose treated with 5% (NH4)2SO3 was highest (58.0%), but no significant changes were detected in cellulose and lignin content using chemical methods after nitrogen source addition. Compared with steam explosion pretreatment, amination by steam explosion increased the nitrogen content of maize stalk. The highest total nitrogen content (2.30%) was obtained by adding urea. The treatment of 5% (NH4)2SO3 led to the highest retention of added nitrogen (84.0%) and 15% NH4OH led to the lowest percentage of retention (18.1%). Amination by steam explosion effectively increased the potential digestibility of DM, and the maximum digestibility value (71.2%) was obtained when 5% (NH4)2SO3 was added. Amination by steam explosion shortened the amination time and was a rapid and effective method of improving the nutritive value of straw.