Effect of ethanol concentration and application period of soyabean meal onthe kinetics of ruminal digestion

Effects of ethanol concentration and duration of treatment of soyabean meal on nitrogen (N) solubility, the kinetics of in situ dry matter, and N disa ppearance in the rumen were determined. Ground (1 mm) soyabean meal was soa ked in 30%, 50%, 70% or 90% ethanol for 12, 24, 36 or 48 h. Seventy percent ethanol solutions applied to soyabean meal fbr 36 h or less lowered N solu bility and the estimated rate of N disappearance, and increased the estimat ed rumen undegradable protein in soyabean meal compared to untreated soyabe an meal. The lowest estimated rate of N disappearance and the highest incre ase in calculated rumen undegradable protein were observed when soyabean me al was treated with 70% ethanol for 36 h. Extending the application period of 70% ethanol to soyabean meal for more than 36 h removed the beneficial e ffect that the treatment had on N kinetics in the rumen and was considered excessive. Regardless of the application period, the 30%, 50%, and 90% etha nol solutions applied to soyabean meal did not lower the estimated rate of N disappearance in soyabean meal. However, extending the treatment time of soyabean meal with 90% ethanol for more than 24 h lowered the estimated rat e of N disappearance compared to the shorter treatment times and the data s uggested that 90% ethanol solutions applied to soyabean meal required longe r application, periods than 70% ethanol solutions to be effective. It was c oncluded that treatment of soyabean meal with 70% ethanol for 36 h had the greatest potential to increase rumen undegradable protein. (C) 1999 Elsevie r Science B.V. All rights reserved.