Abstract
Kinetics of the cell wall hydrolysis by cellulase and its application to estimate the nutritive value were investigated. Following experiments were made to establish the technical procedure. 1. Cell wall samples from two samples of Italian ryegrass were hydrolysed by 1.0% cellulase solution dissolved in pH 4.0 acetate buffer solution for 15〜600 min. 2. Successive treatments of samples with neutral detargent and cellulase were investigated 0.5g air dried sample passed in 1.0mm screen was weighed into reflexing apparatus. After 1-hr boiling with neutral detergent, residual cell wall was washed with water, acetone and acetate buffer and was hydrolysed by 1.0% cellulase for 30〜240 min. 3. Successive treatment were applied to 34 grass and/or grass-legume mixture hays and cubes to estimate the nutritive value of forage. In this experiment cellulase hydrolysis time was 4-hr. Conclusions are summarized as follows from the experiment described above. 1. The structural carbohydrates of the cell wall are divided into at least two fractions by cellulase hydrolysis, one of which is not lignified nor crystallized constituent (NCL region), and the other fraction is associated with lignin and crystallized constituent. (CL region). The reaction of cellulase hydrolysis in both regions was first order reaction and the rate constant of NCL resion showed a higher mean value than that of CL region by 3.5 times. The amount of the NCL region was closely related to the quality of the forage. It appears that the carbohydrates of NCL region may be easily fermented in the rumen, second to the soluble carbohydrates in the cellular contents. 2. In the case of the successive treatments with the neutral detergent and cellulase it would be assumed that cellulase activity is depressed by the residual sodium lauryl. sulfate after the pretreatment. Bearing this problem in mind, washing method was investigated to eliminate completely the sodium lauryl sulfate. By washing it with water-acetone-water-buffer solution, 3-3-6-3 times respectively, no effect was observed of detergent on the cellulase activity. 3. Between the dry matter digestibility or TDN contents in vivo and DM disappearance (%) by successive treatments above mentioned in 34 samples, highly significant correlations were obtained: γ=0.904, 0.880 (P<0.01) respectively.
