Cellulase methods for the efficient digestion of grasses and brassicas

Abstract

A cellulase solubility method for the prediction of grass digestibility was modified by changing pepsin pretreatment conditions so that cellulase values were as high as those obtained using rumen liquor. Raising temperature from 40 to 50°C and acid concentration from 0.1 to 0 . 1 2 5~ during 'pepsin' treatments given before the cellulase stage, increased digestion by 3 to 10% depending on the type of grass, up to the level reached by rumen liquor. For samples of brassicas (digestibilities ranging from 66 to 84%) milder pretreatment conditions were sufficient to give cellulase digestion values as high as rumen liquor estimates.

In‐vitro digestibility of kale (Brassica oleracea) secondary xylem and parenchyma cell walls and their polysaccharide components

“…The results of in-vitro digestibility assessment with rumen liquor and fungal 'cellulase' preparations are usually well correlated with one another and, in the absence of antinutritional factors such as glucosinolates, with rates of digestion in vico (Alexander and McGowan 1966;Allison and Borzucki 1978;Dowman and Collins 1982). (The correlation sometimes breaks down with cereals rich in starch (Dowman and Collins 1982), but there is little starch in brassicas).…”

“…In-vitro cellulase digestion was carried out at the Scottish Crop Research Institute by a modification of the method of Allison and Borzucki (1978), omitting the use of filter aids so that the digested residues could be recovered for analysis. The residue from the highly digestible parenchyma cell walls of cv Maris Kestrel was so small that sufficient could not be prepared for fractionation.…”

Half-sib family selection for yield of digestible organic matter in kale (Brassica oleraceal L.)

“…For generations gen,, gen, and gen, the rumen liquor method of TILLEY & TERRY (1963) was used for this determination whereas for generations gem, and gen, the cellulase method of ALLISON & BORZUCKI (1978) was used. For each family YDoM was calculated as: (fresh weight yield) x (dry matter content) x (content of digestible organic matter).…”

Competition between cultivars of fodder kale (Brassica oleracea L.) in yield trials with single-row plots

“…The fresh-weight yield of each subplot was recorded and a sample of chopped kale was dried in an oven at 80°C for 18 h to determine dry-matter content. The dried samples were milled through a 1 mm sieve in a hammer mill and their contents of digestible organic matter (DOM) determined by the cellulase method of ALLISON & BORZUCKI (1978). Experiment 2.…”