Pasture quality and ruminant nutrition

A digestion technique using a commercially-available crude cellulase preparation from Trichoderma viride is described. The enzyme showed cellulase, hemicellulase and proteolytic activity when tested on herbage or herbage polysaccharides. A high correlation (r = 0.92, P < 0.001, residual standard deviation 2.5) was found between a simple one stage enzyme digestion and in vivo dry matter digestibility for a range of grass species and varieties. In vitro dry matter digestibility and detergent fibre were also determined on the same samples and the results correlated with in vivo dry matter digestibility. The cellulase method is rapid and reproducible and particularly well suited for the evaluation of plant material in breeding programmes.

A cellulase digestion technique for predicting the dry matter digestibility of grasses

Jones

Hayward

1973

Composition of sweet and bitter lupin seed hulls with observations on the apparent digestibility of sweet lupin seed hulls by young rats

Bailey¹,

Mills²,

Hove³

1974

Seed hulls from both sweet and bitter varieties of lupins (Lupinus angustifolius)have been analysed for constituent polysaccharides. The hulls contained 15 to 32% oxalate-soluble pectic polysaccharide, excluding pentose, 12 to 14% hemicellulose, 44 to 51 % cellulose, 0.3 to 0.4% lignin, 2.7 to 3.8 % protein and 2 % ash."Crude fibre" was 54.9%. In agreement with the low lignin values all of the hemicellulose was extractable with alkali without prior delignification and 70 to 80 % of the polysaccharide in depectinated hulls was hydrolysed by cellulase plus hemicellulase, likewise without delignification. Sweet lupin seed hulls, added to a complete basal diet up to 40 %, did not depress growth of young rats significantly; compensatory increase in food consumption occurred. With 60 % hulls in the diet growth and food efficiency were reduced. Ground hulls did depress food and protein digestibility in direct proportion to their amount in the diet, possibly because of physical entrapment in the excessive bulk in the gut. The digestibility of the "crude fibre" of the hulls was 33 % when the diet contained 20% hulls; this decreased to 22% when the content of hulls in the diet was increased to 60%.

Cellulase methods for the efficient digestion of grasses and brassicas

Allison

Borzucki

1978

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.