1. The potential for improving the nutritive value of commercial solvent-extracted, heat-treated soya-bean meal (SBM) by protease treatment was measured using growing broiler chicks and tube-fed broiler cockerels. 2. SBM was pre-treated (50 degrees C for 2 h) with water alone; at alkaline pH (initial pH 8.25) with and without protease P1 (isolated from a Bacillus species) or at acid pH (initial pH 4.5) with and without protease P2 (isolated from an Aspergillus species) and incorporated into diets (290 g SBM/kg diet) for broiler chicks (20 chicks/treatment). Only protease P2 treatment improved chick performance; from 7 to 28 d of age, chicks fed on treated SBM had greater feed intakes and gained more weight than chicks fed on untreated SBM. Both proteases P1 and P2 significantly reduced chick serum anti-soya antibodies while protease P2 treatment increased apparent ileal nitrogen (N) digestibility and apparent N retention across the whole digestive tract. 3. Two tube-feeding experiments established that, of the treated SBMs used in experiment 1, only protease P2 treatment improved apparent N digestibility and true metabolisable energy. Also it was shown that increasing the temperature at which treated SBM was dried to 60 degrees C, compared with freeze-drying or drying at 50 degrees C reduced apparent N digestibility and true metabolisable energy of SBM with no significant interactions between enzyme treatment and drying temperature for both apparent N digestibility and TME. 4. It is concluded that, overall, the nutritional value of SBM assayed in a growth trial and by tube feeding was improved by treatment with protease P2 and not by treatment with protease P1.

This review considers the structure of cellulose and hemicellulose, enzymology of cellulases and xylanases (sources, enzyme assays, substrate specificity, kinetics and subsite mapping, inhibition, transferase activity, mode of action, synergism, catalytic mechanism), other characteristics of cellulases and xylanases (induction and regulation, physicochemical properties, their multiplicity, adsorption, architecture and classification, structure/function relationships) and applications.

A two-stage in vitro assay procedure was developed for predicting the efficacy of microbial enzyme sources in rye-based diets for broiler chicks. The procedure uses the complete diet as substrate to predict the in vivo intestinal viscosity and final weight of birds fed such diets. The optimum conditions for maximizing in vitro viscosity of a rye-based diet consisted of digesting .6 g of diet (ground through a 1-mm screen) in .9 mL of .1 N HCl containing 2,000 U pepsin/mL for 45 min at 40 C. At the end of this incubation phase, .3 mL 1 M NaHCO3 containing 8 mg pancreatin/mL (8 x USP) was added and the tube sealed and incubated for 2 h with intermittent vortexing. The digesta was then centrifuged (12,700 x g) and the supernatant collected for viscosity analysis using a digital viscometer. This assay was used for a rye-based diet containing either 0, .1, .2, .4, .8, or 1.6% of a xylanase source (experimental Trichoderma longibrachiatum product). The results were compared to weight and intestinal viscosity proximal and distal to Meckel's diverticulum of broilers (19 days of age) that had been fed these diets. The in vitro assay accurately predicted the in vivo intestinal viscosity (proximal r2 = .758, P < .0001, distal r2 = .667, P < .0001) and final weight of these birds (r2 = .660, P < .0001). The data suggest that the in vitro assay is a reliable assay for assessing the growth-promoting ability of an enzyme preparation in chicks fed rye-based diets.

Scott, T. A., Silversides, F. G., Classen, H. L., Swift, M. L. and Bedford, M. R. 1998. Effect of cultivar and environment on the feeding value of Western Canadian wheat and barley samples with and without enzyme supplementation. Can J. Anim. Sci. 78: 649-656. The feeding value of nine wheat cultivars grown in replicate in three locations in each of two crop years, and 14 barley cultivars grown in seven locations over three crop years was tested with or without an appropriate commercial enzyme using a broiler chick bioassay. Four pens of six male broilers were fed mash diets containing 80% of the test cereal with or without enzyme from 4 to 17 d. Digestibilities were determined using an acid insoluble ash marker at 1.1% of diet. Significant intraclass correlation coefficients between duplicate wheat samples suggested a common effect of the location, but their low to moderate values suggested the presence of random variation or variation due to unique growing conditions within location. For both wheat and barley samples, the growing location affected the feeding value of the cereal grain and subsequent broiler chick performance. Durum wheat cultivars had higher feeding values than that of other wheat classes, both with and without enzyme supplementation, and the response to enzyme supplementation was low, likely reflecting a low level of soluble non-starch polysaccharides. The values of hulless barley cultivars were similar to those of hulled cultivars without enzyme, but the lower crude fibre in hulless barley resulted in higher feeding values when diets were supplemented with enzyme. The response to enzyme supplementation for both wheat and barley cultivars was dependent on the feeding value of the cereal grain without supplementation. Knowledge of variation in enzyme response could be used by feed manufacturers to determine the economic merit of supplementing with enzymes. Can J. Anim. Sci. 78: 649-656. La valeur alimentaire de neuf cultivars de blé cultivés en double à sept locals dans deux années et 14 cultivars d'orge cultivés à sept locals dans trois années à été verifiée avec ou sans enzyme commercial dans un essai biologique pour les jeunes poussins à chair. Quatre parquets de six poulets mâles ont été alimentés avec des rations moulées contenant 80 % de céréale à tester avec ou sans enzyme de 4 à 17 j. Les digestibilities ont été determinés en utilisant un marquer de cendre insoluble à l'acide à 1.1 % du ration. Des coefficients de corrélation intraclass entre les échantillons de blé en doubles ont suggeré un effet commun du local, mais leurs valeurs faibles ou moderées ont suggeré l'existance de variation soit aléatoire ou du aux conditions unique de culture a l'intérieur du local. Pour les échantillons de blé et d'orge, l'endoit a affecté la valeur alimentaire du céréale et la performance des poulets subséquente. Les cultivars de blé Durum avait des valeurs alimentaires plus elevées que d'autres classes de cultivar avec et sans enzyme et la réponse au supplémentation par enzyme à été faible, vraisembl...

No abstract