The effect of dietary rye (0, 200, 400 and 600 g/kg substituting for wheat) and pentosanase concentration (0, 1, 2, 4, 8, 16 g/kg) on weight gain, molecular weight distribution of soluble carbohydrates in the intestinal lumen and lumenal viscosity in broiler chicks was investigated. A 4 x 6 factorial design was used with four replicates per treatment and six birds per replicate pen. Diets were fed from 1 to 19 d of age, at which time body weight, food intake and intestinal viscosity and molecular weight distribution of carbohydrate complexes in proximal and distal gut sections were determined. Weight gain and food conversion efficiency (FCE) improved with increasing pentosanase and decreasing rye concentration. Intestinal viscosity, which rose as digesta passed from the proximal to distal small intestine, fell with pentosanase addition and decreasing rye concentration. Intestinal viscosity, which correlated positively with reduced weight gain and FCE, was in turn correlated with the lumenal concentration of soluble high-molecular-weight carbohydrates (HMC, greater than 500 kDa), which constituted less than 15% of the total lumenal carbohydrate concentration. The arabinose and xylose content of the HMC increased with increasing rye concentration, suggesting that HMC composition in addition to concentration may determine intestinal viscosity. The results indicate that pentosanase isolated from rye by extraction methods may not be representative of those released by digestion.

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Manipulation of light intensity is an important management tool affecting broiler production and well being. Despite considerable research on light intensity, there is still a debate on the optimum level to be used for intensively housed broilers. Two trials were conducted with the objective of investigating the effect of light intensity, within the practical levels at confinement barns (1, 10, 20, and 40 lx), on production, processing characteristics, and welfare of broilers raised to 35 d of age. Each light intensity treatment was replicated in 2 environmentally controlled rooms in each trial with 950 Ross × Ross 308 chicks per room. Data were analyzed as a randomized complete block design with trial serving as a block. All chicks were exposed to 40 lx of light intensity and 23 h of light for the first 7 d followed by treatment light intensity and 17 h of day length thereafter. Body weight and feed consumption were determined at 7, 14, and 35 d of age. At the end of each trial, 60 birds per treatment were processed to determine the detailed meat yield. Skeletal and footpad and ocular health were monitored at 31 and 32 d of age, respectively. Body weight, feed consumption, feed:gain ratio, and mortality were unaffected by light intensity. Carcass, thigh, and drum yield as a percentage of live weight decreased linearly with increasing light intensity. The 1 lx treatment resulted in heavier wings as a percentage of live weight. Light intensity had no effect on skeletal health, but ulcerative footpad lesions decreased linearly with increasing light intensity. Birds exposed to the 1 lx treatment had heavier and larger eyes. In conclusion, light intensity did not affect broiler production and mortality but did affect carcass characteristics. The 1 lx light intensity treatment had a negative effect on broiler welfare as demonstrated by increased ulcerative footpad lesions and eye size.

Necrotic enteritis, caused by Clostridium perfringens type A, is more prevalent in broilers fed wheat or barley diets than in those fed a corn diet. We compared the effects of wheat, barley and corn diets on in vitro proliferation of C. perfringens type A. Bacteria were inoculated into the supernatants delivered from either digested or non-digested barley, wheat and corn diets mixed with thioglycollate medium (1:3). Colony forming units were counted following incubation for 6 h at 40°C. There were no significant differences in clostridial proliferation among non-digested diets. Bacterial proliferation in the digested wheat and barley diets was significantly higher than in the digested corn diet. These findings suggest that the increased incidence of necrotic enteritis in broilers fed barley and wheat diets compared with those fed a corn diet may be due in part to increased clostridial proliferation associated with the wheat and barley diets, or to decreased proliferation associated with the corn diet.

The kinetics, mineral dependency, and pH dependency of phytate hydrolysis by preparations of chicken small intestinal brush border membrane vesicles were determined. Substantial phytate hydrolysis occurred over the pH range from 5 to 6.5 with a maximum hydrolysis at pH of 6. Inclusion of 25 mM MgCl2 in the media doubled the rate of phytate hydrolysis. The brush border was shown to have no nonspecific acid phosphatase activity and excess phytate had no effect on alkaline phosphatase activity at pH 11. Under optimal conditions of pH 6 plus 25 mM MgCl2, a kinetic model of a single Michaelis-Menten type of enzymatic activity with a Km of 0.160 +/- 0.008 mM and a Vmax of 42.5 +/- 1.0 nmol/mg vesicle protein per min plus a small unsaturable component converged to the data (P < 0.05). The specific and total activities of intestinal brush border phytase were highest in the duodenum (P < 0.05) and decreased progressively down the length of the gut. Intestinal brush border vesicles prepared from broiler chicks and mature laying hens had comparable specific phytase activity. However, the total activity of brush border phytase was 35% higher in the small intestine of laying hens (P < 0.05). Intestinal brush border phytase could contribute to phytate-phosphorus digestibility and may be subject to regulation in response to the dietary phosphorus and vitamin D status of the chicken.

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...

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.