The effect of pelleting, salt, and pentosanase on the viscosity of intestinal contents and the performance of broilers fed rye

Crop beta-glucanase activity limits the effectiveness of a recombinant cellulase used to supplement a barley-based feed for free-range broilers

1. The supplementation of diets rich in soluble polysaccharides with microbial cellulases and hemicellulases decreases digesta viscosity and promotes broiler performance. 2. In contrast, recent experiments suggest that polysaccharidases are ineffective for improving the nutritive value of pasture biomass used by free-range broilers. However, the feasibility of using cellulases and hemicellulases to improve the utilisation of cereal-based feeds by pastured poultry remains to be established. 3. A study was undertaken to investigate the capacity of a recombinant cellulase from Clostridium thermocellum to improve the nutritive value of a barley-based feed for free-range pastured broilers of the RedBro Cou Nu x RedBro M genotype. 4. The results show that supplementation of a barley-based diet with a recombinant beta-glucanase had no effect on the performance of free-range broilers, foraging in legume-based diets from d 28 to 56. In addition, the results confirm that the lack of effect of the recombinant enzyme in improving the nutritive value of the barley-based feed does not result from enzyme proteolysis or inhibition in the gastrointestinal tract. 5. Significantly, beta-glucanase activity was identified in the crop of non-supplemented animals. The data suggest that endogenous cellulases originated both from the barley-based feed and from the crop microflora. 6. The results presented here suggest that in older birds of slow-growing genotypes associated with free-range production systems, previously unknown sources of beta-glucanases, such as the feed and microbial symbiotic microflora, can affect the effectiveness of exogenous enzymes added to the feed.

Pasture intake improves the performance and meat sensory attributes of free-range broilers

Free-range chickens are assumed to consume low to moderate levels of pasture, although the effects of forage intake in broiler performance and poultry meat quality remain to be established. In addition, despite cellulases and hemicellulases being widely used as feed supplements to improve the nutritive value of cereal-based diets for fast-growing broilers, the potential interest of these biocatalysts in the production of free-range chicken is yet to be established. In this study, broilers of the RedBro Cou Nu x RedBro M genotype were fed a cereal-based diet in portable floorless pens located either on a rainfed subterranean clover (Trifolium subterraneum) pasture or on an irrigated white clover (Trifolium repens) pasture. Control birds were maintained at the same site in identical pens but with no access to pastures. The importance of pasture intake and enzyme supplementation in the performance and meat sensory properties of the free-range chicken from d 28 to 56 was investigated. The results revealed that although cellulase and hemicellulase supplementation had no impact on broiler performance (P > 0.05), birds foraging on legume-based pastures reached significantly greater final BW. The data suggest that the improvement in broiler performance results from increased intake of the cereal-based feed rather than from an improvement in the efficiency of nutrient utilization per se. Interestingly, although the intake of the subterranean clover pasture had no impact on the tenderness, juiciness, and flavor of broiler meat, members of a 30-person consumer panel classified the meat from grazing broilers with greater scores for overall appreciation. Together, the results suggest that pasture intake promotes bird performance while contributing to the production of broiler meat with preferred sensory attributes.

Evolving enzyme technology: impact on commercial poultry nutrition

The use of exogenous enzymes to improve the nutritional value of poultry diets is a relatively new concept. The technology is rapidly evolving, with new enzymes, enzyme combinations, and novel applications being developed as rapidly as regulatory restrictions will allow. Most researchers in the field of poultry nutrition would consider phytase to be the last significant leap forward in terms of enzyme use in the animal feed industry. However, there is a great deal of ongoing research into the next generation of enzymes with a focus on ingredient quality, predictability of response via least-square models, improvements in food safety, effect of bird age, effect of various side activities and enzyme dose, maximisation of net income and reduction in environmental pollution. It is the purpose of the present review article to summarise the current research in the area of feed enzymes for poultry and to speculate on future applications of enzymes and new enzyme technologies that may be of value to the industry in the coming years.

Exogenous enzymes for pigs and poultry

Many feed ingredients in use in monogastric diets contain significant quantities of antinutritional factors (ANF) which limit both their feed value and their use. Almost all enzymes currently being used address such factors to varying degrees, allowing for more economic utilization of raw materials. However, animal response to xylanase, β-glucanase and even phytase utilization reported in the literature tends to vary. Factors such as enzyme source, ingredient variety and environment under which the ingredient was grown, stored and processed into animal feed, age of animal, interaction with other dietary ingredients, and health status are shown to affect significantly the response obtained. As a result, the mode of action of xylanases and β-glucanases is still debated due to too much emphasis being placed on interpretation of individual trial results without regard to the interactive factors or the literature dataset as a whole. Better understanding of such factors will improve data interpretation. While results with phytase are not subject to such extreme variation, they are nevertheless inconsistent in the degree to which inorganic phosphorus can be replaced by this enzyme. Greater understanding of the ANF and factors which interact to govern the response to added exogenous enzymes will undoubtedly improve the economic return and confidence in their use. Improved knowledge of ANF structure will result in development of enzymes directed towards far more specific targets, which enhances the likelihood of success and should reduce the overall enzyme usage.

Efficacy of supplementation of α-amylase-producing bacterial culture on the performance, nutrient use, and gut morphology of broiler chickens fed a corn-based diet

A trial was conducted to evaluate the efficacy of an Escherichia coli strain producing alpha-amylase of Bacillus stearothermophilus on growth performance, nutrient use, and the morphology of the small intestine of broilers fed a corn-based diet. One hundred thirty-five 1-d-old chicks (Cobb 500) were randomly divided into 3 groups and treated as follows: (i) basal diet (control); (ii) basal diet and water supplemented with an E. coli strain that produced amylase, and (iii) basal diet and water supplemented with an E. coli strain that produced amylase plus bacterial hemoglobin. At 21 d of age, supplementation of E. coli improved daily gain (P < 0.05) and feed conversion (P < 0.01). At the end of the trial, birds supplemented with water containing bacteria consumed more and grew faster (P < 0.05) and had better feed conversion (P < 0.10) than broilers given no bacteria. Also, the presence of bacteria improved apparent digestibility of organic matter (P < 0.01). However, no effects were detected for CP or fat digestibility. Supplementation with E. coli reduced relative pancreas weight (P = 0.06) but did not affect the weight of the liver (P > 0.05) and length of duedonum, jejunum, ileum, and cecum (P > 0.05). Length of the villi and crypts were significantly increased with bacterial supplementation. Presence of the bacterial hemoglobin gene did not cause a significant difference in changes observed. The data indicated that supplementation of an E. coli strain capable of producing alpha-amylase improved digestibility of nutrients and performance of broilers fed a corn-based diet.

Influence of β-glucanase-producing Lactobacillus strains on intestinal characteristics and feed passage rate of broiler chickens

Two experiments were conducted to study the effects of beta-glucanase produced by transformed Lactobacillus strains on the intestinal characteristics and feed passage rate of broiler chickens fed barley-based diets. Supplementation of transformed Lactobacillus strains to the diet of chickens significantly (P < 0.05) reduced the intestinal fluid viscosity by 21 to 46% compared with chickens fed an unsupplemented diet or a diet supplemented with parental Lactobacillus strains. The relative weights of pancreas, liver, duodenum, jejunum, ileum, ceca, and colon were reduced (P < 0.05) by 6 to 27%, and the relative length of duodenum, jejunum, ileum, and ceca was reduced (P < 0.05) by 8 to 15%. Histological examination of the intestinal tissues showed that the jejunal villus height of chickens fed a diet supplemented with transformed Lactobacillus strains was significantly (P < 0.05) higher than that of chickens fed other dietary treatments. The transformed Lactobacillus strains were found to reduce (P < 0.05) the time of feed passage rate by 2.2 h. Supplementation of transformed Lactobacillus strains to the diet improved the intestinal characteristics and feed, passage rate of the chickens.

Viscoelastic properties of the small intestinal and caecal contents of the chicken

We measured the coefficients of viscosity, shear rates and shear stresses of chicken small intestinal and caecal contents, including solid particles, using a tube-flow viscometer. The coefficients of viscosity of chicken small intestinal and caecal contents were correlated negatively with their shear rates, a characteristic typical of non-Newtonian fluids. The coefficient of viscosity of the small intestinal contents was lower than that of the caecal contents at a shear rate of 1 s(-1). Chicken caecal contents were more viscous than pig caecal contents. The exponential relationship between shear stress and shear rate showed that chicken small intestinal and caecal contents had an apparent Herschel-Bulkley fluid nature. These results indicate that solid particles, including uric acid crystals, are mainly responsible for the viscosity of the digesta in the chicken.

beta-Mannanase ameliorates viscosity-associated depression of growth in broiler chickens fed guar germ and hull fractions

High concentrations of guar meal in broiler chicken diets reduce body weight and feed efficiency. The increased intestinal viscosity that is responsible for reduced measures of performance results from residual guar gum present in guar meal. Two experiments were designed to study the effects of 2 guar meal fractions at 3 different concentrations, germ (0, 5.0, and 7.5%) and hull (0, 2.5, and 5.0%), and the effectiveness of a beta-mannanase at three levels (0, 1x, and 4x; 1x = 1.09 x 10(5) units/ kg) on broiler growth and feed conversion. Growth and performance were measured as a function of intestinal viscosity. Addition of the germ fraction to rations did not reduce body weight, although feed conversion ratio was increased at 7.5% of the diet. Intestinal viscosity also increased significantly at this level. Enzyme addition significantly reduced intestinal viscosity. Due to an interaction that was present between hull and enzyme concentration, each treatment was compared separately. Inclusion of the hull fraction significantly reduced body weight at both levels of inclusion and increased feed conversion ratio at 5% inclusion. Addition of the enzyme significantly increased body weight and reduced feed conversion ratio in diets containing guar hull fractions. Supplementation of beta-mannanase to feeds containing either fraction of guar meal reduced intestinal viscosity and alleviated the deleterious effects associated with guar meal feeding.

Feeding regimen and enzyme supplementation to rye-based diets for broilers

A trial was conducted to study the influence of feeding regimen [ad libitum, (AL) vs. feed restriction, (FR)] and supplementation of the diet with a combination of xylanase and beta-glucanase on physiological parameters and performance of broilers fed rye-based diets. There were 4 dietary treatments arranged factorially with 2 feeding regimens (0 vs. 30% FR from 4 to 14 d), 2 enzyme doses (0 vs. 500 ppm), and an additional corn control diet. Each treatment was replicated 9 times from 4 to 25 d (15 chicks caged together) and 6 times from 25 to 46 d. From 4 to 46 d of age, FR did not affect weight gain and improved feed conversion of broilers (P < 0.05). Also, FR reduced the incidence of leg disorders, digesta viscosity, and pasted vents (P < 0.01) and increased relative weight of gizzard (P < 0.001). Enzyme supplementation (ES) improved average daily gain and feed conversion at all ages (P < 0.01), and the beneficial effects were greater for AL than for FR birds (P < 0.10). Also, ES reduced digesta viscosity (P < 0.001), relative weights of gizzard (P < 0.05) and crop (P < 0.01), and jejunum length (P < 0.05). Compared with feeding corn, feeding rye AL with or without ES impaired growth and feed conversion from 4 to 46 d (P < 0.01) and increased incidence of leg disorders (P < 0.05), viscosity of jejunum content (P < 0.01), and jejunum length (P < 0.05). We concluded that rye in feed impaired broiler performance and increased digesta viscosity and incidence of leg disorders and that FR and ES reduced the magnitude of the problem. The beneficial effects of ES on bird performance were more evident when birds were fed AL.

Heat processing of barley and enzyme supplementation of diets for broilers

The influence of heat processing (HP) of barley and enzyme supplementation (ES) of the diet on digestive and performance traits of broilers to 21 d was studied. There were four treatments arranged factorially with two barley-processing treatments (raw or heated), two levels of ES (0 or 500 ppm), and five replicates per treatment. Chicks fed HP barley grew faster than broilers fed raw barley until 8 d of age, but the effect disappeared thereafter. In general, ES improved broiler performance at all ages. Intestinal viscosity was increased by HP of barley (P < or = 0.05) and reduced by ES (P < or = 0.001), and the decrease in viscosity caused by ES was greater for HP than for raw barley diets (HP x ES; P < or = 0.05). Heat processing of barley and ES of the diet improved apparent retention of nutrients (P < or = 0.001). Age affected apparent retention of nutrients differently. For starch and neutral detergent fiber, retention increased linearly with age (P < or = 0.01), but for the remaining nutrients the retention decreased from d 4 to 8 and then increased until d 21 (P < or = 0.001). Also, the beneficial effects of HP on retention of nutrients were more pronounced at younger ages (HP x age; P < or = 0.05). Both HP (P < or = 0.001) and ES (P < or = 0.01) increased liver weight, and enzymes reduced the weights of pancreas (P < or = 0.05) and small intestine (P < or = 0.001). Villus height was improved by HP (P < or = 0.001) and ES (P < or = 0.01), but villus surface area was only improved by enzymes (P < or = 0.01). It was concluded that broiler performance is improved by HP of barley at early ages and by ES of the diet throughout the trial. Also, HP and ES increased apparent retention of nutrients, AMEn of the diet, and villus height.

Alpha-amylase supplementation of broiler diets based on corn

A 42-d trial was conducted to study the influence of exogenous alpha-amylase on digestive and performance traits in broilers fed a corn-soybean meal diet. There were two treatments (control and alpha-amylase supplemented diet) and six replicates (14 Cobb male chicks caged together) per treatment. At 7 d of age, alpha-amylase supplementation improved daily gain by 9.4% (P < or = 0.05) and feed conversion by 4.2% (P < or = 0.01). At the end of the trial, birds fed the alpha-amylase-supplemented diet ate more and grew faster (P < or = 0.05) and hadbetter feed conversion (P < or = 0.10) than broilers fed the control diet. Also, alpha-amylase supplementation improved apparent fecal digestibility of organic matter and starch (P < or = 0.01) and AMEn of the diet (P < or = 0.001). However, no effects were detected for CP or fat digestibility. Nutrient digestibility and AMEn of the diet increased with age (P < or = 0.001); however, no interactions of alpha-amylase x age were observed for any trait. Coefficients of apparent ileal and fecal digestibility of starch at 28 d of age were similar, which indicated that most of the undigested starch was not fermented in the hindgut of the chick. alpha-Amylase supplementation reduced relative pancreas weight (P < or = 0.001) but did not affect the weight of the remaining organs. Age consistently reduced intestinal viscosity and relative weights of all the organs (P < or = 0.001). The data indicated that alpha-amylase supplementation of a corn-soybean meal diet improved digestibility of nutrients and performance of broilers.

Influence of enzymes on performance and digestive parameters of broilers fed rye-based diets

An experiment was conducted to study the influence of enzyme supplementation (ES) to rye-based diets on rate of food passage through the digestive tract, viscosity of jejunum content, volatile fatty acid concentration in ceca, and performance of broilers. There were seven treatments; six diets arranged factorially with three varieties of rye (Petkus, Prima, and Saratov V) and two levels of ES (0 or 500 ppm of an enzyme complex containing 858 IU of beta-glucanase and 864 IU of xylanase/g) and an additional control diet based on corn. Each treatment was replicated seven times (12 chicks caged together), and the trial lasted 25 d. Rye feeding increased intestinal viscosity and impaired bird performance at 25 d (P < 0.001). Among rye diets the greatest feed intake and weight gain were obtained with Petkus variety, which also produced the lowest intestinal viscosity. Enzyme addition reduced the time needed to recover 1% (0.78 vs. 0.98 h; P < 0.05) and 50% (4.2 vs. 6.5 h; P < 0.01) of the marker in feces and reduced the mean retention time of marker in the gastrointestinal tract (17.1 vs. 18.8 h; P < 0.05). Also, ES reduced intestinal viscosity (P < 0.001) and improved feed intake, daily gain, and feed conversion of birds from 4 to 25 d (P < 0.01) but did not modify volatile fatty acid concentration in ceca. We concluded that ES added to rye diets decreased intestinal viscosity and accelerated digestive transit, improving productive performance of broilers.

Influence of whole barley and grit on live performance and health of turkey toms

Live performance to 96 d was compared for 1,584 turkey toms reared on diets containing four levels of whole barley and two levels of insoluble grit (0 or 9 g/bird per wk). Nutrient specifications for all diets were similar. The six dietary treatments were 1) 0% whole barley plus grit, 2) Treatment 1 minus grit, 3) grit plus 5% whole barley at 0 d increasing to 35% by 19 d, 4) grit plus 5% whole barley at 0 d increasing to 50% by 19 d, 5) Treatment 4 minus grit, and 6) grit plus 5% whole barley at 19 d increasing to 50% by 40 d. The concentrate blended with the whole barley was fed as crumbles or pellets. Nutrients were not diluted. Compared to the control treatments, feeding 35% or more whole barley temporarily reduced weight gain and increased feed:gain prior to 68 d. Cumulative weight gain was reduced in Treatments 3 and 5 compared to treatments in which no barley was fed. Cumulative feed:gain was increased in Treatment 5 compared to Treatments 2 and 3. Total mortality and leg and skeletal problems were reduced in treatments where whole grain slowed early growth rate. Feeding grit had no effect on the live performance of birds fed similar levels of whole barley. In treatments in which whole barley was introduced at 0 d, gizzard pH was decreased at 18 d, and gizzard weight was increased at 32 d. Jejunal viscosity was unaffected by dietary treatment.

Efficiency of different xylanase preparations in diets for pekin ducks

Four experiments were conducted with a total of 2288 pekin ducks. Day-old ducklings were group-penned on straw bedding and were fed complete, pelleted diets ad libitum for up to 49 days depending on experiment. In each experiment, starter diets (until day 21) and grower diets (from day 22) were used adequate in ME content and nutrient content. The sum of wheat, rye, and triticale amounted to at least 57% (starter diet) and 63% (grower diet), respectively. The inclusion level of wheat, rye, and triticale was different between experiments, with a maximum rye inclusion of 45%. Five different enzyme preparations all having, 1,4-beta-xylanase as the main activity were considered in this study with either one (2 preparations) or three (3 preparations) levels of supplementation. The effect of enzyme supplementation on ileal digesta viscosity was studied at the end of two experiments comprising 4 enzyme preparations. A significant reduction in digesta viscosity was determined for all preparations. The viscosity of digesta was higher in birds that were fed 45% rye in their diet as compared to those fed a diet based on triticale and wheat, even with enzyme supplementation. Differences in digesta viscosity were not reflected in growth or feed conversion data. In one experiment, the body weight of ducks on day 21 was significantly improved by enzyme supplementation. This effect disappeared with progress in experiment. In another experiment, feed intake was significantly improved with enzyme supplementation. Apart from this, no statistically significant improvement in performance could be detected. On overall average, the final BW of ducks fed an enzyme was (as compared to the unsupplemented control = 100), 100, and the feed conversion ratio was 101. There is no indication from the growth and feed conversion data that an enzyme effect becomes more pronounced with increasing inclusion rate of soluble NSP by rye. It is concluded that supplementary xylanases are efficient in reducing digesta viscosity in ducks fed diets with high inclusion of wheat, rye and triticale. No consistent effect of enzyme supplementation, however, can be expected on growth and feed conversion.

The dietary effect of different wheat cultivars for broiler chickens

1. An experiment was conducted to examine the variability in chemical composition of 16 wheat cultivars and to study how this variability affected the performance of broiler chickens given diets containing 650 or 815 g wheat/kg diet during the first 3 weeks of life. Intestinal viscosity, apparent fat digestibility and apparent metabolisable energy were determined with all diets. Intestinal pH and the relative weight of different parts of the intestine were measured in chickens fed on diets with the high wheat inclusion. 2. The 16 wheat cultivars varied in chemical composition, with protein content ranging from 112 to 127 g/kg dry matter, starch content from 658 to 722 g/kg dry matter and non-starch polysaccharides from 98 to 117 g/kg dry matter. The effect of the different wheat cultivars on the measured parameters was most pronounced in chickens fed on diets with 815 g wheat/kg diet (P<0.001). However, significant (P<0.001) differences between cultivars were still present at the lower wheat content. 3. Milling-quality wheats resulted in better performance (P<0.001) than feeding-quality wheats at the high inclusion, whereas such an effect could not be registered in diets at the lower wheat inclusion. These results indicate that some of the feeding wheats are comparable in quality to milling wheats when included at the concentrations which are more common in practical broiler diets. 4. Decreasing the wheat content in the diets resulted in significantly (P<0.001) better performance and considerably (P<0.001) lower intestinal viscosity (jejunum; 2.4 to 5.9 cps, ileum; 4.6 to 10.9 cps) than in chickens fed on diets with the higher wheat inclusion level (jejunum; 9.1 to 38.4 cps, ileum; 20.8 to 82.0 cps). 5. Diets with 815 g wheat/kg influenced pH in the caeca, but not in the ileum and gizzard. The relative weights of the gizzard and ileum differed significantly (P<0.05) between treatments, whereas those of duodenum, jejunum and caeca were not affected by dietary addition of the different wheat cultivars. 6. The present study demonstrated that the chemical composition and the nutritive value of Danish wheats for broilers vary markedly. The results indicated that the non-starch polysaccharide and especially the arabinoxylan content of wheat are important factors in the discussion of the result obtained. Poor correlations were seen between performance and AMEn and care should be taken when using AMEn values alone to predict the nutritive value of wheat and wheat-based diets.

Effect of wheat content, fat source and enzyme supplementation on diet metabolisability and broiler performance

1. A 3x3x2 factorial experiment studied the interactions of fat source (tallow, soya, tallow:soya [2:1] blend), wheat level (700, 350, 0 g/kg) and enzyme inclusion (Avizyme 1300, absent, present) in diets for broilers fed ad libitum in individual cages from 7 to 35d. Bird performance, fat digestibility, viscosity of ileal contents and diet metabolisability (AME) were measured. 2. There were no significant effects of fat source on bird performance. However, there was a significant effect on fat digestibility, which was highest for soya and lowest for tallow. Diet AME content was also significantly affected by fat source and reflected differences in fat digestibility. 3. Dry matter (DM) intake, liveweight gain (LWG) and gain:food were all reduced at 700 g wheat/kg. Viscosity of ileal contents increased with increasing wheat inclusion. 4. There were no significant effects of enzyme on DM intake or LWG but gain:food was improved by 2%. Diet AME content was increased with enzyme addition, the effect being greatest (9%) with tallow at 700 g wheat/kg. 5. Viscosity of ileal contents was reduced and fat digestibility increased with enzyme addition and there were significant wheat enzyme interactions attributable to no differences with zero wheat but marked responses to enzyme at 700 g wheat/kg. 6. The results confirm important interactions between wheat content and fat composition in relation to fat digestibility, AME content and food efficiency.

The effects of adding xylanase, vitamin C and copper sulphate to wheat-based diets on broiler performance

1. The study used a 3 x 3 factorial design to evaluate the effects of 3 additives (none; vitamin C [250 mg/kg]; copper sulphate [250 mg/kg]) and 3 enzyme additions (none; Avizyme 1300 [Finnfeeds Ltd, 1 g/kg in food]; Avizyme 1310 [liquid spray, post-pelleting, 0.5 g/kg]). All experimental diets were mixed, heat-conditioned (80 degrees C for 2 min) and pelleted. Copper sulphate (diets NCu; DCu; LCu) and Avizyme 1300 (diets DN; DC; DCu) were added during mixing. Vitamin C was sprayed at 10 ml per kg (diets NC; DC; LC) and the liquid enzyme was diluted 20-fold and sprayed at the same rate (diets LN; LC; LCu), post-pelleting. 2. Additive or enzyme addition did not significantly affect DM intake or liveweight gain (LWG). Enzyme addition improved gain:food (P=0.014), AME:GE (P<0.001), ileal apparent digestibility of DM (P=0.008) and starch (P<0.001), faecal apparent digestibility of starch, crude fat and NDF (P=0.008; <0.001; <0.001 respectively) and reduced in vivo viscosity (P<0.001). 3. Copper sulphate addition depressed gain:food (P=0.047), AME:GE (P=0.002), ileal apparent digestibility of starch (P<0.001) and faecal apparent digestibility of starch (P=0.003) and crude fat (P<0.001) due to a negative additive x enzyme interaction when copper sulphate and dry enzyme were included together. 4. Vitamin C decreased in vivo viscosity by 20% but failed to have any effect on performance. Both enzyme forms gave similar improvements in performance in the absence of copper sulphate.

Studies on rye (Secale cereale L.) lines exhibiting a range of extract viscosities. 1. Composition, molecular weight distribution of water extracts, and biochemical characteristics of purified water-extractable arabinoxylan

Five rye lines exhibiting a wide range of extract viscosities, along with commercial cultivars of rye and wheat, were compared with respect to their physical and chemical properties. Rye wholemeals contained significantly higher concentrations of total and soluble dietary fiber (TDF and SDF, respectively), total and water-extractable arabinoxylan (TAX and WEAX, respectively), and beta-glucan than did wheat. Significant positive correlations were obtained between rye wholemeal extract viscosity and SDF content (r = 0.90, p < 0.05) and WEAX content (r = 0.89, p < 0.05). Gel permeation chromatography (GPC) of water extracts of rye wholemeals revealed the presence of a high molecular weight fraction (HMWF), which was found in higher concentration in the ryes than in wheat. A significant positive correlation (r = 0.84, p < 0.05) was observed between HMWF content (expressed as a proportion of the total carbohydrate in water extracts) and extract viscosity of rye wholemeals. Treatment of a rye wholemeal extract with xylanase, followed by GPC, indicated that the HMWF consisted primarily of WEAX. Successive treatment of a rye wholemeal extract with alpha-amylase, lichenase, protease, and xylanase confirmed that the viscosity of the extract was primarily related to its content of WEAX. WEAX was isolated from high, intermediate, and low extract viscosity ryes. Structural differences were observed among the three arabinoxylans using H NMR and high-pressure size exclusion chromatography with triple detection. The WEAX from high extract viscosity rye was a higher molecular weight macromolecule exhibiting a higher intrinsic viscosity, a larger radius of gyration, a larger hydrodynamic radius, and a lower degree of branching compared to WEAX from low and intermediate extract viscosity ryes.

Enzyme supplementation of dry and wet wheat-based feeds for broiler chickens: performance and gut responses

To test whether the improvements in digestive efficiency due to either wetting of the food or inclusion of enzymes are accompanied by the same changes in gut function, foods with a high content of wheat were fed to broiler chicks from 1-42 d old. Twenty-four birds were caged individually while a further sixty-four were in group pens in experiments of 2 x 2 factorial design with two levels of enzyme (0 or 1 g/kg, designed for wheat) and two levels of water addition (0 and 1300 g/kg). Food intake and live-weight gain were significantly increased by wet feeding (from 89.3 to 153.4 g/d and from 39.7 to 65.4 g/d respectively), the differences increasing with age, while the enzyme had no significant effect (120.5 and 122.2 g/d and 51.9 and 53.1g/week respectively). The viscosity of digesta was greatly reduced both by wetting (from 4.40 to 2.64 kPa. s) and enzyme (from 4.47 to 2.57 kPa. s) but there was a significant interaction with age in which the viscosity was low throughout in the wet only, enzyme only and wet + enzyme treatments but declined with age from a very high level in the dry, no enzyme treatment (11.5 kPa. s at 14 d). While wetting increased weight and length of digestive tract and thickness of some parts of the gut, enzyme had no significant effect, tending to reduce gut wall thickness. Crypt cell proliferation rate (CCPR) was significantly reduced by wet feeding (from 39.4 to 28.7 cells/crypt per 2 h) and by enzyme supplementation (from 38.9 to 29.2 cells/crypt per 2 h). Therefore, while both wetting and enzyme addition to the food reduced digesta viscosity and CCPR to a similar extent, the former had marked stimulatory effects on food intake and weight gain while the latter had little effect. The mode of action of wet feeding is therefore deduced to be not primarily through its effects on viscosity and CCPR.

Effect of diet form and enzyme supplementation on growth, efficiency and energy utilisation of wheat-based diets for broilers

1. The effect of diet form (mash, cold-pelleted, steam-conditioned/pelleted, wet mash, whole wheat with balancer pellet, restricted pellet) and enzyme inclusion (Avizyme 1300, absent, present) was studied in 2 trials using individually caged, male broilers from 14 to 42 d. Bird performance, viscosity of ileal contents and diet metabolisability (AME) were measured. 2. The performance of mash-fed birds was significantly poorer than for the other treatments in relation to dry matter intake, liveweight gain and gain:food. This was not due to reduced diet AME content. 3. There was no significant effect of heat treatment on any of the variables measured, although viscosity of ileal contents was increased by 30% as compared to the cold-pelleted diet. 4. Gain:food was improved with wet-mash feeding in comparison to the dry mash treatment but it was concluded that this was not due to any intrinsic improvement in diet quality, but rather to voluntary food restriction on introduction of the wet food. 5. Whole wheat feeding improved gain:food and diet AME content by 3% as compared to the complete diets and caused approximately a 50% increase in gizzard weight as compared with the pelleted diets. 6. Food enzyme inclusion did not improve performance although a significant improvement in diet AME content was observed with enzyme inclusion in trial 1.

Effects of age and diet on the viscosity of intestinal contents in broiler chicks

1. A standard methodology was developed for the determination of the viscosity of digesta in broiler chickens. 2. The best variables considered for use (those which gave the most consistent results) were: digesta obtained from the foregut area (defined as the region from the pancreas to Meckel's diverticulum) using a minimum of 6 replicates and offering experimental diets for 5 d before slaughter at 25 d of age. 3. There was evidence that the viscosity of digesta obtained from the hindgut (defined as the region between Meckel's diverticulum and the ileo-caecal junction) was reduced the longer the birds were fed on one diet, suggesting possible dietary acclimatisation. Hindgut digesta viscosity from birds fed on a barley-based diet over a longer period was 10% to 30% less than that of birds fed for 5 d. 4. There was an apparent reduction in viscosity with age of bird up to 45 d of age, with hindgut digesta viscosity from birds fed on barley-based diets falling from 20.6 cps at 25 d to 9.8 cps at 45 d. 5. In an assessment of the procedure developed, the following digesta viscosities were obtained at 25 d: 3.1 cps (wheat-based diet, foregut), 19.8 cps (barley-based diet, foregut), 5.7 cps (wheat-based diet, hindgut), 22.8 cps (barley-based diet, hindgut).

Effects of an enzyme feed additive on extent of digestion and milk production of lactating dairy cows

A study was conducted using lactating Holstein cows with ruminal and duodenal cannulas in a 4 x 4 Latin square design to investigate fibrolytic enzyme supplementation on site and extent of nutrient digestion. The four diets consisted of 45% concentrate, 10% barley silage, and 45% cubed alfalfa hay (dry matter basis) and differed in enzyme supplementation: 1) control cubes, 2) cubes treated with 1 g of enzyme mixture/kg of cubes, 3) cubes treated with 2 g of enzyme mixture/kg of cubes, and 4) both concentrate and cubes treated with 1 g of enzyme mixture/kg of dry matter. The enzyme supplement contained primarily cellulase and xylanase activities. Digestion of organic matter and neutral detergent fiber in the total tract was higher for cows fed the high dosage of enzyme than for cows fed the control cubes. Ruminal digestibility of crude protein was higher, but that of organic matter and neutral detergent fiber was only numerically higher, for cows fed the high dosage of enzyme compared with that of cows fed the control cubes. Higher ruminal digestibility associated with the high dosage of enzyme resulted in more microbial protein synthesis. Milk production increased for cows fed the high dosage of enzyme compared with cows fed the control cubes and effects of the addition of enzyme on milk composition were minimal. The results demonstrated the benefits of using a fibrolytic enzyme additive to enhance feed digestion and milk production by dairy cows. The response to enzyme supplementation was affected more by amount of enzyme than by whether the enzyme was added to forage or concentrate.

Effects of grain source and enzyme additive on site and extent of nutrient digestion in dairy cows

Four lactating, cannulated Holstein cows were used in a 4 x 4 Latin square design to investigate the effects of grain source and fibrolytic enzyme supplementation on ruminal fermentation, nutrient digestion in the rumen and in the intestine, and milk production. A 2 x 2 factorial arrangement was used; two grains (barley and hull-less barley) were combined with and without enzyme. The enzyme supplement (Pro-Mote; Biovance Technologies Inc., Omaha, NE) contained primarily cellulase and xylanase activities and was applied daily to the total mixed diet. Dry matter intake was not affected by diet, but starch intake was greatest when hull-less barley was fed. Starch from hull-less barley was more digestible in the rumen and in the total tract than was starch from barley, but opposite results occurred for fiber digestion, indicating that hull-less barley depressed fiber digestion. As a result, cows fed the hull-less barley diets tended to produce more milk with a higher milk lactose content than did cows fed the barley diets. Enzyme supplementation had minimal effects on ruminal digestion but increased nutrient digestibility in the total tract and the proportion of microbial N in nonammonia N. Consequently, cows fed diets supplemented with enzyme had a higher milk protein content and tended to produce more 4% fat-corrected milk than did control cows. These results indicate that the use of hull-less barley rather than barley increased the digestible energy intake of dairy cows, resulting in higher milk production. The use of a fibrolytic enzyme mixture enhanced feed digestibility and milk production.

Effects on chick performance and nutrient digestibility of an endo-xylanase added to a wheat- and rye-based diet in relation to fat source

1. A study with growing chicks investigated the effects of an inclusion of an endo-xylanase preparation (LYXASAN) to a wheat- and rye-based diet on performance and nutrient digestibility in relation to the fat source. 2. The basal diet contained 500 g wheat and 100 g rye/kg of diet. The basal diet was supplemented with either 65 g soya oil/kg or 60 g blended animal fat and 5 g soya oil/kg. 3. Endo-xylanase added to the soya oil diet did not affect weight gain, but there was a numerical improvement in food conversion efficiency which was not statistically significant. When the endo-xylanase preparation was added to the blended animal fat diet, both weight gain and food utilisation were improved by 9.5% and 6.0%, respectively (P < 0.05). 4. Digestibilities of organic matter, crude fat, crude fibre and NFE were not significantly affected by adding endo-xylanase to the soya oil diet. However, when endo-xylanase was included in the blended animal fat diet, digestibility of organic matter, crude fat, crude fibre and NFE were improved (P < 0.05). The improvement in fat digestibility was the most pronounced, amounting to 9.4%. Nitrogen retention and metabolisable energy content were improved significantly by the addition of an endo-xylanase to the animal fat diet (P < 0.05), by 6.6% and 6.5% respectively. 5. From the results of this study, it can be concluded that the effects on chick performance and nutrient digestibility of a dietary endo-xylanase in a wheat- and rye-based diet are influenced to a considerable degree by the type of fat in the diet.

An investigation into the variability of extract viscosity of wheat-relationship with the content of non-starch-polysaccharide fractions and metabolisable energy for broiler chickens

The in vitro extract-viscosity and the content of non-starch-polysaccharides were investigated in 34 defined wheat varieties grown at 5 locations each. Both, wheat genotype as well as growing location clearly influenced the viscosity of soluble extract from wheat. Furthermore, the content of non-starch-polysaccharides (soluble/total) and pentosans (soluble/total) were determined in 13 wheat varieties each grown at two locations. Soluble pentosan contents were highly positively correlated with extract viscosity of wheat at the locations Hayn (r = 0.86) and Biendorf (r = 0.90). The classical apparent metabolisable energy of 5 wheat samples having different extract viscosities was assessed. The AMEN values ranged from 14.0 to 14.6 MJ/kg DM and were significant negatively correlated to content of soluble arabinoxylans (r = 0.67) and to the extract viscosity (r = 0.83). Furthermore, the viscosity of jejunal (4.0 to 22.8 mPas) and ileal (13.1 to 78.0 mPas) digesta exhibited a clear relationship with soluble pentosan contents and extract viscosity. Under the conditions applied in this study the technique of extract viscosity measurement can predict the AME.

Nutritional implications of pectins in chicks in relation to esterification and origin of pectins

An experiment was conducted to examine the effect of feeding high-methylated (HM) and low-methylated (LM) pectin on performance and physiological characteristics in broiler chicks. Two levels each (1.5 and 3%) of HM citrus pectin (HMC), LM citrus pectin (LMC), or HM sugar beet pectin (HMS) were added to a semi-purified basal diet. The experiment was conducted in battery brooders, and chicks received the diets as pellets from 6 to 27 d of age. The inclusion of LMC or HMS in the diet had little or no effect on the performance of chicks; however, when HMC was added to the diet growth and feed utilization were reduced significantly (P < 0.05). Water intake and water:feed ratio were increased (P < 0.05) after inclusion of all three pectin products in the diet. The effect on water consumption was more pronounced in the HMC-containing diets than in the LMC or HMS diets, and was dose-dependent. In vitro viscosity was increased significantly by incorporating HMC or LMC into the diet, whereas HMS had no effect on this parameter. Waterholding capacity of the diets and the excreta were increased significantly by including one (P < 0.05) of the three pectin products in the diet. The concentration of some of volatile fatty acids (VFA) in the cecal chyme was markedly decreased (P < 0.05) by feeding HMC, whereas LMC had no effect (P > 0.05) on the concentration of VFA. In contrast, inclusion of HMS in the diet significantly increased the concentration of VFA in the cecal content (P < 0.05) dose-dependently. Based on the results of the present study, it can be concluded that the effect of dietary pectin on chick performance is dependent on the degree of carboxyl groups that is esterified, the origin of the pectin product, and the amount added to the diet.

Increased small intestinal fermentation is partly responsible for the anti-nutritive activity of non-starch polysaccharides in chickens

1. The mechanism of the anti-nutritive activities of soluble non-starch polysaccharides (NSPs) in broiler diets was investigated with emphasis on the inter-relationship between viscosity and fermentation along the gut. Isolated soluble NSP were added to a control diet to effect high gut viscosity, and in vivo depolymerisation of the NSP was achieved using a commercial glycanase. 2. Addition of soluble NSPs significantly (P < 0.01) increased gut viscosity, reduced the AME of the diet and depressed the growth and FCE of the birds. Enzyme supplementation of the NSP-enriched diet reversed the adverse effects, increasing (P < 0.01) weight gain, FCE and AME. Comparisons of the viscosities (mPa) in birds fed on the NSP-enriched diet and the same diet supplemented with enzyme were respectively: 11.9 v. 2.3 in the duodenum; 78.3 v. 4.4 in the jejunum and 409.3 v. 10.8 in the ileum. 3. Caecal volatile fatty acid concentration was markedly (P < 0.01) elevated by enzyme supplementation, whereas ileal fermentation was inhibited. 4. Microscopic examination revealed that, among birds fed on the NSP-enriched diet, there had been extensive small intestinal fermentation, which was eliminated by the enzyme supplementation. 5. Addition of a synthetic antibiotic (Amoxil) had no beneficial effects. 6. The current study demonstrated that increased fermentation occurs in the small intestine when a large amount of viscous NSPs is present in the diet and this is detrimental to the performance and well-being of poultry.

Effect of dietary fat, fiber, and monensin on cecal activity in turkeys

Two experiments were conducted to determine the physical, chemical, and microbial properties of turkey cecal droppings and relate them to intake of common dietary components, namely fat, fiber, and the anticoccidial, monensin. Experiment 1 involved collection and analysis of physical and chemical properties of cecal and regular droppings from commercial turkey flocks. Experiment 2 tested the effect of dietary fat, fiber, and monensin on growth performance and cecal activity in male turkeys. Compared to regular excreta, cecal droppings analyzed in Experiment 1 were higher in viscosity and fat content, and lower in dry matter, nitrogen, and fiber content (P < 0.05). High dietary fiber and fat significantly (P < 0.05) improved growth performance in Experiment 2. Prolonged feeding of monensin significantly (P < 0.05) reduced cecal evacuation. Results of chemical composition showed that higher dietary fat and fiber significantly (P < 0.01) reduced the fat percentage of cecal contents, whereas prolonged feeding of monensin increased the fat in both cecal contents and droppings. There was no significant effect of any of the treatments on pH, viscosity, and microbial counts of cecal contents. There is the need to identify and characterize the compound responsible for the high viscosity of cecal droppings.

The influence of dietary fibre source and level on the development of the gastrointestinal tract, digestibility and energy metabolism in broiler chickens

The present study was undertaken to provide detailed information about the effect of fibre source (pea fibre, wheat bran or oat bran) at inclusion levels of 0, 187 and 375 g/kg diet on the development of the digestive tract, nutrient digestibility and energy and protein metabolism in broiler chickens. Heat production was measured using open-air-circuit respiration chambers. Diets with increasing levels of pea fibre decreased the DM in droppings and increased excreta output (2.5-fold) relative to DM intake. Adaptation to increased dietary fibre levels included increases in the size of the digestive system, with pea fibre exerting a stronger impact than wheat bran or oat bran. The length of the intestine, and particularly the length and weight of the caecum, increased with the fibre level. The digestibility of all nutrients also decreased with increasing fibre level. The decrease in the digestibility in relation to NSP for the three fibre sources was bigger for oat bran (0.0020 per g dietary NSP) than for pea fibre and wheat bran (0.0014 and 0.0016 per g dietary NSP) indicating that the cell walls in oat bran (aleurone and subaleurone) had a significant negative effect on the digestibility of cellular nutrients, i.e. protein and fat. The degradation of the NSP constituents was far lower in chickens than found in other animal species such as pigs and rats, thus supporting the view that chickens do not ferment fibre polymers to a great extent. Excretion of organic acids (mainly lactic acid and acetic acid) accounted for up to 2% of metabolizable energy (ME) intake with the highest excretion for the high-fibre diets. H2 excretion was related to the amount of NSP degraded and indicated higher microbial fermentation with increasing fibre levels. The chickens' feed intake responded to a great extent to dietary ME concentration but expressed in terms of metabolic body size (W0.75) ME intake was depressed at the high fibre levels. Dietary NSP was able to explain between 86% (oat bran) and 96% (pea fibre) of the variation in ME concentration. The amount of energy available from fermentation of NSP appears to reach a maximum of 42 kJ/d independent of fibre source and level. Expressed in relation to ME intake the NSP fermentation contributed 3-4%. With increasing fibre intake the partitioning of retained energy between body protein and body fat changed in favour of protein.

Effects of pelleting, lactose level, polyethylene glycol 4000, and guar gum compared to pectin on growth performances, energy values, and losses of lactose, lactic acid, and water in chickens

Five mash and two pelleted diets were tested in broiler chickens (7 to 19 d). Mash diets consisted of a basal fraction diluted with either .5% pectin or .5% guar gum. Mash pectin and guar gum diets contained either 3% lactose (PL3m and GL3m diets, respectively) or 6% lactose (PL6m and GL6m diets, respectively). Compositions of pelleted diets (PL3p and GL3p) were those of PL3m and GL3m diets, respectively. All diets contained .5% polyethylene glycol 4000 (PEG) except the PL3m0 diet. The latter diet differed from PL3m diet by the PEG content, only. The real applied viscosities of pectin and guar gum diets were 1.48 and 4.94 mL/g, respectively, No effect of PEG was detected on growth performances, and excreta losses of lactose, lactic acid, and water. No negative effect of guar gum compared to pectin was observed on body weight (19 d), except with pelleted diets (P < .05). Feed:gain ratios for guar gum diets were 7% higher (P < or = .001) that those of pectin diets. The AMEn values of guar gum diets were 4% lower (P < or = .001) than those of pectin diets. For mash diets, lactose digestibilities were lower (P < .05) with guar gum than with pectin. Increasing lactose level from 3 to 6% did not affect (P > .05) AMEn values, feed: gain ratios, and body weights (19 d) but reduced (P > .001) lactose digestibilities from 78 to 64%. The positive effects of pelleting on body weights (19 d) were much less pronounced with guar gum than with pectin (P < .05). The AMEn values of pelleted diets (PL3p) and GL3p) were, on average, 2.5% lower (P = .005) than their mash counterparts (PL3m and GL3m). Water losses related to feed intake were greater with guar gum than with pectin (P < .001) and with 6% lactose than with 3% (P = .001) but were not affected (P > .05) by pelleting. Lactic acid losses related to feed intake were increased by guar gum compared with pectin (P < .001), with more pronounced effects induced by high lactose level (P < .05) and pelleting (P < .05). In many respects, the effects of guar gum seemed similar to those observed in an acid liquid diarrhea.

Xylanase in broiler diets with differences in characteristics and content of wheat

1. Experiments were conducted to measure the effect of xylanase supplementation on the performance of broilers fed on wheat-based diets containing high and low extract viscosity wheat (experiment 1), baking and feeding quality wheat (experiment 2) and with variation in wheat content (experiment 3). 2. Xylanase supplementation improved food conversion ratios by 2.2-2.9% and body weight gain by 0.2-2.5%. This was independent of wheat characteristics but slightly dependent on the wheat content of the diet. These effects were related to a lowering of digesta viscosity. 3. Differences in extract viscosity of wheat were not reflected in broiler digesta viscosity. 4. Reduction of digesta viscosity resulted in only a slight improvement of litter score. Reduced intestinal viscosity decreased relative pancreas weight and to a lesser extent relative small intestinal weight. 5. Baking quality wheat Baldus gave better performance than the feed quality wheats Apollo and Slejpner. 6. It was concluded that xylanase supplementation of wheat-based diets invariably had a positive effect on broiler performance.