Influence of method of whole wheat inclusion and xylanase supplementation on the performance, apparent metabolisable energy, digestive tract measurements and gut morphology of broilers

1. The aim of the present study was to examine the influence of whole wheat inclusion and xylanase supplementation on the performance, apparent metabolisable energy (AME), digesta viscosity, and digestive tract measurements of broilers fed on wheat-based diets. The influence of the method of whole wheat inclusion (pre- or post-pelleting) was also compared. A 3 x 2 factorial arrangement of treatments was used with three diet forms (648 g/kg ground wheat [GW], GW replaced by 200 g/kg of whole wheat before [WW1] or after cold-pelleting [WW2]) and two xylanase levels (0 and 1000 XU/kg diet). 2. Birds given diets containing whole wheat had improved weight gains, feed efficiency and AME compared to those fed on diets containing ground wheat. The relative gizzard weight of birds fed WW2 diets was higher than in those fed GW and WW1 diets. Pre-pelleting inclusion of whole wheat had no effect on relative gizzard weight. Post-pelleting inclusion of whole wheat resulted in greater improvements in feed efficiency and AME than the pre-pelleting treatment. 3. Xylanase supplementation significantly improved weight gain, feed efficiency and AME, irrespective of the wheat form used. Viscosity of the digesta in the duodenum, jejunum and ileum were reduced by xylanase addition. Xylanase supplementation reduced the relative weight of the pancreas. 4. Neither xylanase supplementation nor whole wheat inclusion influenced the relative weight and length of the small intestine. 5. Xylanase supplementation increased ileal villus height. A significant interaction between diet form and xylanase was observed for ileal crypt depth. Xylanase supplementation had no effect on crypt depth in birds fed on diets containing GW, but increased the crypt depth in WW2 diets. No significant effects of diet form and xylanase supplementation were observed for the thickness of the tunica muscularis layer of gizzard or villus height, crypt depth, goblet cell numbers or epithelial thickness in the ileum. 6. Improved performance observed with post-pelleting inclusion of whole wheat was associated with increased size of the gizzard and improved AME. The gizzard development hypothesis, however, will not explain the improvements observed with pre-pelleting inclusion of whole wheat, suggesting the involvement of other factors.     

Effects of a xylanase on individual bird variation, starch digestion throughout the intestine, and ileal and caecal volatile fatty acid production in chickens fed wheat.

1. The effects of a xylanase on digesta viscosity and starch digestibility throughout the small intestine and volatile fatty acid production in the ileum and caeca were investigated in broilers fed on a low-metabolisable energy wheat diet. 2. The xylanase reduced (P<0.01) duodenal (2.9 vs. 1.7), jejunal (4.6 vs. 2.3) and ileal (14.0 vs. 3.9) digesta viscosities (mPas) and increased AME (P<0.01) of the wheat and starch digestibility (P<0.5) in the jejunum and ileum. Between-bird variability in ME and digestibility of starch was also reduced. 3. Enzyme supplementation reduced (P<0.05) fermentation in the ileum, but increased (P<0.05) it in the caeca. 4. The anti-nutritive effect of soluble non-starch polysaccharides (NSP) is related to their ability to increase digesta viscosity along the gut; this in turn causes changes in gut microflora and efficiency of nutrient utilisation by the chicken. Use of appropriate enzymes is an effective way of dealing with grains with high NSP content in poultry diets.     

Effect of food enzymes on utilisation of lupin carbohydrates by broilers

1. The effects of 3 commercial enzyme products on the nutritive value of 2 lupin species were investigated with the emphasis on changes in composition of non-starch polysaccharides (NSPs) along the digestive tract. Enzyme A contained primarily cellulase, beta-glucanase and xylanase activities, enzyme B primarily hemicellulase, pentosanase and xylanase activities, and enzyme C primarily hemicellulase, pectinase and beta-glucanase activities. 2. The enzymes were added to semi-purified diets based on sorghum and casein containing 35% whole seed lupins (Lupinus angustifolius cv Gungurru or Lupinus albus cv Kiev mutant). Control diets contained no lupins. 3. Food conversion ratio (FCR), excreta moisture content and apparent metabolisable energy (AME) were affected by lupin species but not by enzyme supplementation. 4. In diets with L. angustifolius, enzyme C significantly increased digesta viscosity and increased the concentration of soluble NSPs in all sections of the intestine. 5. Digestibility of protein and NSPs in the ileum and microbial fermentation in the ileum and caeca were not affected by adding enzymes to diets containing L. angustifolius. 6. Enzyme addition to diets with L. albus did not affect digesta viscosity nor concentration of soluble NSPs but caused a significantly (P<0.05) reduced concentration of insoluble NSP in the ileum. 7. Enzyme addition to L. albus significantly (P<0.05) increased NSP digestibility in the ileum but had no effects on protein digestibility and fermentation in the ileum and caeca.     

The effect of pectin on amino acid digestibility and digesta viscosity, motility and morphology of the small intestine, and on N-balance and performance of young pigs

Two experiments were carried out using a balanced feed mixture composed of wheat, corn, soyabean meals, casein, and crystalline amino acids (AA) and supplemented with 0, 4, or 8% of apple pectin. The daily dietary allowance provided pigs with the same level of nutrients, apart from the pectin. One experiment was conducted on pigs (within 25 to 40 kg BW) with the post valve T-caecum (PVTC) cannula to determine AA digestibility and ileal digesta viscosity. In the second experiment, the N-balance was measured twice on male pigs at about 20 and 28 kg BW using 6 animals per diet and feed intake and body weight were measured twice during the 28 d. After 40 d of feeding the diets, the pigs were sacrificed and the small intestines were weighed and sampled. The added pectin decreased standardized ileal AA digestibility (on average up to 5% dig. units) and increased digesta viscosity from about 1 to 88 mPa s. The higher pectin level did not affect motility of the duodenum and mid-jejunum, measured as responses to electrical field stimulation and to acetylcholine. However, the response of the duodenum to electrical field stimulation was after feeding the diet with 4% pectin increased compared with other diets. Pectin supplementation did not alter the weight and the length of the small intestine, but induced changes in the intestinal morphology. Muscle layer width increased significantly in the duodenum, the mid-jejunum, and the ileum while villi length increased in the duodenum and ileum. The addition of pectin decreased N retention and increased the F/G ratio but did not affect significantly the ADG of the pigs.     

Influence of particle size and xylanase supplementation on the performance, energy utilisation, digestive tract parameters and digesta viscosity of broiler starters

1. The aim of the present experiment was to examine the influence of particle size and xylanase supplementation on the performance, energy utilisation, and gross morphological and histological parameters of the digestive tract of broiler starters fed wheat-based diets. The experimental design was a 2 x 2 factorial arrangement of treatments evaluating two wheat particle sizes (medium and coarse) and two levels of xylanase supplementation (without or with 1000 xylanase units/kg diet). The two particle sizes were achieved by grinding the whole wheat in a hammer mill to pass through 3 and 7 mm screens, respectively. Broiler starter diets, based on wheat and soybean meal, were formulated and each diet was fed ad libitum to 6 pens of 8 male broilers each from d 1 to 21 post-hatch. 2. Wheat particle size had no effect on the performance of broilers. Xylanase supplementation had no effect on weight gain and feed intake. However, a significant particle size x xylanase interaction was observed for feed per unit gain with xylanase lowering feed per gain only in the coarse particle size diet. Xylanase supplementation improved the nitrogen-corrected apparent metabolisable energy at both particle sizes. 3. Xylanase supplementation decreased the relative weight and relative length of all gut components. Villus height and crypt depth and total extent of the mucosal layer were unaffected by both wheat particle size and xylanase supplementation. 4. The apparent viscosity of intestinal digesta, determined over the physiological range of shear rates, was not influenced by xylanase addition or particle size. 5. The findings of this study suggest that the effectiveness of exogenous xylanase in broiler diets is influenced by wheat particle size.     

Effects of microbial phytase, produced by solid-state fermentation, on the performance and nutrient utilisation of broilers fed maize- and wheat-based diets

1. The influence of a microbial phytase on the performance, toe ash contents and nutrient utilisation of male broilers fed diets based on maize and wheat was investigated. The experiment was conducted as 2 x 2 x 2 factorial arrangement of treatments. Within the factorial, two diet types (maize-soy or wheat-soy) containing two levels of non-phytate phosphorus (3.0 or 4.5 g/kg) were evaluated and each level of non-phytate phosphorus was supplemented with 0 or 500 PU phytase/kg diet. Each of the 8 dietary treatments were fed to 6 pens of 8 birds from d 1 to 21 post-hatching. 2. Main effects of diet type and phytase were observed for all parameters. Main effect of non-phytate phosphorus was significant only for feed/gain and toe ash contents. Phytase addition improved weight gains irrespective of diet type or non-phytate phosphorus level, but the magnitude of improvement in the phosphorus-deficient wheat-soy diet was greater, resulting in a diet type x non-phytate phosphorus interaction. Responses in toe ash contents were noted only in phosphorus-deficient diets, as indicated by a non-phytate phosphorus x phytase interaction. 3. Phytase addition improved apparent metabolisable energy values of wheat-based diets, but had little effect on the apparent metabolisable energy of maize-based diets as shown by a diet type x phytase interaction. The apparent metabolisable energy was not influenced by dietary non-phytate P. 4. Phytase improved ileal nitrogen digestibility in both diet types, but the responses to added phytase tended to be higher in wheat-based diets, as shown by a diet type x phytase interaction. 5. Increasing the dietary non-phytate phosphorus level reduced phosphorus digestibility and increased excreta phosphorus content. Addition of phytase improved phosphorus digestibility, but the increments were higher in low phosphorus diets resulting in a non-phytate phosphorus x phytase interaction. Phytase addition tended to lower the excreta phosphorus content, but the effects were greater in birds fed low phosphorus diets, as shown by a non-phytate phosphorus x phytase interaction.     

Apparent precaecal digestibility of nutrients and level of endogenous nitrogen in digesta of the small intestine of growing pigs as affected by various digesta viscosities.

Sixteen male growing pigs of about 24 kg BW were fitted with both a duodenal re-entrant and a post-valve T-shaped cannula inserted in the caecum. The animals were divided into four groups. Each group received one of the following diets: corn starch-soybean protein isolate-based diet without (diet C) and with carboxymethylcellulose (diet CMC) or a rye-wheat-based diet without (diet RW) and with xylanase addition (diet RWX). The diets provided similar levels of apparent precaecal digestible crude protein (CP), lysine, methionine + cystine, threonine and tryptophan. Additionally, [15N]-yeast was given with the diets during the first 10 days of the experiment. For estimation of digesta viscosity, N-flow of dietary and endogenous origin, apparent precaecal digestibilities of dry matter (DM), CP, amino acids and non starch polysaccharides (NSP) (only in pigs fed diets RW and RWX), ileal and duodenal digesta were quantitatively collected on day 16 and 17, respectively. The endogenous N-proportion was measured by the ratio of 15N enrichment in the digesta and urine. The duodenal and ileal digesta supernatant viscosity increased as carboxymethylcellulose was included into the diet. Xylanase addition to the rye-wheat based diet reduced the viscosity in the ileal digesta. There were no differences in precaecal digestibilities of DM, CP and amino acids between diet C and CMC. The precaecal digestibilities of DM and soluble and insoluble NSP increased from 69.5% to 73.9%, from 1.3% to 47.9% and from 17.0% to 35.4%, respectively, as xylanase was added to the rye-wheat-based diet. The apparent precaecal digestibility of most essential amino acids increased by 2 to 5 percent units. The amounts of endogenous N at the duodenal level were estimated to be 158, 233, 313 and 276 mg per 12 h per kg0.75 BW of pigs fed diets C, CMC, RW and RWX, respectively. The corresponding values at the ileal level were 95, 107, 164 and 150 mg per 12 h per kg0.75 BW. For endogenous N amounts, significant differences were observed between diets C and CMC (duodenum) and also between semi-purified and cereal-based diets (duodenum and ileum). Methodological aspects for the estimation of endogenous N using the isotope dilution technique are discussed. Obviously, the digesta viscosity per se does not affect the nutrient absorption and endogenous N flow within the small intestine of pigs. Other properties of complex dietary fibre, digesta passage rate or bacterial activity probably contribute to the observed changes.     

Histomorphology and small intestinal sodium-dependent glucose transporter 1 gene expression in piglets fed phytic acid and phytase-supplemented diets

An experiment was conducted to determine the effect of dietary phytic acid (PA) and phytase supplementation on small intestinal histomorphology and Na-dependent glucose transporter 1 (SGLT1) gene expression in piglets. Twenty-four piglets with an average initial BW of 7.60 ± 0.73 kg were randomly assigned to 3 experimental diets, to give 8 piglets per diet. The diets were a casein-cornstarch-based diet that was supplemented with 0 or 2% PA, or 2% PA (as Na phytate) plus an Escherichia coli-derived phytase at 500 phytase units/kg. The basal diet was formulated to meet the 1998 NRC energy, digestible AA, mineral, and vitamin requirements for piglets. After 10 d of feeding, the piglets were killed to determine small intestinal histomorphology and small intestinal SGLT1 gene expression. Phytic acid supplementation did not affect (P > 0.1) villus height (VH) and the VH-to-crypt depth (CD) ratio, but did decrease (P < 0.05) CD in the jejunum. Phytase supplementation did not affect (P > 0.1) VH, CD, and the VH-to-CD ratio. Phytic acid supplementation reduced SGLT1 gene expression in the duodenum, jejunum, and ileum by 1.1-, 5.4-, and 2.4-fold, respectively. Phytase supplementation increased SGLT1 gene expression in the jejunum by 2.6-fold, but reduced SGLT1 gene expression in the duodenum and ileum by 2.0- and 4.0-fold, respectively. In conclusion, PA reduced CD in the jejunum and SGLT1 gene expression in the duodenum, jejunum, and ileum, whereas phytase supplementation increased the expression of SGLT1 in the jejunum. The reduced SGLT1 gene expression by PA implies that PA reduces nutrient utilization in pigs partly through reduced expression of SGLT1, which is involved in glucose and Na absorption. The increased expression of SGLT1 in the jejunum by phytase supplementation implies that phytase alleviated the negative effects of PA partly through increased expression of SGLT1.     

Genetic Parameters for Average Daily Gain,Area of M. Longissimus Dorsi,Feed Efficiency and Feed Intake Capacity in Young Bulls of Dairy Populations

Abstract

Effects of phytase and xylanase supplementation to a wheat-based pig diet were studied. The diet was fed without or with supplementation of dicalcium phosphate (diet A), phytase (diet BP), xylanase (diet BX) and phytase + xylanase (diet BPX). Apparent digestibility of P and Ca were higher in diets BP and BPX. Apparent digestibility of crude protein (CP) was higher in pigs which were fed the BPX diet than pigs which were fed the BP and BX diets. Pigs given diet BPX, had highest daily weight gain and had higher daily feed consumption, except for pigs given diet BP. In conclusion, phytase improved the utilisation of P and Ca, while xylanase alone had no positive effects on OM, CP and NDF digestibility. The combination of the two enzymes had some benefits in terms of CP digestibility and resulted in an improved feed intake and daily weight gain, while feed conversion ratio was unaffected.     

小麦日粮中木聚糖酶和植酸酶对肉仔鸡生长和养分消化率的影响

432只艾维因肉仔鸡用于研究小麦基础日粮中添加木聚糖酶(320FXU/kg)或添加750U/kg植酸酶降低日粮中0.08％的非植酸磷后,对生长性能、日粮表观代谢能、粗蛋白和植酸磷表观消化率的影响。试验结果表明:无论是单一添加木聚糖酶或植酸酶,还是同时添加这两种酶,都能提高1-6周龄肉仔鸡的增重和饲料转化率,降低死亡率。添加木聚糖酶可提高肉仔鸡小麦日粮的表观代谢能2.14％,增加氮的存留量2.58％。750U/kg的植酸酶完全可以降低肉仔鸡小麦日粮中0.08％非植酸磷。添加植酸酶的处理组可提高植酸磷的表观消化率43.25％,减少植酸磷排泄量55.0％。植酸酶和木聚糖酶对全期饲料转化率和植酸磷的表观消化率表现有明显的正互作效应(P<0.05)。     

Hydrolysis of phytic acid by intrinsic plant and supplemented microbial phytase (Aspergillus niger) in the stomach and small intestine of minipigs fitted with re-entrant cannulas. 3. Hydrolysis of phytic acid (IP6) and occurrence of hydrolysis products (IP5, IP4, IP3 and IP2)

Hydrolysis of phytate in the stomach and the small intestine as influenced by intrinsic plant (wheat) and supplemented microbial phytase (Aspergillus niger) were investigated with six minipigs (40-50 kg initial body weight) fitted with re-entrant cannulas in the duodenum, 30 cm posterior to the pylorus (animals 1, 4, 5 and 6) and ileocecal re-entrant cannulas, 5 cm prior the ileocecal junction (animals 1, 2 and 3), respectively. Dietary treatments were as follows: (1) diet 1, a corn-based diet [43 U phytase/kg dry matter (DM)]; (2) diet 2, diet 1 supplemented with microbial phytase (818 U/kg DM); and (3) diet 3, a wheat-based diet (1192 U/kg DM). At 07 30 h and 19 30 h, each animal was fed 350 g diet mixed with 1050 ml de-ionized water. Digesta were collected continuously and completely during a 12-h period after feeding. Mean hydrolysis rates of IP6 in the stomach as measured at the proximal duodenum of animals 1, 4, 5 and 6 were 9.0, 77.2 and 66.2% for diet 1, 2 and 3, respectively. Microbial phytase was much more effective in phytate hydrolysis than wheat phytase. Mean IP6 hydrolysis rates of the respective diets in the stomach and small intestine as measured at the distal ileum of animals 1, 2 and 3 were 19.0, 62.6 and 64.6% and were lower than treatment means of the stomach only. Differences existed between experimental animals with respect to their ability to hydrolyse IP6 in the stomach independent of the presence and source of dietary phytase. Considerable amounts of hydrolysis products occurred in both the duodenal and ileal digesta when diets 2 and 3 were fed; however, only traces were determined after ingestion of diet 1. Independent of dietary treatment, four IP5 isomers were detected, but in different amounts.     

木聚糖酶在蛋鸡饲料中代谢能当量值的评定

试验通过蛋公鸡排空强饲法研究了2种木聚糖酶在5种能量饲料和6种产蛋鸡日粮中代谢能的当量值。结果表明:2种木聚糖酶都显著提高了蛋鸡对小麦和玉米小麦豆粕、玉米小麦豆粕棉粕、玉米小麦豆粕菜粕型日粮的代谢能(AME和TME)(P<0.05);酶A显著提高了小麦麸的代谢能(P<0.05);酶B对次粉、玉米豆粕、玉米豆粕棉粕型日粮的代谢能都有显著提高的趋势(P=0.089,P<0.05,P=0.070)。除酶A的代谢能当量值在小麦麸上为ME1.22 MJ/kg外,2种木聚糖酶的代谢能当量值在ME0.21-0.53MJ/kg之间。     

Effect of an organic acid blend and phytase added to a rapeseed cake‐containing diet on performance,intestinal morphology,caecal microflora activity and thyroid status of broiler chickens

The experiment was carried out on 96 female broilers, allocated to eight groups of 12 birds kept in individual cages. Two basal wheat‐ and soyabean meal‐based diets containing 150 g/kg of rapeseed expeller cake were formulated, differing in the level of P: 7.1 g/kg in diet H or 5.9 g/kg in diet L. Rapeseed cake supplied 3.15 μmol alkenyl glucosinolates per gram of diet. The eight treatments were: basal diets only, basal diets + phytase (1000 U/kg), basal diets + organic acid blend (OA, 6 g/kg), or basal diets + both additives. Diets were fed from day 8 to 28 of life. The results showed that the lower dietary P content and OA supplementation did not significantly affect feed intake or BWG, while both increased (p < 0.001) after phytase supplementation. Tibia ash content as well as tibia ultimate strength were lower (p < 0.001) in birds fed diets L compared with diets H, and increased (p < 0.01) with phytase supplementation of diet L, while OA had no influence on either parameter. Dietary P levels and OA supplementation had no influence on the pH of gut digesta, but the pH of jejunal digesta increased following phytase supplementation (p < 0.01). Morphological measurements of the small intestinal mucosa of chicks indicated that OA added to diet L depressed villi height (p < 0.001) and crypt depth (p < 0.001); both parameters increased after phytase supplementation (p < 0.01). The lower total SCFA as well as acetic, propionic and butyric acid concentrations in caecal digesta indicated lower activity of caecal microflora in birds fed diets L compared with H. OA supplementation had no influence, while phytase supplementation increased the concentration of acetic acid in caecal digesta. Supplementation of diets with either phytase or OA increased thyroid weight by 16% (p < 0.01) and 11% (p < 0.05) respectively. The increase in thyroid weight because of phytase supplementation was greater at the lower dietary P level, and the greatest when both phytase and OA were added to the diet.     

Optimum inclusion of field peas, faba beans, chick peas and sweet lupins in poultry diets. I. Chemical composition and layer experiments

1.Experiments were undertaken to determine the chemical composition and apparent metabolisable energy (AME) of field peas, faba beans, sweet lupins and chick peas and the production of hens when each was included in nutritionally similar diets at 250 g/kg in 2 experiments. 2. Amino acid composition, crude protein and AME agreed well with previously published measurements. Detailed analysis of the non-starch polysaccharides (NSPs) showed that sweet lupins were much higher than the other grain legumes in the soluble NSPs and that the NSPs were particularly high in arabinose. The condensed tannin content was highest in field peas followed by faba beans. 3. In the 1st layer experiment over 40 weeks, hen-day egg production was lowest on the faba bean-based diet and egg weight and egg mass were also lowest. Relative viscosity of digesta in the small intestine of hens fed on the sweet lupin-based diet was highest, followed by that of hens fed on field peas. Enlargement of the pancreas was observed in hens consuming chick peas. 4. In experiment 2, in which only sweet lupins and faba beans were used, steam or cold pelleting showed few effects, nor did dehulling of faba beans but egg weight was lower when diets were steam pelleted. Daily food intake was 5.7 g/bird lower on the steam than cold pelleted diets and food conversion ratio tended to be improved (P=0.082). 5. It was concluded that field peas could support good production at 250 g/kg of layer diet. Although chick peas and sweet lupins supported good performance, there was concern about the increased weight of the pancreas and high gut viscosity respectively. Faba beans showed similar hen-d egg production in the 2nd experiment to that of sweet lupins but egg weight tended to be about 0.8 g lower than when on the sweet lupin-based diets.     

Effects of dietary phytase on performance and nutrient metabolism in chickens

1. A broiler growth study was conducted to compare the effect of different concentrations of an Escherichia coli-derived phytase on performance, apparent metabolisable energy (AME), nitrogen (N), amino acid and mineral metabolisability, sialic acid excretion and villus morphology when fed to broiler chickens. 2. Female Ross 308 broilers (480) were reared in floor pens from 0 to 28 d of age. All birds were fed on nutritionally complete starter (0 to 21 d of age) and grower diets (21 to 28 d of age) with the exception that they were low in P (28 and 23 g/kg available P, respectively). These maize-soy diets were supplemented with 0, 250, 500 or 2500 phytase units (FTU)/kg feed. 3. Between 21 and 28 d of age, two birds from each floor pen were selected, and each pair placed in one of 32 metabolism cages (two birds per cage). Feed intake was recorded and excreta collected for the last 2 d of the feeding period, and AME, N, amino acid and mineral metabolisability coefficients and endogenous losses were determined following a total collection procedure. 4. Feed intake and weight gain increased in a linear manner in response to phytase dose, with an average increase of approximately 11.7 and 13.5%, respectively, compared with chickens fed on the low-P diet. Birds given diets with 2500 FTU weighed 6.6% more and had a 2.4% higher feed conversion efficiency (FCE) than those fed on diets containing 500 FTU. 5. Enzyme supplementation increased the intake of AME and metabolisable N by 10.3 and 3.9%, respectively, principally through increases in feed intake. Birds given enzyme-supplemented diets also improved their intake of metabolisable amino acids and P by approximately 14 and 12.4%, respectively, compared with birds fed on the control diet. Enzyme supplementation did not affect ileal villus morphometry of the birds.     

Response of broiler chickens to microbial phytase supplementation as influenced by dietary phytic acid and non-phytate phosphorous levels. II. Effects on apparent metabolisable energy, nutrient digestibility and nutrient retention

1. Male broilers (n=900) were fed on wheat-sorghum-soyabean meal based diets containing 3 concentrations of phytic acid (10.4, 13.2 and 15.7 g/kg; equivalent to 2.9, 3.7 and 4.4 g/kg phytate P), 2 concentrations of non-phytate (or available) phosphorus (2.3 and 4.5 g/kg) and 3 concentrations of microbial phytase (0, 400 and 800 FTU/kg) from day 7 to 25 post-hatch. The dietary concentrations of phytic acid were manipulated by the inclusion of rice pollards. All diets contained celite (20 g/kg) as a source of acid-insoluble ash. 2. The apparent metabolisable energy (AME) concentrations of the diets were determined using a classical total collection procedure during the 3rd week of the trial. On d 25, digesta from the terminal ileum were collected and analysed for phosphorus, nitrogen and amino acids. Nutrient digestibilities were calculated using acid-insoluble ash as the indigestible marker. 2. Ileal digestibilities of nitrogen and essential amino acids were negatively influenced by increasing dietary levels of phytic acid but these negative effects were overcome by the addition of phytase. 3. Supplemental phytase increased AME, ileal digestibilities of phosphorus, nitrogen and amino acids and the retention of dry matter, phosphorus and nitrogen in broilers. There were no differences in the phytase responses between additions of 400 and 800 FTU/kg. 4. The responses in all variables, except AME, were greater in low non-phytate phosphorus diets. 5. In the case of AME, the response to added phytase was greater in adequate non-phytate phosphorus diets. Supplemental phytase increased AME values from 13.36 to 13.54 MJ/kg dry matter in low non-phytate phosphorus diets and from 12.66 to 13.38 MJ/kg dry matter in adequate non-phytate phosphorus diets.     

The effects of xylanase supplementation on growth, digestion, circulating hormone and metabolite levels, immunity and gut microflora in cockerels fed on wheat-based diets

1. The xylanase product used in this study was derived from a genetically modified isolate of Aspergillus niger. Two trials were conducted to investigate the effects of xylanase supplementation on growth, digestion, circulating hormone and metabolite levels, immune parameters and composition of the gut microflora in cockerels fed on wheat-based diets. 2. The experimental diets consisted of a wheat-based control diet supplemented with 0 or 0.1% enzyme preparation. The diets were fed between 7 and 21 d of age. 3. Enzyme supplementation improved growth and feed conversion efficiency. The addition of enzyme to wheat-based diet increased the apparent total digestibility of dry matter (DM), crude protein and fat. 4. Enzyme supplementation reduced the relative weight of digestive organs to a certain extent, but there was no significant difference. Enzyme supplementation reduced digesta viscosity in the jejunum. There was no significant difference between the two experimental groups in counts of lactobacillus and coliform bacteria in the caeca. 5. Enzyme supplementation increased the concentration of blood thyroxine (T(4)), insulin-like growth factor I (IGF-I) and insulin, reduced the concentrations of blood uric acid, but had no significant effect on the concentrations of blood glucose and triiodothyronine (T(3)). 6. Enzyme supplementation increased the relative weight of spleen of cockerels, serum antibody titres to Newcastle disease virus (NDV), lymphocyte proliferation in response to phytohaemagglutinin (PHA) and the natural killer (NK) cell activity. 7. It is concluded that supplementation with an enzyme preparation (xylanase), which hydrolyses non-starch polysaccharides can improve growth in cockerels fed on wheat-based diets. This improvement is achieved through enzyme effects on digestion, absorption, metabolism and immunity of cockerels.     

Influence of partial replacement of ground wheat with whole wheat and exogenous enzyme supplementation on growth performance,nutrient digestibility and energy utilization in young broilers

This study investigated the influence of pre‐pelleting inclusion of whole wheat (WW) and exogenous enzyme supplementation on growth performance, coefficient of apparent ileal nutrient digestibility (CAID) and apparent metabolizable energy (AME) in broilers fed wheat‐based pelleted diets. A 2 × 3 factorial arrangement of treatments was used with two methods of wheat inclusion [622 g/kg ground wheat (GW) and 250 g/kg WW replaced GW (wt/wt) pre‐pelleting (PWW)] and three enzymes (xylanase, phytase and xylanase plus phytase). A total of 288, one‐day‐old male broilers (Ross 308) were individually weighed and allocated to 36 cages (8 broilers/cage), and the cages were randomly assigned to the six dietary treatments. Birds fed PWW diets gained more (p < 0.05) weight than those fed GW diets. There was no effect (p > 0.05) of WW inclusion on feed intake (FI). Phytase alone increased (p < 0.05) FI compared to xylanase or the combination. Whole wheat inclusion increased (p < 0.05) the gain‐to‐feed ratio (G:F). Feeding xylanase plus phytase and phytase‐added diets resulted in the greatest and lowest G:F, respectively, with xylanase supplemented diets being intermediate. Birds fed PWW diets had greater (p < 0.05) relative gizzard weights than those fed GW diets. There was no effect (p > 0.05) of WW inclusion on the CAID of nitrogen (N), starch and fat. Combination of xylanase and phytase resulted in greater (p < 0.05) digestibility of N, starch and fat than that of individual additions. Feeding PWW diets resulted in greater (p < 0.05) AME values than GW diets. Combination of xylanase and phytase increased (p < 0.05) the AME compared to the diets with individual additions of xylanase or phytase. The current results suggest that the influence of pre‐pelleting WW inclusion and exogenous enzymes on nutrient digestibility and broiler performance is not additive.     

Influence of inclusion level of barley in wheat-based diets and supplementation of carbohydrase on growth performance,nutrient utilisation and gut morphometry in broiler starters

ABSTRACT

1. The influence of barley inclusion level and supplementation of a multi-component non-starch polysaccharide degrading enzyme on performance and nutrient utilisation in broilers was investigated. Normal-starch hulled barley was evaluated with five levels of inclusion (0, 141, 283, 424 and 565 g/kg) in a wheat-based diet and two levels of enzyme supplementation (0 and 150 g/tonne of feed; a 5 × 2 factorial arrangement of 10 dietary treatments). All diets were equivalent in metabolisable energy and digestible amino acid contents. A total of 400, one-d old male broilers (five cages/treatment; eight birds/cage) were used in the experiment.

2. Regardless of enzyme supplementation, weight gain (WG) increased up to 283 g/kg of barley and was reduced afterwards (P < 0.01). Increasing levels of barley resulted in greater (P < 0.001) gain per feed (G/F). Enzyme addition increased WG (P < 0.05) and G/F (P < 0.001) at each barley inclusion level.

3. Birds fed diets with 0 and 565 g/kg barley showed the lowest and highest (P < 0.001to 0.05) digestibility for all nutrients measured, respectively. Digestibility of all nutrients was improved by enzyme supplementation at each barley inclusion level (P < 0.05). The nitrogen-corrected apparent metabolisable energy improved with increasing inclusion of barley (P < 0.001) and supplemental enzyme (P < 0.01). Increasing inclusion of barley increased the relative weight of gizzard (P < 0.001) and reduced jejunal digesta viscosity (P < 0.001). Supplemental enzyme (P < 0.001) reduced digesta viscosity.

4. The optimum inclusion level of barley, with respect to growth performance, was 283 g/kg of diet. Increasing barley inclusion improved nutrient and energy utilisation, possibly through lowered digesta viscosity and better function of the gizzard. Feed efficiency and nutrient and energy utilisation can benefit from carbohydrase supplementation in barley-based diets, regardless of barley inclusion level.     

Effects of different feed additives alone or in combination on broiler performance, gut microflora and ileal histology

1. The objectives of this experiment were to investigate the effects of different xylanases, alone or in combination with different organic acid and oligosaccharide sources, on bird performance, gut microflora and ileal histology. 2. Birds were given a diet based on a commercial formulation, which was split into 8 batches. Batch 1 contained the antibiotic growth promoter Avilamycin and acted as the positive control. To batch 2 the enzyme Allzyme PT was added and to batch 3 Allzyme PT was added with the organic acid and oligosaccharide mixture Avimos. To batch 4, Allzyme PT was added with the oligosaccharide mixture Biomos. To batch 5, yeast extract 2012 was added with the organic acid mixture Gustor and the enzyme xylanase XP20. To batch 6, yeast extract 2012 and feed acidifier Gustor were added as before, with the enzyme Avizyme 1300. Batches 7 and 8 both acted as negative experimental controls, with no added growth promoters. 3. A total of 64 birds were housed in individual wire cages in each of three consecutive experimental replicates (24 birds/treatment). Birds were fed ad libitum from 7 to 28 d and a 7-d excreta collection was carried out to determine apparent metabolisable energy (AME) content. 4. At 28 d, the birds were killed and viscosity of jejunal digesta supernatant and gizzard weight were determined. Samples were taken from the crop, ileum and caecum and analysed for viable presumptive lactic acid bacteria and coliforms. The overall microbial flora was determined using denaturing gradient gel electrophoresis of 16S ribosomal DNA followed by DNA sequence analysis in order to assign amplicons to a bacterial species. Ileal sections were also collected for histological analysis. 5. Total live weight gain (12%) and gain:feed (9%) were significantly improved for all diets containing additives, compared to the negative control diets. All diets containing xylanases gave significantly lower in vivo viscosity values than the positive and negative controls. Diet treatment significantly affected viable coliform numbers in the ileum and also viable lactobacilli in the ileum and caecum. A substantial proportion of the bacteria present in the GI tract (40%) belong to unknown species. No effects of diet treatment on histological measurements were observed in this study. 6. All the additive combinations studied were at least as effective as the antibiotic growth promoter and the results for Allzyme PT suggest that xylanase alone is as effective as any of the combinations studied.