Influence of phytase and xylanase, individually or in combination, on performance, apparent metabolisable energy, digestive tract measurements and gut morphology in broilers fed wheat-based diets containing adequate level of phosphorus

1. The aim of the present study was to examine the influence of microbial phytase and xylanase, individually or in combination, on performance, apparent metabolisable energy, digesta viscosity, digestive tract measurements and gut morphology in broilers fed on wheat-soy diets containing adequate phosphorus (P). The wheat-soy basal diet was formulated to contain 4.5 g/kg non-phytate P and the experimental diets were formulated by supplementing the basal diet with xylanase (1000 xylanase units/kg diet), phytase (500 phytase units/kg diet) or a combination of phytase and xylanase. 2. Supplemental phytase improved the weight gains and feed efficiency by 17.5 and 2.9%, respectively. Corresponding improvements due to the addition of xylanase were 16.5 and 4.9%, respectively. The combination of phytase and xylanase caused no further improvements in broiler performance. 3. Individual additions of xylanase or phytase resulted in numerical improvements in apparent metabolisable energy (AME), but the differences were not significant. The combination of the two enzymes significantly increased AME. Addition of xylanase and the combination of the two enzymes reduced the viscosity of digesta in all sections of the intestine. Phytase supplementation reduced digesta viscosity in the duodenum and ileum, but not in the jejunum. 4. Enzyme supplementation lowered the relative weight and length of the small intestine. Additions of xylanase and phytase reduced the relative weight of the small intestine by 15.5 and 11.4%, respectively, while the corresponding reductions in the relative length of the small intestine were 16.5 and 14.1%, respectively. The combination of phytase and xylanase had no further effects on the relative weight and length of the small intestine compared with the xylanase group. 5. The addition of phytase increased villus height in the duodenum and decreased the number of goblet cells in the jejunum compared with those on the unsupplemented basal diet. Xylanase supplementation tended to increase goblet cell numbers in the duodenum and decreased crypt depth in thejejunum. The combination of phytase and xylanase increased villus height in the ileum and crypt depth in thejejunum and ileum. 6. In summary, the present results showed that the addition of a microbial phytase, produced by solid state fermentation and containing significant activities of beta-glucanase and xylanase, was as effective as xylanase in improving the performance of broiler chickens fed on wheat-based diets containing adequate levels of P. Improved performance with enzyme supplementation was generally associated with reduced digesta viscosity, increased AME, and reduced relative weight and length of small intestine.     

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.     

Ileal amino acid digestibility and performance of growing pigs fed wheat-based diets supplemented with xylanase

Two experiments were conducted to determine the effect of supplementation of xylanase to a wheat-based diet on the apparent ileal digestibility (AID) of AA and the performance of growing pigs fed diets limiting in AA. In Exp. 1, eight pigs (average initial BW = 20.5+/-1.2 kg) fitted with a simple T-cannula at the distal ileum, were fed four diets according to a repeated 4 x 4 Latin square design. Diet 1 was a basal diet that contained 97.6% wheat. Diets 2, 3, and 4 were the basal diet supplemented with xylanase at rates of 5,500, 11,000, and 16,500 units of xylanase activity (XU), respectively (as-fed basis). There were linear and quadratic effects (0.062 < P < 0.001) of xylanase supplementation on the AID of CP and most of the AA. The largest increases in AID of CP and AA were obtained when xylanase was supplemented at a rate of 11,000 XU; no further increases were observed with xylanase supplementation at a rate of 16,500 XU. In Exp. 2, 30 pigs (average initial BW 21.4+/-1.8 kg) were randomly allotted to six dietary treatments. Diets 1 to 4 were similar to those used in Exp. 1. Diet 5 was the same as Diet 1, but supplemented with 0.53% lysine, 0.12% threonine, and 0.05% methionine. Diet 6 (positive control diet) was a wheat-soybean meal diet that contained 18.2% CP (as-fed basis). The total contents of lysine, threonine, and methionine were similar for Diets 5 and 6. There was a linear effect of xylanase supplementation on ADG (P = 0.093) and feed:gain ratio (P = 0.089), and a quadratic effect on ADG (P = 0.067) and feed:gain ratio (P = 0.074). But, the greatest response was obtained with the supplementation of 11,000 XU. The supplementation of lysine, threonine, and methionine to Diet 1 increased (P = 0.001) ADG and ADFI and improved (P = 0.01) feed:gain ratio. There was no difference (P = 0.508) in the performance of pigs fed the AA-supplemented or control diet. In conclusion, the supplementation of xylanase to a diet in which wheat provided the sole source of protein and energy improved the AID of AA, ADG, and feed:gain ratio; however, this improvement was very small compared with that obtained with the supplementation of synthetic amino acids.     

Effects of exogenous xylanase on performance,nutrient digestibility,volatile fatty acid production and digestive tract thermal profiles of broilers fed on wheat- or maize-based diet

1. A previous experiment reported that caecal temperature was negatively correlated with d 49 feed conversion ratio (FCR). This increased temperature in the caeca may indicate a prebiotic effect. An experiment was designed to investigate whether caecal temperature was affected in diets based on maize and whether other portions of the tract were affected.

2. A total of 25 Ross 308-d-old male broilers were allocated to each of 8 replicate pens per treatment. Treatments followed a 2 × 3 factorial design: two diets based on wheat or maize and three levels of enzyme addition, 0, 16 000 or 32 000 BXU/kg. Growth performance was assessed between d 1 and 49. Digestibility measurements were taken at d 28 and 49. On d 49, the excised small and large intestine of each bird was thermally imaged, weighed and volatile fatty acids (VFA) measured.

3. On d 28 and d 49, birds on the maize diets had higher feed intake and weight gain than those offered wheat diets. Additionally, on d 28, birds that received the maize diet had lower FCR than those offered the wheat diet. Enzyme improved FCR at d 49, independently of cereal. On d 28, enzyme improved the coefficient of apparent ileal DM digestibility and the coefficient of apparent ileal nitrogen digestibility. Enzyme only improved apparent ileal digestible energy in wheat-based diets (interactive term). On d 49, all digestibility parameters were improved by enzyme. Enzyme increased gizzard weight in maize-fed birds and the caeca of those fed wheat were heavier. The higher enzyme dose decreased duodenal temperature. In summary of VFA data, wheat-based diets produced more total VFAs and the total amount also increased with enzyme.

4. It appears from this study that there is equal potential in both wheat and maize diets for xylanase to improve performance of broilers probably through different mechanisms.     

Influence of conditioning temperature on the performance, nutrient utilisation and digestive tract development of broilers fed on maize- and wheat-based diets

1. The influence of conditioning temperature on the performance, nutrient utilisation and digestive tract development of broilers fed on maize- and wheat-based diets was examined up to 21 d of age. The experimental design was a 2 × 3 factorial arrangement of treatments evaluating two grain types (maize and wheat) and three conditioning temperatures (60°C, 75°C and 90°C). Broiler starter diets, each based on one grain (maize or wheat), were formulated and pelleted at the three temperatures. 2. Increasing conditioning temperature decreased the body-weight gain and feed intake in wheat-based diets, but birds fed on maize-based diets conditioned at 60°C and 90°C had higher body-weight gain and feed intake than those fed on the diet conditioned at 75°C. Increasing conditioning temperature increased feed per body-weight gain in both grain-type diets but improved pellet durability index (PDI) only in wheat-based diets; PDI was unaffected in maize-based diets. 3. In wheat-based diets, increasing conditioning temperature decreased the ileal digestibility of nitrogen and starch. Ileal nitrogen digestibility of maize-based diets conditioned at 60°C and 90°C was higher than at 75°C. Starch digestibility was unaffected by conditioning temperature in maize-based diets. No effect of conditioning temperature was found for apparent metabolisable energy (AME). Increasing conditioning temperature decreased digestible protein and AME intakes in wheat-based diets but, in maize-based diets, birds fed on the diet conditioned at 75°C had lower digestible protein and AME intakes compared to those fed on diets conditioned at 60°C and 90°C. 4. Small intestine was longer in birds fed on diets conditioned at 75°C and 90°C compared with those fed on diets conditioned at 60°C. 5. Overall, the data suggest that while the effects of conditioning temperature on body-weight gain and feed intake of broilers to 21 d of age differed depending on the grain type, feed per body-weight gain was adversely affected by higher conditioning temperatures.     

Influence of pellet diameter and length on the quality of pellets and performance,nutrient utilisation and digestive tract development of broilers fed on wheat-based diets

1. The influence of pellet diameter and length on the quality of pellets and performance, nutrient utilisation and digestive tract development of broilers given wheat-based diets was examined from 10 to 42 d of age. The experimental design was a 2 × 2 factorial arrangement of treatments evaluating two pellet diameters (3 and 4.76 mm) and two pellet lengths (3 and 6 mm). From 0 to 9 d of age, all birds were offered a common starter diet pelleted with a 3-mm diameter die and 3-mm length. Broiler grower (d 10 to 21) and finisher (d 22 to 42) diets, based on wheat, were formulated and then subjected to the 4 different treatments.

2. In grower diets, increasing pellet diameter and pellet length reduced the gelatinised starch (GS) content of the diets. In finisher diets, GS content of 3-mm diameter pellets did not change with increasing pellet length but decreased in 4.76-mm diameter pellets.

3. In grower and finisher diets, increments in intact pellet weight, pellet durability index and pellet hardness with increasing pellet length were greater in 3-mm diameter pellets than those with 4.76-mm diameter.

4. Increasing pellet length from 3 to 6 mm increased apparent metabolisable energy values. Neither the interaction nor main effects were significant for the ileal digestibility of nitrogen and starch.

5. During the grower period (d 10 to 21), birds given pellets of 6-mm length had greater body-weight gain than those given 3-mm length pellets. Feeding 6-mm length pellets decreased feed per body-weight gain compared to 3-mm length pellets. During the finisher (d 22 to 42) and whole grow-out (d 10 to 42) periods, while different pellet lengths had no effect on feed per body-weight gain values at 3-mm pellet diameter, increasing the pellet length decreased feed per body-weight gain at 4.76-mm pellet diameter.

6. Increasing pellet diameter and pellet length reduced the relative length of duodenum. Birds given 3-mm diameter pellets had heavier proventriculus compared to those given 4.76-mm diameter pellets.

7. Overall, the data suggest that increasing the pellet length from 3 to 6 mm improved the body-weight gain and feed per body-weight gain during the grower period (d 10 to 21). While the positive effect on body-weight gain disappeared as the birds grew older, improvements in feed per body-weight gain were maintained over the finisher and whole grow-out periods only in 4.76-mm diameter pellets. Small diameter die holes and longer pellet lengths may be considered as potential manipulations to manufacture high-quality pellets under low conditioning temperatures.     

Effects of exogenous xylanase on performance,nutrient digestibility and caecal thermal profiles of broilers given wheat-based diets

1. Five dietary treatments were used in a 49 d broiler trial to assess the effect of xylanase on performance, nutrient digestibility and thermal profiles of the caeca and head. Treatments included an industry-standard control diet and four further diets where xylanase was introduced with or without a metabolisable energy density dilution either from day one or the introduction was delayed until d 28.

2. The addition of xylanase with no associated energy dilution from day one resulted in the most consistent beneficial effects on performance, with significant improvements in weight gain compared with the industry-standard to d 28 and at d 49. Addition of xylanase from d 28 (with no energy dilution) was the second most successful strategy and resulted in a significant improvement in feed conversion ratio (FCR) from d 29 to 49 and overall.

3. Addition of xylanase improved ileal digestible energy values at d 28 by around 0.35 MJ/kg and ileal nitrogen digestibility coefficients by around 3%. On d 49 xylanase improved ileal digestible energy values by around 0.9 MJ/kg and ileal nitrogen digestibility coefficients by around 4.6%.

4. Thermal imaging of the head and caeca of three birds per replicate on d 49 revealed a significant increase in caecal surface temperature following xylanase addition with no effect on head temperature profile. These increases were particularly large (around 1.4ºC, or 3.9%) when xylanase was added from day one with no corresponding energy dilution in feed formulation.

5. It can be concluded that supplemental xylanase is effective in improving performance and nutrient digestibility in broilers given wheat-based diets. The correlation between the magnitude of this effect and the increased temperature in the caeca presents additional evidence that the hind-gut microflora may play an important, if yet unquantified, role in the outworking of these mechanisms.     

小麦型日粮添加木聚糖酶和植酸酶对肉鸡生长性能、回肠氨基酸表观消化率及常量元素沉积的影响

本文旨在研究小麦型日粮中添加木聚糖酶和植酸酶对肉鸡生长性能、回肠氨基酸表观消化率及矿物元素沉积的影响。试验选择1日龄科宝白羽肉仔鸡850只,随机分成5组,每组5个重复,每个重复34只鸡。一共有5种日粮,即低磷日粮、高磷日粮、低磷日粮+2000 IU/kg木聚糖酶、低磷日粮+500 FTU/kg植酸酶,低磷日粮+2000 IU/kg木聚糖酶+500 FTU/kg植酸酶,试验进行21 d。低磷组较高磷组显著降低了肉鸡的日增重、日采食量及趾骨灰分含量(P <0.05),与低磷组相比,木聚糖酶组显著降低了肉鸡的料比(P <0.05),而植酸酶组显著提高了肉鸡日增重、日采食量、趾骨灰分及饲料利用率(P <0.05)。复合酶组显著提高了15种氨基酸回肠表观消化率(P <0.05)。与低磷组相比,木聚糖酶组显著提高了表观消化能和可消化代谢能及回肠氮消化率(P <0.05),而植酸酶显著提高了氮沉积及回肠氮消化率(P <0.05),复合酶组显著提高了代谢能、可消化代谢能及氮沉积量(P <0.05)。植酸酶和复合酶组较高磷组显著提高了磷表观消化率和沉积量(P <0.05),但低磷组较高磷组显著提高了钙的表观消化率(P <0.05),植酸酶酶和复合酶组较其他3组显著提高了钾的沉积量(P <0.05)。结论 :小麦型日粮同时添加植酸酶和木聚糖酶对肉鸡生长和消化的影响要优于单独添加这两种酶。     

Influence of phytase and xylanase supplementation of a wheat-based diet on ileal and total tract digestibility in growing pigs

The effect of phytase and xylanase supplementation of a wheat-based pig diet on the ileal and total tract apparent digestibility of dietary components and minerals were studied in eight growing pigs fitted with a PVTC cannula in a randomized block design experiment. The diets (A and B) were similar in major ingredient composition and in nutrient content. In diet A, part of the limestone was replaced with di-calcium phosphate to increase the content of available phosphorus (P). Diet B was fed without or with supplementation with phytase (500 FTU/kg; diet BP), xylanase (4000 XU/kg; diet BX) and phytase + xylanase (500 FTU and 4000 XU/kg; diet BPX). There were no differences (P > 0.05) between diets in the ileal or total tract digestibility of organic matter (OM), NDF and crude protein (CP). The ileal and total tract digestibility for P and Ca differed (P < 0.05) between diets, while there were no treatment effects for Zn. The ileal and total tract digestibility for P and Ca was higher (P < 0.05) on diets BP and BPX than on the other diets. In conclusion, phytase improved the utilization of dietary P and Ca in a wheat-based diet, while xylanase had no additional benefits in terms of OM and CP digestibility or mineral utilization. Phytase had no effect on the digestibility of OM, CP or NDF.     

Effects of diet acidification and xylanase supplementation on performance, nutrient digestibility, duodenal histology and gut microflora of broilers fed wheat based diet

1. The objective of this experiment was to study the influences of xylanase and citric acid on the performance, nutrient digestibility, digesta viscosity, duodenal histology, and gut microflora of broilers fed on a wheat based diet.

2. The experiment was carried out as a 2?×?3 factorial arrangement with two concentrations of xylanase (0 and 200?mg/kg) and three concentrations of citric acid (0, 20 and 40?g/kg). A total of 408 one-day-old chickens with similar body weight were distributed into 24 pens with 17 birds/pen. Each dietary treatment was given to 4 replicate pens from 0 to 24?d of age. To determine the apparent nutrient digestibility, chromic oxide (3?g/kg) was added to the diets as an indigestible marker.

3. Xylanase significantly increased body weight gain at 24?d of age by 1·4% and improved gain-to-feed (G:F) by 3·6%. The inclusion of 40?g/kg citric acid decreased feed intake and body weight gain by 15·4% and 11·8%, respectively. The inclusion of 20?g/kg of citric acid decreased feed intake, but it did not affect body weight gain of broilers at 24?d of age. The inclusion of 20 and 40?g/kg citric acid improved G:F by 3·8 and 4·3% respectively. Xylanase significantly decreased the viscosity of digesta and improved retention of DM, CP, and energy.

4. Xylanase and citric acid did not have any effect on the histo-morphology of the duodenum and intestinal microbial population.

5. In conclusion, citric acid at 20?g/kg decreased feed intake, did not have a negative effect on body weight gain, and improved G:F. Xylanase decreased digesta viscosity, increased nutrient retention and consequently improved performance of broilers fed on a wheat based diet.     

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.     

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.     

The effects of exogenous xylanase supplementation on the in vivo generation of xylooligosaccharides and monosaccharides in broilers fed a wheat-based diet

ABSTRACT

1. This study quantified xylanase-induced changes in soluble monosaccharides, xylooligosaccharides (XOS) and volatile fatty acid (VFA) contents of the different sections of the gastrointestinal tract (GIT) and whether these were related to altered bird performance.

2. An in vitro digestion of the wheat-based diet was carried out with the xylanase (Econase XT at 16,000BXU/kg diet) to compare the in vitro and in vivo generation of these XOS and monosaccharides. For the in vivo study, 80 male Ross 508 b roiler chicks were split into two groups fed a wheat-based diet with or without Econase XT (16,000BXU/kg diet) for 21 days.

3. There were no effects of Econase XT inclusion on growth performance characteristics, likely a result of the high-quality wheat diet, the corresponding high performance of the control group (FCR average of 1.45 in controls) and the relatively young age of the birds (from four to 26 days of age).

4. Econase XT supplementation increased the xylotetraose (X₄) content in the colon (P = 0.046, enzyme x GIT section interaction) and the xylose contents in the colon and caeca (P < 0.001, enzyme x GIT section interaction).

5. The trend for increased acetate production in the caeca of Econase XT treated birds (P = 0.062) suggested that the XOS generated were subsequently fermented in the caeca, potentially impacting upon the types of microbiota present.

6. The present study suggested that wheat arabinoxylan degradation was enhanced by xylanase supplementation, which may have increased the production of beneficial volatile fatty acids (VFA) in the caeca, and thereby potentially modulated the caecal microbiome, but without affecting bird performance at this early age.     

小麦型日粮中添加限制性酶对肉鸡生长性能和胃肠道发育的影响

文章旨在研究小麦型日粮中添加木聚糖酶对肉鸡生长性能和胃肠道发育的影响。试验选择健康、平均体重一致的1日龄肉仔鸡800只,随机分为5组,每组5个重复,每个重复32只。共开展两个试验,试验1共5种日粮:对照组(小麦型1～28 d),处理1(小麦型日粮+0.3 g/kg木聚糖酶21～28 d),处理2(小麦型日粮+0.3 g/kg木聚糖酶14～28 d),处理3(小麦型日粮+0.3 g/kg木聚糖酶7～28 d),处理4(小麦型日粮+0.3 g/kg木聚糖酶1～28 d);试验2同样5种日粮:对照组(小麦型1～36 d),处理1(小麦型日粮+0.3 g/kg木聚糖酶27～36 d),处理2(小麦型日粮+0.3 g/kg木聚糖酶18～36 d),处理3(小麦型日粮+0.3 g/kg木聚糖酶9～36 d),处理4(小麦型日粮+0.3 g/kg木聚糖酶1～36 d)。结果显示:1～28 d肉鸡饲喂添加木聚糖日粮较未添加组和21～28 d显著提高了肉鸡的末重(P <0.05);与对照组相比,各处理组在15～21 d,22～28 d和1～28 d料重比均表现为显著降低(P <0.05)。1～36 d肉鸡日粮添加木聚糖酶较对照组(无酶)或27～36 d组显著提高了肉鸡末重(P <0.05);试验期间(1～36 d)添加木聚糖酶较对照组和27～36 d添加木聚糖酶组显著降低了料重比(P <0.05)。1～36 d肉鸡日粮添加木聚糖酶较对照组显著降低了回肠内容物黏度(P <0.05)。结论 :在小麦型日粮中添加木聚糖酶可以有效促进肉鸡生长后期的生长,而整个试验期不需要一直添加木聚糖酶。     

日粮中添加不同有机酸对肉鸡生产性能的影响

选择体重相近、健康的1日龄罗曼肉用雏120只,在基础日粮中分别添加0.2%柠檬酸、乳酸和延胡索酸,观察有机酸对肉鸡生产性能的影响。结果表明:在22～42日龄,添加柠檬酸组和延胡索酸组采食量均比对照组显著增加(P<0.05);在1～21日龄及全期,添加柠檬酸组日增重比对照组显著增加(P<0.05),在22～42日龄添加柠檬酸组日增重比对照组和添加乳酸组有显著增加(P<0.05);3种有机酸对料肉比指标影响有下降趋势,但均未达到显著水平(P>0.05)。     

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.     

Effects of thermostable phytase supplemented in diets on growth performance and nutrient utilization of broilers

Phytase is an enzyme that has the ability to release phosphorous (P) from phytate by hydrolyzing inositol-phosphate linkages. Recently, thermostable phytases have gained great consideration because the reduction in phytase activity was found when exposed to heat during feed pelleting. In this study, the effects of the granular thermostable phytase (Aspergillus niger) on growth performance and nutrient utilization of broilers were investigated. A total of 96 21-day-old Arbor Acres broilers were randomly distributed into six treatments including basal diet (control) and basal diet supplemented with 500, 1,000, 2,000, 4,000, 8,000 U of phytase/kg. In general, the metabolizable energy (ME) and the apparent and true availability of dry matter (DM), organic matter (OM), ether extract (EE), crude protein (CP), and amino acids (AA) showed both linearly (p < .01) and quadratically (p < .01) increase with increasing levels of phytase in the diet. Additionally, diet supplementation with phytase could improve (p < .05) body weight (BW), average daily gain (ADG), and feed/gain (F/G) on day 42 compared with the control. The results suggested that diet supplementation of the granular thermostable phytase in the crumbled pellets could improve chicken growth performance and nutrient utilization.     

Influence of a microbial phytase on the performance and the utilisation of energy,crude protein and fatty acids of young broilers fed on phosphorus-adequate maize- and wheat-based diets

1. The effects of microbial phytase on the performance and nutrient utilisation in broilers fed on phosphorus-adequate starter diets were examined in this study. The effect of phytase on the apparent ileal digestibility of fatty acids was of particular interest. Two grain types (maize and wheat) and two inclusion concentrations of a phytase enzyme from Escherichia coli expressed in Schizosaccaromyces pombe (0 or 500 phytase units (FTU)/kg of feed) were evaluated in a 2 × 2 factorial arrangement of treatments.

2. Supplemental phytase improved the weight gain and feed per gain, but had no effect on the feed intake of young broilers receiving phosphorus-adequate diets.

3. Phytase supplementation improved the apparent ileal digestibility of nitrogen and phosphorus in both diet types. Phytase supplementation tended to improve the apparent ileal digestible energy in wheat-based diets, but had no effect on the apparent metabolisable energy in both diet types.

4. Supplementation of phytase increased the apparent ileal digestibility of fat, with similar effects for the different fatty acids measured. Increments on ileal fat digestibility due to phytase were not dependent on the type of diet.

5. Dietary supplementation of microbial phytase enhanced not only the digestibility of phosphorus, but also that of nitrogen and fat, exhibiting increased ileal digestibility for all fatty acids in P-adequate maize- and wheat-based diets.     

Dietary organic acid and fiber sources affect performance,intestinal morphology,immune responses and gut microflora in broilers

This experiment was designed to investigate the effects of a dietary organic acid (OA) mixture and 2 fiber sources on performance, intestinal morphology, immune responses and gut microflora in broilers. A total of 390 one-day-old broiler chicks (Ross 308) were allocated to 6 dietary treatments with 5 replicate pens and 13 chicks each based on a factorial arrangement (2 × 3) in a completely randomized design. The experiment lasted 42 d. The following experimental diets and as well as their interaction were considered: a basal diet supplemented with or without OA (0 or 1 g/kg) and 2 fiber sources (sugar beet pulp [soluble fiber] or rice hull [insoluble fiber]; 0 or 30 g/kg). Dietary supplementation of OA increased daily weight gains of broilers across the entire rearing period (P < 0.05). The dietary fibrous materials did not affect the performance of broilers. Antibody titer against influenza disease virus was higher in birds fed diets containing rice hull compared with other experimental groups (P < 0.05). The population of Lactobacillus bacteria was greater in birds fed OA-added diets without or with 30 g/kg rice hull supplementation compared with other experimental groups (P < 0.05). In conclusion, dietary supplemental OA improved performance of broilers, and dietary supplemental OA with rice hull enhanced humoral immune responses.