饲粮中添加植酸酶对生长肥育猪矿物元素利用和排泄的影响

选用60头平均体重28.3 kg的杜洛克×长白×大约克夏三元杂交猪,随机分成2组,每组30头,研究在饲粮中添加植酸酶(750 FTU/kg)对生长肥育猪矿物元素利用和排泄的影响。结果表明:1)添加植酸酶使生长猪对铜和锌的消化率、肥育猪对粗灰分、磷、铜和锌的消化率显著提高(P<0.05或P<0.01)。2)添加植酸酶使生长猪对铜和锌的吸收量、肥育猪对粗灰分、磷、铜和锌的吸收量显著提高(P<0.05或P<0.01)。3)添加植酸酶显著降低生长猪粪中铜、肥育猪粪中粗灰分和磷的排泄量(P<0.05)。     

断奶仔猪饲粮中添加微生物植酸酶和柠檬酸对钙、磷利用率的影响

本试验研究了在断奶仔猪饲粮中添加微生物植酸酶和柠檬酸对钙、磷利用率的影响。试验采用完全随机设计,将72头体重相近、遗传基础相似的35日龄断奶的杜长大三元杂交仔猪分为4组,每组3个重复,每个重复6头猪。试验在相同钙水平基础上设4个处理组。对照组饲喂玉米-豆粕型基础饲粮;处理1基础饲粮-50%磷酸氢钙;处理2基础饲粮 植酸酶(500U/kg)-50%磷酸氢钙;处理3基础饲粮 植酸酶(500U/kg) 柠檬酸(0.5%)-50%磷酸氢钙。试验结果表明,(1)添加植酸酶或植酸酶和柠檬酸,钙、磷消化率显著高于对照组;血钙和血磷浓度,各处理与对照组无显著差异。(2)添加植酸酶或植酸酶和柠檬酸不影响血清碱性磷酸酶(AKP)活性(P>0.05)。(3)添加植酸酶或植酸酶和柠檬酸使胃中植酸磷消化率极显著提高,粪中磷排出量极显著降低。(4)添加植酸酶或植酸酶和柠檬酸,猪的掌骨灰分和跖骨强度与采食正常磷饲粮的对照组无显著差异。(5)植酸酶与柠檬酸合用较之单添植酸酶有更高植酸磷消化率和更低的粪磷排出量(P<0.05)。总之,在断奶阶段,在猪玉米-豆粕型饲粮中添加植酸酶或植酸酶和柠檬酸可代替部分磷酸氢钙,促进了钙、磷消化利用,促进了骨骼生长,也促进了植酸磷的利用,降低了粪磷排出。植酸酶与柠檬酸合用,有助于提高植酸磷的消化率和降低粪磷排出,存在显著的协同效应。     

植酸酶和磷酸氢钙对生长猪生长性能和养分消化率的影响

选择体重(35.92±4.84)kg的长白X大约克二元杂种阉公猪56头,随机分为4个处理,分别饲喂常磷不加植酸酶饲粮、低磷不加植酸酶饲粮、常磷加植酸酶饲粮和低磷加植酸酶饲粮,每个处理14个重复,每个重复1头猪,研究饲粮添加植酸酶(750 IU/kg饲料)和不添加磷酸氢钙对生长猪的生长性能和养分代谢的影响.结果表明:低磷不加植酸酶组与常磷不加植酸酶组相比,采食量降低1.23%(P>0.05),料重比增加13.82%(P<0.01),日增重降低18.52%(P<0.01),单位增重饲料成本增加13.50%(P<0.01),磷表观消化率降低13.83%(P<0.01),钙表观消化率降低4.21%(P>0.05).粗蛋白质表观消化率降低2.55%(P>0.05);常磷加植酸酶组与常磷不加植酸酶组相比,采食量增加2.06%(P>0.05),料重比降低4.73%(P<0.01),日增重增加7.33%(P<0.01),单位增重饲料成本降低4.70%(P<0.01),磷表观消化率提高12.45%(P<0.05),钙表观消化率提高5.63%(P<0.05),粗蛋白质表观消化率提高4.00%(P>0.05);低磷加植酸酶组与低磷不加植酸酶组相比,采食量增加5.00%(P>0.05),料重比降低12.14%(P<0.01),日增重增加27.67%(P<0.01),单位增重饲料成本降低12.07%(P<0.01),磷表观消化率提高39.59%(P<0.01),钙表观消化率提高7.94%(P<0.01),粗蛋白质表观消化率无显著变化(P>0.05);低磷加植酸酶组与常磷不加植酸酶组相比采食量、日增重、料重比和单位增重饲料成本均差异不显著,磷表观消化率提高20.28%(P<0.01),钙表观消化率提高3.39%(P<0.05),粗蛋白质表观消化率无显著变化(P>0.05).结论:1)添加植酸酶(常磷加植酸酶组与常磷不加植酸酶组比,低磷加植酸酶组与低磷不加植酸酶组比)能够提高生长猪生长性能和钙、磷的表观消化率,降低生产成本,对粗蛋白质表观消化率无显著影响;2)不添加磷酸氢钙(低磷加植酸酶组与常磷加植酸酶组比,低磷不加植酸酶组与常磷不加植酸酶组比)会降低生长猪生长性能,但对钙和粗蛋白质的表观消化率无显著影响;3)低磷加植酸酶组与常磷加植酸酶组相比,猪的生长性能和钙、粗蛋白质的表观消化率无显著差异,但磷的消化率大大提高了,有利于环境保护;4)低磷加植酸酶饲粮有利于猪的生长、降低生产成本和环境保护,为最佳饲粮.     

转植酸酶基因乳酸杆菌对仔猪营养物质消化率及血清生化指标的影响

本研究选择88头长白猪断奶仔猪,用于测定转植酸酶基因的乳酸杆菌对其营养物质消化率的影响。研究结果表明添加转植酸酶基因乳酸杆菌试验组粗蛋白质的消化率比未转植酸酶基因乳酸杆菌和植酸酶试验组分别提高了40.72%(P0.01)和18.59%(P0.05);添加转植酸酶基因乳酸杆菌试验组钙的消化率比对照组、抗生素、未转植酸酶基因乳酸杆菌、植酸酶试验组分别提高了29.77%(P0.01)、40.77%(P0.01)、95.31%(P0.01)、23.32%(P0.05);添加转植酸酶基因乳酸杆菌试验组磷的消化率比对照组、抗生素、未转植酸酶基因乳酸杆菌、植酸酶试验组分别提高了30.39%(P0.01)、18.45%(P0.05)、64.90%(P0.01)、22.24%(P0.05)。另外,选择32头长白猪断奶仔猪用于测定转植酸酶基因的乳酸杆菌对其血清生化指标的影响。结果表明,转植酸酶基因的乳酸杆菌能够显著提高血液中甘油三酯含量(P0.05),而对其他指标的影响并不显著(P0.05)。由此可知,饲料中添加转植酸酶基因乳酸杆菌能提高仔猪对粗蛋白质、钙和磷等营养物质的消化率,可提高猪对饲料中脂类的吸收效率,促进断奶仔猪的生长发育。     

生长猪植酸酶的磷当量研究

本文旨在研究饲粮中添加植酸酶对植酸磷利用的影响,确定生长猪的植酸酶磷当量。本试验采用单因素试验设计,以NaH2PO4.2H2O提供外源无机磷,同时添加植酸酶,设计1个低磷基础日粮、4个加磷日粮和3个加酶日粮,分别提供0.4、0.8、1.2、1.6g/kg的有效磷或500、750、1000FTU/kg植酸酶。选择96头体重22kg左右的杜长大三元杂交猪,随机等分到8个处理中。通过回归分析,建立响应指标(猪趾骨折断强度和趾骨灰分磷含量)与外源磷添加量之间的线性关系,进而确定植酸酶的磷当量值。结果表明:(1)随外源磷和植酸酶水平的提高,试验猪生产性能明显改善(P<0.05),趾骨灰分磷含量和血磷水平都极显著地升高(P<0.01);(2)无机磷添加水平与响应指标之间存在较强线性关系:y=10.79x 27.23(x-添加磷(g/kg),y-趾骨强度(kg),R2=0.92);y=1.44x 6.86(x-添加磷(g/kg),y-灰分磷(%),R2=0.99);(3)植酸酶的磷当量值与日粮中植酸酶和无机磷水平密切相关,同时也受相应指标种类的影响。本试验条件下,500、750、1000FTU/kg植酸酶分别可替代1kg玉米-豆粕日粮中0.09g、0.44g和0.72g(折断强度)或0.23g、0.58g、1.06g(灰分磷)无机磷。     

植酸酶在饲料中的应用

<正>植酸酶能水解植物性饲料中植酸·磷,从而提高猪禽等单胃动物对磷的利用率。植酸酶不仅可以提高磷的利用率,降低饲料生产成本,同时又可以大幅度降低磷的消耗以及随之带来的污染。植酸酶是迄今为止最为成功     

不同植酸酶对生长育肥猪生产性能及养分利用的影响

选择"杜×长×大"三元杂交生长猪54头,研究了大肠杆菌、黑曲霉来源植酸酶替代日粮中部分磷酸氢钙对生长育肥猪生长性能、养分消化率、血液生化指标及粪磷、氮排泄的影响。试验猪随机分成对照组、试验Ⅰ组、试验Ⅱ组,每组3个重复。对照组饲喂常规日粮,试验Ⅰ组饲喂低磷+植酸酶Ⅰ的日粮,试验Ⅱ组饲喂低磷+植酸酶Ⅱ的日粮。试验结果表明,在生长育肥猪日粮中添加植酸酶替代部分磷酸氢钙,改善了生长育肥猪生长性能,其中添加大肠杆菌植酸酶显著改善生长育肥猪的生长性能;显著改善了干物质、粗蛋白质、钙、磷、总能的表观消化率,并显著降低了粪中氮、磷的排泄;显著提高了血清中总蛋白、球蛋白、血清磷的浓度,而尿素氮、血清钙浓度显著降低。添加黑曲霉植酸酶后,血糖浓度下降,而碱性磷酸酶的活性无显著变化;添加大肠杆菌植酸酶后,碱性磷酸酶的活性显著降低,而血糖浓度无显著变化。     

植酸酶对玉米、豆粕日粮中生长猪代谢的影响

本文通过植酸酶对生长猪的代谢的不同来评估饲喂低植酸玉米、低植酸豆粕、常规玉米、常规豆粕对其的影响。将48头去势的生长猪随机分成8个组,每组6头猪,采用2×2×2的试验设计,猪只日粮均符合日粮标准。结果表明,低植酸玉米组比常规玉米组(2.85:3.24±0.119g/d;P=0.024),低植酸豆粕组比常规豆粕组(2.79:3.30±0.119g/d;P=0.007),植酸酶组比不饲喂植酸酶组(2.80:3.29±0.119g/d;P=0.009),低植酸玉米、豆粕、添加植酸酶组比常规玉米、豆粕和无植酸酶组(2.16:3.70±0.237g/d;P0.001)的粪中的磷都要低。低植酸玉米日粮比常规玉米日粮(48.4:39.9±2.27%;P=0.012),植酸酶日粮比无植酸酶日粮(48.4:39.9±2.27%;P=0.019),低植酸玉米、豆粕、添加植酸酶组比常规玉米、豆粕和无植酸酶组日粮(47.2:41.1±2.27%;P=0.075)的磷的消化率都有所增加,这些说明低植酸玉米、低植酸豆粕或者直接添加植酸酶酶制剂均可以提高磷的利用率并且可以通过粪中磷的降低而改善对环境的污染问题。     

耐热植酸酶在低钙磷饲粮中添加对仔猪和生长猪的饲用效果研究

为确认经基因工程改造以酵母发酵生产的植酸酶的耐热性及其在肉猪饲粮中的应用效果,本试验结合颗粒饲料生产实际条件检测植酸酶样的耐热性,并以仔猪和生长猪为对象开展饲养试验.以玉米725.00 kg、豆粕203.24 kg、统糠11.26 kg、次粉15.00kg、大豆油15.00 kg和植酸酶30.50kg(5000 U/g)组成混合料,经调质温度为85℃和调质时间为30 s的生产线制粒,分别抽取调质前、调质后和制粒后等3个处理阶段各5个点样,测定各样的植酸酶活量,分别计算出植酸酶在调质前、调质后和制粒后的酶活回收率(%).饲养试验一:90头杜长大仔猪(9.86±0.09)kg随机分为3个处理,每个处理3个重复,每个重复10头;3组分别饲喂3种等蛋白质等能量等钙磷比的玉米-豆粕型试验饲粮(20.0%、13.39 MJ/kg和1.26),为期4周;正对照饲粮含钙0.82%和磷0.65%,负对照饲粮含钙0.62%和磷0.49%,植酸酶饲粮为在负对照饲粮基础上添加植酸酶的饲粮(500 U/kg).饲养试验二:60头杜长大生长猪(22.45±0.67)kg随机分为2个处理,每个处理3个重复,每个重复10头;2组分别饲喂2种等蛋白质等能量等钙磷比的生长猪试验饲粮(17.5%、13.00 MJ/kg和1.0),为期4周;对照饲粮含钙0.66%和磷0.67%,植酸酶饲粮含钙0.56%、磷0.56%和植酸酶(500 U/kg).试验结果表明:(1)调质前、调质后和颗粒产品样的酶活回收率分别为104.8%、73.2%和68.2%(P＜0.05);(2)饲养试验一中的植酸酶组仔猪生产性能与正对照组的差异不显著(P＞0.05),但负对照的增重和耗料增重比分别显著低和高于正对照的(P＜0.05);(3)饲养试验二中的植酸酶组生长猪的耗料量较对照组的降低了9%,耗料增重比降低了11%(P＜0.05).增重提高了2%.此酶样经颗粒料生产全程工序后仍具68.2%的存酶活,具较好的耐热性;在低磷饲粮中应用可提高饲料转化率,因而提高仔猪及生长猪的增重,并降低饲料成本.     

南方高温环境下植酸酶对杜长大猪生产性能和钙、磷、蛋白质利用率的影响

本研究选用60头4周龄杜长大断奶仔猪(7.33±0.45kg),评价在我国南方夏季高温环境下植酸酶对高生产性能猪的生物学功效.试验设5个处理组,每个处理组设6个重复(每重复2头猪),饲喂玉米-米糠-豆粕型饲粮.在低磷水平的饲粮(负对照组)中,分别添加250PTU/kg、500PTU/kg、750PTU/kg植酸酶和0.15%无机磷(正对照组),组成5种不同的试验饲粮.试验结果表明植酸酶的添加,显著提高了断奶到育成阶段猪的日增重和采食量;改善了血清无机磷、钙浓度;提高了饲粮中磷、钙的消化率,降低了粪中磷的排放量.试验结果表明,植酸酶可以部分替代断奶到育成阶段猪饲粮中无机磷,并减轻磷对环境的污染.本研究根据植酸酶和无机磷对猪生产性能、血清相关生化指标和饲粮中磷、钙的消化率反应的比较推断,500～750PTU/kg植酸酶即可替代0.15%饲料无机磷.     

植酸酶及其在畜禽生产中的最新应用研究

植酸酶是一种新型饲料添加剂,它能提高动物对饲料中植酸磷的利用率,降低粪便中磷的排泄量。本文对植酸的化学结构、理化性质与植酸酶的来源、生物学特性,并对影响植酸酶活力的因素及其在畜禽生产中的最新应用研究作了简要介绍。     

肉仔鸡体外消化模拟技术评定不同剂量植酸酶作用效果的研究

对肉仔鸡体外消化模拟技术评定不同剂量植酸酶在玉米-豆粕日粮中作用效果的可行性进行了检验.在体外条件下,分别测定了添加与不添加植酸酶的6种玉米-豆粕日粮磷体外消化率和无机磷释放量.结果表明：磷体外消化率和无机磷释放量随植酸酶添加水平的增加而增加（P＜0.01）,添加不同剂量的植酸酶日粮,磷体外消化率和无机磷释放量与肉仔鸡日增重、采食量、回肠磷消化率、胫骨灰分和磷的沉积以及胫骨灰分中磷的含量等指标均存在强相关（R^2=0.971,0.990,0.962,0.903,0.866,0.986和R^2=0.970,0.987,0.976,0.898,0.859,0.984）.利用肉仔鸡体外消化模拟技术,可以评定和预测玉米-豆粕日粮中添加不同剂量植酸酶对肉仔鸡生产性能和磷利用的影响.     

Response of broiler chickens to microbial phytase supplementation as influenced by dietary phytic acid and non-phytate phosphorus contents. I. Effects on bird performance and toe ash

1. Seven-day old 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 phosphorus), 2 of non-phytate phosphorus (2.3 and 4.5 g/kg) and 3 of microbial phytase (Natuphos 5000 L; 0, 400 and 800 FTU/kg) in a 19-d trial. The dietary phytic acid contents were manipulated by the inclusion of rice pollard. 2. Each dietary treatment was fed to 5 pens (10 birds/pen) from 7 to 25 d of age. Records of body weight, food intake and mortality were maintained. On d 25, all surviving birds were killed and toe samples were obtained for toe ash measurements. 3. Increasing dietary phytic acid negatively influenced body weight gain, food intake and food/gain. These adverse effects were partially overcome by the addition of microbial phytase. 4. Supplemental phytase caused improvements in weight gain and food efficiency of broilers but the magnitude of the responses was greater in low non-phytate phosphorus diets, resulting in significant non-phytate phosphorus x phytase interactions. 5. Toe ash contents were improved by phytase addition but the response was greater at the highest concentration of phytic acid, resulting in a significant phytic acid x phytase interaction. Responses were also greater in low non-phytate phosphorus diets as indicated by significant non-phytate phosphorus x phytase interaction. 6. In general, there was very little difference in the responses to phytase additions at 400 and 800 FTU/kg. 7. The performance responses to added phytase in birds receiving adequate non-phytate phosphorus diets provide evidence for the influence of the enzyme on animal performance independent of its effect on phosphorus availability.     

Evaluation of phytase concentration needed for growing-finishing commercial turkey toms

1. Growth performance, serum bone markers, and bone strength and mineralisation were determined in tom turkeys grown from 9 to 17 weeks of age. 2. Dietary non-phytate phosphorus was formulated to be reduced by 1.0 g/kg in the low phosphorus diet compared to a control diet and phytase was added to provide 0, 150, 300, 450 or 600 units/kg activity to the low phosphorus diet. 3. From 9 to 12 weeks of age, body weight and gain:food were reduced by the low phosphorus diet without added phytase, compared to the adequate phosphorus diet. Increasing the concentration of phytase linearly increased these growth parameters. There were no significant growth responses at 17 weeks of age. 4. Serum osteocalcin was reduced by increasing dietary phosphorus at 12 weeks of age when growth was affected, but not at later ages. Serum pyridinoline was reduced by higher dietary phosphorus and decreased linearly with increasing phytase activity at 17 weeks of age. 5. Fracture force of the ulna and femur increased linearly with increasing phytase activity but bone strength was not affected when corrected for bone cross-sectional area. Bone strength of the ulna and ash concentration of the ulna and tibia were increased by higher dietary phosphorus. Humerus and ulna ash increased linearly with increasing phytase activity. 6. Water-soluble phosphorus content of the litter was increased by higher dietary phosphorus and addition of phytase to the low phosphorus diet. The increase in water-soluble phosphorus content of the litter when phytase was fed may indicate that phosphorus could be fed at a lower concentration than used in this trial, at least in the finisher diet when phytase is added to the food. 7. Bone fracture force, strength and ash were generally optimised when 450 units/kg phytase activity was added to the low phosphorus diet. However, growth performance was best in the grower I (9 to 12 weeks) phase when 600 units/kg phytase was added to the diet.     

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.     

植酸酶的研究进展

植酸酶是能降解饲料中植酸及其盐的酶。它能提高磷利用率,解除植酸对一些矿物元素如钙、锌、铁、铜等的抗营养效应,不仅对动物具有良好的增重效果,同时可降低动物排泄磷量,有利于环境保护。植酸酶作为饲料添加剂其作用效果受到饲料中钙、磷水平和钙磷比例以及维生素Ｄ含量的影响。植酸酶的运用需要降低饲料中钙、磷水平,维生素Ｄ与植酸酶之间可能存在协同效应。对植酸酶运用的经济分析表明,使用植酸酶能代替饲料中需添加的无机磷。     

不同清洁型日粮降低规模猪场中氮、磷污染物排泄的研究

本试验旨在研究在肥育猪日粮中添加植酸酶、复合酶及微生态制剂3种清洁型日粮对规模猪场氮、磷排泄的影响。试验选取健康无病的60 kg左右的苏钟猪15头,随机分为5个处理,分别为对照组(正常磷水平)、负对照组(不加CaHPO₄)、负对照+植酸酶组、对照+植酸酶+复合酶+和美酵素组、对照+微生态制剂组。结果表明,3种清洁型日粮均可降低粪、尿中氮的排泄量,其中植酸酶组粪中氮的排泄量较对照组降低了0.55%(P＞0.05),植酸酶+复合酶+和美酵素组降低了10%(P＜0.05),微生态制剂组降低了6.11%(P＞0.05),其中植酸酶+复合酶+和美酵素组减排效果更佳,尿氮含量各组之间差异不显著(P＞0.05);粪中磷的排泄量植酸酶组较对照组降低了19.19%(P＞0.05),植酸酶+复合酶+和美酵素组降低了36.63%(P＜0.05),微生态制剂组降低了16.28%(P＞0.05),其中植酸酶+复合酶+和美酵素组减排效果最佳,尿磷的排泄量植酸酶组降低了12%(P＞0.05),植酸酶+复合酶+和美酵素组降低了16%(P＜0.05),微生态制剂组降低了12%(P＞0.05),以植酸酶+复合酶+和美酵素组减排效果最好。由此表明,在肥育猪日粮中添加清洁饲料可有效降低规模猪场中氮、磷排泄造成的环境污染,且以植酸酶、复合酶及和美酵素联合应用效果最佳。     

Effect of super dosing of phytase on growth performance,ileal digestibility and bone characteristics in broilers fed corn–soya‐based diets

A feeding trial was designed to assess the effect of super dosing of phytase in corn–soya‐based diets of broiler chicken. One hundred and sixty‐eight day‐old broilers were selected and randomly allocated to four dietary treatment groups, with 6 replicates having 7 chicks per treatment group. Two‐phased diets were used. The starter and finisher diet was fed from 0 to 3 weeks and 4 to 5 weeks of age respectively. The dietary treatments were consisted of normal phosphorus (NP) group without any phytase enzyme (4.5 g/kg available/non‐phytin phosphorus (P) during starter and 4.0 g/kg during finisher phase), three low‐phosphorus (LP) groups (3.2 g/kg available/non‐phytin P during starter and 2.8 g/kg during finisher phase) supplemented with phytase at 500, 2500, 5000 FTU/kg diet, respectively, to full fill their phosphorus requirements. The results showed that super doses of phytase (at 2500 FTU and 5000 FTU/kg) on low‐phosphorus diet improved feed intake, body weight gain, ileal digestibility (serine, aspartic acid, calcium, phosphorus), blood P levels and bone minerals such as calcium (Ca), P, magnesium (Mg) and zinc (Zn) content. It could be concluded that super doses of phytase in low‐phosphorus diet were beneficial than the normal standard dose (at 500 FTU/kg) of phytase in diet of broiler chicken.     

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.