植酸酶替代双低菜籽饼型肉鸡日粮中磷酸氢钙的代谢试验

为研究植酸酶在双低菜籽饼型肉鸡日粮中的应用效果,本试验在含8%的双低菜籽饼的肉鸡日粮中,添加600U/kg的植酸酶替代不同比例的磷酸氢钙进行代谢试验.结果表明以植酸酶替代1/2、4/5的磷酸氢钙,可显著提高钙、磷的利用率(P＜0.05),并且明显地降低了磷的排泄量(P＜0.05),在蛋白质的利用率上虽有提高的趋势,但差异不显著(P＞0.05).以植酸酶替代日粮中4/5的磷酸氢钙是完全可行的.     

在双低菜籽饼型日粮中添加植酸酶对肉鸡的增重效果研究

选择出壳重相近,发育正常的70只1日龄的肉鸡(土杂鸡),随机分成2组,饲喂含5％双低菜籽饼的日粮,并以植酸酶取代日粮中的磷酸氢钙作饲养对比试验。结果表明：在双低菜籽饼型的肉鸡日粮中以600u／kg的植酸酶取代50％的磷酸氢钙,其增重速度、饲料报酬和经济效益都优于常规无机磷日粮。     

含10%双低菜籽饼肉鸡日粮中添加植酸酶的饲喂效果试验

选用1日龄的铁脚麻肉鸡240只,进行为期28天的饲养试验,试验日粮含10%双低菜籽饼,试验组添加600 U/kg植酸酶取代50%的磷酸氢钙,对照组不添加植酸酶。结果表明:试验组鸡群的成活率、日增重和饲料转化率比对照组有所提高,经济效益明显。     

植酸酶、柠檬酸和碳酸化合物酶对肉鸡生长性能和养分利用率的影响

文章旨在研究低磷、低钙水平日粮添加植酸酶、柠檬酸和碳水化合物酶对1~21 d肉鸡生长性能及养分消化率的影响。试验选择1日龄肉仔鸡576只,随机分为6组,每组4个重复,每个重复24只鸡。试验共分为6种日粮,阳性对照组日粮(正常钙磷水平)、阴性对照日粮(低磷、低钙)、阴性对照日粮+600 IU/kg植酸酶,阴性对照日粮+600 IU/kg植酸酶+5 g/kg柠檬酸,阴性对照日粮+600 IU/kg植酸酶+500 mg/kg复合碳水化合物酶,阴性对照日粮+600 IU/kg植酸酶+5 g/kg柠檬酸+500 mg/kg复合碳水化合物酶。试验共开展21 d。结果显示:阳性对照组肉鸡日增重和采食量显著高于阴性对照组(P<0.05);植酸酶组添加碳水化合物酶较单独添加植酸酶组显著提高了肉鸡的日增重(P<0.05);植酸酶+碳水化合物酶较阴性对照组显著改善了料肉比(P<0.05)。阳性对照组较阴性对照组显著提高肉鸡胫骨灰分含量(P<0.05);植酸酶组显著提高了总磷、有效磷和植酸磷的回肠表观消化率(P<0.05),同时植酸酶组添加柠檬酸或碳水化合物酶进一步提高了总磷和植酸磷的回肠表观消化率(P<0.05)。阴性对照组添加植酸酶显著提高了表观代谢能及干物质、总能、氮和总磷的表观沉积量(P<0.05),而植酸酶组添加碳水化合物酶提高了干物质和总磷表观沉积量(P<0.05)。结论:在本试验条件下,低磷、低钙水平日粮添加植酸酶和碳水化合物酶改善了肉鸡生长性能、提高了营养物质的消化率和沉积量,而植酸酶日粮添加柠檬酸可以改善营养物质消化率和沉积量。     

超量添加液体植酸酶在肉鸭上应用效果的研究

本试验研究饲粮植酸酶和磷酸氢钙的添加水平对15~43日龄肉鸭生长性能、血液指标中血清Ca、P和碱性磷酸酶的影响,确定植酸酶与磷酸氢钙添加量的关系。试验设计11个处理,每个处理4个重复,每个重复20只鸭。基础日粮磷酸氢钙添加13kg(有效磷NPP:3.5g/kg,植酸磷PP:3g/kg),其他处理组分别为在此基础上减少磷酸氢钙的添加量,然后加不同剂量的植酸酶。结果显示:①随着磷酸氢钙添加量的减少,肉鸭体增重、采食量、饲料转化率、血清钙磷含量和碱性磷酸酶活性降低;②随着植酸酶水平的升高,肉鸭生长性能、血清及利用率等指标达到对照组水平;③当日粮植酸酶水平达到2000、4000、6000U/kg时,不添加磷酸氢钙,效果达到正常对照水平。     

含25-羟基维生素D_3日粮中植酸酶对21~42日龄肉鸡生长性能、骨骼矿化和钙磷利用的影响

为研究植酸酶对21~42日龄罗斯308肉鸡生长性能、骨骼矿化和钙磷利用的影响,本试验将120只前期(1~21日龄)采食相同日粮的21日龄罗斯308肉鸡随机分为3组,每组4个重复。设计3种日粮,在基础日粮[0.90%Ca、0.20%非植酸磷(NPP)、25μg/kg 25-羟基维生素D3]中添加3个不同水平植酸酶(0、1000、10000 U/kg)。结果显示:日粮中添加植酸酶可改善21~42日龄肉鸡胫骨和股骨强度,增加胫骨、股骨和跖骨磷含量,提高跖骨灰分和钙含量,增加血浆磷含量,改善总磷利用率,但未改善肉鸡生产性能;基础日粮中添加1000 U/kg和10000 U/kg植酸酶对肉鸡生长影响差异不显著。结果表明:在本试验条件下,含25-羟基维生素D3日粮中添加1000 U/kg植酸酶可改善21~42日龄肉鸡的胫骨、股骨、跖骨的矿化,提高日粮磷利用率及血浆磷水平。     

植酸酶和柠檬酸对肉鸡生产性能及钙、磷利用率的影响

植物籽实及谷物中60%～80%的磷以植酸磷的形式存在。家禽消化道缺乏水解植酸的酶对植酸磷的利用率很低。业已证明,添加植酸酶可提高植酸磷、Ca、蛋白质等养分的利用,减少粪磷对环境的污染。肉鸡日粮中添加450U/kg的植酸酶,可将日粮的CP水平降低一个百分点而不影响生长性能、胴体品质和AA的消化率,同时可使氮排出量减少10%(Kemme等,1995)。磷消化试验和长期饲养试验的结果表明,300FTU/kg的植酸酶相当于磷酸一钙中的1.0g磷。肉鸡日粮中添加300FTU/kg植酸酶,日粮磷(无论是TP或AP)含量应降低0.1%,Ca水平应减低0.1个百分点。近年来的研究…     

玉米-豆粕型日粮中添加高剂量植酸酶对肉鸡养分利用率的影响

本试验研究了玉米-豆粕型日粮中添加高剂量不同水平的植酸酶对0~3和4~6周肉鸡养分利用率的影响。选用1日龄AA肉鸡公雏576只,随机分为6组,每组8个重复,每个重复12只。试验日粮分0~3和4~6周两个阶段,6个处理组:正对照组(前期为总磷0.69%,0.45% NPP;后期为总磷0.59%,0.35% NPP);负对照组(前期总磷0.60%,0.35% NPP;后期为总磷0.49%,0.25% NPP);4个试验组在负对照日粮中分别添加500、2000、8000和32000 FTU/kg 4种植酸酶水平。结果显示:①日粮添加高剂量不同水平的植酸酶显著影响生长前期(17~21日龄)肉鸡的钙、磷的消化利用率(P<0.05),随着植酸酶添加水平增加,钙的消化利用率显著增加(P＜0.05)。②日粮添加高剂量不同水平的植酸酶显著影响38~42日龄肉鸡磷的消化利用率(P＜0.05)。在负对照组日粮中随着植酸酶水平添加的提高,钙的消化利用率呈现先增加后降低的趋势,磷的养分利用率反而显著减少。③日粮添加高剂量不同水平植酸酶显著增加生长前期(17~21日龄)肉鸡的粗蛋白质的消化利用率和表观代谢能(P＜0.05),在生长后期(38~42日龄)对肉鸡的粗蛋白质的消化利用率和表观代谢能提高达到显著水平(P ＜0.05)。因此,高剂量不同水平的植酸酶显著提高肉鸡AME和粗蛋白质、钙、磷的消化利用率,添加高水平植酸酶可以适当调低日粮能量和蛋白质水平,日粮中总磷(tP)水平应低于NRC标准,减少无机磷和钙的添加量,以提高钙、磷在体内的存留量。     

非淀粉多糖(NSP)酶与植酸酶在肉仔鸡玉米-豆粕型日粮中互作效应的研究

试验选择一日龄的AA+肉仔鸡384只,按体重相近、性别各半的原则,随机分成8组,每组设6个重复,每个重复12只。设计两组4×2的全因子试验,NSP酶(0、50、100、150 mg/kg)和植酸酶(0、100 mg/kg)。试验结果表明,在肉鸡玉米-豆粕型日粮中添加NSP酶、植酸酶,能显著提高饲料转化率,增加日增重;饲粮中添加植酸酶可显著提高肉鸡对钙、磷、灰分的利用,NSP酶不影响日粮中的钙、磷、灰分的利用率;饲粮中添加NSP酶、植酸酶,提高了粗蛋白利用率,但差异不显著(P>0.05);植酸酶显著提高了赖氨酸、苏氨酸、缬氨酸、亮氨酸、酪氨酸、苯丙氨酸、组氨酸的利用率;在肉鸡日粮中添加NSP酶、植酸酶显著提高肉鸡对饲粮的表观代谢能的利用率,并且NSP酶和植酸酶对玉米-豆粕型的饲粮能量利用呈现协同作用。     

肉鸡饲粮能量水平对植酸酶作用效果的影响

试验选用324只1日龄AA肉鸡(公鸡),采用3×2因子设计,研究在不同能量水平的饲粮中添加植酸酶对肉鸡生长性能和养分利用率的影响。试验设3个能量水平(12.33、12.13、12.03MJ/kg)和2个酶水平(0、500FTU/kg),共计6个处理组,每个处理组6个重复,每个重复9只鸡,试验期42d。结果表明:饲粮添加植酸酶显著(P<0.05)或极显著(P<0.01)提高了肉鸡日增重、采食量,改善了饲料利用率,提高了干物质、粗蛋白、钙、磷的利用率,但对能量利用率没有明显影响(P>0.05);降低饲粮能量水平极显著降低了肉鸡对干物质、能量、钙的利用率(P<0.01),显著降低了其对磷的利用率(P<0.05),但对生产性能和粗蛋白利用率没有显著影响(P>0.05);植酸酶和能量对肉鸡饲料利用率、干物质和钙的利用率存在显著的交互作用(P<0.05),表现为处理2组能量水平条件下添加植酸酶在生长性能和养分利用率上改善幅度最大,表明植酸酶在适宜降低能量水平的饲粮中的作用效果更好。试验中,以能量水平为12.13MJ/kg的肉公鸡饲粮中添加500FTU/kg植酸酶(处理5组)为最佳组合。     

微生物植酸酶对猪钙、磷利用率及骨骼发育的影响

本试验旨在研究从断奶到肥育结束,在饲粮中添加微生物植酸酶对猪钙、磷代谢及骨骼发育的影响。试验采用完全随机设计,将72头35日龄断奶的仔猪分为4组,每组3个重复,每个重复6头。试验在相同钙水平基础上设4个组,分别为:1)玉米-豆粕基础日粮(对照组);2)基础日粮 植酸酶-50%磷酸氢钙(处理1);3)基础日粮 植酸酶-75%磷酸氢钙(处理2);4)基础日粮 植酸酶-100%磷酸氢钙(处理3)。试验期按体重分3个阶段:8~20 kg、20~50 kg、50~90 kg,3个阶段植酸酶的添加量分别为750、500和250 U/kg。试验结果表明:(1)在8~20 kg和20~50 kg阶段,添加植酸酶的3个处理,钙、磷消化率显著高于对照组(P<0.05);血钙和血磷浓度,处理1和处理2与对照组无显著差异(P>0.05),处理3显著低于对照组(P<0.05)。在50~90 kg阶段,添加250 U/kg植酸酶代替100%磷酸氢钙,血磷、血钙浓度显著低于对照组(P<0.05);(2)在试验的3个阶段添加植酸酶同时降低饲粮无机磷水平,对血清碱性磷酸酶活性均无显著影响(P>0.05);(3)添加植酸酶使胃中植酸磷消化率显著提高(P<0.0 1),粪中磷排出量显著降低(8~2 0 kg、2 0~5 0 kg阶段,P<0.0 1;5 0~9 0 kg阶段,P<0.0 5);(4)添加植酸酶代替50%或75%磷酸氢钙,猪的掌骨灰分与采食正常磷日粮的对照组无显著差异,但代替100%磷酸氢钙组,猪的掌骨灰分和蹠骨强度则显著低于对照组(P<0.05);添加植酸酶代替50%磷酸氢钙组,猪的蹠骨强度显著高于对照组(P<0.05),代替75%磷酸氢钙组与对照组差异不显著(P>0.05)。总之,在断奶和生长阶段,在猪玉米-豆粕日粮中添加植酸酶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。     

不同能量和非植酸磷水平下植酸酶对肉仔鸡生产性能和胫骨矿化的影响

试验选用640只1日龄爱拔益加(AA)肉仔鸡公雏,采用2×2×2因子设计,通过在不同能量水平(11.90、11.70 MJ/kg)和非植酸磷(NPP)水平(0~3周0.35%,0.25%;3~6周0.30%,0.20%)的肉鸡饲粮中添加植酸酶0、500 FTU/kg,考察了植酸酶对肉鸡生产性能和胫骨矿化的影响。试验共8个处理,每个处理8个重复,每个重复10只鸡,试验期42 d。结果表明:(1)饲粮添加植酸酶降低了肉仔鸡前期的平均日采食量(ADFI)和全期的料重比(F/G)(P<0.05),分别下降2.52%、1.81%;降低了前期胫骨灰分(P<0.05)、后期胫骨Ca(P<0.05)和P含量(P<0.01);但对日增重无显著影响(P>0.05)。(2)植酸酶与饲粮能量和NPP水平对生产性能没有显著的交互作用(P>0.05);植酸酶和能量对前期胫骨Ca、P和后期胫骨Ca含量存在极显著的交互作用(P<0.01),表现为低能加酶组前后期胫骨Ca含量极显著高于低能组,但前期胫骨P含量极显著低于低能组。结论:以生产性能为标识,本试验条件下低磷或低能或低磷低能日粮添加植酸酶可以获得和对照组相似的生产性能。     

植酸酶对产蛋高峰期蛋鸡生产性能及主要营养素存留的影响

在分别含非植酸磷为０．３７％,０．３７％,０．２７％和０．１７％的四种（ＣＬ,Ｔ１,Ｔ２和Ｔ３）等钙（３．７５％）蛋鸡（２５￣３５周龄）日粮中,Ｔ１,Ｔ２和Ｔ３均添加５００Ｕ／ｋｇ植酸酶。结果,主要营养素（干物质、氮、灰分、钙、磷）的存留率显著提高。当非植酸磷水平降到０．１７％时,不影响产蛋量和蛋品质。     

The apparent digestibility of phytate phosphorus and the influence of supplemental phytase in horses

Availability of phytate-bound P as influenced by supplemental phytase was studied in eight horses consuming four diets in a 4 x 4 Latin square design experiment. The treatments were a control (containing a low P level, 18.4 g/d) and three high-P diets. These diets contained P as monocalcium phosphate (MCP; 43.7 g/d), myoinositol hexakisphosphate in the form of wheat and rice bran (MIHP; 41.8 g/d), or MIHP with microbial phytase (MIHPP; 42.5 g/d). The proportions of phytate-bound P were 3, 1, 55, and 56% for the control, MCP, MIHP, and MIHPP, respectively. The MIHPP diet was supplemented with 300 phytase units (FTU)/kg (as-fed basis). Feces and urine were collected quantitatively and analyzed for P, Ca, and Mg. Urinary P excretion was lower (P < 0.05) with the control diet (0 g of P/d) than with the MCP diet (1.0 g of P/d). The low urinary P excretion (0.3 g of P/d) for the MIHP diet suggested low P availability compared with the MCP diet, but apparent digestibility of P expressed as a percentage of intake did not differ (P = 0.065) between these diets. Apparent Ca digestibility was lower (P < 0.05) for the MIHP diet than for the MCP diet (26.4 vs. 42.4%). This difference may have been caused by the origin of the Ca in these diets. Phytase supplementation increased apparent Ca digestibility from 26.4 to 31.5% (P < 0.05). Magnesium was not influenced by the level of phytate in the diet. Our data indicate that phytase supplementation had more influence on Ca digestibility than on P digestibility and suggest that phytase supplementation may be beneficial for improving Ca digestibility for horses receiving a phytate-rich diet.     

Effects of microbial phytase on growth and mineral utilisation in broilers fed on maize soyabean-based diets.

1. A 3-week feeding trial with 96 sexed d-old broiler chickens was conducted to examine the effects of microbial phytase supplementation (Natuphos 5000) at 2 dietary energy concentrations on their performance, and the utilisation of nitrogen (N), phosphorus (P), calcium (Ca) and zinc (Zn) and on tibiae ash, Ca, P and Zn concentrations. Four replicate pens (6 birds per pen) of a completely randomised design were used in a 2x2 factorial arrangement of treatments with 2 contents of metabolisable energy (11.72 and 12.55 MJ ME/kg) and 2 additions of phytase (0 and 500 U of microbial phytase/kg). 2. Phytase supplementation significantly improved the utilisation of N, P, Ca and Zn (as a percentage of intake) and increased the concentration of Ca and Zn in the tibiae (P<0.05) because of higher intakes of dry matter, N, P, Ca and Zn. Phytase also significantly reduced the amount of P in the excreta (P<0.05). 3. The AME content of the diet influenced significantly (P<0.05) the excretion of N, P, Ca and Zn and the concentration of P and Ca in tibiae with the birds fed on the high AME diet excreting more minerals and having a smaller percentage of these minerals in their tibiae. However, there were strong interactions between phytase addition and AME in tibia ash and P, with the phytase supplementation producing a higher ash content at the higher AME a and a lower P content at the lower AME.     

Formulation of diets for pigs based on a ratio between digestible calcium and digestible phosphorus results in reduced excretion of calcium in urine without affecting retention of calcium and phosphorus compared with formulation based on values for total calcium

An experiment was conducted to test the hypothesis that formulating diets for pigs based on a ratio between standardized total tract digestible (STTD) Ca and STTD P instead of total Ca and STTD P does not decrease Ca retention, but increases P utilization. Forty barrows (59.4 ± 3.8 kg) were individually housed in metabolism crates and allotted to four corn-soybean meal-based diets in a randomized complete block design with two blocks and five pigs per diet in each block. Diets were formulated using a 2 × 2 factorial design with two diet formulation principles (total Ca or STTD Ca) and two inclusion levels of microbial phytase (0 or 500 units per kg of feed). Phytase was assumed to release 0.11% STTD P and 0.16% total Ca. Diets were formulated based on requirements for total Ca and STTD P or a ratio between STTD Ca and STTD P of 1.25:1. Diets were fed for 11 d and fecal and urine samples were collected from feed provided from day 6 to day 10. Interactions (P < 0.05) between diet formulation principle and phytase level were observed for Ca intake, Ca in feces, Ca absorbed, Ca retained, P digestibility, P absorbed, and P in urine. Phytase increased (P < 0.05) the digestibility of Ca in both total Ca and STTD Ca diets. Without phytase, Ca intake, Ca in feces, and Ca absorbed was greater (P < 0.05) from pigs fed total Ca diets than from pigs fed STTD Ca diets, but P absorbed, P digestibility, and P in urine was greater (P < 0.05) from pigs fed STTD Ca diets than from pigs fed total Ca diets. However, in the presence of phytase, no differences between diet formulation principles were observed in these variables. Regardless of phytase, Ca in urine was lower (P < 0.05) from pigs fed STTD Ca diets than from pigs fed total Ca diets. There were no differences in Ca retention between pigs fed STTD Ca diets and total Ca diets, but pigs fed total Ca diets retained less (P < 0.05) Ca if diets contained phytase. No differences in P retention were observed between diet formulation principles, but pigs fed non-phytase diets retained more (P < 0.05) P than pigs fed diets with phytase. In conclusion, because diets formulated based on STTD Ca contain less Ca than total Ca diets, pigs fed STTD Ca diets excreted less Ca in urine, but retention of Ca was not affected. Formulating non-phytase diets based on STTD Ca instead of total Ca increased P absorption, which confirms the detrimental effect of excess Ca on P digestibility. However, P retention was not improved if pigs were fed STTD Ca diets.     

Formulating diets based on digestible calcium instead of total calcium does not affect growth performance or carcass characteristics,but microbial phytase ameliorates bone resorption caused by low calcium in diets fed to pigs from 11 to 130 kg

An experiment was conducted to test the hypothesis that the requirement for Ca expressed as a ratio between standardized total tract digestible (STTD) Ca and STTD P obtained in short-term experiments may be applied to pigs fed diets without or with microbial phytase from 11 to 130 kg. In a 5-phase program, 160 pigs (body weight: 11.2 ± 1.8 kg) were randomly allotted to 32 pens and 4 corn–soybean meal-based diets in a 2 × 2 factorial design with 2 diet formulation principles (total Ca or STTD Ca), and 2 phytase inclusion levels (0 or 500 units/kg of feed) assuming phytase released 0.11% STTD P and 0.16% total Ca. The STTD Ca:STTD P ratios were 1.40:1, 1.35:1, 1.25:1, 1.18:1, and 1.10:1 for phases 1 to 5, and STTD P was at the requirement. Weights of pigs and feed left in feeders were recorded at the end of each phase. At the conclusion of phase 1 (day 24), 1 pig per pen was euthanized and a blood sample and the right femur were collected. At the end of phases 2 to 5, a blood sample was collected from the same pig in each pen. At the conclusion of the experiment (day 126), the right femur of 1 pig per pen was collected and carcass characteristics from this pig were measured. No interactions were observed between diet formulation principle and phytase inclusion for growth performance in any phase and no differences among treatments were observed for overall growth performance. Plasma Ca and P and bone ash at the end of phase 1 were also not influenced by dietary treatments. However, on day 126, pigs fed nonphytase diets formulated based on total Ca had greater bone ash than pigs fed STTD Ca-based diets, but if phytase was used, no differences were observed between the 2 formulation principles (interaction P < 0.05). At the end of phases 2 and 3, pigs fed diets without phytase had greater (P < 0.05) plasma P than pigs fed diets with phytase, but no differences were observed at the end of phases 4 and 5. A negative quadratic effect (P < 0.05) of phase (2 to 5) on the concentration of plasma Ca was observed, whereas plasma P increased (quadratic; P < 0.05) from phases 2 to 5. However, there was no interaction or effect of diet formulation principle or phytase inclusion on any carcass characteristics measured. In conclusion, STTD Ca to STTD P ratios can be used in diet formulation for growing-finishing pigs without affecting growth performance or carcass characteristics and phytase inclusion ameliorates bone resorption caused by low dietary Ca and P.     

Nutrient digestibility and performance responses of growing pigs fed phytase- and xylanase-supplemented wheat-based diets

Three experiments were conducted to evaluate the effect of supplementing phytase and xylanase on nutrient digestibility and performance of growing pigs fed wheat-based diets. In Exp. 1, 10 diets were fed to 60 pigs from 20 to 60 kg of BW to determine the effect of combining phytase and xylanase on apparent total tract digestibility (ATTD) of nutrients and growth performance. The 10 diets included a positive control diet (PC; 0.23% available P; 0.60% Ca) and a negative control diet (NC; 0.16% available P; 0.50% Ca) supplemented with phytase at 0, 250, and 500 fytase units (FTU)/kg and xylanase at 0, 2,000, and 4,000 xylanase units (XU)/kg in a 3 x 3 factorial arrangement. In Exp. 2, 6 ileally cannulated barrows (initial BW = 35.1 kg) were fed 4 wheat-based diets in a 4 x 4 Latin square design, with 2 added columns to determine the effect of combining phytase and xylanase on apparent ileal digestibility (AID) of nutrients. The 4 diets were NC (same as that used in Exp. 1) or NC supplemented with phytase at 500 FTU/kg, xylanase at 4,000 XU/kg, or phytase at 500 FTU/kg plus xylanase at 4,000 XU/kg. In Exp. 3, 36 barrows (initial BW = 55.5 kg) were fed 4 diets based on prepelleted (at 80 degrees C) and crumpled wheat for 2 wk to determine the effect of phytase supplementation on ATTD of nutrients. The 4 diets fed were a PC (0.22% available P; 0.54% Ca) and a NC (0.13% available P; 0.43% Ca) alone or with phytase at 500 or 1,000 FTU/kg. All diets in the 3 experiments contained Cr(2)O(3) as an indigestible marker. No synergistic interactions were detected between phytase and xylanase on any of the response criteria measured in Exp. 1 or 2. There were no dietary effects on growth performance in Exp. 1. In Exp. 1, phytase at 250 FTU/kg increased the ATTD of P and Ca by 51 and 11% at 20 kg of BW or by 54 and 10% at 60 kg of BW, respectively, but increasing the level of phytase to 500 FTU/kg only increased (P < 0.05) ATTD of P at 20 kg of BW. In Exp. 2, phytase at 500 FTU/kg increased (P < 0.05) the AID of P and Ca by 21 and 12%, respectively. In Exp. 3, phytase at 500 FTU/kg improved (P < 0.05) ATTD of P by 36%, but had no further effect at 1,000 FTU/kg. Xylanase at 4,000 XU/kg improved (P < 0.05) AID of Lys, Leu, Phe, Thr, Gly, and Ser in Exp. 2. In conclusion, phytase and xylanase improved P and AA digestibilities, respectively, but no interaction between the 2 enzymes was noted.     

Effects of a New Recombinant Phytase on the Performance and Mineral Utilization of Broilers Fed Phosphorus-Deficient Diets

An experiment was conducted with Arbor Acres broiler chickens that were fed 3 experimental diets—a control diet containing an adequate level of available phosphorus (AP) and 2 diets that were deficient in AP but supplemented with phytase at a level of either 500 or 750 phytase units/kg—to assess the effects of a novel microbial phytase supplement in broilers fed AP-deficient diets on growth performance and mineral utilization. Similar average daily gain, feed intake, and feed efficiency (P > 0.05) were obtained among broilers fed different diets. Compared with broilers fed the control diet, broilers fed diets with phytase had greater (P < 0.05) retention of Ca, P, and Zn. Moreover, the levels of Cu, Zn, Mg, and Mn in the tibia bone at 28 d of age, and Zn and Mn at 42 d of age in birds fed diets with phytase exceeded (P < 0.05) those of birds fed the control diet. Supplementation of phytase increased Zn and Mg contents in the plasma at 42 d of age. Birds responded similarly to phytase supplemented at a level of 500 or 750 phytase units/kg in terms of growth performance, mineral retention, and mineral content in the serum and bone. Therefore, with the supplementation of this novel phytase, it is possible to reduce the dietary levels of P and other minerals to below the recommended levels of the Feeding Standard of Chicken in P. R. China (ZB B 43005-86).     

葡萄糖酸钠和植酸酶对1～3周龄肉鸡磷利用的影响

用350只1周龄的Arbor Acres(AA)商品肉公鸡进行试验,采用2×3＋1试验设计,其中葡萄糖酸钠2个水平（0.2%）,植酸酶3个水平（0.500、1000 U/kg）,另有一满足NRC钙、磷需要的正常日粮,共7个处理,每个处理5个重复,每个重复10只鸡。研究玉米-豆粕型低磷日粮中添加葡萄糖酸钠和植酸酶对肉鸡磷利用的影响。试验期1～3周。结果表明,在低磷日粮中添加葡萄糖酸钠显著提高了肉鸡的钙（P=0.003）和磷（P<0.001）的表观存留率,降低了血清碱性磷酸酶活性（P=0.038）;植酸酶提高了肉鸡的胫骨灰分重量（P<0.001）、钙（P=0.005）和磷（P<0.001）的表观存留率。在胫骨灰分重量（P=0.030）和磷表观存留率（P=0.008）上,葡萄糖酸钠和植酸酶存在互作。