小麦-杂粕型饲粮中添加木聚糖酶和植酸酶对肉仔鸡生长及饲料利用的影响

为了探讨小麦和菜籽粕等非常规饲料资源在肉仔鸡生产中的应用,并降低磷添加水平以减少环境污染,试验选取体重相近的1日龄柳州麻花鸡150只,随机分成4组:对照组、木聚糖酶组、低磷植酸酶组、低磷复合酶组,各组雏鸡分别饲喂基础饲粮(小麦-杂粕型饲粮)、基础饲粮+木聚糖酶1 000 U/kg、75%有效磷基础饲粮+植酸酶900 U/kg、75%有效磷基础饲粮+植酸酶900 U/kg+木聚糖酶1 000 U/kg。每组设3个重复,每个重复10～15只鸡,试验期21 d。测定每组鸡的采食量和体重,计算每组鸡的日增重、日均采食量、料重比。结果:基础饲粮+木聚糖酶1 000 U/kg可显著提高肉仔鸡的体重和日增重(P0.05);75%有效磷基础饲粮+植酸酶900 U/kg的肉仔鸡增重、采食量和饲料转化率与对照组相近(P0.05);75%有效磷基础饲粮+植酸酶900 U/kg+木聚糖酶1 000 U/kg并不能进一步促进肉仔鸡生长和提高饲料转化率。结论:在小麦-杂粕型饲粮中添加木聚糖酶1 000 U/kg可显著提高肉仔鸡生长性能;植酸酶900 U/kg可替代饲粮中25%有效磷,而不影响肉仔鸡生长。     

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。     

非淀粉多糖酶和植酸酶对肉仔鸡生长性能和养分利用性的影响

以 8 8 8只艾维因肉仔鸡为试验动物 ,研究添加非淀粉多糖酶 (40 0mg/kg)和植酸酶 (30 0mg/kg)对肉仔鸡的生长性能和养分利用性的影响。试验结果表明 :玉米 -菜粕 -豆粕日粮中添加非淀粉多糖酶 (减少 1.4 %AME)和植酸酶(减少 0 .0 8%非植酸磷 ) ,甚至再减少 0 .0 1%赖氨酸 ,都不会显著影响肉仔鸡 4 2日龄体重 (P >0 .0 5 ) ,但饲料转化率得到改善 ,死亡率降低。添加非淀粉多糖酶可提高AME和TME(P >0 .0 5 )和氮沉积量和氮表观消化率 (P >0 .0 5 )。非淀粉多糖酶对总磷的消化率没有显著影响 (P >0 .0 5 ) ,但同时添加非淀粉多糖酶和植酸酶 (减少 0 .0 8%非植酸磷 ) ,可显著提高总磷的表观消化率和真消化率分别为 16和 16 .1个百分点 (P <0 .0 5 )。     

新型耐热植酸酶对肉仔鸡营养物质表观消化率及胫骨灰分含量的影响

试验在低磷日粮中分别添加普通植酸酶与耐高温植酸酶,研究两种植酸酶对肉仔鸡营养物质表观消化率及胫骨灰分含量的影响。选用4 800只1日龄AA肉仔鸡,随机分为6个处理,每个处理设5个重复。试验分2期进行,1~3周和4~6周。对照组饲喂基础日粮,处理1组降低基础日粮的磷水平,处理2组与处理3组分别在其基础上添加普通植酸酶500、2 000 U/kg,处理4组和处理5组分别添加耐高温植酸酶250、500 U/kg。结果表明:①当降低基础日粮中磷添加水平时,降低了磷的表观消化率;在此基础上添加500~2 000 U/kg普通植酸酶或250~500 U/kg耐热植酸酶,显著提高了磷的表观消化率,且超过了对照组,其中以250~500 U/kg耐热植酸酶与2 000 U/kg普通植酸酶效果理想。降低磷添加水平或添加不同来源植酸酶对粗蛋白质和钙的表观消化率基本没有影响;②当降低基础日粮中磷添加水平时,显著降低了胫骨灰分和磷的含量(P<0.05),同时钙含量呈降低趋势(P>0.05);在此基础上添加500~2 000 U/kg普通植酸酶或250~500 U/kg耐热植酸酶,胫骨灰分和钙、磷的含量恢复到或超出对照组水平。     

菜粕型日粮添加植酸酶和木聚糖酶对肉鸡生长性能及小肠氨基酸和矿物质元素表观消化率的影响

试验旨在研究菜粕型日粮中添加植酸酶和木聚糖酶对肉鸡生长性能,小肠氨基酸、矿物质元素表观消化率的影响。选取健康、体重一致的1 d雌性AA商品代肉仔鸡480只,采用完全随机设计分为4个组,每组6个重复,每个重复20羽。对照组饲喂菜粕型日粮,处理组分别在对照组日粮基础上添加650 U/kg植酸酶、1500 U/kg木聚糖酶及1000 U/kg植酸酶和2000 U/kg木聚糖酶复合物。结果显示:各处理组对21 d肉鸡日均采食量和日增重均无显著差异(P0.05)。木聚糖酶组和木聚糖酶+植酸酶组较其他两组显著提高了空肠内容物停留时间(P0.05)。木聚糖酶组和木聚糖酶+植酸酶组显著提高钙、磷、钠、锌、镁、锰和铜回肠表观消化率(P0.05)。植酸酶和木聚糖酶复合组较其他各组显著提高了十二指肠和空肠氮消化率(P0.05)。木聚糖酶+植酸酶组较其他三组显著提高了回肠氨基酸表观消化率(P0.05)。结果表明:在本研究中,植酸酶和木聚糖酶在菜粕型日粮中应用对肉鸡的生长性能和营养物质消化率具有促进作用。木聚糖酶可以提高矿物质的消化率,这对肉鸡日粮中使用较多比例的菜粕具有优势作用。     

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。     

饲粮中植酸酶、钙、磷不同水平组合对肉仔鸡生长和屠宰性能的影响

利用正交实验[L(934)]把270只艾维茵肉仔鸡随机分为9组,研究植酸酶、非植酸磷和钙水平的不同组合对艾维茵肉仔鸡生长性能、死淘率、屠宰性能及肉品质的影响。结果表明,添加非植酸磷0.18%+钙0.8%组肉仔鸡生长最差,全部发生腿病,并于试验中期死亡或被淘汰;在非植酸磷0.18%+钙0.65%组的饲粮中添加植酸酶600FTU/kg,一定程度上改善了肉仔鸡的生长发育,但日增重仍较差,且死淘率较高;而添加植酸酶1200FTU/kg+非植酸酶0.18%+钙1.00%的组合显著降低了肉仔鸡的食欲与生长发育速度,腿病发生率和死淘率仍较高。饲粮中添加非植酸磷0.28%+不添加植酸酶+钙1.00%组仔鸡生长很差、死淘率较高;添加植酸酶600FTU/kg+非植酸磷0.28%+钙0.80%的组生长效果良好,而非植酸磷0.28%+钙0.65%+植酸酶1200FTU/kg组并未进一步提高生长效果。饲粮非植酸磷为0.38%时的3个组合都表现出较佳的日增重,说明非植酸磷0.38%能满足仔鸡需要。试验处理对仔鸡屠宰性能与肉品质未产生明显影响。饲粮中添加非植酸磷0.28%+钙0.80%+植酸酶600FTU/kg时,肉仔鸡的综合效益较佳。     

不同植酸酶的热稳定性和生物学活性比较

试验评定了3种植酸酶产品的制粒稳定性,并通过动物试验评价了其在肉仔鸡日粮中的生物学活性。1日龄AA肉仔鸡770只,随机分为11个处理,分别采食添加不同剂量植酸酶(500、1 0002、000 U/kg)的低磷日粮。结果表明,产品A植酸酶的热稳定性明显优于产品B和产品C。在90℃和95℃制粒,产品A的存留率分别为96.3%和90.7%;产品B和C的存留率分别为26.4%、24.2%和12.6%、14.2%。采食低磷负对照日粮的肉仔鸡生长性能显著低于正对照日粮组(P<0.05)。在低磷日粮中添加植酸酶显著提高了肉仔鸡生长性能(P<0.05);肉仔鸡的生产性能随植酸酶的添加量增加而提高,植酸酶产品A趋势明显,添加量由500 U/kg提高到1 000 U/kg和2 000 U/kg,肉仔鸡体增重分别提高3.7%和6.1%,料重比降低3.5%和5.0%。根据配方中植酸磷的含量,植酸酶的添加量可由传统的500 U/kg提高到1 000 U/kg及以上。     

木聚糖酶对肉仔鸡养分利用和消化器官发育的影响

本试验研究了小麦型饲粮中添加木聚糖酶对肉仔鸡养分利用及消化器官发育的影响.将240只1日龄爱拔益加肉仔鸡随机分为4个处理,每个处理5个重复,每个重复12只鸡,分别饲喂在含40%小麦的饲粮中添加不同水平木聚糖酶(0、500、1 000和5 000 U/kg)的试验饲粮.试验期21 d.结果表明,木聚糖酶对17～21日龄肉仔鸡粗蛋白质、钙及总磷利用率及粪便含水率无显著影响(P>0.05);趋于提高17～21日龄肉仔鸡干物质利用率(P=0.093)及表观代谢能值(P=0.110);各组肉仔鸡养分表观利用率无显著差异(P>0.05).添加木聚糖酶未显著影响21日龄肉仔鸡小肠、胃、胰腺和脾脏相对重量(P>0.05).1 000 U/kg酶组显著降低了21日龄肉仔鸡回肠相对长度(P<0.05).木聚糖酶对21日龄肉仔鸡胫骨干重、长度、灰分及磷含量无显著影响(P>0.05).本研究表明:含40%小麦的肉仔鸡饲粮中添加不同水平的木聚糖酶对肉仔鸡养分利用及大部分肠道器官发育均未产生显著作用;超量添加对肉仔鸡养分利用无进一步改善作用,也未产生负面影响.     

植酸和有效磷水平对植酸酶作用效果的影响

900只7日龄肉鸡，试验期19天，小麦－高粱－豆粕型日粮。试验设计为3×2×3，即3个植酸水平，2个有效磷水平，3个酶他富植酸酶水平。试验结果表明：肉鸡的生产性能和蛋白质、氨基酸的消化率随植酸含量增加而降低．。添加植酸酶可提高肉鸡日增重、饲料报酬、表观代谢能、磷、蛋白质和氨基酸的消化率以及干物质和氮的沉积。     

Effect of increasing supplemental phytase concentration in diets fed to Hubbard × Cobb 500 male broilers from 1 to 42 days of age

Phytase supplementation beyond the standard doses used for phosphorus release has been reported to result in extraphosphoric effects by enhancing nutrient digestibility resulting in improved performance of broilers. A study was conducted to examine the effects of the progressive addition of an enhancedEscherichia Coli phytase (400–1,600 phytase units; FTU) on growth performance and carcass characteristics from 1 to 42 d of age in male broilers. One thousand four hundred Hubbard × Cobb 500 1-d-old chicks were randomly distributed into 56 floor pens (0.08 m²/bird). Seven dietary treatments were provided in a 3-phase feeding program consisting of (1) a positive control (adequate Ca and nonphytate P; PC); (2) 1 negative control (Ca and nonphytate P reduced by 0.14% and 0.13%; NC); (3 to 6) the NC diet with 4 increasing supplemental phytase concentrations (NC + 400 FTU, NC + 800 FTU, NC + 1,200 FTU, and NC + 1,600 FTU, respectively); and (7) a low-energy NC diet without phytase and xylanase (reduced 66 kcal of AME_n/kg). Body weight gain, feed conversion, mortality, weight and yield of whole carcass, abdominal fat, and pectoralis major and minor muscles were evaluated. Progressive supplementation of phytase decreased cumulative FCR linearly. Broilers fed diets containing 1,600 FTU had heavier total breast meat by 49 g compared with birds receiving the PC diets. Broilers consuming the NC + 400 FTU or the low-energy NC diet had similar growth performance and meat yield compared with birds provided PC diet. These data indicated that phytase supplementation beyond the need for phosphorus enhances growth performance and carcass characteristics.     

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.     

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.     

Supplementation of carbohydrases or phytase individually or in combination to diets for weanling and growing-finishing pigs

The overall objective of the studies reported here was to evaluate the growth and nutrient utilization responses of pigs to dietary supplementation of phytate- or nonstarch polysaccharide-degrading enzymes. In Exp. 1, growth performance and nutrient digestibility responses of forty-eight 10-kg pigs to dietary supplementation of phytase or a cocktail of xylanase, amylase, and protease (XAP) alone or in combination were evaluated. The growth response of one hundred fifty 23-kg pigs to dietary supplementation of phytase or xylanase individually or in combination was studied in Exp. 2 in a 6-wk growth trial, whereas Exp. 3 investigated the nutrient digestibility and nutrient retention responses of thirty 24-kg pigs to dietary supplementation of the same enzymes used in Exp. 2. In Exp. 1, the pigs were used in a 28-d feeding trial. They were blocked by BW and sex and allocated to 6 dietary treatments. The treatments were a positive control (PC) diet; a negative control (NC) diet marginally deficient in P and DE; NC with phytase added at 500 or 1,000 phytase units (FTU)/kg; NC with xylanase at 2,500 units (U)/kg, amylase at 400 U/kg, and protease at 4,000 U/kg; and NC with a combination of phytase added at 500 FTU/kg and XAP as above. In Exp. 2 and 3, the 5 dietary treatments were positive control (PC), negative control (NC), NC plus 500 FTU of phytase/kg, NC plus 4,000 U of xylanase/kg, and NC plus phytase and xylanase. In Exp. 1, low levels of nonphytate P and DE in the NC diet depressed (P < 0.05) ADG of the pigs by 16%, but phytase linearly increased (P < 0.05) ADG by up to 24% compared with NC. The cocktail of XAP alone had no effect on ADG of pigs, but the combination of XAP and phytase increased (P < 0.05) ADG by 17% compared with the NC treatment. There was a linear increase (P < 0.01) in Ca and P digestibility in response to phytase. In Exp. 2, ADG was 7% greater in PC than NC (P < 0.05); there were no effects of enzyme addition on any response. In Exp. 3, addition of phytase alone or in combination with xylanase improved (P < 0.05) P digestibility. Phosphorus excretion was greatest (P < 0.01) in the PC and lowest (P < 0.05) in the diet with the combination of phytase and xylanase. The combination of phytase and xylanase improved P retention (P < 0.01) above the NC diet to a level similar to the PC diet. In conclusion, a combination of phytase and carbohydrases improved ADG in 10-kg but not 23-kg pigs, but was efficient in improving P digestibility in pigs of all ages.     

Effects of step-up and step-down phytase regimens on performance and processing yields of male broilers from 1 to 35 d of age

An experiment was conducted to evaluate increasing or decreasing concentrations of dietary phytase on growth performance and processing yields of male broilers from 1 to 35 d of age. Treatments consisted of a positive control, a negative control (NC; less 0.14% Ca, 0.13% nonphytate P, and 0.03% Na), and 6 additional treatments based on the NC supplemented with phytase. Treatments 3 through 5 consisted of the NC diet supplemented with 500 phytase units (FTU)/kg of phytase in the starter phase that was either continued throughout the remainder of the study (treatment 3) or increased to 1,500 FTU/kg beginning in the finisher (treatment 4) or grower (treatment 5) phases. Treatment 6 had 1,500 FTU/kg of phytase throughout the study. Treatments 7 and 8 had 1,500 FTU/kg in the starter and decreased to 500 FTU/kg in the finisher or grower phases, respectively. At 35 d of age, broilers fed diets containing 1,500 FTU/kg of phytase had increased BW gain compared with birds fed diets formulated to contain 500 FTU/kg of phytase. Increasing phytase concentration between the starter and grower phases or decreasing phytase concentration between the grower and finisher phases negatively affected FCR from 1 to 35 d of age. Phytase supplementation did not affect weight and yield of carcass characteristics. Therefore, dietary phytase concentration should not be varied throughout production for optimum growth performance.     

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.     

High dietary phytase levels maximize phytate-phosphorus utilization but do not affect protein utilization in chicks fed phosphorus- or amino acid-deficient diets

Four trials investigated the effect of high levels of three phytase enzymes on P and protein utilization in chicks. The three phytases were derived from Aspergillus (Fungal Phytase 1), Peniophora (Fungal Phytase 2), and E. coli. Within each assay, 8-d-old male chicks were given ad libitum access to their experimental diet for 10 to 14 d. For Trials 1, 2, and 3, the basal diet was a corn-soybean meal diet deficient in P that was analyzed to contain 23% CP and 0.38% total P (0.10% estimated available P, as-fed basis). Phytase supplementation levels were based on the assessment of phytase premix activity (i.e., P release from Na phytate at pH 5.5 and 37 degrees C). In Trial 1, supplementation of inorganic P from KH2PO4 (0 to 0.20%) resulted in a quadratic (P < 0.05) response in weight gain, gain:feed, and tibia ash concentration but a linear (P < 0.01) increase in tibia ash weight. Tibia ash was higher (P < 0.01) for chicks fed E. coli phytase than for those fed Fungal Phytase 1 at 500, 1,000, and 5,000 phytase units (FTU)/kg, but did not differ between these two phytases at 10,000 FTU/kg. In Trial 2, E. coli phytase supplementation at 1,000 FTU/kg maximized growth and bone responses, whereas addition of either of the two fungal phytases resulted in increasing responses up to 5,000 and 10,000 FTU/kg. Dietary addition of Fungal Phytase 2 resulted in the poorest (P < 0.01) responses among the three phytases. Escherichia coli phytase supplementation at 10,000 FTU/kg in Trial 3 resulted in tibia ash (millligrams) responses that were greater (P < 0.05) than those resulting from either 0.35% inorganic P supplementation or 10,000 FTU/kg of Fungal Phytase 1 or 2. Trial 4 showed that E. coli phytase supplementation at either 500 or 10,000 FTU/ kg did not improve protein efficiency ratio (gain per unit of protein intake) of chicks fed low-protein soybean meal or corn gluten meal diets that were first-limiting in either methionine or lysine, respectively. These results demonstrate that high dietary levels of efficacious phytase enzymes can release most of the P from phytate, but they do not improve protein utilization.     

The efficacy of an Escherichia coli-derived phytase preparation

Five experiments were conducted to evaluate the effect of an Escherichia coli-derived phytase on phytate-P use and growth performance by young pigs. The first experiment involved time course, pH dependence, and phytase activity studies to investigate the in vitro release of P from corn, soybean meal, and an inorganic P-unsupplemented corn-soybean meal negative control diet. In Exp. 2, which was designed to determine the efficacy of the E. coli-derived vs. fungal phytase-added diets at 0, 250, 500, 750, 1,000, or 1,250 FTU/kg (as-fed basis; one phytase unit or FTU is defined as the quantity of enzyme required to liberate 1 micromol of inorganic P/min, at pH 5.5, from an excess of 15 microM sodium phytate at 37 approximately C) and a positive control diet, eight individually penned 10-kg pigs per diet (12 diets, 96 pigs) were used in a 28-d growth study. The third experiment was a 10-d nutrient balance study involving six 13-kg pigs per diet (four diets, 24 pigs) in individual metabolism crates. In Exp. 4, eight pens (four pigs per pen) of 19-kg pigs per treatment were used in a 42-d growth performance study to examine the effect of adding the E. coli-derived phytase to corn-soybean diets at 0, 500, or 1,000 FTU/kg (as-fed basis) and a positive control (four diets, 128 pigs). In Exp. 5, six 19-kg pigs per treatment were used in a 10-d nutrient balance study to investigate the effects of the E. coli-derived phytase added to diets at 0, 250, 500, 750, or 1,000 FTU/kg (as-fed basis) and a positive control diet (six diets, 36 pigs). The in vitro study showed that the E. coli-derived phytase has an optimal activity and pH range of 2 to 4.5. Inorganic phosphate release was greatest for soybean meal, least for corn, and intermediate for the negative control diet. Dietary supplementation with graded amounts of E. coli-derived phytase resulted in linear increases (P < 0.05) in weight gain, feed efficiency, and plasma Ca and P concentrations in 10-kg pigs in Exp. 2. Phytase also increased P digestibility and retention in the 13-kg pigs in Exp. 3. In Exp. 4, dietary supplementation with E. coli-derived phytase resulted in linear increases (P < 0.05) in weight gain and feed efficiency of 19-kg pigs. Supplementation of the diets of 19-kg pigs with the E. coli-derived phytase also improved Ca and P digestibility and retention in Exp. 5. In the current study, the new E. coli-derived phytase was efficacious in hydrolyzing phytate-P, both in vitro and in vivo, in young pigs.     

The influence of phytase,pre-pellet cracked maize and dietary crude protein level on broiler performance via response surface methodology

Background: The reduction of crude protein levels in diets for broiler chickens may generate economic,environmental and flock welfare and health benefits; however, performance is usually compromised. Whole grain feeding and phytase may improve the utilization of reduced crude protein diets.Results: The effects of pre-pellet cracked maize(0, 15% and 30%) and phytase(0, 750 and 1500 FTU/kg) in isoenergetic maize-soy diets with three levels of crude protein(22%, 19.5% and 17%) were evaluated via a BoxBehnken response surface design. Each of 13 dietary treatments were offered to 6 replicate cages(6 birds/cage) of male Ross 308 broiler chicks from 7 to 28 d post-hatch. Model prediction and response surface plots were generated from experimental data via polynomial regression in R and only significant coefficients were included and discussed in the predicted models. Weight gain, feed intake and FCR were all influenced by pre-pellet cracked maize, phytase and crude protein level, where crude protein level had the greatest influence. Consequently, the reduction from 22% to 17% dietary crude protein in non-supplemented diets reduced weight gain, feed intake,relative gizzard weight, relative gizzard content and relative pancreas weight but improved FCR. However, the inclusion of 30% cracked maize to 17% crude protein diets restored gizzard weight and 1500 FTU phytase inclusion to 17% crude protein diets increased relative gizzard contents and pancreas weights. Cracked maize and phytase inclusion in tandem to 17% crude protein diets increased weight gain, feed intake and FCR; however, this FCR was still more efficient than broilers offered the non-supplemented 22% crude protein diet. Broilers offered the prepellet cracked maize and phytase inclusions reduced AME in 22% crude protein diets but improved AME by 2.92 MJ(14.16 versus 11.24 MJ; P 0.001) in diets containing 17% crude protein. Ileal N digestibility was greater in broilers offered diets with 17% crude protein than those offered the 22% crude protein diet; irrespective of phytase and pre-pellet cracked maize.Conclusion: Pre-pellet cracked maize and phytase inclusions will improve the performance of broilers offered reduced crude protein diets.     

Effects of Source of Inorganic Phosphorus and Phytase Supplementation on Performance, Physiological Parameters and Bone Mineralization in Broilers

The objective of this study was to eval- uate the effects of inorganic phosphorus source and phytase addition on performance, nutrient digestibility and bone mineralization in broiler chickens. In Exp. 1,150 two-day old, male broiler chicks were fed a corn-soybean meal basal diet supplemented with phos- phorus provided by dicalcium phosphate, tricalcium phosphate or defluorinated rock phosphate. Five cages containing 10 birds were allotted to each of the three treatments. In Exp. 2,120 three-day old, male broiler chicks were fed the basal diet from Exp. 1 supplemen- ted with 0,250,500 ,or 1,000 P-＇rU phytase per kg of diet. Six cages containing five chicks were allotted to each of the four treatments. In Exp. 1, there was no difference in weight gain, feed intake or feed conver- sion as a result of feeding the different sources of in- organic phosphorus. The digestibility of phosphorus was significantly lower （P =0.01 ） for chicks fed di- ets supplemented with tricalcium phosphate than for chicks fed the other two diets. However, despite the lower digestibility, serum phosphorus levels did not differ among the three treatments. For Exp. 2, feedconversion showed a linear improvement （P = 0.03 ） with increasing levels of phytase inclusion （ days 0 to 33 ）. Phytase supplementation resulted in linear increa- ses in the digestibility of dry matter （P = 0.02 ）, crude protein （ P --- 0.04 ） and energy （ P 〈 0.01 ）. Chicks fed 1,000 FTU/kg phytase had significantly higher bone calcium （ P = 0.05 ） and bone breaking strength （P = 0.04 ） than chicks fed the basal diet on day 33. In conclusion, the results of the current study indicated that the performance of birds fed diets sup- plemented with dicalcium phosphate, tricalcium phos- phate or defluorinated phosphate was similar and therefore production costs could be lowered by choo- sing the cheapest inorganic phosphorus source when formulating diets for poultry. When diets were formu- lated to meet dietary phosphorus requirements, the growth of broilers was not enhanced with phytase sup- plementation. However, increases in feed conversion and bone breaking strength and its potential to impact culling and mortality in broiler operations may be suf- ficient justification for the routine inclusion of phytase in diets fed to broilers.