植酸酶对中华绒螯蟹幼蟹生长、消化性能及物质利用率的影响

为探讨植酸酶对中华绒螯蟹(Eriocheir sinensis)幼蟹生长、消化性能及物质利用率的影响, 设计了6种配合饲料, 以不含植酸和植酸酶的组别为对照组(C), 在含有10 g/kg植酸的饲料中, 分别加入0、500、1000、1500 U/kg的植酸酶, 分别记为P0、P500、P1000、P1500和P2000。投喂初始体重为(4.34±0.05) g的幼蟹, 56d后称重并取样分析。结果发现: P0幼蟹增重率、特定生长率、蛋白质效率低于对照组, 饲料系数则高于对照组(P<0.05); 幼蟹增重率、特定生长率、蛋白质效率随着饲料中植酸酶含量的增加而升高, 在P2000达到最高, 且该组的饲料系数最低(P<0.05); P1500和P2000全蟹体磷含量显著高于P0 (P<0.05); 在P2000中, 幼蟹肝胰腺中胰蛋白酶、淀粉酶以及肠道胰蛋白酶活力达到最高(P<0.05); 中华绒螯蟹蛋白质消化率和磷透析率随着饲料中植酸酶含量的增加而逐渐升高, 其中P2000显著高于P0(P<0.05), 与对照组无显著差异(P>0.05); P2000幼蟹的氮、磷保留率最高(P<0.05)。以上结果表明, 在含有植酸的饲料中添加2000 U/kg的植酸酶, 能够显著提高幼蟹的生长和胰蛋白酶活力, 进而提高幼蟹对蛋白质的利用率, 降低饲料系数。此外, 植酸酶的添加也能有效提高幼蟹体磷含量和氮/磷保留率。     

不同添加方式植酸酶处理豆粕对牙鲆生长和饲料利用率的影响

以初始平均体重(2.02±0.02)g的牙鲆(Paralichthys olivaceus)为实验对象,进行为期70d的摄食生长实验,研究不同添加方式的植酸酶对牙鲆生长和饲料利用的影响。在5000.0g豆粕中添加2.5g植酸酶,然后用产朊假丝酵母(Candidautilis)进行发酵预处理,得到植酸酶预处理豆粕。共制作4种等氮等能(粗蛋白49.7%、总能20.9kJ/g)饲料,对照饲料主要以鱼粉为蛋白源;在对照饲料的基础上,用豆粕蛋白替代45%的鱼粉蛋白配制成豆粕组饲料;在每千克豆粕组饲料中添加1000IU植酸酶,配制成植酸酶组饲料;用植酸酶预处理豆粕蛋白替代45%的鱼粉蛋白配制成植酸酶预处理豆粕组饲料。结果表明,与对照组相比较,用豆粕蛋白替代饲料中45%的鱼粉蛋白,若不添加植酸酶则显著降低牙鲆的特定生长率(P0.01)、饲料效率、蛋白质效率和氮贮积率(P0.05);直接添加植酸酶组、植酸酶预处理豆粕组牙鲆的特定生长率、饲料效率、蛋白质效率和氮贮积率与鱼粉对照组相比较没有出现显著差异(P0.05);与不添加植酸酶的豆粕组相比较,在含豆粕饲料中添加1000IU/kg饲料的植酸酶显著提高牙鲆的特定生长率(P0.01)、氮贮积率(P0.05)和磷贮积率(P0.01),显著降低氮排放率(P0.05)和磷排放率(P0.01),但饲料效率和蛋白质效率没有显著变化(P0.05);在豆粕中添加植酸酶进行发酵预处理,降低了豆粕中植酸含量,在饲料中添加植酸酶预处理豆粕显著提高牙鲆的特定生长率(P0.01)、饲料效率、蛋白质效率和氮贮积率(P0.05),显著降低氮(P0.05)、磷和钙的排放率(P0.01)。       

植酸酶和非淀粉多糖酶对鲈鱼生长和消化酶活性的影响

以初始体重为(6.26 ± 0.10)g鲈鱼(Lateolabrax japonicus Cuvier)为研究对象,探讨饲料中添加植酸酶（PY）和非淀粉多糖酶（WX和VP）（WX为木聚糖酶和葡聚糖酶的复合酶制剂,VP为纤维素酶、半纤维素酶、葡聚糖酶和果胶酶的复合酶制剂）对鲈鱼生长、体组成以及胃和肠道消化酶活性的影响。以含36.1%鱼粉和18.0%复合蛋白(豆粕：肉骨粉：花生粕：菜籽粕 = 4：3：2：1并添加赖氨酸、蛋氨酸和异亮氨酸以模拟鱼粉必需氨基酸含量)的饲料为基础饲料(Diet 1),分别向每千克基础饲料中添加200 mg PY (Diet 2)和400 mg VP + 800 mg WX (Diet 3),配制出3种等氮(粗蛋白43%)等能(20 kJ/g)的实验饲料。实验在1.5 m× 1.5 m × 2.0 m的浮式海水网箱中进行,每个处理设3个重复,每个重复放养60尾鲈鱼。 每天饱食投喂2次(06：00和18：00)。实验期间水温为27.5－29.5 ℃, 盐度为25‰－28‰,溶解氧大于7 mg / L。实验结果表明饲料中添加外源酶对鲈鱼的成活率无显著影响（92%－95%）,但却显著提高了鲈鱼的增重百分率（从859.3%提高到947.2%和905.2%）和特定生长率（从4.0提高到4.2和4.1） (p<0.01)。与基础饲料组相比,饲料中添加非淀粉多糖酶对鲈鱼鱼体水分、粗蛋白、粗脂肪、灰分以及身体总能均无显著影响;饲料中添加植酸酶对鲈鱼鱼体水分、粗脂肪含量以及身体总能也无显著影响,但却显著提高了鱼体的粗蛋白和灰分含量（p<0.05）。饲料中添加植酸酶和非淀粉多糖酶后,鲈鱼胃和肠道消化酶均有上升趋势。饲料中添加植酸酶对鲈鱼胃和肠道中的脂肪酶和淀粉酶的活性无显著影响,但是显著提高了其胃和肠道中蛋白酶的活性（分别从0.74 U / mg提高到1.02 U / mg和1.09 U / mg提高到1.71 U / mg）(p<0.01)。而饲料中添加非淀粉多糖酶对鲈鱼胃和肠道中的蛋白酶和脂肪酶活性无显著影响,但显著提高了其胃和肠道中淀粉酶的活性（分别从0.05 U / mg提高到0.16 U / mg和0.12 U / mg提高到0.21 U / mg）(p<0.01)。     

无鱼粉低磷饲料中添加中性蛋白酶和植酸酶对建鲤生长及营养物质利用的影响

在无鱼粉低磷饲料中添加中性蛋白酶、中性植酸酶, 考察对建鲤(Cyprinus carpio var. Jian)生长、营养物质消化率和沉积率、血浆生化指标及肠道组织学的影响。配制含鱼粉5%和磷酸二氢钙1.5%的正对照饲料、无鱼粉饲料、无鱼粉低磷饲料(磷酸二氢钙1.0%)和在无鱼粉饲料中添加175 mg/kg蛋白酶, 在无鱼粉低磷饲料中添加175 mg/kg蛋白酶+300 mg/kg植酸酶的5组等蛋白饲料, 饲喂初始体重为(52.5±2.0) g的建鲤10周。结果表明: 对照组具有最高增重率和最低饲料系数(P<0.05), 无鱼粉饲料和无鱼粉低磷饲料组的增重率、蛋白质和磷沉积率、蛋白质和钙消化率均显著下降(P<0.05); 在无鱼粉饲料中添加蛋白酶后, 提高了建鲤增重率13.1%(P<0.05), 达到和对照组基本一致的水平; 显著提高了蛋白质、钙消化率和肠绒毛高度, 降低了饲料系数(P<0.05); 在无鱼粉低磷饲料中添加蛋白酶和植酸酶后, 显著提高了脂肪、蛋白质、磷沉积率和蛋白质、钙、磷消化率(P<0.05), 增加了前肠绒毛长度和隐窝深度(P<0.05), 提高了血浆磷浓度(P<0.05)。以上结果表明, 在全植物性蛋白饲料中添加蛋白酶, 在全植物蛋白的低磷饲料中同时添加蛋白酶和植酸酶可以促进建鲤生长, 提高对营养物质的消化率和沉积率, 促进肠道生长发育。     

植酸酶对草鱼和新吉富罗非鱼消化酶活性的影响

植酸酶能水解植酸络合物,释放被植酸束缚的各种营养因子,因此能有效解除植酸与内源性消化酶的结合,促进消化酶的作用。本实验在全植物性饲料中添加植酸酶,研究其对草鱼(Ctenopharyngodon idellus)和新吉富罗非鱼(Oreochromis niloticus)淀粉酶及蛋白酶比活力的影响。以全植物性饲料为阴性对照组,添加磷酸氢钙(dibasic calcium phosphate,DCP)实验组为阳性对照组,另设4个不同梯度的植酸酶实验组(250 U/kg、500 U/kg、1 000 U/kg和2 000 U/kg)。实验选取健壮、规格齐整平均体质量为(12.59±0.09)g的草鱼和平均体质量为(9.59±0.12)g的新吉富罗非鱼,分别随机分为6个组,每组5个平行,每个平行20尾鱼。养殖8周后,草鱼平均体质量(18.29±0.63)g,新吉富罗非鱼平均体质量为(24.68±1.34)g,抽样取出胃、肠和肝胰脏用来分析淀粉酶和蛋白酶比活力。结果表明,植酸酶对无胃鱼草鱼和有胃鱼罗非鱼淀粉酶及蛋白酶比活力都有显著的促进作用。相比较而言,植酸酶对罗非鱼的应用效果较明显,低剂量就能显著提高其淀粉酶及蛋白酶比活力(P<0.05)。当植酸酶添加量达到1 000 U/kg时,草鱼和罗非鱼淀粉酶及蛋白酶比活力均达到峰值,此时,罗非鱼淀粉酶和蛋白酶比活力与阳性对照组无显著差异(P>0.05),而草鱼肝胰脏蛋白酶比活力显著高于阳性对照组(P<0.05)。植酸酶2 000 U/kg实验组,罗非鱼淀粉酶和蛋白酶比活力与1 000 U/kg植酸酶实验组无显著差异(P>0.05),但草鱼肝胰脏蛋白酶比活力显著低于1 000 U/kg植酸酶实验组(P<0.05)。因此,本实验条件下,植酸酶在草鱼和新吉富罗非鱼全植物性蛋白质配合饲料中的适宜添加量均为1 000 U/kg,生产实践中可通过添加植酸酶部分替代无机磷源。     

维生素A对养成期草鱼生长性能以及骨骼中钙磷含量变化的影响

实验旨在探究养成期草鱼对饲料中维生素A的需求及维生素A对养成期草鱼的骨骼中钙磷含量的影响。选取养成期（254.6±0.5）g草鱼420尾,随机分为7组,每组3个重复,每个重复20尾。分别用维生素A含量为89、732、1129、2378、4688、7218和9802 IU/kg的等氮等能实验饲料喂养84d。实验结果表明:（1）饲料中添加4688 IU/kg的维生素A显著提高了养成期草鱼的特定生长率（P < 0.05）,并显著降低了饲料系数（P < 0.05）,但饲料维生素A含量对鱼体摄食率、成活率以及肝脏指数没有显著影响（P>0.05）。（2）饲料添加维生素A对鱼体粗蛋白、粗脂肪、灰分没有显著影响（P>0.05）,但是9802 IU/kg组的鱼体水分显著低于其他实验组（P < 0.05）。（3）饲料中4688 IU/kg的维生素A显著提高血清中超氧化物歧化酶的活性（P < 0.05）,但饲料维生素A水平对血清丙二醛、钙、磷含量以及碱性磷酸酶活性没有显著影响（P>0.05）。（4）饲料添加4688和7218 IU/kg的维生素A能显著提高草鱼头骨和脊椎骨中灰分以及钙、磷含量（P < 0.05）。在实验条件下,以特定生长率、饲料系数以及血清SOD活性为评价指标,通过折线分析得出养成期草鱼适宜维生素A的需求量分别为3184和3077 IU/kg。     

饲料中添加外源酶对大黄鱼和鲈氮磷排泄的影响

本研究以大黄鱼和鲈为实验对象,探讨饲料中添加植酸酶(PY)和非淀粉性多糖酶(WX和VP)对其氨氮和可溶性磷(PO3-4-P)排泄的影响.以含植物蛋白的饲料为基础饲料,分别向每千克饲料中添加200mg植酸酶(酶的活性为2500IU/g)、 800mg WX(主要包括葡聚糖酶、戊聚糖酶和纤维素酶,各种酶的活性皆为50IU/g)、 400mg VP(主要为木聚糖酶,酶的活性为1000IU/g)以及800mg WX 400mg VP配制出5种实验饲料.实验鱼在海水网箱中经过8周的摄食驯养后,转入室内水族箱中进行氮磷排泄测定实验.在水族箱中经2天的适应后,测定饥饿状态下氨氮及可溶性磷的排泄率.然后饱食投喂,并连续测定摄食后48h内鱼体氨氮和可溶性磷的排泄率.实验期间水温为26.5-32.5℃,盐度为32.5‰-36‰,溶氧在7 mg/L以上.实验结果表明,饥饿状态下实验鱼的氨氮和可溶性磷排泄不受实验饲料影响(p>0.05).而在饱食条件下,实验饲料中添加非淀粉性多糖酶(WX、VP及WX VP)显著降低了实验鱼的氨氮排泄率(p<0.05),而添加植酸酶组实验鱼的氨氮排泄率与对照组差异不显著.饲料处理对实验鱼可溶性磷的排泄率的影响不显著(p>0.05),但添加植酸酶组实验鱼的可溶性磷排泄率有增加的趋势.     

凝结芽孢杆菌与酵母核苷酸对团头鲂生长和肠道的影响

目的 考察饲料中单独添加凝结芽孢杆菌或与酵母核苷酸联合添加,对团头鲂生长和其肠道的影响.方法 以团头鲂为试验对象随机分为3组,对照组饲喂基础饲料,A试验组饲喂“基础饲料+1 000 mg/kg凝结芽孢杆菌制剂”;B试验组饲喂“基础饲料+1 000 mg/kg凝结芽孢杆菌制剂+200 mg/kg酵母核苷酸”.饲喂56 d后,测定鱼体的各项生长指标、小肠绒毛高度、肠道菌群数量和消化酶活力.结果 与对照组比较,A组的特定生长率、蛋白质效率、肠道凝结芽孢杆菌数量和蛋白酶活力显著提高(P＜0.05),饲料系数和肠道大肠埃希菌数量显著降低(P＜0.05),但肠绒毛高度和肠道淀粉酶活力无明显增加(P＞0.05).与对照组和A组比较,B组的特定生长率、蛋白质效率、肠绒毛高度、肠道凝结芽孢杆菌数量、蛋白酶和淀粉酶活力均有显著提高(P＜0.05),饲料系数和肠道大肠埃希菌数量均有显著降低(P＜0.05).3组的摄食率没有明显改变(P＞0.05).A组和B组均不能提高肠道二糖酶活力(P＞0.05).结论 凝结芽孢杆菌与酵母核苷酸能协同促进团头鲂的生长和其肠道功能.     

饲料中添加牛乳铁蛋白肽对大口黑鲈幼鱼生长性能、消化酶活力、肠道组织结构及抗病力的影响

为探讨饲料中添加不同水平牛乳铁蛋白肽(Bovine lactoferricin, LfcinB)对大口黑鲈(Micropterus salmoides)幼鱼生长性能、消化酶活力、肠道组织结构及抗病力的影响,试验选取了初均重为(19.88±0.03) g的450尾大口黑鲈,随机分成5组,每组3个重复,分别在基础饲料中添加0(阴性对照组)、1000、1500和2000 mg/kg牛乳铁蛋白肽,并设置基础饲料+30 mg/kg氟苯尼考为阳性对照组,共5种试验饲料。试验周期为8周。结果表明:(1)随着牛乳铁蛋白肽添加量的增加,大口黑鲈的末均重(FBW)、增重率(WGR)和特定生长率(SGR)均呈现先升高后降低的趋势, 1000 mg/kg牛乳铁蛋白肽组大口黑鲈的生长性能最好且与对照组(阴性对照、阳性对照)对应数据差异显著(P<0.05)。(2)与两个对照组比, 1000 mg/kg牛乳铁蛋白肽组大口黑鲈的肠道胰蛋白酶、α-淀粉酶和脂肪酶活力均显著上升(P<0.05)。(3)与两个对照组比,饲料中添加1000 mg/kg牛乳铁蛋白肽可显著提高大口黑鲈前肠、中肠及后肠的绒毛高度和宽度(...     

异育银鲫幼鱼对饲料中维生素K需求的研究

以不同维生素K水平(0.13、2.15、3.25、6.40、12、17.20和23.20 mg/kg饲料)的7种精制饲料喂养初始体重约为(2.17±0.01) g的异育银鲫(Carassius auratus gibelio)10周, 每个处理3个重复, 研究异育银鲫对维生素K的需求量。结果显示: 饲料中维生素K的添加可以明显降低摄食率, 饲料中维生素K含量为2.15 mg/kg时, 摄食率出现最大值, 之后显著下降(P<0.05), 在12 mg/kg时达到最低值。特定生长率随着维生素K的添加表现出升高的趋势, 饲料中维生素K含量为12 mg/kg时, 出现最大值, 但是差异不显著(P>0.05)。饲料中维生素K的含量从0.13 mg/kg升至3.25 mg/kg时, 饲料效率显著升高(P<0.05), 随着饲料中维生素K的进一步添加, 趋于稳定(P>0.05), 在12 mg/kg时达到最大值, 并且与特定生长率呈正相关关系(SGR=0.01 FE+0.95, R²=0.95)。血液红细胞数目随着饲料维生素K含量的增加先显著升高(P<0.05), 在6.40 mg/kg时达到最大值, 之后趋于稳定(P>0.05)。血红蛋白含量、血球容积比、血清钙含量与血液中红细胞数目表现出相似的趋势, 均在不添加维生素K组出现最低值, 但是差异不显著(P>0.05)。肝体比、肥满度及鱼体生化组成均不受饲料维生素K水平的影响(P>0.05)。分别对饲料效率、红细胞数目进行折线回归得出异育银鲫幼鱼对维生素K的最适需求量为3.73—6.72 mg/kg饲料。     

Sparing effect of microbial phytase on zinc supplementation in maize-soya-bean meal diets for chickens

The experiment was conducted to evaluate the sparing effect of microbial phytase on the need for dietary zinc supplementation in chicks. A maize–soya-bean meal basal diet, containing 33 mg of zinc and 16 mg of copper per kg, supplemented with 0, 6, 12, 18, 24, 30 or 60 mg of zinc as sulphate per kg or with 250, 500, 750 or 1000 units (FTU) of microbial phytase (3-phytase from Aspergillus niger, Natuphos®) per kg was given to 1-day-old chicks for 20 days. Sixteen chicks placed in individual cages were assigned to each diet except the unsupplemented basal diet which was assigned to 32 cages. Actual range of phytase supplementation was 280 to 850 FTU per kg diet. Growth performance was not affected by microbial phytase. Chicks given the unsupplemented basal diet and the basal diet supplemented with 60 mg of zinc per kg displayed similar performance. Bone weight, bone ash, liver weight and liver dry matter were independent (P > 0.1) of zinc and phytase supplementations. Plasma, bone and liver zinc concentrations increased linearly (P < 0.001) and quadratically (P < 0.001; P < 0.001 and P < 0.05, respectively) with zinc added. Plasma zinc tended to increase linearly (P = 0.07) and bone zinc increased linearly (P < 0.01) with phytase added but no quadratic response was detected (P > 0.1). Liver zinc was unresponsive to phytase added (P > 0.1). Liver copper decreased linearly (P < 0.001) and quadratically (P < 0.01) with zinc supplementation. Mathematical functions were fitted to the responses of plasma and bone zinc to zinc and phytase added and used to calculate zinc equivalency values of phytase. The models included a linear plateau response to zinc added and a linear response to phytase added. In diets without phytase, plasma and bone zinc concentrations were maximised for a dietary zinc concentration of 55 and 51 mg/kg, respectively. Over the range of 280 to 850 FTU, 100 FTU was equivalent to 1 mg of zinc as sulphate. Consequently, in a maize–soya-bean meal chicken diet formulated to contain 60 mg zinc per kg, zinc ingested, and in turn, zinc excreted may be reduced by around 10% if the diet contains 500 FTU as Natuphos® per kg.     

Effect of inorganic phosphate supplementation on egg production in Hy-Line Brown layers fed 2000 FTU/kg phytase

Phytase has long been used to decrease the inorganic phosphorus (Pi) input in poultry diet. The current study was conducted to investigate the effects of Pi supplementation on laying performance, egg quality and phosphate–calcium metabolism in Hy-Line Brown laying hens fed phytase. Layers (n = 504, 29 weeks old) were randomly assigned to seven treatments with six replicates of 12 birds. The corn–soybean meal-based diet contained 0.12% non-phytate phosphorus (nPP), 3.8% calcium, 2415 IU/kg vitamin D₃ and 2000 FTU/kg phytase. Inorganic phosphorus (in the form of mono-dicalcium phosphate) was added into the basal diet to construct seven experimental diets; the final dietary nPP levels were 0.12%, 0.17%, 0.22%, 0.27%, 0.32%, 0.37% and 0.42%. The feeding trial lasted 12 weeks (hens from 29 to 40 weeks of age). Laying performance (housed laying rate, egg weight, egg mass, daily feed intake and feed conversion ratio) was weekly calculated. Egg quality (egg shape index, shell strength, shell thickness, albumen height, yolk colour and Haugh units), serum parameters (calcium, phosphorus, parathyroid hormone, calcitonin and 1,25-dihydroxyvitamin D), tibia quality (breaking strength, and calcium, phosphorus and ash contents), intestinal gene expression (type IIb sodium-dependent phosphate cotransporter, NaPi-IIb) and phosphorus excretion were determined at the end of the trial. No differences were observed on laying performance, egg quality, serum parameters and tibia quality. Hens fed 0.17% nPP had increased (P < 0.01) duodenum NaPi-IIb expression compared to all other treatments. Phosphorus excretion linearly increased with an increase in dietary nPP (phosphorus excretion = 1.7916 × nPP + 0.2157; R² = 0.9609, P = 0.001). In conclusion, corn–soybean meal-based diets containing 0.12% nPP, 3.8% calcium, 2415 IU/kg vitamin D₃ and 2000 FTU/kg phytase would meet the requirements for egg production in Hy-Line Brown laying hens (29 to 40 weeks of age).     

Phytase can reduce theneedfor monocalcium phosphate supplementation in soybean and rapeseed meal‐based diets of black sea bream,Acanthopagrus schlegelii (Bleeker, 1854)

A feeding trial was conducted to study the effect of partial replacement of dietary monocalcium phosphate (MCP) with phytase on growth performance, feed utilization and phosphorus discharge in black sea bream, Acanthopagrus schlegelii. In the feeding trial, the control diet (designated as P1.5) was prepared with 1.5% MCP but without phytase, and the three other diets (designated as PP1.0, PP0.5 and PP0, respectively) were supplemented with 1.0%, 0.5% and 0% MCP, respectively, along with 200 mg (400 U) phytase/kg diet in each. Each diet was tested in triplicate tanks and fish were fed twice daily to satiation. After an 8‐week feeding trial in indoor flow‐through cylindrical fibreglass tanks (25 fish per tank, initial body weight: 11.5 ± 0.12 g), fish fed with PP1.0 and PP0.5 had no significant change in weight gain (WG), specific growth rate (SGR), protein efficiency rate (PER) or feed conversion ratio (FCR) compared to the control (p > .05), whereas fish fed with PP0 showed a significantly lower growth performance in the above parameters (p < .05). The addition of phytase did not affect the body composition or muscle composition. The apparent digestibility coefficients (ADCs) of crude protein and phosphorus increased when fish were fed diets in which MCP was replaced by phytase. Phosphorus discharge was also significantly reduced in fish fed diets in which MCP was replaced by phytase (10.2 ± 0.50 to 8.01 ± 0.47 g/kg weight gain). The present study suggests that dietary MCP can be reduced when phytase is added to the black sea bream diet, with a maximum MCP reduction level of up to 1% when phytase is supplemented at 200 mg (400 U)/kg diet. Thus, phytase in the diet of black sea bream is economically and ecologically beneficial.     

Effects of exogenous enzymes (phytase, non-starch polysaccharide enzyme) in diets on growth, feed utilization, nitrogen and phosphorus excretion of Japanese seabass, Lateolabrax japonicus

A feeding experiment was conducted to investigate the effects of exogenous enzymes (phytase, non-starch polysaccharide enzymes: WX and VP, supplied by DSM) on growth performance and excretion of Japanese seabass (Lateolabrax japonicus) (initial mass 6.26+/-0.10 g). A basal diet was used as a control that contained a mixed protein source, and lysine, methionine and valine were supplemented to simulate the essential amino acid pattern of fish meal. Four other diets were supplemented with 200 mg phytase (500 IU), 400 mg VP, 800 mg WX, or a combination of 800 mg WX and 400 mg VP per kg diet, respectively. Each diet was assigned to triplicate groups of fish in floating sea cages, and each cage was stocked with 60 fish. The results showed specific growth rate (SGR) and feed efficiency ratio (FER) were not significantly improved by the phytase supplementation. However, supplementations with WX and VP significantly enhanced the SGR and FER (P<0.05). Phosphorus retention was significantly increased by the supplementation with phytase, whereas nitrogen retention was also enhanced by supplementations of non-starch polysaccharide enzymes (P<0.05). The excretion experiment showed that the soluble phosphorus and ammonia nitrogen in starved fish were constant, irrespective of dietary treatments. The total phosphorus effluent in fish fed the diet with phytase supplementation was significantly lower compared with the control group after feeding to satiation (P<0.05), but soluble phosphorus excretion was still independent of dietary treatments. The ammonia excretion in satiated fish significantly decreased with supplementations of non-starch polysaccharide enzymes.     

Dietary pharmacological or excess zinc and phytase effects on tissue mineral concentrations, metallothionein, and apparent mineral retention in the newly weaned pig

Feeding pharmacological zinc (Zn) to weaned pigs improves growth, and dietary phytase improves P and Zn availability. Metallothionein (MT) increases in the duodenum, kidney, and liver of pigs fed 1000 mg Zn/kg with phytase or 2000 mg Zn/kg with or without phytase when fed for 14 d postweaning. The goal of this study was to determine the effects of feeding pharmacological Zn and phytase on tissue minerals, MT, mineral excretion, and apparent retention. Twenty-four newly weaned pigs (20 d; 7.2 kg) were individually fed twice daily, a basal diet supplemented with 0, 1000, or 4000 mg Zn/kg as Zn oxide, without or with phytase (500 phytase units [FTU]/kg) for 14 d, followed by a basal diet (100 mg Zn/kg) without phytase for 7 d. Pigs fed 4000 mg Zn/kg without phytase had higher (p=0.01) plasma, hepatic, renal Zn, renal Cu, and hepatic, renal, and jejunal MT than pigs fed the basal diet or 1000 mg Zn/kg. Duodenal MT was higher (p=0.0001) in pigs fed 1000 and 4000 mg Zn/kg than in pigs fed the basal diet. In pigs fed 1000 and 4000 mg Zn/kg, Zn loading occurred during the first 11 d of supplementation; by d 14, excess Zn was being excreted in the feces.     

Supplemental sodium phytate and microbial phytase influence iron availability in growing rats.

Five groups of individually housed albino rats (n = 7 each, initial average weight = 42 g) were fed diets based on corn starch and casein over a 4-week period. All diets were supplemented with 35 mg/kg of iron from FeSO4 x 7 H2O. Group I (control) was fed the basal diet free of phytic acid (PA) and phytase. By replacing corn starch by 7.5 g (groups II and IV) and 15 g phytic acid (groups III and V) from sodium phytate per kg diet, molar PA/iron ratios of 18 and 36 were obtained. In groups IV and V, 1000 U phytase from Aspergillus niger per kg diet were added. Food conversion efficiency ratio and growth rate as well as iron in plasma and spleen, hemoglobin, red blood cell count and erythrocyte zinc protoporphyrin were not influenced by the different dietary treatments. Dietary phytate reduced apparent iron absorption in groups II and III. Furthermore hematocrit, transferrin saturation and iron concentration in liver and femur were lowered in rats fed diets with PA, while total and latent iron-binding capacity of plasma increased. Microbial phytase supplementation (groups IV and V) partly counteracted the antinutritive effects of phytic acid on iron availability.