植酸酶对黄河鲤鱼生长性能及植酸磷代谢的影响

选用120尾当年鱼种,体重50.10±1.43g,随机分为四组:对照组、Ⅰ组、Ⅱ组、Ⅲ组,每组 30尾、对照组饲喂基础日粮,Ⅰ组饲喂基础日粮+500U植酸酶,Ⅱ组饲喂基础日粮+1000U植酸酶, Ⅲ组饲喂基础日粮+1500U植酸酶。结果表明:与对照组相比,Ⅰ、Ⅱ、Ⅲ组鲤鱼的平均日增重、平均日 采食量都有升高,而饵料系数、死亡率都降低了。而且,饲料中添加植酸酶,提高了植酸磷的利用率, 减少饲料中无机磷的添加量,减少植酸磷对养殖水体的污染。本试验证实:在黄河鲤鱼的饲料中添加 植酸酶可促进鲤鱼的生长和提高植酸磷的利用率。     

植酸酶对异育银鲫生产性能及鱼体成分的影响

选用360尾体重为(12.0±0.2)g的异育银鲫(Carassius auratus gibelio)鱼种,随机分为Ⅰ、Ⅱ、Ⅲ、Ⅳ四个组,每组设置3个重复,其中Ⅰ为对照组,饲喂基础日粮,Ⅱ、Ⅲ、Ⅳ为试验组,分别在基础日粮中添加500 U/kg、1000 U/kg、1500 U/kg的植酸酶。饲喂60 d,试验结果表明:(1)与对照组比较,添加1000 U/kg植酸酶的试验组鱼增重率提高8.8个百分点,饲料系数下降0.18,植酸磷利用率提高20.6个百分点,说明在异育银鲫鱼种配合饲料中添加适宜的植酸酶能促进鱼的生长,提高植酸磷的利用;(2)添加植酸酶各组异育银鲫鱼种的鱼体成分中,粗灰分、粗蛋白、钙、磷及部分矿物质元素(铁、铜、镍)含量显著提高,表明植酸酶能释放植酸的螯合物,促进矿物质元素在动物体内的沉积。     

饲料中添加植酸酶对南美白对虾生长及磷利用率的影响

在半精制饲料中分别添加1000IU／kg、2000IU／kg、3000IU／kg的植酸酶以及2％Ca(H2PO4)2，以不添加外源磷及植酸酶组为对照，研究以植物蛋白为主要蛋白源的饲料中添加植酸酶对南美白对虾生长和磷消化率的影响。40天的养殖实验结果表明，饲料中添加2％Ca(H2PO4)2，能提高南美白对虾的增重率，但与对照组无显著差异。饲料中添加1000IU／kg植酸酶组的南美白对虾增重率达到最高，但与其它各组没有显著差异。饲料的磷消化率在2％Ca(H2PO4)2组达到最高，蛋白质消化率在各组之间没有明显差异。综上所述，饲料中添加1000IU／kg植酸酶即能有效改善南美白对虾的生长和磷利用率，降低磷排泄。     

植酸酶对金鳟体成分及金鳟椎骨中钙、磷含量的影响

采用喷涂法和预处理两种方法,在豆粕型金鳟饲料中添加不同浓度的植酸酶,通过90 d的饲喂试验,研究植酸酶对金鳟(Oncorhynchus mykiss Walbaum)体成分及其椎骨中钙、磷含量的影响。结果显示:喷涂法和预处理法添加植酸酶的处理组与对照组相比,粗蛋白、粗脂肪的含量均有所下降;喷涂法添加植酸酶的处理组的鱼体粗灰分、磷和钙含量均高于对照组,其中,喷涂法添加1500 U/Kg植酸酶组鱼体磷含量、灰分含量和钙含量显著高于对照组(P(0.05),且此组鱼体磷高于其它试验组;喷涂法各组椎骨中粗灰分、磷含量较对照组提高显著(P(0.05),2500 U/kg植酸酶组椎骨磷含量最高,椎骨中钙含量除D1和D8组外,添加植酸酶的处理组均较对照组提高显著(P(0.05)。预处理法添加植酸酶的处理组与对照组相比,鱼体和椎骨中粗灰分、磷和钙含量均有显著提高(P(0.05),但植酸酶试验组间椎骨中粗灰分、磷含量和钙含量差异均不显著(P(0.05)。结果表明,金鳟饲料喷涂法添加植酸酶1500~2500 U/kg浓度最适,预处理法添加植酸酶500 U/kg浓度较为宜。     

酵母多糖对鲤鱼生长性能的影响

本试验旨在研究鲤鱼饲料中添加不同水平的酵母多糖对其生长性能的影响.试验选取240尾整齐规格、体质量相近、健康的鲤鱼随机分为4组,对照组鲤鱼饲喂基础饲料,试验1组、试验2组、试验3组鲤鱼分别饲喂添加0.5 g/kg、1.0 g/kg、2.0 g/kg的酵母多糖的基础饲料.结果表明:试验2组和试验3组鲤鱼的试验末重比对照组...     

酵母多糖对鲤鱼抗氧化能力的影响

在鲤鱼饵料中添加不同水平的酵母多糖,研究对其抗氧化功能的影响.试验选取400尾整齐规格、体质量相近、健康的鲤鱼随机分为4组,每组包含10个重复,每个重复10尾鲤鱼.对照组鲤鱼饲喂基础饵料,试验1组、试验2组、试验3组鲤鱼分别饲喂含有0.5 g/kg、1.0 g/kg、1.5 g/kg的酵母多糖的基础饵料,预试验7天,正...     

植酸酶对金鳟粪磷及水环境中磷含量的影响

通过喷涂和预处理两种方法将不同浓度植酸酶添加到豆粕型金鳟(Oncorhynchus mykissW albaum)饲料中,研究了植酸酶对金鳟粪磷及养殖水环境中磷含量的影响。金鳟粪磷分析结果显示,喷涂法添加植酸酶,对照组中粪磷含量最高,其他各试验组较对照组差异显著(P<0.05),但500~2000 U/kg组中粪磷含量差异显著(P<0.05),2500~6000 U/kg组中粪磷含量无显著差异(P(0.05);预处理法添加植酸酶,对照组粪磷含量最高,其他各试验组粪磷含量较对照组降低显著(P<0.05),但添加植酸酶的各试验组之间差异不显著(P(0.05)。通过水中磷含量试分析结果显示,无论是喷涂法添加植酸酶还是预处理法添加植酸酶,各试验组水体总磷含量分别较其对照组差异不显著(P(0.05),各试验组的活性磷含量均未检出。实验结果表明,金鳟饲料中添加植酸酶可以降低粪磷含量,对养殖生产过程中控制磷的排放,减少磷污染具有重要的意义。     

植酸酶对3种植物性原料中植酸磷含量的影响

利用微生物植酸酶分别对3种植物性原料(豆粕、玉米蛋白粉、小麦)进行酶处理,研究不同浓度植酸酶作用下3种植物性原料中植酸磷含量的变化。3种原料分别有6组处理(植酸酶对照0 U/kg,柠檬酸对照,500U/kg,750 U/kg,1000 U/kg,1500 U/kg),每组处理3个重复。结果表明:植酸酶能够显著降低3种植物性原料中植酸磷的含量(P<0.05),同时提升有效磷的含量。通过对磷当量的分析,本试验中以植酸酶组1000 U/kg最为经济有效。植酸酶对照组中植酸磷含量也有所下降,说明柠檬酸单独对植酸起到了一定的分解作用。     

微生态制剂在80∶20池塘养殖中的应用及经济效益分析

本试验研究了在80∶20养殖模式池塘中应用微生态制剂的生产效益及经济效益。试验塘两口,面积均为0.13hm2,水深为1~1.3 m,放养平均体质量242g的鲤鱼0.42kg/m3,160g鲢鱼和330g鳙鱼0.07kg/m3。处理组鲤鱼投喂添加微生态制剂Ⅰ和Ⅱ(每千克饲料各5mL的饲料,对照组鲤鱼只投喂同样颗粒饲料。40d和80d的养殖试验表明,处理组鲤鱼的平均体质量(627g)高于对照组鲤鱼(565g),质量增加量(8961.67kg/hm2)较对照组(6319.80kg/hm2)高2641.87kg/hm2,增加41.8%;处理组滤食性鲢和鳙质量增加量低于对照组。处理组池水氨氮含量低,pH值正常,溶氧量高;饲料系数(饲料成本)比对照组低7.8%;处理组鱼总产值比对照组增加了36 888.90元/hm2。     

天蚕素抗菌肽对网箱养殖鲤鱼生长性能的影响

为研究天蚕素抗菌肽对水产动物生长性能的影响,选取2700尾体质量约57g的鲤鱼进行试验,分别设置对照组、试验1组和试验2组。试验组在对照组饲料基础上分别添加100mg/kg和200mg/kg的天蚕素抗菌肽,进行为期30d的试验,观察鲤鱼生长和摄食情况。试验结果发现,与对照组相比,添加天蚕素抗菌肽可显著提高鲤鱼体质量和特定生长率。     

Effects of Fungal Phytase on Utilization of Dietary Protein and Minerals, and Dephosphorylation of Phytic Acid in the Alimentary Tract of Channel Catfish Ictalurus punctatus Fed an All-Plant-Protein Diet

A feeding trial was conducted to quantify the effects of phytase at levels of 0, 500, 1,000, 2,000, 4,000, and 8,000 units (U) per kg diet on utilization of dietary protein and minerals by fingerling (12 g) channel catfish Ictalurus punctatus fed an all‐plant‐protein diet composed of soybean meal, corn, and wheat middlings. The effects of phytase on dephosphorylation of phytic acid (phytate) in the alimentary tract of catfish also were determined. After 14 wk, mean weight gains (30.2–43.9 g/fish), feed conversion ratios (2.27–2.40 g feed consumed/g weight gain), protein efficiency ratios (1.47–1.61 g weight gaid/g protein consumed), and dietary protein retentions (23.8–26.7%) did not differ significantly (P > 0.05) among treatment groups. A digestibility trial conducted after the feeding trial showed no difference (P > 0.05) in mean digestibility of diet dry matter (49.0–58.3%) or crude protein (85.4‐88.5%) among treatment groups. Concentrations of ash (46.7–48.6%), calcium (Ca, 17.9–18.5%), phosphorus (P, 9.1–9.5%), and manganese (Mn, 65.5–74.1 mg/kg) were significantly higher (P ≤ 0.05) in bone of fish fed ≥ 500 U/kg than in bone of fish fed 0 U/kg (ash, 43.5%; Ca, 16.4%; P, 8.4%; and Mn, 49.0 ma/kg), but concentrations of these minerals did not differ (P > 0.05) in bone of fish fed ≥ 500 Uk/g. The magnesium (Mg) content of bone did not differ (P > 0.05) between fish fed 0 U/kg (0.29%) or 500 U/kg (0.34%), but was significantly lower in fish fed 0 U/kg than in fish fed ≥ 1,000 U/kg (0.35–37%). Bone Mg levels did not differ (P > 0.05) among fish fed ≥ 500 U/kg. The amount of zinc (Zn) in bone of fish fed 8,000 U/kg (153.3 mg/kg) was significantly higher than that in fish fed 0 U/kg (115.7 mg/kg) or 500 U/kg (130.3 mg/ kg), but did not differ from Zn levels in bone of fish fed 1,000–4,000 U/kg (134.5–135.8 mg/ kg). Dephosphorylation of phytate occurred primarily in the stomach within 2–8 h after diet ingestion, depending on the level of phytase supplementation. Initial levels of total phytate in the diet decreased 32–94% in stomach contents of fish fed l,000–8,000 U/kg within 2 h after feeding. Eight hours after feeding, stomach contents of fish fed ≥ 1,000 U/kg contained less than 6% of initial total dietary phytate. Stomach contents of fish fed 500 U/kg retained 92% of initial total dietary phytate 2 h after feeding and 15% of total dietary phytate 8 h after feeding. Results of this study indicate that phytase supplementation at levels up to 8,000 U/kg diet did not increase weight gain or improve dietary protein utilization of channel catfish fed an all‐plant‐protein diet. Addition of phytase at a level of 1,000 U/kg diet was sufficient to significantly increase the Ca, P, Mg, and Mn content of bone, relative to fish fed an unsupplemented diet, and significantly decrease the quantity of total phytate in feces. A phytase level of 8,000 U/kg diet significantly increased the bioavailability of naturally occurring Zn in feed ingredients and increased the rate of phytate dephosphorylation in the stomach, compared with a diet containing no added phytase. Increased utilization of naturally occurring minerals in feed ingredients reduces the need for mineral supplements in diets and results in decreased elimination of minerals in feces. Thus, use of phytase in catfish feeds can be expected to provide both economic and environmental benefits.     

Top-spraying soybean meal-based diets with phytase improves protein and mineral digestibilities but not lysine utilization in rainbow trout, Oncorhynchus mykiss (Walbaum)

Two digestibility trials and two growth trials were carried out to evaluate the influence of top‐sprayed phytase on apparent digestibility coefficients (ADCs) of protein and mineral and utilization in rainbow trout fed with soybean meal‐based diets. In Trial 1, a semi‐purified diet containing 50% soybean meal was supplemented with graded levels of phytase (0, 500, 1000, 2000 and 4000 U kg^?1 diet), and fed to triplicate groups of fish. In Trial 2, commercial‐type extruded feeds containing 36% soybean meal with either 0 or 2000 U phytase kg^?1 were fed to five replicate groups of fish. Phytase clearly decreased phytic acid content of feces from 35 to 5 mg and from 34 to 14 mg phytic acid per g faecal dry matter in Trials 1 and 2 respectively. Apparent digestibility coefficient of P improved from 23% to 83% in Trial 1 and from 35% to 54% in Trial 2 by phytase. Apparent protein increased by 1.2% and 3.2%‐units by phytase in Trials 1 and 2. Zinc digestibility was significantly increased in Trial 1, but not in Trial 2. Trials 3 and 4 were conducted to evaluate the influence of phytase on dietary P (Trial 3) and lysine (Trial 4) utilization. Three diets were prepared for each trial: P (Trial 3)‐ or lysine (Trial 4)‐deficient basal diets, basal diets with phytase supplementation (2000 U kg^?1) and P (Trial 3)‐ or lysine (Trial 4)‐fortified diets. Rainbow trout (initial weight 20 g) were fed for 10 weeks using four and six replicates for Trials 3 and 4 respectively. Phytase increased P utilization in Trial 3 as demonstrated by an increase in vertebra ash from 24.1% to 45.4%, and by an increase in weight gain from 243% to 459% of the initial weight. Phytase did not increase lysine utilization, since neither protein retention nor weight gain were enhanced by phytase. Supplemental lysine increased protein retention and weight gain to 43.1% and 514%, respectively, and also decreased whole‐body lipid contents significantly from 120 to 123 g kg^?1 in fish fed the basal diet and phytase‐supplemented diet to 106 g kg^?1 in fish fed with lysine‐fortified diet.     

Microbial Phytase Can Replace Inorganic Phosphorus Supplements in Channel Catfish Ictalurus punctatus Diets1

Abstract.– Juvenile channel catfish Ictalurus punctatus (initial weight: 6.8 g/fish) were fed four practical diets containing 0, 250, 500, and 750 units of microbial phytase/kg and a diet containing 1% feed grade dicalcium phosphate (but no microbial phytase) under laboratory conditions for 12 wk. Fish fed the diets containing 250 units of microbial phytase/kg and above consumed more feed, gained more weight, and had a lower feed conversion ratio (FCR) in comparison to fish fed the basal diet containing no microbial phytase. Fish fed the diet containing dicalcium phosphate had intermediate weight gain and feed conversion ratio as compared to fish fed the basal diet and diets containing microbial phytase. Bone ash and phosphorus concentrations were lower for fish fed the basal diet than for fish fed other diets. No differences in weight gain, feed consumption, FCR, bone ash and bone phosphorus were observed among fish fed the diets containing various levels of microbial phytase. Fish fed the diet containing dicalcium phosphate had a lower bone phosphorus concentration than fish fed diets containing microbial phytase. Fecal phosphorus concentrations were lower for fish fed the diets containing microbial phytase than for fish fed the basal diet and the diet containing dicalcium phosphate. Results from the present study indicated that addition of 250 units of microbial phytase/kg to practical diets can effectively improve bioavailability of phytate phosphorus to channel catfish and may possibly eliminate the use of an inorganic phosphorus supplement in channel catfish diets. However, these data must be verified in trials conducted in ponds, prior to recommending removal of supplemental phosphorus from channel catfish diets.     

Use of Microbial Phytase in Channel Catfish Ictalurus punctatus Diets to Improve Utilization of Phytate Phosphorus1

A 10-wk feeding trial was conducted in the laboratory during which channel catfish Ictalurus punctatus (average initial weight: 6.5 g/fish) were fed five practical diets containing either 0, 500, 1,000, 2,000, or 4,000 units of microbial phytase/kg diet. Fish fed diets containing 500 or more units of microbial phytase/kg consumed more feed and gained more weight than fish fed the basal diet without supplemental phytase. Feed conversion ratios (FCR) did not differ among treatments except the FCR for fish fed 1,000 units of microbial phytase/kg diet was lower than that of fish fed no supplemental phytase. Fish survival was not different among treatments. Contrast analysis showed that weight gain, feed consumption, bone ash, and bone phosphorus were higher and feed conversion ratio was lower for fish fed diets supplemented with phytase as compared to fish fed no supplemental phytase. The concentration of fecal phosphorus decreased linearly as phytase supplementation increased. Results from this study demonstrate that microbial phytase is effective in improving bioavailability of phytate phosphorus to channel catfish, which may eventually lead to a reduction in the amount of supplemental phosphorus added to commercial channel catfish feeds.     

Growth and Mineral Absorption by Striped Bass Morone saxatilis Fed a Plant Feedstuff Based Diet Supplemented with Phytase

Two experiments were conducted to determine the effects of phytase on growth, apparent phosphorus (P), calcium (Ca), iron (Fe), zinc (Zn), magnesium (Mg), and copper (Cu) absorption, and apparent protein digestibility by striped bass Morone saxatills fed a high phytate diet. In experiment one, four diets with graded levels of phytase supplementation, 0, 500, 1,000, and 2,000 phytase units/kg of diet (PUkg), and a diet supplemented with inorganic P (positive control, total P, 0.73%; phytin P, 0.35%) were assigned to duplicate tanks, and were fed to fingerling striped bass for 16 wk. A digestibility trial was conducted at weeks 16–18, using 0.5% Cr₂O₃ as an indigestible marker in the diets. Phytase was sprayed post-extrusion on the basal diet (P-total, 0.58%; P-phytin, 0.35%). Experiment two consisted of a 2-wk digestibility trial with three treatments: 0 (basal; total P, 0.73%; phytin P, 0.34%), 1,000, and 2,000 PU/kg, assigned to four, three and three replicate tanks respectively. Each tank contained an average of 20 striped bass (mean weight: 400 9). The diet used was similar to the basal in experiment one, which was modified to have low essential trace mineral concentrations, in order to increase the sensitivity of the assay. In experiment one, significant improvements (P≤ 0.05) in growth, feed conversion ratios, and vertebral and scale ash concentrations of fish at the end of the experiment were achieved with either added inorganic P or increasing phytase supplementations. Results from both digestibility trials indicated that P absorption was improved with the addition of at least 500 PUkg. Absorptions of Ca and Fe were significantly increased (P≤ 0.05) and Zn absorption marginally improved (P≤ 0.06) when at least 2,000 PU/kg was supplemented to the diet. Protein digestibility, Mg and Cu absorption were not significantly different in any treatment. Whole carcass P retention was significantly improved with the addition of 1,000 PU/kg, and 2,000 PU/kg, when compared to fish fed the basal diet, 500 PU/kg and positive control treatments. Results from these experiments indicate that phytase supplementation of at least 1,000 PU/kg is adequate to maintain growth rate and health comparable to an inorganic P supplemented diet. In addition, bioavailability and utilization of P is increased with increasing phytase supplementation. Diet supplementation of 2,000 PU/kg increased Ca, Fe, and Zn digestibility by striped bass fed a high phytate diet.     

The Efficacy of a Novel Microbial 6‐Phytase Expressed in Aspergillus oryzae on the Performance and Phosphorus Utilization of Cold‐ and Warm‐Water Fish: Rainbow Trout,Oncorhynchus mykiss,and Nile Tilapia,Oreochromis niloticus

The efficacy and tolerance of a novel microbial 6‐phytase were investigated in rainbow trout, Oncorhynchus mykiss, and Nile tilapia, Oreochromis niloticus. Reference diets were sufficient in available phosphorus (P). The test diet limiting in available P was supplemented with phytase at 500, 1000, or 2000 phytase units/kg feed. The enzyme was effective in increasing total P apparent digestibility coefficient in relation to increasing the dose of phytase in rainbow trout and Nile tilapia. Zinc apparent digestibility improved in relation to phytase supplementation in rainbow trout. P release due to phytase supplementation ranged from 0.06 to 0.18% P/kg feed in rainbow trout and from 0.13 to 0.26% P/kg feed in Nile tilapia. A 58‐d performance trial was conducted to evaluate tolerance of fish to phytase supplementation. Dietary treatments consisted of a basal diet without phytase or supplemented with 2000 and 200,000 phytase units/kg feed. Results indicate that this novel microbial 6‐phytase is well tolerated by fish. Significant improvements for growth as well as feed conversion ratio were observed when the phytase was fed at 2000 phytase units/kg feed. This phytase is proven efficient in releasing P from phytate and could be added when plants are used for fish meal replacement in diets for salmonid and omnivorous fish.     

Effects of Microbial Phytase Supplementation and Dosage on Apparent Digestibility Coefficients of Nutrients and Dry Matter in Soybean Product-Based Diets for Rainbow Trout Oncorhynchus mykiss

Three experiments were conducted to evaluate the effects of microbial phytase (Ronozyme P(L) and dosage on apparent digestibility coefficients of dry matter, crude protein, amino acids, and minerals in soybean product-based diets for rainbow trout Oncorhynchus mykiss. In experiments 1 and 2, fish were fed soy protein concentrate and soybean meal-based semi-purified diets, respectively. In experiment 3, fish were fed soybean meal-based practical diets. A total of 900 fish (average body weight 100.1 ± 7.4 g) were stocked into 30 150-L fiberglass tanks with 30 fish per tank and two tanks per diet. Phytase was supplemented into soybean product-based diets at 0, 500, 1,000, 2,000, and 4,000 FTU/kg diet. Yttrium oxide (0.01%) was used as inert marker. Feces were collected by hand stripping three times at 3-d intervals. Results of experiments 1 and 2 showed that phytase supplementation significantly increased apparent digestibility coefficients of minerals (except copper and iron), but not dry matter. Experiment 3 showed that phytase supplementation significantly increased apparent digestibility coefficients of dry matter, crude protein, amino acids (except tryptophan and tyrosine), and minerals (except copper and iron). The optimum level of phytase supplementation in rainbow trout diets was approximately 500 FTU/kg diet.     

Effect of partial replacement of dietary monocalcium phosphate with neutral phytase on growth performance and phosphorus digestibility in gibel carp,Carassius auratus gibelio (Bloch)

A feeding trial was conducted to study the effect of partial replacement of dietary monocalcium phosphate (MCP) with neutral phytase on growth performance and phosphorus digestibility in gibel carp, Carassius auratus gibelio (Bloch). Control diet was prepared with 2% MCP but without phytase (P0). Other three experimental diets were prepared by replacement of MCP by 25%, 50% and 75% respectively in comparison with control with supplementation of neutral phytase at 500 U kg^?1 diet in each and designated as P25, P50 and P75 respectively. Gibel carp (initial body weight of 30.22 ± 1.98 g) were reared in twelve 300‐L cylindrical fibreglass tanks provided with filtered flow‐through tap water at 26–28°C. After 8‐week experiment, gibel carp fed with P50 had no obvious differences from the control group on weight gain (WG), specific growth rate (SGR), feed conversion ratio (FCR), protein efficiency rate (PER) and survival rate. Phytase supplementation did not affect body compositions or muscle compositions. Crude protein and phosphorus (P) contents in the faeces of fish fed with the phytase‐supplemented diets were significantly lower than those of the control group. The apparent digestibility coefficients (ADCs) of crude protein and P in gibel carp were increased when fish fed with the diets in which MCP was replaced by neutral phytase. This study suggested that partial replacement of dietary MCP at 50% with neutral phytase was considered as a recommended dietary supplemental level and increased dietary P and protein availability.     

Effects of Microbial Phytase Supplementation in Corn Distiller's Dried Grain with Solubles on Nutrient Digestibility and Growth Performance of Rainbow Trout,Oncorhynchus mykiss

Abstract

Two experiments were conducted to evaluate the effects of microbial phytase in corn distiller's dried grain with solubles (DDGS) on apparent digestibility coefficients (ADCs) and growth performance of rainbow trout, Oncorhynchus mykiss. In experiment 1, DDGS was supplemented with phytase at 0,300,600,900, and 1200 FTU/kg diet. A total of 180 fish (129.1±9.3 g) were stocked into six 140-L tanks with 30 fish/tank. Fish were assigned randomly to a reference diet and each of the 5 diets containing DDGS. Yttrium oxide was used as an inert marker. Results showed that ADCs in DDGS supplemented with different dosages of phytase were: dry matter, 49.1-58.6%; crude fat, 78.9-88.9%; crude protein, 80.0-91.9%; gross energy, 50.5-66.6%; minerals, -7.3-99.7%; and amino acids: 73.9 to 96.8%. In experiment 2, abasal diet containing 15% DDGS supplemented with lysine and methionine was used to determine if trace mineral supplemental levels in rainbow trout diets could be reduced if microbial phytase was supplemented. Six diets were made with trace mineral premix supplementation at 0.1, 0.08, 0.06, 0.04, 0.02, and 0%. Phytase was not supplemented in the basal diet, but supplemented at 500 FTU/kg diet in all other diets. Ten-week results showed that there were no significant differences in fish weight gain, feed conversion ratio, and survival (P < 0.05). There were no significant differences in fish body composition and apparent nutrient retention among fish fed all diets, except that fish fed a diet without trace mineral supplementation had the lowest zinc level and the highest manganese retention. Results indicated that phytase was effective in releasing most of minerals, and that trace mineral supplementation level could be reduced when phytase was used in rainbow trout diets.