外源酶及其添加时间对鸡饲粮氨基酸消化率影响的研究

30只18周龄的伊莎褐种公鸡随机分为6组，每组5只。一组用于内源氨基酸校正的样品采集。其它5组作强饲试验，其中一组采用常规日粮预试一周并强饲常规日粮；另外四组饲喂加酶日粮，预试期分别为一周、二周、三周及四周，再强饲加酶日粮，氨基酸消化率采用“TME”法测定。结果表明：（1）酶及不同的预试期可使17种氨基酸的表观消化率有不同程度的提高，但提高幅度因不同氨基酸而异。采用加酶日粮预试并强饲可减少氨基酸消化率的变异范围和标准差。（2）与常规日粮组相比，加酶日粮预试一周、二周、三周及四周再强饲，可使总氨基酸表观消化率分别提高3．85、3．49、2．76及4．12个百分点。以预试四周为佳。（3）Sibbald＇s“TME”法测定鸡加酶饲粮氨基酸消化率时，采用加酶日粮预试一周后强饲为宜。     

产酶益生素对鸡营养物质消化利用率影响的研究

选取3月龄体重相近的蛋鸡公雏40只，随机分成10组，每组4只。其中5组为对照组，饲喂基础日粮，另外5组为试验组，饲喂基础日粮＋0.1％产酶益生素。采用强饲法来评定产酶益生素对鸡营养物质消化利用率的影响。经1周的预饲期后，进行为期4d的强饲试验。按常规方法测定日粮和粪便中的粗蛋白质、钙和磷的表观消化率。结果表明：饲料中添加0.1％的宝来利来产酶益生素，可使鸡粗蛋白质、钙和磷的表观消化率分别提高4、77％、3．99％、和2．36％，并可使粪便的含水量下降8．98％。     

差量法和酶解酪蛋白法测定鸭饲料氨基酸真消化率及内源排泄量的比较研究

本试验研究了差量法和酶解酪蛋白法测定动物在采食正常含氮日粮条件下的内源氨基酸排泄量及饲料氨基酸真消化率的差异,并同时与无氮日粮法作比较。差量法以豆粕为唯一蛋白源,配制成15%和20%2种粗蛋白质水平的试粮;酶解酪蛋白法以酶解酪蛋白作为蛋白质来源,配制成17.5%粗蛋白质水平的试粮;无氮日粮用淀粉和纸纤维进行配制。每种方法选用7周龄、平均体重(2.77±0.16)kg天府肉公鸭64只,分为4组,分别饲喂4种不同日粮,每组4个重复,每重复4只鸭,采用Sibbald的强饲法进行代谢试验,测定各试粮氨基酸表观消化率、内源氨基酸排泄量及真消化率。结果显示:差量法、酶解酪蛋白法和无氮日粮法测定的内源氨基酸排泄量分别为0.9946、1.2243和0.9297mg/gDMI;差量法测定的氨基酸真消化率(%)为88.93±4.43,用酶解酪蛋白法和无氮日粮法测定的内源氨基酸排泄量计算的15%和20%2个粗蛋白质水平日粮氨基酸真消化率(%)分别为91.15±4.33和91.97±4.16、88.55±4.29和88.82±4.61。以上结果表明,在15%～20%的日粮蛋白质水平范围,差量法测定的氨基酸真消化率和内源氨基酸排泄量较酶解酪蛋白法准确,酶解酪蛋白法可能高估了内源氨基酸排泄量和氨基酸真消化率。     

促禽康对鸡营养物质消化利用率影响的研究

选取3月龄体重相近的蛋鸡公雏40只，随机分成10组，每组4只，其中5组为对照组，饲喂基础日粮，另外5组为试验组，饲喂基础日粮 0.1%促禽康，采用强饲法对评定促禽康对鸡营养物质消化利用率的影响，经1周的预饲期后，进行为期4天的强饲试验，按常规方法测定日粮和粪便中的粗蛋白质，钙和磷的表观消化率，结果表明：饲料中添加0.1%北京好友巡天公司生产的促禽康，可使鸡粗蛋白质，钙和磷的表观消化率分别提高7.37%,4.90%和4.34%。并可使粪便的含水量下降11.09%。     

加酶预消化饲料对断奶仔猪生长和养分表观消化率的影响

为研究体外加酶预消化饲料对断奶仔猪生长与养分消化率的影响,选用28日龄断奶杜长大仔猪80头,按试验要求随机分为4组,每组2个重复,每个重复10头,分别饲喂基础饲粮颗粒料(Ⅰ组)、基础饲粮预消化颗粒料(Ⅱ组)、普通加酶饲粮颗粒料(Ⅲ组)、加酶预消化饲粮颗粒料(Ⅳ组),预试期7 d,正试期28 d.结果表明,Ⅳ组仔猪日增体质量(P<0.05)和饲料转化率(P<0.05)显著高于Ⅰ和Ⅱ组,腹泻率极显著低于Ⅰ、Ⅱ和Ⅲ组(P<0.01);Ⅳ组仔猪能量和钙表观消化率均高于Ⅰ和Ⅱ组(P<0.05),但与Ⅲ组比较差异不显著(P>0.05);Ⅳ组仔猪磷表观消化率显著高于Ⅲ组(P<0.05)、Ⅰ和Ⅱ组(P<0.01),Ⅳ组粗蛋白表观消化率虽略有提升,但与其它3组相比差异不显著.加酶预消化饲料可提高断奶仔猪对饲料养分的消化,进而促进其生长.     

不同组型饲粮中添加复合蛋白酶对鲁烟白猪氨基酸回肠表观消化率的影响

本试验旨在研究不同组型饲粮中添加复合蛋白酶对鲁烟白猪氨基酸回肠表观消化率的影响。试验选取去势、初始体重为(35.0±0.5)kg的健康鲁烟白猪生长公猪7头,采用2×3因子试验设计进行代谢试验,2因子分别为加酶(加酶组和对照组)和饲粮组型(玉米-豆粕型、玉米-杂粕型和小麦-杂粕型),其中加酶组的复合蛋白酶添加量为0.1%,对照组不添加复合蛋白酶。试验共分6期,每期7 d。结果表明,3种组型饲粮中添加复合蛋白酶显著提高了鲁烟白猪对蛋氨酸、缬氨酸、亮氨酸、异亮氨酸、苯丙氨酸和脯氨酸的回肠表观消化率(P0.05);在饲喂玉米-杂粕型饲粮时,除苏氨酸外各加酶组氨基酸回肠表观消化率均显著或极显著高于对照组(P0.05或P0.01),其中丝氨酸、谷氨酸、半胱氨酸的回肠表观消化率都显著高于饲喂其他2种组型饲粮时(P0.05)。由此可见,饲粮中添加复合蛋白酶可显著提高鲁烟白猪氨基酸回肠表观消化率,其中在玉米-杂粕型饲粮中添加复合蛋白酶效果较优。     

饲粮中添加不同生物制剂对杜寒杂交肉羊营养物质消化利用的影响

本试验旨在比较在饲粮中添加不同生物制剂对杜寒杂交肉羊营养物质表观消化率、氮和能量代谢的影响。采用单因素试验设计,选取体重约32 kg的杜寒杂交F1代肉羊160只,随机分为5组,每组4个重复,每个重复8只。对照组采用不添加任何生物制剂的基础饲粮,试验组在基础饲粮中分别添加21 mg/kg莫能菌素、4×10~9CFU/kg地衣芽孢杆菌、3.2×10~9CFU/kg酿酒酵母菌、1.1 g/kg酶菌制剂(包含地衣芽孢杆菌≥6×10~9CFU/g、酿酒酵母菌≥4×10~9CFU/g、碱性蛋白酶≥1 000 U/g)。预试期10 d,正试期56 d。当酶菌制剂组试验羊体重约达37 kg时,每组选取4只羊进行消化代谢试验,预试期7 d,正试期5 d。结果表明:1)各试验组干物质表观消化率、酸性洗涤纤维表观消化率均显著高于对照组(P0.05),酶菌制剂组干物质表观消化率、有机物表观消化率最高,显著高于莫能菌素组和地衣芽孢杆菌组(P0.05)。2)各试验组总能表观消化率、总能代谢率显著高于对照组(P0.05)。3)各试验组氮表观消化率显著高于对照组(P0.05),酶菌制剂组表观可消化氮、氮表观消化率显著高于对照组、莫能菌素组、地衣芽孢杆菌组(P0.05)。结果提示,从作为饲料添加剂对杜寒杂交肉羊营养物质消化利用、能量代谢和氮代谢的作用效果分析,地衣芽孢杆菌、酿酒酵母菌和酶菌制剂均优于莫能菌素,酶菌制剂最佳。     

β-甘露聚糖酶对肉鸭椰籽粕消化率的影响

选取8周龄体质量一致成年24只樱桃谷肉鸭公鸭,随机分为3组。A组70%基础饲粮+30%椰籽粕+β-甘露聚糖酶;B组70%基础日粮+30%椰籽粕;C组100%基础日粮。试验肉鸭单笼饲养,自由饮水。以Sibbald真代谢能顶替法测定β-甘露聚糖酶对肉鸭椰籽粕消化率的影响。试验结果表明:A组蛋白质表观消化率与真实消化率比B组分别高8.04%与7.35%,差异均显著;A组能量表观消化率与真实消化率比B组分别高3.61%与3.38%,差异均显著;A组干物质消化率比B组高4.59%,差异显著;A组粗纤维消化率比B组高18.16%,差异显著。加酶后,樱桃谷肉鸭对椰籽粕表观代谢能与真代谢能分别提高了12.02%与15.01%。加酶后,除了赖氨酸、蛋氨酸和组氨酸,其他各种氨基酸消化率加酶后均比不加酶时要高;椰籽粕总氨基酸消化率提高了3.92%。试验结果表明:加入β-甘露聚糖酶后对椰籽粕氨基酸养分消化率有促进作用。     

低磷日粮中添加植酸酶对生长猪生产性能及饲料中磷、钙和蛋白质表观消化率的影响

本试验研究低磷日粮中添加植酸酶对生长猪生产性能及饲料中磷、钙和蛋白质表观消化率的影响。试验采用2个4×4拉丁方设计,对照组(饲粮中不添加植酸酶)和加酶组(植酸酶浓度为500 FTU/kg饲粮)。以8头始重为35～40 kg的杜长二元杂种阉猪为试材,运用平衡试验法,研究植酸酶对小麦、稻谷和高粱3种植物性饲料中磷、钙和蛋白质表观消化率的影响。试验采用限量饲喂,即在满足维持能量需要的基础上,满足生长能量需要的80%饲喂。结果:①试验猪的平均日增重稍低于该品种正常饲养条件下的平均日增重,但加酶组与对照组比较,试猪的平均日增重均较高。②试验测得,与对照组比较,添加植酸酶使小麦、高粱和稻谷中的总磷表观消化率分别提高27.64%、47.87%和41.84%,3种饲料多重比较差异均极显著(P<0.01);与对照组相比,小麦、高梁和稻谷饲粮组磷的沉积率分别是提高27.98%、47.35%和40.63%,3种饲料多重比较差异均极显著(P<0.01);③钙的表观消化率,加酶组均高于对照组,但差异不显著(P>0.05);④蛋白质的表观消化率,加酶组均高于对照组,但差异不显著(P>0.05)。研究表明,在低磷日粮中添加植酸酶能改善生长猪的生长性能,显著提高饲料原料中磷的表观消化率,也提高了饲粮中钙和蛋白质的表观消化率。     

低蛋白质饲粮中苏氨酸水平对离乳前期梅花鹿仔鹿生长性能和营养物质表观消化率的影响

本试验旨在研究低蛋白质饲粮中苏氨酸水平对离乳前期梅花鹿仔鹿生长性能和营养物质表观消化率的影响。选择24只健康无病的3月龄雄性梅花鹿,随机分为4组,每组6只。4组仔鹿限量饲喂4种不同的饲粮,各组饲粮赖氨酸、蛋氨酸水平均分别为0.87%、0.28%。其中,高蛋白质饲粮对照组(Ⅰ组)仔鹿饲喂蛋白质水平为16%的高蛋白质饲粮,低蛋白质饲粮试验组(Ⅱ~Ⅳ组)仔鹿饲喂蛋白质水平为14%并添加不同水平苏氨酸的低蛋白质饲粮,各组饲粮中苏氨酸水平分别为0.54%(Ⅰ组)、0.46%(Ⅱ组)、0.59%(Ⅲ组)、0.72%(Ⅳ组)。预试期为15 d,正试期为30 d。结果表明:1)高蛋白质饲粮对照组的平均日增重(ADG)极显著高于Ⅱ组(P0.01),与Ⅲ、Ⅳ组差异不显著(P0.05);高蛋白质饲粮对照组的料重比(F/G)极显著高于Ⅲ、Ⅳ组(P0.01),极显著低于Ⅱ组(P0.01)。2)高蛋白质饲粮对照组的粗蛋白质表观消化率极显著低于Ⅲ和Ⅳ组(P0.01),极显著高于Ⅱ组(P0.01);高蛋白质饲粮对照组能量表观消化率极显著低于Ⅲ、Ⅳ组(P0.01),与Ⅱ组无显著差异(P0.05);Ⅲ组钙表观消化率极显著高于Ⅱ组(P0.01),与其他组差异不显著(P0.05)。3)高蛋白质饲粮对照组的组氨酸、天冬氨酸、谷氨酸、甘氨酸、半胱氨酸表观消化率显著高于Ⅱ组(P0.05),与Ⅱ组其他氨基酸表观消化率无显著差异(P0.05);高蛋白质饲粮对照组赖氨酸、蛋氨酸、苏氨酸、精氨酸、丙氨酸、酪氨酸表观消化率极显著低于Ⅲ组(P0.01),缬氨酸、亮氨酸、苯丙氨酸、丝氨酸表观消化率显著低于Ⅲ组(P0.05);高蛋白质饲粮对照组除丙氨酸的表观消化率极显著低于Ⅳ组(P0.01)以及赖氨酸、苏氨酸、缬氨酸、丙氨酸表观消化率显著低于Ⅳ组(P0.05)外,其他氨基酸的表观消化率与Ⅳ组无显著差异(P0.05)。由此得出,低蛋白质饲粮中适宜水平的苏氨酸对离乳前期梅花鹿仔鹿的生长性能和营养物质消化利用具有促进作用;当饲粮赖氨酸、蛋氨酸水平相同时,饲喂蛋白质水平为14%、苏氨酸水平为0.59%的低蛋白质饲粮的梅花鹿仔鹿的生长性能和营养物质表观消化率均优于饲喂蛋白质水平为16%的高蛋白质饲粮的梅花鹿仔鹿。     

浙江鱼粉和秘鲁鱼粉氨基酸对鸡的消化率比较

本试验以去盲肠鸡和正常鸡各１６只测定了浙江鱼粉和秘鲁鱼粉的氨基酸表观消化率（ＡＡＡＤ）和真消化率（ＴＡＡＤ）。结果表明，以去盲肠鸡测定，浙江鱼粉多数氨基酸的ＡＡＡＤ和ＴＡＡＤ超过秘鲁鱼粉（Ｐ＜０．０５）。以正常鸡测定，两者大多数氨基酸消化率无显著差异（Ｐ＞０．０５）。说明新鲜优质浙江鱼粉的氨基酸可消化性与进口鱼粉相当，甚至更优     

去盲肠鸡和未去盲肠鸡测定花生粕、胡麻粕、芝麻粕氨基酸消化率的研究

分别用２４只去盲肠和未去盲肠健康公鸡，测定了花生粕、胡麻粕和芝麻粕的氨基酸消化率。结果表明：去盲肠鸡内源氨基酸排泄量显著高于未去盲肠鸡（Ｐ＜０．０５）；在花生粕中，胱氨酸、赖氨酸、天冬氨酸和谷氨酸的ＡＡＤ未去盲肠鸡显著高于去盲肠鸡（Ｐ＜０．０５）；在胡麻粕和芝麻粕中，除酪氨酸和脯氨酸外，其它各种氨基酸及１６种氨基酸总和的ＡＡＡＤ和ＴＡＡＤ未去盲肠鸡显著高于去盲肠鸡（Ｐ＜０．０５）。鸡盲肠微生物对内源及饲料中未消化蛋白质、多肽及氨基酸具有分解作用，干扰饲料ＡＡＡＤ和ＴＡＡＤ测定。对于不易消化、氨基酸含量相对不平衡的低品质蛋白质饲料干扰尤其严重。在测定的３种饼粕中，花生粕氨基酸消化率最高，胡麻粕次之。过度热处理的芝麻粕氨基酸平均消化率为４７．３％，赖氨酸消化率为２１．７％。     

豆粕和棉粕日粮中添加α-半乳糖苷酶对肉仔鸡生长性能的影响

试验研究了豆粕日粮和含5%～8%棉粕的日粮中添加α-半乳糖苷酶对肉仔鸡生长性能的影响及可能机制。试验Ⅰ为肉仔鸡饲养试验,选用1日龄AA商品代肉仔鸡公雏672只,随机分为4个处理,每个处理12个重复,每个重复14只鸡,试验期42d。结果表明:在棉粕和豆粕日粮中添加α-半乳糖苷酶对42日龄肉仔鸡体增重分别提高了4.35%和3.49%。试验Ⅱ为排空强饲代谢试验。结果显示:豆粕日粮中添加α-半乳糖苷酶增加蛋公鸡色氨酸真消化率(P<0.001),对其他氨基酸消化率无影响。添加α-半乳糖苷酶的豆粕的,真代谢能值与不添加酶的相比,提高了4.69%(0.51MJ/kg)。本研究表明,在玉米-豆粕型日粮中添加α-半乳糖苷酶,提高了色氨酸真消化率和真代谢能,有利于提高肉仔鸡生长性能。     

Comparison of amino acid digestibility using the ileal digesta from growing chickens and cannulated adult cockerels

Meat-and-bone meal (MBM), which had been heated (150 degrees C) for 0, 1.5, 3 or 5 h, was used along with an indigestible marker in four diets which were fed to young growing chickens and adult cockerels fitted with ileal cannulae. The ileal digesta from each group of birds were sampled and the apparent amino acid digestibilities of the four diets containing MBM were determined. The apparent digestibility values from growing chickens were higher (P less than 0.05) than those from cannulated cockerels. Differences in apparent digestibility of amino acids between diets as a result of heat treatment were consistent for all amino acids when comparing both techniques, with the exception of glutamic acid and arginine.     

Influence of food input and procedure of determination on metabolisable energy and digestibility of a diet measured with young and adult birds

Two series of balance trials were performed with adult cockerels and with broiler chickens during their 5th week of life, and one with adult colostomised hens. The latter served to determine the digestibility of protein of the diet under test. All birds were fed the same diet with one exception: in the case of colostomised hens limestone (100 g/kg) was added before feeding. The main purpose of the experiments was to compare the Sibbald procedure for determining the so-called true metabolisable energy (TME) with apparent metabolisable energy (AME) or TME values obtained by applying a conventional addition method (CAM). The results showed that the Sibbald procedure was less precise than CAM. The Sibbald procedure delivered incorrect TME and AME values, the reason for this being the use of starved birds. This led not only to wrong intercepts but also to misleading regression coefficients in the regression equations used to calculate energy excretion on food intake. In CAM there existed no differences between AME and TME. This was not true for the Sibbald procedure, in which AME values differed considerably from TME values. Because of the errors inherent in the Sibbald procedure it is suggested that it should be replaced by CAM, in which several feeding inputs should be used.     

Digestibilities of amino acids in maize, wheat and barley meals, determined with intact and caecectomised cockerels

1. Maize, wheat and barley meals, and a protein-free diet were each force-fed to 24 intact and 24 caecectomised adult cockerels. For each test, birds were starved of solid food for 48 h, fed, and then excreta collected for 48 h. 2. Quantities of nitrogen (N) and amino acids excreted after feeding the protein-free diet did not differ between intact and caecectomised birds. 3. True digestibility coefficients of N and amino acids did not differ between intact and caecectomised birds. 4. Differences between cereals in apparent digestibility of amino acids were inconsistent and more readily attributed to differences between amino acid intake than bioavailability. 5. Differences between cereals in true digestibility of amino acids were confined to higher values for N, aspartic acid, alanine and leucine in maize than in barley or wheat meals.     

脱毒菜籽饼对鸡饲养效果的评价——Ⅱ.代谢能与氨基酸消化率的测定

在京黄肉鸡和京白蛋鸡上应用 Sibbald“鸡真代谢能”快速测定法,测定了脱毒菜籽饼,菜籽饼、豆饼和鱼粉的表观代谢能含量和氨基酸的消化率。试验结果表明:(1)酸法脱毒工艺生产的脱毒菜籽饼与原菜籽饼的表观代谢能含量相近,分别为8.91和9.41MJ/kg(蛋鸡);(2)在13种饲料氨基酸中,脱毒菜籽饼和菜籽饼低于鱼粉和豆饼,各占21.65%,20.41%;(3)脱毒菜籽饼在蛋鸡体内氨基酸的平均消化率为87.73%,比鱼粉或豆饼中氨基酸的平均消化率仅低4.25%或2.36%,但比原菜籽饼高15.32%,说明脱毒工艺提高了菜籽饼中氨基酸的消化率。试验证明,用脱毒菜籽饼代替鸡饲粮中的豆饼是可行的。同时,还测得肉鸡对饲料中能量的利用和氨基酸的消化率高于蛋鸡,用四种蛋白质饲料饲喂京黄肉鸡的 AME 值平均比京白蛋鸡高3.74%,氨基酸的消化率京黄肉鸡比京白蛋鸡高5.79%。     

去盲肠和未去盲肠公鸡测定饲料氨基酸消化率的比较研究

应用Sibbald“TME”方法,比较了去盲肠和未去盲肠公鸡对饲料氨基酸的消化率。试验测定了10种饲料的去盲肠和未去盲肠公鸡的氨基酸消化率。结果表明,未去盲肠鸡对10种饲料的氨基酸表观和真消化率均高于去盲肠鸡。轻度受热鱼粉、重度受热鱼粉、脱毒棉籽饼、未脱毒棉籽饼和豆饼的表观氨基酸消化率在去盲肠鸡和未去盲肠鸡之间存在显著差异(P<0.05),未受热鱼粉和芝麻饼的表观氨基酸消化率在去盲肠鸡和未去盲肠鸡之间不存在显著差异(P>0.05)。轻度受热鱼粉、重度受热鱼粉、豆饼的真氨基酸消化率在去盲肠鸡和未去盲肠鸡之间存在显著差异(P<0.05);未受热鱼粉、脱毒棉籽饼、未脱毒棉籽饼和芝麻粕的真氨基酸消化率在去盲肠鸡和未去盲肠鸡之间不存在显著差异(P>0.05)。去盲肠鸡内源氨基酸排出量显著高于未去盲肠鸡(P>0.05)。微生物对未消化食糜中的肽类、氨基酸具有降解作用。     

Determination of amino acid digestibility using caecectomised and intact adult cockerels

Four subsamples of meat and bone meal (MBM) were heated (150 degrees C) for 0, 1.5, 3 and 5 h and then incorporated into four individual diets (100 g MBM/kg diet). The diets were precision-fed to 10 caecectomised and 10 intact adult cockerels. The apparent amino acid digestibility (ApAAD) and true amino acid digestibility (TAAD) of the diets were determined by analysis of the excreta. The digestibility coefficients measured using caecectomised birds were lower than those determined with intact birds. Coefficients of digestibility were statistically examined by analysis of variance for the effects of bird type (caecectomised or intact), type of calculation (apparent or true) and diet (heat-treatment) with and without accommodation for individual bird variability. If individual bird variability was not considered in the analysis the bird type X diet interactions (P less than 0.01) included glutamic acid, tyrosine and serine. When individual bird variability was included in the analysis, significant (P less than 0.01) bird type X diet interactions occurred for aspartic acid, serine, glutamic acid, leucine, tyrosine and lysine and the precision of the data was markedly improved. Amino acid digestibility using the precision-feeding procedure is affected by the selection of either intact or caecectomised birds.     

Intestinal function and gut microflora of broiler chickens as influenced by cereal grains and microbial enzyme supplementation

A study was conducted to investigate the effect of the key cereal grains and a microbial enzyme supplement on broiler chicken performance, gut microflora and intestinal function. Ingestion of the barley-based diet was associated with low 28-day body weight, decreased feed intake and high FCR. The supplemental enzyme increased feed intake and weight gain of the chickens on a wheat-based diet. The pH of the gizzard and caecal contents varied with the grain type. Enzyme supplementation reduced ileal viscosity, particularly in birds that received the diet based on wheat. The birds on the barley-based diet had lower ileal digestibility of dry matter, protein and energy than those given maize and sorghum-based diets. The ileal digestibility of starch was increased by enzyme supplementation. Enzyme supplementation increased the number of total anaerobic bacteria in the gizzard of birds fed on sorghum and increased lactobacilli in the gizzard of those fed both sorghum and wheat. The birds fed the sorghum-based diet had the lowest counts of caecal total anaerobic bacteria and lactobacilli. Jejunal villus height and villus:crypt ratio of birds fed the barley-based diet were the lowest when compared with those fed the other diets. Enzyme application induced an increase in villus height and villus:crypt ratio of birds on wheat, crypt depth on barley and a reduction in crypt depth of chickens on the sorghum-based diets. The highest activity of maltase and the lowest activity of sucrase were observed in tissue from birds fed on maize and sorghum-based diets respectively. The differences in the performance of broilers on cereal grains could be explained by changes in intestinal morphology, enzyme activities and gut microflora as well as nutrient digestibility. The improved performance by supplemental enzyme in wheat-fed chickens was associated with beneficial changes in intestinal morphology and digesta viscosity.