三种小麦混合日粮表观有效能值测定方法的比较研究

采用全收粪法、指示荆法、回肠末端食糜法测定14种不同来源小麦混合日粮的表观代谢能值(AME)和氮校正表观代谢能值(AMEn),同时用回肠末端食糜法测定回肠表观消化能(IDE)和回肠氮校正表观消化能(IDEn),然后比较3种方法所得表观有效能值之间的差别,结果表明:3种生物学方法所得的小麦混合日粮的表观有效能值有显著差异(P<0.05),其中全收粪法所得的AME最高为12.32 MJ/kg,显著高于指示剂法和回肠末端食糜法所得值;以回肠末端食糜法所得的IDEn最低为10.84 MJ/kg,显著低于全收粪法和指示剂法;全收粪法所得的AMEn的C.V较大为7.69%,回肠末端食糜法所得IDE的C.V较小为6.44%,其余表观有效能值的C.V比较接近.     

不同来源菜籽粕有效能值的变异度分析及酶制剂的添加效果研究

本试验采集10份代表性菜籽粕样品,选用28~35日龄科宝肉仔鸡,采用全收粪法、指示剂法、回肠食糜法3种试验方法,结合套算法测定菜籽粕的表观代谢能(AME)、氮校正表观代谢能(AMEn)和回肠表观消化能(IDE),并评估有效能值的变异。从上述结果中选取有效能值高、中、低的3个菜籽粕样品,进一步评估添加复合酶制剂对其有效能值的影响。结果表明,10个不同来源菜籽粕间AME和AMEn存在较大变异,变异范围分别为6.73~10.01 MJ/kg和6.62~9.81 MJ/kg。指示剂法和回肠食糜法测得的菜籽粕有效能值相当,均显著低于全收粪法测定值(P0.05)。三种测定方法测得的有效能值变异系数为10.04%~10.93%。与对照组相比,添加两种复合酶制剂(A和B)均可提高菜籽粕的AME、AMEn和IDE,但差异均不显著(P0.05)。酶制剂B对菜籽粕有效能值的提高幅度略高于酶制剂A,且品质较差的菜籽粕添加酶制剂的效果优于品质好的。     

全收粪法与Cr2O3指示剂法测定家禽表观代谢能方法比较

通过全收粪法和Cr2O3指示剂法,对20种不同来源玉米-豆粕型日粮的肉鸡的表观代谢能(AME)进行测定.结果表明全收粪法测定玉米AME在绝干基础上是14.92～16.10 MJ/kg,平均15.60 MJ/kg,RSD为2.15%;指示剂法所测玉米AME在绝干基础上是15.05～16.16 MJ/kg,平均15.65 MJ/kg,RSD为2.11%;两种方法所测代谢能值相关分析,相关方程式AME(全)=1.00142×AME(指)-0.06918(R2=0.9708),二者高度相关;配对T检验,指示剂法比全收粪法值高,但差异不显著(P＞0.05).可见,Cr2O3指示剂法与全收粪法在测定肉禽AME时具有高度相关性,指示剂法可作为一种快速准确的评定家禽表观代谢能的方法在试验研究和生产实践中推广.     

90～100日龄慢速型黄羽肉鸡常规能量和糠麸类饲料原料代谢能评定

试验旨在为慢速型黄羽肉鸡日粮配制提供数据参考并完善我国黄羽肉鸡饲料原料基础数据库,选用90日龄清远麻鸡168只,按体重随机均分成7组,每组6个重复,每个重复4只鸡。试验预饲3 d,全收粪3 d。7组分别饲喂基础日粮、30%玉米日粮、30%大麦日粮、30%小麦日粮、30%高粱日粮、25%麦麸日粮、30%米糠日粮。采用全收粪和套算法测定总能(GE)代谢率、表观代谢能(AME)和氮校正代谢能(AMEn)。结果表明:玉米、大麦、小麦、高粱、麦麸和米糠的总能代谢率分别为83.0%、82.5%、83.3%、83.9%、39.5%、65.9%,AME分别为13.56、12.98、13.10、13.61、6.99、11.92 MJ/kg,AMEn分别为13.41、12.61、12.93、13.41、6.54、11.52 MJ/kg。     

不同比例豆粕组合的营养价值及肉仔鸡代谢能预测模型的建立

本试验通过不同比例豆粕和豆皮配制出不同种类的6种人工豆粕,测定人工豆粕营养成分含量和代谢能,旨在建立豆粕的肉仔鸡代谢能预测模型。选取1 008只1日龄爱拔益加(AA)公雏鸡,随机分为7组(其中1组为饥饿组),每组8个重复,每个重复18只鸡。于14～16日龄采用全收粪法测定肉仔鸡的表观代谢能(AME)、氮校正表观代谢能(AMEn)、真代谢能(TME)和氮校正真代谢能(TMEn),并采用营养成分逐步回归建立肉仔鸡代谢能预测方程。结果表明:1)配制的6种人工豆粕中粗蛋白质(CP)含量呈梯度增加,粗脂肪(EE)、粗纤维(CF)、中性洗涤纤维(NDF)和酸性洗涤纤维(ADF)含量变异系数较大,分别为24.65%、42.57%、33.86%和45.09%。2)碳水化合物成分中蔗糖、棉子糖和水苏糖含量平均值分别为49.86、12.88和42.79 g/kg。3)14～16日龄肉仔鸡不同人工豆粕饲粮AME、AMEn、TME和TMEn平均值分别为11.68、11.48、12.30和12.06 MJ/kg,不同人工豆粕原料AME、AMEn、TME和TMEn平均值分别为11.36、11.17、12.74和12.51 MJ/kg。4)用常规营养成分含量逐步回归建立肉仔鸡代谢能预测方程如下:AME=9.078-0.123CF+0.060CP(R2=0.982, P 0.01), AME=2.236+0.187CP-0.120EE(R2=0.911,P 0.01);用寡糖含量建立肉仔鸡预测方程为AME=4.825+0.121CP+0.019蔗糖-0.229EE(R2=0.970,P0.01)等。用交叉验证法验证常规营养成分的预测方程,预测值和实测值接近,建立的肉仔鸡代谢能预测模型较成功。     

肉仔鸡饲料原料代谢能的生物学评定及可加性研究

本试验选用22日龄爱拔益加商品代肉仔鸡336只(公母各半),随机分为7个处理,每个处理8个重复(公母各4个重复),每个重复6只鸡.分别饲喂玉米、豆粕、棉粕、菜粕、玉米-豆粕、玉米-棉粕、玉米-菜粕7种试验日粮,测定28日龄肉仔鸡的表现代谢能(AME)和氮校正表观代谢能(AMEn).玉米、豆柏、棉粕、菜粕的AME分别为14.82、12.10、11.17、9.79 MJ/kg,AMEn分别为14.80、11.81、10.81、9.60 MJ/kg.三种混合日粮AME匝和AMEn的预测值与测定值差异不显著(P＞0.05),表明玉米和豆粕、棉粕、菜粕的AME和AMEn存在可加性.     

黄羽肉鸡饲料原料代谢能的测定

试验选用35日龄快大型黄羽肉鸡96只,随机分为4组,每组6个重复,每个重复4只鸡,分别饲喂以玉米淀粉、大麦、鱼粉和花生粕为基础原料配制的4种日粮。采用指示剂法测定玉米淀粉、大麦、鱼粉和花生粕的总能消化率、表观代谢能(AME)和氮校正表观代谢能(AMEn)。结果表明:黄羽肉鸡玉米淀粉、大麦、鱼粉和花生粕的总能消化率分别为68.77%、65.67%、89.57%、75.85%,AME分别为8.82、9.45、13.27、11.22 MJ/kg,AMEn分别为8.71、9.34、13.00、10.99 MJ/kg。     

河南省小麦肉鸡代谢能预测方程的建立

本试验采用化学分析和肉鸡代谢试验建立了河南省小麦养分含量与代谢能的回归方程。试验1:选取河南省11种不同的成熟小麦,测定概略养分含量和容重,分析养分含量变化范围。试验2:用小麦、次粉、麸皮、面粉按照总戊聚糖含量梯度配制人工小麦,再添加一定量的维生素和矿物质,配制成人工小麦代谢饲粮。选取常规饲养的商品代罗斯308雄性白羽肉鸡进行代谢试验,分别在11~13日龄和25~27日龄,用全收粪法测定人工小麦代谢饲粮的表观代谢能(AME)、真代谢能(TME)、氮校正表观代谢能(AMEn)和氮校正真代谢能(TMEn),并采用逐步回归法建立AME、TME、AMEn和TMEn的回归方程。结果表明:1)河南省小麦粗脂肪(EE)、中性洗涤纤维(NDF)、酸性洗涤纤维(ADF)及总磷(TP)含量的变异系数相对较大,分别为16.67%、15.84%、14.96%、19.32%。2)肉鸡对人工小麦代谢饲粮的养分表观代谢率在11~13日龄和25~27日龄存在差异,25~27日龄肉鸡对人工小麦代谢饲粮ADF、粗纤维(CF)的表观代谢率高于11~13日龄,AME、TME、AMEn和TMEn也高于11~13日龄。3)采用逐步回归法建立河南省小麦肉鸡代谢能的预测方程为:11~13日龄,AME=14.628-0.184NDF(R2=0.842,P<0.01),TME=15.49-0.197NDF(R2=0.854,P<0.01),AMEn=14.571-0.184NDF(R2=0.847,P<0.01),TMEn=15.49-0.197NDF(R2=0.854,P<0.01);25~27日龄,AME=15.462-0.217NDF(R2=0.797,P<0.01),TME=16.124-0.214NDF(R2=0.809,P<0.01),AMEn=15.179-0.208NDF(R2=0.801,P<0.01),TMEn=16.123-0.214NDF(R2=0.809,P<0.01)。4)通过预测方程计算所得人工小麦代谢饲粮AME、TME、AMEn和TMEn的预测值与实测值很接近,计算所得的河南省小麦AME、TME、AMEn和TMEn符合预期值。由此得出,不同品种河南省小麦之间EE、NDF、ADF及TP的含量差异相对较大;不同日龄阶段的肉鸡对小麦代谢能存在差异,设计肉鸡饲粮配方时,不同阶段饲粮代谢能应采用对应的代谢能值;低于14日龄的肉鸡,预测方程为AME=14.628-0.184NDF,TME=15.49-0.197NDF,AMEn=14.571-0.184NDF,TMEn=15.49-0.197NDF;14日龄以上的肉鸡,预测方程为AME=15.462-0.217NDF,TME=16.124-0.214NDF,AMEn=15.179-0.208NDF,TMEn=16.123-0.214NDF。     

鹅对几种原料代谢能值的测定

本试验以24只175日龄扬州鹅公鹅为试验对象,用真代谢能(TME)测定法,测定了鹅对玉米、豆粕、小麦麸、稻谷、棉籽粕、苜蓿粉6种原料的代谢能值。试验结果表明:1)鹅对玉米、稻谷、小麦麸、豆粕、棉籽粕、苜蓿粉的表观代谢能(AME)值分别为12.23、10.93、8.03、8.99、6.67、4.25MJ/kg;真代谢能值分别为12.89、11.59、8.93、9.85、7.60、5.19MJ/kg。2)测得6种原料的TME值高于AME值,且TME∶AME为1.05～1.25;TME值的变异系数(CV)小于AME值,表明TME值的稳定性优于AME值。     

添加木聚糖酶的小麦型日粮对肉仔鸡表观代谢能的影响

试验旨在比较研究不同木聚糖酶产品对小麦代谢能的影响。624只AA肉仔鸡随机分为13组,每组8个重复,每个重复6只鸡。其中1组为基础日粮对照组,另外12个处理组组成一个3×4二因素(小麦和木聚糖酶)完全随机试验。其中小麦设4个水平(样本),木聚糖酶设3个水平(不加酶、加酶A 400 mg/kg、加酶B 257.56 mg/kg),两种酶的添加活性均为1 500 U/kg饲料。采用外源指示剂法评定添加木聚糖酶制剂前后小麦代谢能的变化。结果表明,不同小麦样品的AME和AMEn有极显著差异(P0.01),其中以小麦1和小麦4能值最高。日粮中添加两种木聚糖酶均极显著提高了小麦的AME和AMEn(P0.01),其中以酶B的效果最为明显,极显著高于酶A(P0.01)。添加酶A平均提高小麦AME和AMEn 420 kJ/kg和300 kJ/kg,添加酶B平均提高小麦AME和AMEn 790 kJ/kg和710 kJ/kg。     

近红外光谱分析技术在小麦麸的饲料营养价值评定上的应用

<正> 前言 随着集约化饲养业及配合饲料工业的迅速发展,对饲料营养价值评定手段的精度和效率提出了愈来愈高的要求。近几十年来常规化学分析技术有了一系列突破,在手段简化、试剂节约以及自动化方面都取得了许多卓有成效的进展。但是所有方法都还需要对饲料样品进行破坏性的预处理及经过相应的测试程序;对饲料营养价值的评定则还需要通过试验动物。由于这些条件的限制,在分析某一饲料时,一般只能采取压缩样品量,     

Ileal digestibilities of neutral detergent fiber, crude protein, and amino acids associated with neutral detergent fiber in wheat shorts for growing pigs

An experiment was carried out to determine the ileal digestibility values of NDF, CP, and AA associated with NDF in different samples of wheat shorts consisting of different proportions of wheat bran, shorts, and flour, hereafter referred to as wheat fractions. Six barrows (average initial BW 37.2 kg, and fitted with a simple T-cannula at the distal ileum) were fed one of six experimental diets, formulated to contain 17% CP (as-fed basis), according to a 6 x 6 Latin square design. Diets A, B, C, D, and E contained 17.53% soybean meal (SBM), which contributed 50% CP to these diets. The diets contained shorts, bran, or flour alone or in combination, contributing the remaining 50% CP to these diets. The proportions of shorts, bran, and flour in the wheat fractions were 70% shorts and 30% bran in diet A, 85% shorts and 15% bran in diet B, 100% shorts in diet C, 85% shorts and 15% flour in diet D, and 70% shorts and 30% flour in diet E. Diet F contained 35.05% soybean meal, which provided the sole source of dietary CP. Chromic oxide was used as a digestibility marker. During the first experimental period, the daily dietary allowance was provided at a rate of 5% (wt/wt) of the average BW. Thereafter, the allowance was increased by 100 g at each successive period. Each experimental period comprised 12 d. Following a 7-d adaptation period, feces were collected for 48 h and ileal digesta for a total of 24 h. The contribution of CP and AA associated with NDF gradually decreased from wheat fraction A to E, reflecting a decrease in NDF content from 42.3 to 29.5%. Of the indispensable AA in wheat fraction A, the contributions ranged from 12.9 to 15.9%. In wheat fraction E, these values ranged from 9.0 to 11.3%. The ileal digestibility values of NDF ranged from 11.8% in diet E to 17.1% in diet C (P > 0.05). There were usually no differences (P > 0.05) in the ileal digestibilities of AA associated with NDF between the wheat fractions. However, with the exception of lysine and tyrosine, there were negative correlations (P < 0.05) between the apparent ileal AA digestibilities and the content (%) of CP associated with NDF in the wheat fractions. Furthermore, there was no effect (P > 0.05) of the diets containing wheat fractions on the recovery of bacterial protein and mucin in ileal digesta.     

Influence of method of whole wheat inclusion and xylanase supplementation on the performance, apparent metabolisable energy, digestive tract measurements and gut morphology of broilers

1. The aim of the present study was to examine the influence of whole wheat inclusion and xylanase supplementation on the performance, apparent metabolisable energy (AME), digesta viscosity, and digestive tract measurements of broilers fed on wheat-based diets. The influence of the method of whole wheat inclusion (pre- or post-pelleting) was also compared. A 3 x 2 factorial arrangement of treatments was used with three diet forms (648 g/kg ground wheat [GW], GW replaced by 200 g/kg of whole wheat before [WW1] or after cold-pelleting [WW2]) and two xylanase levels (0 and 1000 XU/kg diet). 2. Birds given diets containing whole wheat had improved weight gains, feed efficiency and AME compared to those fed on diets containing ground wheat. The relative gizzard weight of birds fed WW2 diets was higher than in those fed GW and WW1 diets. Pre-pelleting inclusion of whole wheat had no effect on relative gizzard weight. Post-pelleting inclusion of whole wheat resulted in greater improvements in feed efficiency and AME than the pre-pelleting treatment. 3. Xylanase supplementation significantly improved weight gain, feed efficiency and AME, irrespective of the wheat form used. Viscosity of the digesta in the duodenum, jejunum and ileum were reduced by xylanase addition. Xylanase supplementation reduced the relative weight of the pancreas. 4. Neither xylanase supplementation nor whole wheat inclusion influenced the relative weight and length of the small intestine. 5. Xylanase supplementation increased ileal villus height. A significant interaction between diet form and xylanase was observed for ileal crypt depth. Xylanase supplementation had no effect on crypt depth in birds fed on diets containing GW, but increased the crypt depth in WW2 diets. No significant effects of diet form and xylanase supplementation were observed for the thickness of the tunica muscularis layer of gizzard or villus height, crypt depth, goblet cell numbers or epithelial thickness in the ileum. 6. Improved performance observed with post-pelleting inclusion of whole wheat was associated with increased size of the gizzard and improved AME. The gizzard development hypothesis, however, will not explain the improvements observed with pre-pelleting inclusion of whole wheat, suggesting the involvement of other factors.     

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.     

回归分析法评价4种麦类饲料原料的肉鸡有效能值

本试验旨在评价大麦、黑小麦、小麦和黑麦4种麦类饲料原料在肉鸡上的有效能值,以期优化现有配方数据库,逐步实现饲粮营养的精准供给。采用回归分析法,试验分2批进行,试验1评价大麦和黑小麦的肉鸡回肠消化能(IDE)、代谢能(ME)、氮校正代谢能(MEn),试验2评价小麦和黑麦的肉鸡IDE、ME、MEn。每个批次试验均选用320只1日龄雄性罗斯708肉鸡为试验动物,将其随机分为5个组,每组设8个重复,每个重复8只鸡。1~20日龄为预试期,饲喂基础饲粮;21~28日龄为试验期,分别饲喂基础饲粮和试验饲粮。试验1的5个组21~28日龄所喂饲粮如下:基础饲粮、含250 g/kg大麦的饲粮、含500 g/kg大麦的饲粮、含250 g/kg黑小麦的饲粮、含500 g/kg黑小麦的饲粮。试验2的5个组21~28日龄所喂饲粮如下:基础饲粮、含250 g/kg小麦的饲粮、含500 g/kg小麦的饲粮、含250 g/kg黑麦的饲粮、含500 g/kg黑麦的饲粮。结果表明:在饲粮中添加大麦、黑小麦、小麦和黑麦对肉鸡生长性能均无显著影响(P>0.05)。大麦替代量与干物质、能量的回肠消化率以及干物质、氮、能量的全肠道代谢率,以及IDE、ME、MEn存在极显著的线性降低关系(P<0.01);黑小麦替代量与氮全肠道代谢率、IDE、ME、MEn存在极显著的线性降低关系(P<0.01),且与干物质、能量回肠消化率、IDE存在显著或极显著的二次曲线关系(P<0.05或P<0.01);小麦替代量与干物质、氮、能量、氮校正能量的全肠道代谢率显著或极显著的线性降低关系(P<0.05或P<0.01),且与干物质、能量的回肠消化率和IDE存在显著或极显著的二次曲线关系(P<0.05或P<0.01);黑麦替代量与干物质、能量的回肠消化率以及干物质、氮的全肠道代谢率存在显著或极显著线性降低关系(P<0.05或P<0.01);且与干物质、能量的回肠消化率和干物质、氮、能量、氮校正代谢能的全肠道代谢率以及IDE、ME、MEn存在显著或极显著的二次曲线关系(P<0.05或P<0.01)。通过回归分析得出大麦的肉鸡IDE、ME和MEn分别为9.31、10.50、10.29 MJ/kg,黑小麦分别为10.99、11.80、11.43 MJ/kg,小麦分别为10.59、11.81、11.28 MJ/kg,黑麦分别为11.97、12.56、11.83 MJ/kg。     

不同纤维来源饲粮和细胞壁降解酶对猪肠道微生物菌群多样性的影响

本试验旨在利用末端限制性片段长度多态性技术研究不同纤维来源饲粮和细胞壁降解酶对猪肠道微生物菌群多样性及其组成结构的影响。试验选用8头平均体重为(35.0±2.5)kg的"杜×长×大"三元杂交生长猪,统一安装回肠末端T型瘘管,随机分为4组,每组2个重复。试验分4期,每期每组猪按4×4拉丁方设计饲喂小麦麸、小麦麸加酶、大豆皮和大豆皮加酶4种试验饲粮之一。每期预试期15 d,正试期6 d。试验结果表明:1)大豆皮饲粮组猪回肠食糜微生物的多样性显著高于小麦麸饲粮组(P0.05)。2)小麦麸饲粮组显著提高猪回肠食糜中普氏菌属(Prevotella)和乳酸杆菌属(Lactobacillus)的丰度(P0.05),而大豆皮饲粮组则显著提高猪回肠食糜中瘤胃球菌属(Ruminococcus)及粪便中拟杆菌属(Bacteroides)、毛螺菌属(Lachnospira)的丰度(P0.05)。3)添加细胞壁降解酶显著提高各饲粮组猪回肠食糜中Lachnospira、真细菌属(Eubacterium)及粪便中Lachnospira的丰度(P0.05),但也同时降低了回肠食糜中Lactobacillus、Prevotella及粪便中Lactobacillus、Bacteroides和克雷伯氏菌属(Klebsiella)的丰度(P0.05)。综上所述,纤维饲粮可显著提高猪肠道内非淀粉多糖降解菌的丰度,而细胞壁降解酶则可选择性改变肠道微生物菌群的多样性及其组成。     

Lack of relationship between either specific weight or presence of the 1B1R gene and nutritive value of wheat in broiler diets

1. A study of the relationship between specific weight (SW) and nutritive value of wheat in diets offered to broilers up to 4 weeks of age was carried out using 10 varieties of wheat grown at three different locations; this gave rise to a range of specific weights from 59 to 76 kg/hl. 2. Because five varieties contained the 1B1R translocation and 5 did not, this allowed the effects of 1B1R on the performance of birds given high concentrations of dietary wheat to be further investigated. 3. The diets, which contained wheat at 744 g/kg with casein (142 g/kg) as the sole protein supplement, were heat-treated and pelleted. They were fed ad libitum to male, Ross broiler chicks from 7 to 28 d, in individual cages in a controlled environment room. 4. A 7 d excreta collection was made from 14 to 21 d for determination of apparent metabolisable energy (AME) content and wheat AME was calculated from the diet values. A separate determination of true metabolisable energy (TME) was undertaken using the method of McNab and Blair (British Poultry Science, 29: 697-707, 1988). 5. Wheat samples were analysed for proximate constituents, starch, total and soluble non-starch polysaccharides (NSP), amino acid content and gross energy and specific weight, thousand grain weight and in vitro viscosity were recorded. They were also subjected to near infrared reflectance spectroscopy (NIRS) with a view to establishing relationships with chemical constituents and performance parameters. 6. At 28 d the birds were humanely killed and in vivo viscosity was determined on the jejunal digesta supernatant. 7. There was quite a narrow range of crude protein content (N x 5.83) across the 30 wheat samples, the means for the three locations (Crossnacreevy, Downpatrick and Limavady, respectively) being 112, 121 and 122 g/kg. Starch contents of individual samples ranged from 604 to 679 g/kg, total NSP from 92.1 to 122.6 g/kg, soluble NSP from 17.6 to 32.6 g/kg and in vitro viscosity from 10.6 to 26.3 cps. 8. There were no significant varietal effects for dry matter intake (DMI), live weight gain (LWG) or gain:feed ratio. Apparent metabolisability of energy (ME:GE) for the diets ranged from 0.738 (Hussar) to 0.778 (Harrier) the effect being significant (P < 0.05) and there was a significant (P < 0.001) relationship (r(2) = 0.46) between ME:GE and gain:feed ratios. Calculated wheat AME for individual varieties ranged from 14.1 to 15.0 MJ/kg DM (P > 0.05). TME values ranged from 16.3 to 16.6 MJ/kg DM (NS). 9. In vivo viscosity ranged from 12.3 (Ritmo) to 23.7 cps (Hussar), the varietal effects being significant (P < 0.001). Viscosity was significantly higher for the 1B1R varieties than for the non-1B1R (22.7 vs 16.3 cps) but there were no significant effects on mean DM intake, LWG, gain:feed, ME:GE, calculated wheat AME, ME:gain (MJ AME per kg gain) or TME. 10. Wheat AME was negatively correlated (P < 0.05) with total NSP (slope -0.035) but was significantly affected by variety, constants ranging from 16.74 to 17.79. For wheat TME there were significant variety*total NSP interactions with slopes ranging from 0.29 to -0.07. There was no significant relationship between wheat AME and soluble NSP and there were significant variety*soluble NSP interactions for TME with slopes ranging from 0.09 to -0.14. 11. Despite the relatively wide range of in vitro viscosity there was no significant correlation of either calculated wheat AME or wheat TME with in vitro viscosity. For TME there were significant variety*viscosity interactions with slopes ranging from 0.21 to -0.13 (P < 0.001). There was also no significant correlation between soluble NSP and in vivo viscosity. 12. AME values for the NIRS calibration set varied from 13.7 to 15.6 MJ/kg and averaged 14.6 MJ/kg, whereas for the validation set, the values ranged from 14.0 to 16.1 MJ/kg with the mean value being 14.7 MJ/kg. The best correlation coefficient (r(2)) of 0.90 was obtained when the calibration sample set was subjected to SMLR using the second-order derivatised data. However, moving to validation, the outcome was extremely poor with 1-VR values being 0.12 and 0.09, respectively, for the external validation and an internal validation subset. 13. In summary, none of the production characteristics showed a good correlation with specific weight. Using the linear estimates for wheat AME and TME the effect of a 10 kg/hl change in SW equates to a 3 or 1.4% change, respectively. The estimate for AME is likely to be a worst-case value due to the high inclusion level of wheat. The range of calculated wheat AME (approximately 1 MJ) across the 30 wheat samples is similar to that seen in previous studies for wheat grown in Northern Ireland and much lower than in some other studies. 14. None of the other parameters examined gave any better relationship with nutritive value (assessed as AME or TME) than SW. This is a disappointing outcome, particularly in view of some previous studies which suggested that in vitro viscosity provides a good prediction of nutritive value.     

Ileal amino acid digestibility assay for the growing meat chicken--comparison of ileal and excreta amino acid digestibility in the chicken

1. The apparent and true amino acid digestibilities in sorghum, wheat, soyabean meal, meat-and-bone meal, fish meal and blood meal for growing meat chickens were determined using an assay based on the collection of digesta from the terminal ileum and comparison was made with digestibility values determined using an excreta-based assay. 2. Five-week-old meat chickens were given maize-soyabean meal basal diet or mixtures of the basal diet and test diets containing the 6 ingredients as the sole source of dietary protein (50:50 on weight basis). Apparent amino acid digestibility values of assay diets at ileal and excreta levels were calculated using chromic oxide as the indigestible marker. True digestibility values were calculated using endogenous outputs determined by feeding a protein-free diet. Amino acid digestibilities of the ingredients were calculated by difference. 3. The site of measurement had no influence on endogenous amino acid output, the exceptions being aspartic acid and glutamic acid. The output of these two amino acids was higher in the excreta. 4. Significant differences were found between ileal and excreta-based digestibility of certain amino acids in some ingredients, with excreta values being usually higher than the ileal values, indicating a net catabolism of amino acids in the large intestine. The degree of net amino acid disappearance was found to be variable among amino acids and ingredients. In general, threonine had the lowest digestibility at the ileal level and, compared with other amino acids, the highest degredation during passage through the hindgut. 5. The results showed that digestibility determination based on excreta collection will overestimate the uptake for some amino acids in some feeds. The degree of overestimation was often considerable, ranging from 8.9% (apparent digestibility of threonine in soyabean meal) to 56% (apparent digestibility of aspartic acid in wheat). It is concluded that digestibility values measured at the terminal ileum provide a more reliable measure of amino acid availability than those measured in the excreta.     

Effects of guar gum and cellulose on digesta passage rate, ileal microbial populations, energy and protein digestibility, and performance of grower pigs

Dietary guar gum and cellulose were studied as purified soluble and insoluble nonstarch polysaccharide (NSP) sources, respectively. A control diet containing 14% cornstarch was formulated. A 7% guar gum, a 7% cellulose, and a 7% guar gum + 7% cellulose diet were formulated by adding the NSP to the control diet at the expense of cornstarch (wt/wt), forming a 2 x 2 factorial arrangement. The objectives were to determine whether guar gum and cellulose altered 1) the passage rate of digesta through the small intestine and total tract; 2) the digestibility of energy and CP, characteristics of the digesta, and microbial populations in the ileum; 3) plasma glucose and ghrelin concentrations; and 4) short-term voluntary feed intake and growth performance of grower pigs. In Exp. 1, 12 pigs (27.0 +/- 1.5 kg of BW) were fitted with an ileal T-cannula and were used in a 2-period change-over design, providing 6 observations per diet. Each period included 18 d: a 12-d acclimation period followed by 2-d feces, 3-d digesta, and 1-d venous blood collection periods. In Exp. 1, guar gum and cellulose slowed the passage rate of digesta through the small intestine by 26 and 18%, respectively (P < 0.05). Guar gum increased total tract retention time of the digesta by 14% (P < 0.05). Guar gum and cellulose increased the viscosity of ileal digesta by 72 and 76%, respectively (P < 0.05). Cellulose reduced ileal energy and CP digestibility (P < 0.05), but guar gum only tended to decrease ileal energy digestibility (P < 0.10). Guar gum and cellulose reduced total tract energy and CP digestibility (P < 0.05). At 60 min after feeding, guar gum decreased plasma glucose by 10% (P < 0.10). Guar gum interacted with cellulose to reduce plasma ghrelin before and after feeding (P < 0.05). Guar gum and cellulose interacted to increase ileal bifidobacteria and enterobacteria (P < 0.05); however, guar gum, but not cellulose, increased ileal clostridia (P < 0.05). In Exp. 2, 20 individually housed grower pigs (5 pigs per diet) had free access to the 4 diets used in Exp. 1 for 14 d. Guar gum and cellulose decreased ADG and reduced ADFI on d 0 to 14 (P < 0.05). In summary, increasing purified NSP in the diet reduced the passage rate of digesta, energy and protein digestibility, and feed intake, but increased ileal bifidobacteria and enterobacteria populations. The effects of cellulose were similar to those of guar gum. In conclusion, monitoring of dietary NSP is a critical factor to achieve predictable digestible nutrient intake and intestinal bacterial populations.     

Effects of a xylanase on individual bird variation, starch digestion throughout the intestine, and ileal and caecal volatile fatty acid production in chickens fed wheat.

1. The effects of a xylanase on digesta viscosity and starch digestibility throughout the small intestine and volatile fatty acid production in the ileum and caeca were investigated in broilers fed on a low-metabolisable energy wheat diet. 2. The xylanase reduced (P<0.01) duodenal (2.9 vs. 1.7), jejunal (4.6 vs. 2.3) and ileal (14.0 vs. 3.9) digesta viscosities (mPas) and increased AME (P<0.01) of the wheat and starch digestibility (P<0.5) in the jejunum and ileum. Between-bird variability in ME and digestibility of starch was also reduced. 3. Enzyme supplementation reduced (P<0.05) fermentation in the ileum, but increased (P<0.05) it in the caeca. 4. The anti-nutritive effect of soluble non-starch polysaccharides (NSP) is related to their ability to increase digesta viscosity along the gut; this in turn causes changes in gut microflora and efficiency of nutrient utilisation by the chicken. Use of appropriate enzymes is an effective way of dealing with grains with high NSP content in poultry diets.