回─直肠吻合猪的排泄规律对内源氨基酸校正的影响

为了探讨猪内源氨基酸的估测方法，本试验研究了饲喂粗纤维含量分别为：２．０％、５．０％和８．０％的３种纯合无氮日粮时，荷术猪每天回肠末端干物质排泄量和排泄物中氨基酸含量的变化规律。结果指出：（１）饲喂不同纯合无氮日粮时，荷术猪各天回肠末端干物质排泄量变异系数（Ｃ．Ｖ％）随日粮粗纤维含量的增加而减小：（２）从各组荷术猪回肠末端干物质排泄量变化规律看，至少需３头试验猪，经预饲３天后，再收集３天食糜才能保证排泄物样品的代表性；（３）回肠末端排泄物中氨基酸含量随着无氮日粮饲喂期的延长呈稳定到锐减的趋势型，因此用无氮日粮法进行内源氨基酸校正时，排泄物采样时间不宜过长。     

回—直肠吻合猪的排泄规律对内源氨基酸校正的影响

为了探讨猪内源氨基酸的估测方法，本试验研究了饲喂粗纤维含量分别为：２．０％、５．０％和８．０％的３种纯合无氨日粮时，荷术猪每天回肠末端干物质排泄量和排泄物中氨基酸含量的变化规律。结果指出：（１）饲喂不同纯合无氮日粮时，荷术猪各天回肠末端干物质排泄量变异系数（Ｃ．Ｖ％）随日粮粗纤维含量的增加而减小；（２）从各组荷术猪回肠末端干物质排泄量变化规律看，至少需３头试验猪，经预饲３天后，再收集３天食糜才能保     

产蛋鸡内源氮排泄变化规律的研究

选５０周龄罗曼蛋鸡５只，用强饲法供给无氮日粮５３克／千克Ｗ０．７５·天。收集９天的排泄物。结果表明，试验的前３天每日排泄内源氮极显著地高于后６天的日排出量（Ｐ＜０．０１）。而后６天每日的排出量趋于稳定（Ｐ＞０．０５）。测得产蛋鸡内源氮的排泄量为１３３．０毫克／千克Ｗ０．７５·天     

不同日粮蛋白质水平对绍鸭产蛋期氮存留率的影响

采用代谢试验方法，研究了不同日粮蛋白质水平（ＣＰ１５％，１７％，１９％，２１％，２３％）对绍鸭产蛋期氮存留率的影响。结果表明，试鸭氮存留车受日粮蛋白质水平的极显著影响（Ｐ＜０．０１），日粮蛋白质水平越高，氮存留率越低。第一次代谢试验１５％，１７％，１９％ＣＰ组氮存留率显著高于２３％ＣＰ组（Ｐ＜０．０１）和２１％ＣＰ组（Ｐ＜０．０５），第二次试验１５％，１７％ＣＰ组直存留率显著高于２３％ＣＰ组（Ｐ＜０．ｏｆ）和２１％ＣＰ组（Ｐ＜０．０５），其它各组间差异均不显著（Ｐ＞０．０５）。研究还表明，日粮蛋白质水平对绍鸭单位代谢体重氮存留量无显著影响（Ｐ＞０．０５）。随绍鸭周龄增长，氮存留率显著降低（Ｐ＜０．０５）。     

溢酸宝对仔猪日粮营养物质消化率影响的研究

以５头断奶仔猪进行两期消化试验。第一期为对照期,饲喂基础日粮;第二期为试验期,饲喂基础日粮＋０．１５％溢酸宝。采用内源指示剂法测定日粮中营养物质消化率。试验结果,试验期日粮中粗蛋白质,总氨基酸,粗脂肪,粗纤维,钙和磷的表观消化率分别为：８６．６１％,８４．６６％,６８．０３％,２７．１８％,８４．７１％和６３．３２％;比对照期分别提高９．３７％（Ｐ＜０．０１）,９．７６％（Ｐ＜０．０１）,１１．０７％（Ｐ＜０．０５）,２６．５４％（Ｐ＜０．０１）,１．４７％（Ｐ＞０．０５）和６．４０％（Ｐ＞０．０５）。试验结果表明,仔猪日粮中添加０．１５％的溢酸宝能显著地提高日粮中有机营养物质的消化率。     

饲喂不同蛋白水平日粮的牦牛瘤胃氮代谢与十二指肠各氮组分流量

采用瘘管手术方法对３头生长牦牛在饲喂代谢能ＭＥ均为９．６ＭＪ／ｋｇＤＭ，粗蛋白（ＣＰ）为８％和１２％的日粮时的复胃氮代谢与瘤胃、肠道消化代谢进行研究。试验结果表明，日粮ＣＰ水平升高后，生长牦牛瘤胃氨氮浓度由３．３升至５．９ｍｇ／１００ｍｌ（Ｐ＜０．０１），瘤胃内氮的消失率由１．９％升到２１．１％（Ｐ＜０．０１）。瘤胃微生物蛋白质合成效率基本不变（平均６９．１ｇＣｐ／ｋｇＤＯＭ）；一昼夜进入十二指肠的食糜量及食糜干物质量基本不变；食糜总氮、氨氮及非氨氮量均显著增加（Ｐ＜０．０１），其中非氨氮增加２０％：非氨氮中微生物氮的比例由４５％降至３９％（Ｐ＜０，０５）；日粮ＤＭ，ＯＭ，ＣＰ和ＡＤＦ整体消化率分别提高１２．９％、１３．４％、３４％和２２．３％（Ｐ＜０．０１）。日粮ＣＰ由８％升至１２％后，生长牦牛瘤胃ＴＶＦＡ中乙酸比例由５４％降至４３．５％（Ｐ＜０．０１）．丙酸比例由２４．８％升至２８．４％（Ｐ＜０．０５），丁酸比例也由２１．１％增至２８．５％（Ｐ＜０．０１）。同时Ｃ２／Ｃ３比由２．１９降至１．５４（Ｐ＜０．０１）。     

饲粮中添加包被蛋氨酸对肉鸡生长性能、血液生化指标和养分表观回肠消化率的影响

本试验旨在研究饲粮中添加不同水平包被蛋氨酸对肉鸡生长性能、血液生化指标和氨基酸表观回肠消化率的影响。选用 １８日龄科宝 ５００肉鸡 ３７８０只,按试验要求随机分为 ７组,每组设 ３个重复,每个重复 １８０只鸡。对照组（Ａ组）饲粮添加 ０．１６％的消旋蛋氨酸（ＤＬ Ｍｅｔ）,试验组饲粮添加含量为 ５０％的包被蛋氨酸,添加量分别为饲粮的 ０．３２％（Ｂ组）、０．２９％（Ｃ组）、０．２６％（Ｄ组）、０．２２％（Ｅ组）、０．１９％（Ｆ组）、０．１６％（Ｇ组）。饲喂至 ４２日龄结束。结果表明：Ｂ组和 Ｃ组末重、平均日增重和平均日采食量均显著高于对照组（Ｐ＜０．０５）,Ｂ组死亡率显著低于对照组（Ｐ＜０．０５）,其他组与对照组均差异不显著（Ｐ＞０．０５）;各试验组（除 Ｇ组外）血浆谷胱甘肽过氧化物酶活性均显著高于对照组（Ｐ＜０．０５）,Ｂ组和 Ｃ组血浆总超氧化物歧化酶活性均显著高于 Ｇ组（Ｐ＜０．０５）,其他生化指标各组间均差异不显著（Ｐ＞０．０５）;各试验组干物质和粗蛋白质表观回肠消化率均与对照组差异不显著（Ｐ＞０．０５）,除 Ｇ组多种氨基酸表观回肠消化率显著低于对照组（Ｐ＜０．０５）外,其他试验组的各种氨基酸表观回肠消化率均与对照组差异不显著（Ｐ＞０．０５）或显著高于对照组（Ｐ＜０．０５）。结果提示,随着包被蛋氨酸添加量的增加,肉鸡生长性能逐渐改善,氨基酸回肠消化率逐渐提高。饲粮添加 ０．１９％包被蛋氨酸（替代对照组 ６０％的蛋氨酸）即可满足肉鸡需要,即采用包被方式后,蛋氨酸最多可节约 ４０％。     

饲粮赖氨酸水平对生长獭兔生长性能、氮代谢及血清免疫和生化指标的影响

本文旨在探讨饲粮赖氨酸水平对生长獭兔生长性能、氮代谢及血清免疫和生化指标的影响。选用平均体重为（６６５±１２３）ｇ的断奶獭兔 ２００只,随机分成 ５组（每组 ４０个重复,每个重复 １只）,分别饲喂赖氨酸水平为 ０．５５％、０．７０％、０．８５％、１．００％和 １．１５％的试验饲粮。预试期 ７ｄ,正试期 ５３ｄ。结果表明：饲粮赖氨酸水平对平均日采食量、平均日增重和料重比无显著影响（Ｐ＞０．０５）。饲粮赖氨酸水平显著或极显著影响食入氮（Ｐ＝０．００６５）、氮沉积（Ｐ＝０．０４５９）和氮生物学效价（Ｐ＝０．０２２６）,而对粪氮排出量、尿氮排出量、可消化氮、氮表观消化率和氮利用率无显著影响（Ｐ＞０．０５）。饲粮赖氨酸水平为 １．００％和 １．１５％的组的食入氮极显著高于饲粮赖氨酸水平为 ０．５５％和 ０．７０％的组（Ｐ＜０．０１）。饲粮赖氨酸水平为 ０．７０％、０．８５％、１．００％和 １．１５％的组的氮沉积和氮生物学效价显著高于饲粮赖氨酸水平为 ０．５５％的组（Ｐ＜０．０５）。饲粮赖氨酸水平极显著影响血清免疫球蛋白 Ａ（Ｐ＜０．０００１）、免疫球蛋白 Ｇ（Ｐ＜０．０００１）和免疫球蛋白 Ｍ 含量（Ｐ＜０．０００１）。饲粮赖氨酸水平为 ０．７０％、０．８５％、１．００％和 １．１５％的组的免疫球蛋白 Ａ、免疫球蛋白 Ｇ和免疫球蛋白 Ｍ 含量均极显著低于饲粮赖氨酸水平为 ０．５５％的组（Ｐ＜０．０１）。饲粮赖氨酸水平除显著影响血清胆固醇浓度（Ｐ＝０．０１６７）外,对血清总蛋白、球蛋白、尿素氮含量以及谷丙转氨酶活性均无显著影响（Ｐ＞０．０５）。综合考虑本试验所测指标,生长獭兔的饲粮适宜赖氨酸水平为 ０．５５％ ～０．７０％。     

低蛋白质氨基酸平衡饲粮对早期断奶仔猪腹泻和生产性能的影响

本研究选用１８头２８±１日龄断奶的杂交仔猪（平均体重约５．５ｋｇ），研究低蛋白质氨基酸平衡饲粮对早期断奶仔猪腹泻和生产性能的影响。试验结果显示：（１）低蛋白质氨基酸平衡饲粮使仔猪血浆挥发性盐基氨含量、血浆尿素氨含量和腹泻指数降低（Ｐ＜０．０５或０．０１）。（２）采食全植物蛋白型氨基酸平衡饲粮（ＣＰ１８．３％）的仔猪，其平均日增重（ＡＤＧ）、平均日采食量（ＡＤＦＩ）和料肉比（Ｐ／Ｇ）与采食复合蛋白型对照饲粮（ＣＰ１９．７％）的仔猪差异不显著（Ｐ＞０．０５），但前者的增重成本比后者降低（Ｐ＜０．０５）３１％。（３）采食复合蛋白型氨基酸平衡饲粮（ＣＰ１８．４％）的仔猪的生产性能优于采食复合蛋白型对照饲粮（ＣＰ１９．７％）的仔猪，前者的ＡＤＧ和ＡＤＦＩ分别提高（Ｐ＜０．０５）６１％和３２％，Ｆ／Ｇ和增重成本分别下降（Ｐ＜０．０５）２４％和３７％。（４）采食全植物蛋白型氨基酸平衡饲粮的仔猪，其ＡＤＧ和ＡＤＦＩ低于（Ｐ＜０．０１）采食复合蛋白型氨基酸平衡饲粮的仔猪。前者的Ｆ／Ｇ和增重成本趋于高于后者，但差异不显著（Ｐ＞０．０５）。以上结果表明，低蛋白质氨基酸平衡饲粮可显著降低仔猪断奶后腹泻和提高仔猪生产性能。复合蛋白型?     

低蛋白质饲粮中添加尿素对肉兔生长发育及血液指标的影响

本试验旨在研究低蛋白质饲粮中添加尿素对肉兔生长发育与血液指标的影响。采用单因子随机区组试验设计,选择 １２０只 ５０日龄、体重相近的健康新西兰兔,随机分为 ４组,１个对照组和 ３个试验组,每组 １５个重复,每个重复 ２只。对照组饲喂粗蛋白质含量为 １１．１１％的基础饲粮,３个试验组分别饲喂在基础饲粮中以糊化淀粉缓释尿素的方式添加 １％、２％和 ３％尿素的试验饲粮。预试期为 １０ｄ,正试期为 ３０ｄ。结果表明：试验第 ２天,３％尿素组 ８０％试验兔因发生氨中毒而死亡。１％尿素组试验兔末重、增重和日增重均极显著高于对照组和 ２％尿素组（Ｐ＜０．０１）。与对照组相比,１％和 ２％尿素组试验兔全血氨氮含量、血清谷丙转氨酶活性显著或极显著升高（Ｐ＜０．０５或 Ｐ＜０．０１）,而肝脏重和系数则显著或极显著降低（Ｐ＜０．０５或 Ｐ＜０．０１）。２％尿素组试验兔日干物质进食量、胴体重和屠宰率均极显著低于对照组和 １％尿素组（Ｐ＜０．０１）,而料重比则极显著高于对照组和 １％尿素组（Ｐ＜０．０１）。２％尿素组试验兔血清尿素氮含量以及谷草转氨酶、碱性磷酸酶活性均极显著高于对照组和 １％尿素组（Ｐ＜０．０１）。２％尿素组试验兔心脏、脾脏和肾脏重均显著低于对照组和 １％尿素组（Ｐ＜０．０５）,而肾脏系数则极显著高于对照组和 １％尿素组（Ｐ＜０．０１）。２％尿素组试验兔胃重、十二指肠重与长、空肠重与长、回肠重与长、盲肠重与系数、蚓突重与系数及长、大肠重与长显著或极显著低于对照组和 １％尿素组（Ｐ＜０．０５或 Ｐ＜０．０１）,且回肠系数及盲肠长显著或极显著低于对照组（Ｐ＜０．０５或 Ｐ＜０．０１）。由此得出,低蛋白质饲粮中添加 ３％的尿素会造成肉兔氨中毒死亡;添加 ２％的尿素会使肉兔生长发育停滞;添加 １％的尿素可改善肉兔育肥性能,但会对肝脏的发育产生不利影响。     

无氮日粮纤维类型及进食量对猪内源氨基酸测值的影响

分别以醋酸纤维素与微晶纤维素为纤维源配制成粗纤维水平为５％的两种无氮日粮。其中微晶纤维日粮设高进食量（１０００ｇ／ｄ）与低进食量（５００ｇ／ｄ）两个处理,醋酸纤维日粮只设一个进食量（１０００ｇ／ｄ）处理,共三个处理,以３＊３拉丁方式验研究纤维来源及进食量对回－直肠吻合猪消化道内源氨基酸排泄的影响。     

Effects of Different Dietary Crude Protein Levels on the Nutrient Absorbability in the Small Intestine of Lambs

This experiment was conducted to study the effects of different dietary crude protein levels on the nutrient absorbability in the small intestine of lambs.Three Kazakh lambs (30 kg body weight) fitted with permanent ruminal,duodenal and ileal fistula were selected.3×3 Latin square design was adopted.A dual-phase marker system with LiCr-EDTA and Yb-Ac as the liquid-phase or particulate-phase digesta flows maker was adopted to measure the true digesta flows at duodenal and ileal fistula,respectively.The results showed that nitrogen intake,total tract apparent digestibility,N deposition,the apparent digestibility of dry matter and organic matter were significantly increased with increasing levels of dietary crude protein (P<0.05),but had no significant effects on intestinal digesta flows (P>0.05).Increasing dietary crude protein levels had significant effects on most part of nutrients of duodenal digesta except fat and purine (P<0.05),while it only significantly effected CP,Ash,dry matter,neutral detergent fibre and acid detergent fiber of ileal digesta flows (P<0.05).In addition,intestinal absorbability of nutrients except for CP,Ash,dry matter,neutral detergent fibre and acid detergent fiber were significantly affected with increasing levels of dietary crude protein(P<0.05).The test provided basis for further study of the effects of dietary CP level on the digestibility and utilization of lamb.     

不同粗蛋白质水平日粮对育肥羊小肠养分吸收率的影响

本研究旨在比较不同粗蛋白质（CP）水平日粮对育肥羔羊小肠养分吸收率的影响。选用体重30 kg左右,安装有瘤胃、十二指肠近端和回肠末端瘘管的3只哈萨克育肥羊为试验动物,采用3×3拉丁方试验设计,采用醋酸镱（Yb-Ac）、锂铬乙二胺四乙酸（LiCr-EDTA）分别作为消化道固相和液相食糜标记物测定小肠食糜流量。结果显示,增加全混合日粮中CP水平可显著提高育肥羊N的进食量、全消化道表观消化率和N沉积（P<0.05）,显著提高干物质（DM）和有机物（OM）的表观消化率（P<0.05）,但对小肠食糜流量无显著影响（P>0.05）;提高日粮CP水平对十二指肠食糜除EE和嘌呤外的营养成分流量均产生显著的影响（P<0.05）,仅对回肠食糜中CP、粗灰分（Ash）、DM、中性洗涤纤维（NDF）和酸性洗涤纤维（ADF）流量的影响显著（P<0.05）,且对CP、Ash、DM、NDF和ADF的小肠吸收率影响显著（P<0.05）。本试验为进一步深入分析增加日粮CP水平对其在育肥羊体内的消化利用奠定基础。     

ORIGINAL ARTICLE: The effect of dietary methionine levels on endogenous nitrogen and endogenous amino acids flows in growing goats

The effect of dietary methionine (Met) levels on endogenous N and amino acids (AA) flows at different part of the digestive tract of growing goats was determined using a ¹⁵N isotope dilution technique. Three goats (25 ± 2.5 kg) were fitted with the ruminal, duodenal and ileal cannulae and allocated to three dietary treatments in a 3 × 3 Latin square design. The dietary treatments consisted of a total mixed ration containing three levels of Met (0.15%, 0.25% and 0.35%) respectively. It was found that at 0.15% Met level, the lowest flow in endogenous N and total AA at the duodenum and ileum occurred. The endogenous N secretion contributed to 26% and 23% of the duodenal and ileal total N flows, respectively, and the proportions were not affected by the dietary Met levels. The duodenal and ileal flows of endogenous total AA were 11.1, 11.8, 11.3 g/d and 2.9, 3.9, 4.1 g/d respectively. The average real digestibility of N was 65%, 87% and 95% in the forestomach, intestine and whole digestive tract respectively.     

Apparent precaecal digestibility of nutrients and level of endogenous nitrogen in digesta of the small intestine of growing pigs as affected by various digesta viscosities.

Sixteen male growing pigs of about 24 kg BW were fitted with both a duodenal re-entrant and a post-valve T-shaped cannula inserted in the caecum. The animals were divided into four groups. Each group received one of the following diets: corn starch-soybean protein isolate-based diet without (diet C) and with carboxymethylcellulose (diet CMC) or a rye-wheat-based diet without (diet RW) and with xylanase addition (diet RWX). The diets provided similar levels of apparent precaecal digestible crude protein (CP), lysine, methionine + cystine, threonine and tryptophan. Additionally, [15N]-yeast was given with the diets during the first 10 days of the experiment. For estimation of digesta viscosity, N-flow of dietary and endogenous origin, apparent precaecal digestibilities of dry matter (DM), CP, amino acids and non starch polysaccharides (NSP) (only in pigs fed diets RW and RWX), ileal and duodenal digesta were quantitatively collected on day 16 and 17, respectively. The endogenous N-proportion was measured by the ratio of 15N enrichment in the digesta and urine. The duodenal and ileal digesta supernatant viscosity increased as carboxymethylcellulose was included into the diet. Xylanase addition to the rye-wheat based diet reduced the viscosity in the ileal digesta. There were no differences in precaecal digestibilities of DM, CP and amino acids between diet C and CMC. The precaecal digestibilities of DM and soluble and insoluble NSP increased from 69.5% to 73.9%, from 1.3% to 47.9% and from 17.0% to 35.4%, respectively, as xylanase was added to the rye-wheat-based diet. The apparent precaecal digestibility of most essential amino acids increased by 2 to 5 percent units. The amounts of endogenous N at the duodenal level were estimated to be 158, 233, 313 and 276 mg per 12 h per kg0.75 BW of pigs fed diets C, CMC, RW and RWX, respectively. The corresponding values at the ileal level were 95, 107, 164 and 150 mg per 12 h per kg0.75 BW. For endogenous N amounts, significant differences were observed between diets C and CMC (duodenum) and also between semi-purified and cereal-based diets (duodenum and ileum). Methodological aspects for the estimation of endogenous N using the isotope dilution technique are discussed. Obviously, the digesta viscosity per se does not affect the nutrient absorption and endogenous N flow within the small intestine of pigs. Other properties of complex dietary fibre, digesta passage rate or bacterial activity probably contribute to the observed changes.     

Progress in ileal endogenous amino acid flow research in poultry

The progress in our understanding of the endogenous protein concept over the past century is reviewed. Nondietary proteins found in the digesta at the terminal ileum of poultry, known as endogenous protein loss, are comprised of digestive secretions, mucus and sloughed gut epithelial cells. The measurement of this loss is of fundamental importance because it is an indicator of gut metabolism and is essential to adjust apparent estimates of ileal amino acid digestibility. The ileal endogenous amino acid losses comprise of two components, namely basal and specific losses. The basal losses are fixed and associated with feed dry matter intake, whereas the specific losses are variable and induced by the presence of dietary components such as fibre and anti-nutrients. Currently there is no methodology available to directly measure the specific endogenous losses and these losses are calculated by determining the basal and total(basal plus specific) losses and, then subtracting the basal losses from total losses.The seminal features, specific applications and shortcomings of available methodologies are briefly outlined as well as the practical challenges faced in using the published endogenous amino acid loss values for true digestibility corrections. The relevance of taurine as a component of endogenous protein flow in poultry is identified for the first time.     

Effect of graded levels of dietary betaine on ileal and total tract nutrient digestibilities and intestinal bacterial metabolites in piglets*

The study was conducted to investigate the effects of graded dietary inclusion levels of betaine on ileal and total tract nutrient digestibilities and intestinal bacterial metabolites in piglets. A total of eight barrows with an average initial body weight of 7.9 kg were randomly allocated to one of the four assay diets with two pigs per treatment in four repeated measurement periods. The assay diets included a basal diet based on wheat, barley and soybean meal alone, or supplemented with a liquid betaine product at dietary levels of 1.5, 3.0, or 6.0 g betaine per kilogram diet (as‐fed). Ileal digestibilities of dry matter and neutral detergent fibre increased both quadratically and linearly, and ileal digestibility of glycine increased linearly as dietary betaine level increased (p < 0.05). Furthermore, total tract digestibility of crude protein increased quadratically (p < 0.05) and total tract digestibilities of most amino acids tended to increase quadratically (p = 0.06 to p = 0.11) with increasing dietary betaine level. Moreover, there were linear increases in the concentrations of most bacterial metabolites which were significant p < 0.05 for ileal d ‐lactic acid and for faecal diaminopimelic acid. The results demonstrate that dietary betaine supplementation stimulates bacterial fermentation of fibre in the small intestine and bacterial degradation of crude protein in the large intestine.     

Effect of feeding level on ileal and total tract digestibility of nutrients and energy from soybean meal‐based diets for piglets

A total of 36 piglets with an initial body weight (BW) of 5.6 ± 0.7 kg, fitted with simple T‐cannulas at the distal ileum, were used to evaluate the effect of three graded feeding levels (50, 75 or 100 g/kg BW^0.75 day) on apparent ileal digestibility (AID) and total tract digestibility (ATTD) of dry matter (DM), nitrogen (N) and energy, and on ATTD of organic matter (OM), ether extracts (EE), neutral detergent fibre (NDF), acid detergent fibre (ADF) and digestible (DE), metabolisable (ME) and net energy (NE) content in soybean meal (SBM)–casein–cornstarch‐based diets. The AID of DM, N and energy and ATTD of NDF, ADF and EE in the diets were not affected (p > 0.05) by the feed intake (FI) level. There was a small decrease in ATTD of DM, N (CP), OM, ash and energy, and in DE, ME and NE content in the diets (p < 0.05) with increasing FI level. The net disappearance in the large intestine (in % of ileal recovery) decreased for DM, N and energy (p < 0.05) with increasing FI level. The design of the study allowed for estimating ileal endogenous loss of N and total tract endogenous loss of ash, N and EE, for estimating corresponding true ileal and total tract digestibility values, and for estimating urinary endogenous N loss. High variability in estimates of ileal endogenous N loss and total tract endogenous losses of N, EE and ash reflects great variation in individual endogenous losses between animals. Estimation of true total tract digestibility of N, EE and ash by regression analysis was affected by their decrease in ATTD with increasing FI level, as estimates for true digestibility were lower compared to their apparent values. The present results suggest that FI level can affect both apparent and true total tract nutrient digestibility in piglets.     

Neutral detergent fiber increases endogenous ileal losses but has no effect on ileal digestibility of amino acids in growing pigs

Two experiments were conducted to determine the effect of neutral detergent fiber (NDF) on endogenous amino acids and protein ileal losses; and also apparent ileal digestibility (AID), and standardized ileal digestibility (SID) of amino acids and crude protein. Sixteen barrows were fed four protein‐free diets containing graded NDF levels in Experiment 1. NDF was a mixture of sugarcane bagasse and corn leaves (SBCL). Twenty‐four barrows were fed diets with soybean protein concentrate (SPC) or casein as protein sources and SBCL or corncobs (CC) as NDF sources in Experiment 2. In Experiment 1, a linear increase (P < 0.05) in endogenous amino acid and protein ileal losses was observed with increased NDF levels, except for arginine, histidine, methionine and proline. In Experiment 2, protein (P < 0.001) and NDF (P < 0.01) sources significantly affected AID of dry matter, which was higher in casein diets (71.7%) and CC diets (70.7%). Protein and NDF sources significantly affected (P < 0.05) SID of crude protein, which was higher in casein diets (92.8%) and CC diets (92.7%). NDF source had no effect (P > 0.05) on SID of amino acids. Overall, this study showed that NDF increased endogenous amino acid and protein ileal losses, but did not affect ileal digestibility of amino acids.