Comparison of various amino acids for estimation of microbial nitrogen in digesta

Methods of estimating microbial N in digesta were compared, and two simplified methods were described for separation of diaminopimelic acid (DAP) from methionine in acid hydrolysates of biological samples using an automated amino acid analyzer. Recoveries of DAP when added to bacterial, abomasal and feed samples were 92 to 98%. All samples analyzed (bacteria, protozoa and several feedstuffs) contained detectable DAP (or another amino acid with similar elution time). Apparent DAP-N (percentage of total sample N) in feeds ranged from 12 to 78% of bacterial DAP-N concentration. These values are greater than can be accounted for by bacterial contamination. Correction for apparent dietary DAP was appropriate when using this microbial marker. Reasonable estimation of bacterial N was made in abomasal digesta of steers fed high-grain diets using DAP, lysine or combinations of DAP and leucine or lysine and leucine. There was excellent agreement among these marker methods in ranking dietary treatment regimens with respect to bacterial N present in the abomasum. The use of leucine alone, or the combination of DAP and lysine, gave nonrealistic values. Two-amino-ethylphosphonic acid (AEP) was not detected in acid hydrolysates of mixed ruminal protozoa or abomasal digesta. Two other ninhydrin-reactive compounds with elution times close to AEP were detected in all samples analyzed, which may have been identified as AEP in other studies. It was concluded that corrected DAP and lysine were the best estimates of bacterial N and AEP was precluded as a marker of protozoal N.     

氨基酸分析仪测定饲料及其原料中的含硫氨基酸

本文采用过甲酸氧化水解法处理饲料及饲料原料样品、通过日立L-8900氨基酸自动分析仪检测样品中的含硫氨基酸含量,结果显示：每份试样平行测试结果相对偏差小于4％．蛋氨酸和胱氨酸峰面积回收率在93．02％～102．06％．该方法测定含硫氨基酸的重复性和准确性良好．氧化水解法比常规盐酸水解法处理样品检测含硫氨基酸．检测结果更为准确。     

酸解法-氨基酸分析仪测定蚕蛹中的17种氨基酸

文章采用酸解法-氨基酸分析仪测定蚕蛹中17种氨基酸含量。该法预处理过程简单,17种氨基酸在65 min内完全分离。此法简便、快捷、重复性好,灵敏度高。     

A simple estimation of ideal profile of essential amino acids and metabolizable energy for growing Japanese quail

An experiment was conducted to determine apparent metabolizable energy (AME) and amino acid requirements of growing Japanese quail based on ideal protein concept using artificial neural network and desirability function (D‐ANN). Seven‐day‐old quail chicks were assigned to nine experimental diets based on central composite design (CCD) containing five levels of AME (2809–3091 kcal/kg) and CP (19–24.8% of diet). The ratio of lysine (Lys) to CP was set at 0.053 among all treatments, and remaining essential amino acids (EAA) were adjusted to Lys. The experimental data of CCD were fitted to D‐ANN model to compute the optimal values for independent variables. The optimal values of inputs including AME, CP, digestible Lys (dLys), methionine (dMet), total sulphur amino acids (dTSAA), threonine (dThr), tryptophan (dTrp), isoleucine (dIle), valine (dVal) and arginine (dArg) for maximizing gain and minimizing feed conversion ratio were estimated at 2865 kcal/kg, 25, 1.32, 0.55, 0.88, 0.84, 0.20, 0.75, 1.04 and 1.45% of diet, respectively, with D (desirability function) = 0.94. The corresponding optimal amounts of amino acids based on total amino acids were 1.42, 0.59, 0.95, 0.90, 0.22, 0.81, 1.12 and 1.56% of diet respectively. The ideal pattern of essential amino acids to Lys was as follows: dMet: dLys = 0.42, dTSAA: dLys = 0.67, dThr: dLys = 0.64, dTrp: dLys = 0.15, dIle: dLys = 0.57, dVal: dLys = 0.79 and dArg: dLys = 1.09. The results of this study showed that amino acid requirements of modern quails might be higher than those reported by NRC.     

氨基酸分析仪测定鱼粉中的氨基酸

利用氧化水解法测定鱼粉中17种氨基酸含量,采用Amino Acid Analyzer全自动氨基酸分析仪,水合茚三酮做柱后衍生,结果表明:该方法操作简便,适用于鱼粉中氨基酸的测定并取得较好的结果。     

The estimation of utilizable amino acids (uAA) of feeds for ruminants using an in vitro incubation technique

The in vitro incubation technique of Zhao and Lebzien (2000; Arch. Anim. Nutr. 53, 293-302) was used for the estimation of utilizable amino acids (uAA) (sum of amino acids from undegraded feed protein and microbial protein, when N is not limiting) of feeds for ruminants. The rumen fluid from a cow fed only with hay (Expt. 1) and that from a sheep fed with a mixed ration (Expt. 2) was compared with respect to estimation of uAA. In Expt. 1, 30 feeds and feed mixtures were tested and in Expt. 2, 33 feeds and feed mixtures were tested. A close linear relationship was found between the utilizable crude protein (uCP=undegraded feed protein + microbial protein) (X, g/kg) calculated from in vivo experiments and the uAA (Y, g/kg) estimated from in vitro incubations both in Expt. 1: y= 0.95 x-1.39, r2=0.85, p<0.001,n=30; and in Expt. 2: Y=0.85X-6.67,r2= 0.85,p<0.001,n=33. Statistical analysis indicates that there was a significant regressive relationship between uAA determined with the rumen fluid of a sheep (X, g/kg) and uAA determined with the rumen fluid of a cow (Y, g/kg): Y=1.06X+12.4,r2= 0.80,p<0.001,n=27. The results indicate that the in vitro incubation technique of Zhao and Lebzien (2000) can be used for the estimation of uAA of feeds for ruminants. As a rumen-fistulated cow is more expensive than a rumen-fistulated sheep, it is suggested to use a sheep fed a mixed ration as the donor of rumen fluid for the estimation of uAA of feeds with in vitro incubation. Further experiments should be performed to standardize the method and to test the most valid length of the incubation period.     

氨基酸类饲料添加剂的合理应用

氨基酸是构成蛋白质的基本单位，参与机体的生化反应和生理机能过程，是动物最重要的一类营养物质。目前已经发现的氨基酸有25种以上，构成动物蛋白质的氨基酸有20种左右。这些氨基酸又分为两类：一类是动物体内不能合成，或合成量很少，不能满足动物机体正常的需求，需要从饲料中摄入的氨基酸，叫做必需氨     

水产饲料中外源性氨基酸的应用

近年来,饲料工业,特别是水产饲料工业的迅速发展,导致对鱼粉的需求量不断增加,而全球鱼粉资源是有限的,特别是受今年智利地震的影响,更导致鱼粉价格一路攀升,达到历史新高.     

猪几种氨基酸需要量研究进展

最近几年,随着低蛋白日粮研究的深入,发现NRC（1998）标准逐渐不能完全满足养猪生产对氨基酸的需求。越来越多的研究者积极探索氨基酸的适宜补充量以满足实际生产的需要。经过试验研究取得了很大的进展,现将几种氨基酸需求的最新研究成果综述如下。     

Insulin responses to administrations of amino acids and fatty acids in healthy cats

In order to compare the stimulation ability of insulin secretion, we determined changes in plasma glucose and insulin concentrations after intravenous administration of various amino acids and essential fatty acids in clinically healthy adult cats. Plasma glucose concentrations were within the normal ranges after injection of amino acids and fatty acids. Plasma insulin concentrations increased rapidly 2 to 4 min after injection of arginine, then decreased to the basal levels at 20 min in all five cats. Insulin peak responses were significantly greater in arginine injections than in normal saline (P<0.01). Areas under the curve (AUC) of plasma insulin concentrations from 0 to 10 min after injection of arginine were significantly larger than after injection of normal saline (P<0.01) and glucose (P<0.05). Increases in AUC of plasma insulin concentration from 0 to 60 min were observed after injection of arginine, leucine, alanine, and fat emulsion. Arginine had a strong insulinotropic effect, and leucine, alanine, and fatty acids had weak ones. Besides, valine, methionine, taurine and glutamine had no stimulant activity of insulin. Given the risk of glucose toxication and required time for testing, the intravenous arginine tolerance test may be useful for estimation of insulin responses in cats.     

鸡对饲料氨基酸有效利用率的研究

采用Sibbald“真代谢能”法测定饲料原料的氨基酸有效利用率。试验鸡分别强饲玉米、大豆粕和鱼粉 ,测定鸡强饲后的氨基酸排出量。结果表明 ,不同种类饲料原料的氨基酸利用率存在差异 ,玉米与大豆粕、鱼粉间差异显著 (P <0 0 5)。不同种类氨基酸之间利用率也有差异。 3种饲料原料的氨基酸真利用率均大于表观利用率 ,其中玉米的差异达到极显著水平 (P <0 0 1 ) ,表明内源性氨基酸对氨基酸利用率有影响 ,且这种影响随饲料原料中粗蛋白质水平的下降而增大。 3种饲料原料的氨基酸利用率在去盲肠鸡与正常鸡之间存在差异。盲肠微生物对饲料原料的氨基酸利用率有影响 ,且对不同种类氨基酸的影响有差异 ,这种影响不能通过内源性氨基酸的校正而消除。另外 ,内源性氨基酸的排泄量在去盲肠鸡大于正常鸡。表明内源性氨基酸也受到盲肠微生物的影响