2007~2008年国际反刍动物营养研究进展 Ⅳ.蛋白质与氨基酸营养

蛋白质是生命活动的最基本物质。随着反刍动物蛋白质营养研究的深入,如何最大化提高瘤胃微生物蛋白量,增加瘤胃后非降解蛋白（rumen undegraded protein, RUP）的消化率,合理搭配日粮,减少氮的排放量,通过日粮途径改善乳蛋白含量和产量,提高氮的利用率已成为当今研究的热点。同时,蛋白质、氨基酸和肽营养在瘤胃、小肠、大肠和乳腺中的代谢机理、影响其利用的因素还不是很清楚,但随着分子生物学技术、血插管技术和动静脉差异技术在蛋白质、氨基酸和肽的转运、吸收及乳蛋白合成机理上的应用,为深入研究其转运、利用机制提供了可能。牛奶中的活性功能成分近年来随着消费需求也日益成为研究的热点。作者主要从蛋白质如何在瘤胃内代谢及影响因素、小肠内代谢及影响因素、大肠内代谢及影响因素、乳腺内代谢和乳蛋白合成、乳中的免疫活性蛋白等方面对蛋白质营养研究作一综述。     

反刍动物乳腺氨基酸的吸收与代谢

乳腺是合成乳蛋白的重要器官,其蛋白质和氨基酸代谢功能非常活跃。氨基酸作为前体物直接参与反刍动物乳蛋白的合成。为了提高反刍动物产奶量、乳蛋白的合成量,深入研究反刍动物乳腺对氨基酸的吸收和代谢显得尤为重要。本文主要从乳腺氨基酸吸收方式及其影响氨基酸吸收因素、氨基酸的代谢和氨基酸对乳蛋白合成的调节4个方面,对反刍动物乳腺氨基酸的吸收与代谢进行综述。     

生长猪肠道氨基酸代谢研究进展

本文按照蛋白质在猪消化道内的消化利用过程,综述了氨基酸消化、吸收、代谢和利用方面的有关研究进展,对影响肠道氨基酸代谢的因素及氨基酸代谢对猪氨基酸需要量的影响进行了讨论,并提出今后有待进一步研究的问题。     

生长猪肠道氨基酸代谢研究进展

本文按照蛋白质在猪消化道内的消化利用过程,综述了氨基酸消化、吸收、代谢和利用方面的有关研究进展,对影响肠道氨基酸代谢的因素及氨基酸代谢对猪氨基酸需要量的影响进行了讨论,并提出今后有待进一步研究的问题。     

反刍动物的理想氨基酸与小肠氨基酸供给模式的研究

<正>随着对反刍动物蛋白质营养研究的深入,以小肠氨基酸为基础的新蛋白质体系逐步代替传统的粗蛋白或可消化粗蛋白等营养体系,新的体系更能反映反刍动物蛋白质消化代谢的实质,从而准确地指导饲养实践。小肠氨基酸的数量及比例不仅影响氨基酸在肠内的吸收和利用,而且和反刍动物的生产性能及成本     

功能性氨基酸对生长猪的重要性

在集约化猪场中生长猪经常受到环境变化、生物安全、管理和饲料等导致健康的影响因素,这些问题导致机体炎症和免疫防御的激活。炎症状态改变动物的新陈代谢,营养尤其是用于生长的氨基酸转移到用于合成一氧化氮、硫化氢、谷胱甘肽等支持免疫功能的活动,如免疫细胞和肠上皮细胞快速分裂。此外,在炎症过程中氨基酸可能作为信号分子调节相关的代谢途径。因此,需要对每种氨基酸的具体作用和代谢有新的认识,从而为不同表型和基因型猪的精准营养提出方案,以保持动物健康和在次优饲养条件下的生长性能。本文旨在综述近年来有关氨基酸对猪健康功能的研究进展,强调目前关于炎症对氨基酸摄入和代谢的影响,它们与肠黏膜物理屏障和抗氧化防御的关系,以及它们在合成防御分子和调节免疫反应中的作用。     

氨基酸的生物活性及其营养调控功能的研究进展

随着氨基酸营养研究的深入,发现部分氨基酸及其代谢产物在体内具有的生物活性对营养物质代谢、神经内分泌调节、基因表达、信号转导及免疫功能等都具有调控作用,这些氨基酸包括精氨酸、谷氨酰胺、亮氨酸、色氨酸、苏氨酸等,本文综述了这些氨基酸在动物体内的代谢途径以及它们的营养调控功能的研究进展。     

奶牛瘤胃脂肪酸代谢研究进展

本文综述了脂肪酸在奶牛瘤胃和小肠内的消化代谢机理，重点讨论了不饱和脂肪酸在瘤胃的脂解、氢化、微生物脂类的合成及影响因素。     

鱼类对外源氨基酸利用的研究进展

氨基酸是鱼类生长和代谢最重要的营养素之一,也是人们一直关注和研究的重点。外源性氨基酸在鱼饲料中的使用效果受鱼消化道结构、饲料加工技术以及氨基酸自身性质影响。本文就鱼类对外源性氨基酸吸收特点以及影响外源性氨基酸利用效果因素作以简述。     

氨基酸的生物活性及其营养调控功能的研究进展

随着氨基酸营养研究的深入,发现部分氨基酸及其代谢产物在体内具有的生物活性对营养物质代谢、神经内分泌调节、基因表达、信号转导及免疫功能等都具有调控作用,这些氨基酸包括精氨酸、谷氨酰胺、亮氨酸、色氨酸、苏氨酸等,本文综述了这些氨基酸在动物体内的代谢途径以及它们的营养调控功能的研究进展。     

精氨酸对畜禽营养调控及肠道屏障功能的影响研究进展

在畜禽体内,精氨酸是一种条件性必需氨基酸,参与多种营养物质的合成与代谢,同时对胃肠道的发育及功能有重要作用.肠道屏障功能是肠道主要生理功能之一,文章阐述了精氨酸对畜禽肠道屏障功能的重要作用;重点从Toll样受体途径等方面简述精氨酸对肠道免疫屏障的影响,为深入了解精氨酸在畜禽生产中的调节作用提供参考.     

Research Advanced on Functions of Nutritional Regulation and Intestinal Barrier of Arginine

Arginine is one of the most important amino acids for animals,and participates in the synthesis and metabolism of many nutrients,plays a role in the development and function of the gastrointestinal tract.Intestinal barrier function is one of the most functions for intestine.The article will summarize the effect of arginine on intestinal barrier.It was explicated the influence on inteseinal immunity of Toll-like receptor.This research provided some references for further study of arginine regulation on animal production.     

Effect of acute deficiency of dietary proline on proline balance in the rat small intestine and liver

Introduction Proline is widely found in all types of mammalian tissue, and accounts for about 20% of the amino acids that constitute collagen (A dams 1970). Proline is nutritionally nonessential but biologically it is an important amino acid and consequently mammalian organisms synthesize the required amounts of proline even in the absence of sufficient proline consumption via food. The metabolism of higher animals is unique, and amino acid metabolism differs from one tissue to the next. Some organs are capable of synthesizing nonessential amino acids for use throughout the body. For example, arginine is primarily synthesized in the kidney and then released and distributed throughout the body. Pyrroline-5-carboxylate reductase is the enzyme responsible for the final stage of proline synthesis, and its activity has been confirmed in many important organs and tissue such as the cartilage, liver, small intestine, kidney and thymus gland (H erzfeld et al. 1977; S mith and P hang 1978). However, the different levels of pyrroline-5-carboxylate reductase activity among these organs has led to the belief that different amounts of proline are synthesized in these organs. In order to ascertain biological responses to dietary proline deficiency, it is important to identify the organs that release and distribute proline throughout the body when insufficient proline is consumed through the diet, thus reducing the blood proline concentration. Few studies have investigated this issue, but when ascertaining biological responses to dietary proline deficiency, it is more important to elucidate the effect of dietary proline deficiency on the metabolism of proline and other amino acids that are closely related metabolically to proline, in proline synthesizing organs. One of the most effective ways to assess amino acid metabolism in a target tissue of higher animals is to measure the difference between the arterial and venous concentrations of amino acids. I shikawa (1974) measured arteriovenous differences in order to examine the release of proline from the kidney and small intestine of fasted rats and the uptake of proline by the liver. In a previous study, it was found that when the plasma proline concentration was reduced to the fasting level by the consumption of a proline-deficient diet, proline was released from the kidney (W atanabe et al. 1995, 1997). In the present study, to ensure the induction of dietary proline deficiency, a completely purified diet containing all amino acids except for proline was prepared and fed to rats under experimental conditions. To investigate the role of the small intestine and liver in supplying and ingesting proline when the uptake of proline through food is restricted, the release and uptake of amino acids in the small intestine and liver were assessed by measuring carotid artery–portal vein and portal–hepatic vein differences in proline in rats.     

Dynamics of amino acid and protein metabolism of laying hens after administration of 15N-labeled wheat protein. 7. Incorporation into the amino acids and peptides of the gastrointestinal tract and the pancreas

In a 15N labelling experiment 12 colostomized laying hens received 15N labelled wheat with 14.37 atom-% 15N excess (15N') over 4 days. 3 hens each were butchered after 12 h, 36 h, 60 h and 108 h after the last 15N' application. The gastro-intestinal tract was divided into 3 parts (oesophagus with crop and gizzard as well as glandular stomach, small intestine, large intestine). These parts and the pancreas were hydrolysed with 6 N HCl and the individual basic as well as the sum of acid and neutral amino acids were determined in the hydrolysed fractions. In addition, the amino acids and peptides were determined in the TCA soluble N fraction. The atom-% 15N' was determined in the individual amino acid and peptide fractions. The labelling of the basic amino acids in the individual tract segments was lower than in the acid and neutral amino acids. In comparison to the peptides, a higher atom-% 15N' could be determined in the free amino acids.     

内蒙古白绒山羊的限制性氨基酸研究

本文旨在对内蒙古白绒山羊限制性氨基酸进行研究。选用12只装有瘤胃、十二指肠和回肠瘘管的内蒙古白绒山羊,采用随机区组试验设计,并采用递减法进行十二指肠氨基酸灌注,试验分别测定了小肠可吸收氨基酸的量、氨基酸的平衡性、氮沉积、日增重等指标。试验结果表明:(1)减少蛋氨酸、组氨酸、精氨酸、丝氨酸、半胱氨酸对内蒙古白绒山羊的小肠氨基酸消失量、氨基酸的平衡性均有显著影响。(2)氨基酸灌注量减少后,根据氮沉积求出的各种氨基酸的相对限制程度依次为半胱氨酸(72.17%)、丝氨酸(54.25%)、精氨酸(51.76%)、蛋氨酸(29.07%)、组氨酸(20.45%)。内蒙古白绒山羊的限制性氨基酸是半胱氨酸、丝氨酸、精氨酸、蛋氨酸和组氨酸。     

Porcine intestinal yeast species,Kazachstania slooffiae,a new potential protein source with favourable amino acid composition for animals

There is little information about Kazachstania slooffiae which dominates among other yeasts in the pigs’ intestine. Therefore, the aims of this study were to characterise the yeast cell contents and to investigate which nitrogen sources, organic acids and alcohols may be utilised or produced by this species. The results showed that, K. slooffiae could use urea, ammonium sulphate, peptides and single amino acids and produce thereby ethanol and formic acid. However, this yeast did not metabolise amino acids, lactic, butyric, propionic and acetic acids as sole carbon source. Using a global metabolite profiling approach employing gas chromatography and high‐resolution liquid chromatography mass spectrometry, was found that the amount of peptides and dehydroascorbic acid considerably increased in the fermentation residues after yeast cultivation. It is noteworthy that the cells of K. slooffiae had higher contents of nitrogen and total amino acids (especially lysine) than the cells of nutritional yeast (Saccharomyces cerevisiae). This study indicates that due to potential production of peptides and formic acid in the intestinal tract, K. slooffiae might have an impact on the gut health. Moreover, from a nutritional standpoint, the cells of this yeast can be a good source of protein with useful amino acid composition for animal.     

Site and extent of digestion and amino acid flow to the small intestine in beef cattle consuming limited amounts of forage

Eight Angus x Gelbvieh heifers (445 +/- 74.5 kg) fitted with ruminal and duodenal cannulas were used in a 4 x 4 Latin square double double-crossover designed experiment to assess the effect of restricted forage intake on site and extent of digestion and flow of essential AA amino acids to the small intestine. Heifers were fed chopped (2.54 cm) bromegrass hay (9.2% CP, 64% NDF on an OM basis) at one of four percentages of maintenance (30, 60, 90, and 120%). Experimental periods were 21 d in length, with 17 d of adaptation followed by 4 d of intensive sample collection, after which maintenance requirements and subsequent level of intake were adjusted for BW change. True ruminal OM, NDF, and N digestion (g/d) decreased linearly (P < 0.001) with decreasing forage intake. When expressed as a percentage of OM intake, true ruminal OM and N digestibility were not affected (P = 0.23 to 0.87), whereas ruminal NDF digestibility tended to increase (P = 0.09) as forage intake decreased. Total and microbial essential amino acid flow to the duodenum decreased linearly (P = 0.001) from 496.1 to 132.1 g/d and 329.1 to 96.0 g/d, as intake decreased from 120 to 30% of maintenance intake, respectively. Although the profile of individual essential amino acids in duodenal digesta (P = 0.001 to 0.07) and isolated ruminal microbes differed (P = 0.001 to 0.09) across treatment, the greatest difference noted for total and microbial essential amino acid profile was only 0.3 percentage units. Because total and microbial flow of essential amino acids to the small intestine decreased as OM intake decreased, but true ruminal degradability of individual essential amino acids (P = 0.17 to 0.99) and digesta essential amino acid profile were comparable across treatments, total essential amino acid supply to the small intestine was predicted using OM intake as the independent variable. The resulting simple linear regression equation was: total essential amino acid flow = (0.055 x OM intake) + 1.546 (r2 = 0.91). The model developed in this experiment accounted for more of the variation in the data set than the current beef cattle NRC model, which under-predicted total flow of essential amino acids to the duodenum. The prediction equation developed herein can be used to estimate the supply of essential amino acids reaching the small intestine when formulating supplements to compensate for potential amino acid deficiencies resulting from restricted forage intake.     

赖氨酸席夫碱对到达绵羊小肠游离氨基酸和蛋白质流量的影响

选用4只体重在40 kg左右,安装永久性十二指肠瘘管的中国美利奴（新疆型）细毛羊,采用拉丁方设计,分别添加3.42和6.84 g赖氨酸席夫碱（分别含赖氨酸2、4 g）、2.56和5.12 g赖氨酸盐酸盐作为对照（分别含赖氨酸2、4 g）,以研究对进入绵羊小肠游离氨基酸和蛋白质流量的影响。结果表明,在赖氨酸实际添加水平都为4 g/d时,赖氨酸席夫碱使绵羊小肠液中游离Lys、Glu和Tyr的流量分别提高了25.17%、38.35%和33.88%（P<0.05）,对其他游离氨基酸流量的影响不明显。添加赖氨酸席夫碱对到达绵羊小肠的微生物蛋白质流量、过瘤胃蛋白质（瘤胃非降解蛋白）流量没有影响。添加赖氨酸席夫碱可提高到达绵羊小肠的游离赖氨酸量,且与添加量有关。