单胃动物肠道细菌对氨基酸的代谢作用

单胃动物肠道内寄居着各种各样的微生物,在健康状态下与宿主处于共生关系。肠道微生物通过对宿主日粮中蛋白质等含氮化合物进行发酵,产生一系列代谢产物,不但可以为自身生长提供氮源,也可为宿主提供某些氨基酸,以消除日粮中氨基酸缺乏带来的不良影响。本文综述了几个主要氨基酸家族的合成途径、参与其中的主要菌种和酶类及宿主动物对肠道微生物合成氨基酸的吸收和利用。     

微生态制剂及其在动物生产上的作用研究进展

动物微生态制剂（Microecologics）是根据动物微生态学原理，利用正常微生物群成员或其促进物质制成的，调节微生态平衡的活的微生物制剂。美国学者Parker（１９７４）将其命名为Probiotics，其含义是“使肠道微生物达到平衡的微生物和物质；Fuler（１９８９）则将其定义为“一种可通过改善肠道菌群平衡而对动物施加有利影响的活的微生物饲料添加剂。微生态制剂能调整或维持肠道内正常微生物菌群的平衡，增强动物机体免疫功能，促进营养物质的消化吸收。从而达到防病治病、提高饲料转化率和动物生产性能的目的。此外，微生态制剂还可降低…     

酶菌复合物对于幼龄动物肠道调节的研究进展

酶制剂不仅会促进机体对营养物质的消化吸收,而且会影响肠道中特定微生物的发育;微生态制剂可调节动物肠道菌群动态平衡。酶菌复合物主要是指由特定的酶制剂与筛选的微生态组合而成的一类复合生物制剂,其对于幼龄动物生长发育有着非常重要的调节作用。本文就酶菌复合物对猪、家禽及反刍动物的肠道调节作用进行综述。     

乳酸杆菌及其在微生态制剂中的作用

微生态制剂亦称益生素、生菌剂、活菌制剂等。Fuller(1989)定义为：微生态制剂是一种可通过改善肠道菌群平衡而对动物施加有利影响的活微生物饲料添加剂。微生态制剂是生物制品的一种，它是根据动物微生态学基本原理研制，可用于调节动物机体微生态平衡。它能通过增强机体对肠道内有害微生物的抑制     

动物微生态制剂研究概况及应用前景

微生态,就是人类、动物、植物有机体内各种微生物相互之间以及微生物同宿主之间所保持的相对平衡的状态。在动物体肠道微生态系统中,一个最基本的稳定结构就是由需氧菌、氧与厌氧菌共同形成的因果回路,此时,需氧菌是厌氧菌的1％至1‰,氧也保持着一定的水平。如果这个平衡被打乱,就可能发生传染病。微生态制剂的作用就是调整和维护动物肠道菌群的正常比例关系,并能产生多种消化酶、维生素、抗生素、氨基酸等有益物质,从而起到防病治病、提高动物生长速度的作用,对仔猪、肉牛、肉鸡、蛋鸡等均能取得良好效果。 微生态制剂又名益生素、促生素、利生素、活菌制     

猪肠道微生物群落组成变化及其影响因素

肠道微生物群不仅为宿主提供营养,也有利于维持其肠道微生态的平衡,保证肠道的健康和发育,因此,维持动物肠道微生态平衡在动物生产中具有重要的意义。动物肠道微生物容易受各种因素的影响,但通过日粮调控以及微生物调控均能得到一定的改善。本文综述了猪肠道微生物组成变化及其影响因素,旨在使人们在养猪生产中能够了解和控制这些因素,从而为肠道微生物与猪的消化代谢、肠道健康维持以及疾病预防等的研究提供帮助。     

肠道微生物及代谢产物对动物肠道免疫的研究进展

动物肠道内栖息着大量微生物,肠道微生物及其代谢产物积极参与肠道免疫稳态的建立,对防控肠道疾病具有积极影响,在动物健康中发挥不可或缺的调节作用。本文对肠道微生物及其代谢产物对宿主肠道免疫的影响进行综述,旨在为调控肠道免疫、治疗动物疾病及保障机体健康提供思路和参考。     

乳酸杆菌的肠道调节作用及其在动物生产中应用的研究进展

作者从乳酸杆菌对肠道表面的作用、免疫激活作用、对肠道微生态的平衡作用及对代谢的调节作用4个方面介绍了乳酸杆菌对机体的调节作用,并介绍了其在动物生产中的应用状况。本综述重点阐述了乳酸杆菌的作用机制与应用效果,以期为其应用提供参考。     

微生态制剂在饲料工业中的应用

研究表明 ,在正常动物肠道内稳定定植了40 0多种不同类型细菌 ,微生物总数可达 1 0 1 4个。这些定植的微生物群落之间以及微生物与宿主之间 ,在动物的不同发育阶段均建立了动态的平衡关系 ,这种平衡关系是动物健康的基础。在外界不良因素的作用下 ,肠道微生物与宿主之间的平衡关系一旦被打破就会表现出病理变化。导致微生态失衡的外界不良因素包括 :引入抗生素、激素、免疫疗法、细胞毒性药物及动物应激等。根据微生态环境的动态规律 ,人们可以采用多种措施来维持或恢复微生态平衡 ,微生态制剂的应用就属于这些措施之一。1　微生态制剂的菌…     

乳酸杆菌及其在微生态制剂中的作用

微生态制剂亦称益生素、生菌剂、活菌制剂等。Fuller(1989)定义为:微生态制剂是一种可通过改善肠道菌群平衡而对动物施加有利影响的活微生物饲料添加剂。微生态制剂是生物制品的一种,它是根据动物微生态学基本原理研制,可用于调节动物机体微生态平衡。它能通过增强机体对肠道内     

Synthesis and absorption of cysteine from the hindgut of the horse

The extent to which cysteine synthesised by microbes within the hindgut of the horse is incorporated into plasma cysteine was estimated by an isotopic technique in two horses fed four different diets. The results showed that between 1 per cent and 6 per cent of the plasma cysteine was of microbial origin. It is argued that the maximum contribution of microbial cysteine, and presumably other amino acids of microbial origin, to the plasma pool is 12 per cent of the net supply. These data support the hypothesis that microbial amino acid synthesis within the hindgut of the horse does not significantly affect its amino acid status.     

Mutual interaction between gut microbiota and protein/amino acid metabolism for host mucosal immunity and health

In recent years, many studies have shown that the intestinal microflora has various effects that are linked to the critical physiological functions and pathological systems of the host. The intestinal microbial community is widely involved in the metabolism of food components such as protein, which is one of the essential nutrients in diets. Additionally, dietary protein/amino acids have been shown to have had a profound impact on profile and operation of gut microbiota. This review summarizes the current literature on the mutual interaction between intestinal microbiota and protein/amino acid metabolism for host mucosal immunity and health.     

The effect of microbial phytase on ileal phosphorus and amino acid digestibility in the broiler chicken

1. The study aimed to assess the effect of a commercially available microbial phytase on phytate phosphorus and total phosphorus content at the terminal ileum as well as true ileal amino acid digestibility. 2. Five diets, each containing a different plant-based feedstuff, were supplemented with microbial phytase and fed, along with a non-supplemented corresponding diet, to 28-d-old broiler chickens, Chromic oxide was used as an indigestible marker. Ileal contents were collected and analysed, along with the diets, for total phosphorus, phytate phosphorus and amino acids. 3. Endogenous phosphorus determined at the terminal ileum was 272 +/- 108 mg/kg food dry matter (mean +/- SE). Endogenous ileal amino acid flows ranged from 58 +/- 10 mg/kg food dry matter for methionine to 568 +/- 47 mg/kg food dry matter for glutamic acid. 4. Supplementation with microbial phytase resulted in a significantly greater phytate P disappearance from the terminal ileum for rice bran (17% units), but not for soyabean meal, maize, wheat or rapeseed meal. Similarly total phosphorus digestibility was significantly (P < 0.05) higher when microbial phytase was added to the rice-bran-based diet but not for any of the other feedstuffs. 5. Amino acid digestibility was significantly greater in the presence of microbial phytase for all the amino acids examined in wheat, for several of the amino acids each in maize and rapeseed meal and for one amino acid in rice bran and soyabean meal. The average increase in amino acid digestibility for those amino acids affected, was 13, 6, 10, 7 and 12% units for wheat, maize, rapeseed meal, rice bran and soyabean meal, respectively. 6. It appears that microbial phytase improves phosphorus digestibility and amino acid digestibility for certain plant-based feedstuffs.     

Effect of Fusarium toxin-contaminated triticale and forage-to-concentrate ratio on fermentation and microbial protein synthesis in the rumen

In this study, the effect of Fusarium toxin-contaminated triticale (FUS) at high (60%) and low (30%) concentrate proportion in ruminant rations on ruminal fermentation, microbial protein synthesis and digestibility was investigated, using in vivo and in vitro methods. Significant effects of the forage-to-concentrate ratio on ruminal degradation and digestibility of crude nutrients and detergent fibre fractions as well as on the pH value and the concentration of short chain fatty acids (SCFA) in rumen fluid were found. The production of SCFA was affected, and the degradation of crude fibre and neutral detergent fibre in the rumen was reduced by the inclusion of FUS at high concentrate proportion. The efficiency of microbial crude protein synthesis was higher in diets with 60% than in diets with 30% concentrates, but was impaired in the presence of FUS in vitro at the high concentrate level. Marginal effects of FUS on the amino acid pattern of microbial protein were detected. It was concluded that the use of FUS in high concentrate diets can influence ruminal fermentation and microbial protein synthesis at a dietary deoxynivalenol concentration below 5 mg/kg dry matter.     

The Influence of Tallow on Rumen Metabolism,Microbial Biomass Synthesis and Fatty Acid Composition of Bacteria and Protozoa

Abstract

Rumen metabolism, microbial biomass synthesis and microbial long chain fatty acid composition were studied in lactating cows fed at two levels of dry matter intake (L, 8.6 kg DM and H, 12.6 kg DM) with 0, 4 and 6% added tallow at the low feed level (L0, L4 and L6) and 0, 2, 4 and 6% at the high feed level (H0, H2, H4 and H6).

Fibre digestibility was not significantly affected by tallow addition. Increasing tallow level in the diet decreased the total VFA concentration, the ratio of acetic acid to propionic acid and the ammonia concentration in the rumen. Crude fat and fatty acid content in bacterial and protozoal dry matter increased with increased tallow level, especially due to an increase in fatty acids originating from the feeds. Microbial synthesis in the rumen and flow of amino acids to the duodenum was highest for medium fat intake at the high feed level.     

Response of dairy cows to protein level in early lactation

The comparison of cows' protein requirements with the supply of microbial and feed proteins digestible in the intestine shows a large deficit for the first weeks just after calving. The magnitude and duration of the deficit is reflected in the blood parameters of the protein status (protein, urea and free amino acid contents and composition) and of the energy status (glucose, free fatty acid content). Great increases in milk production are noted in this period by meeting protein requirements at all times during the first eight weeks after calving. Sometimes they are achieved at the expense of body stores, but in other cases they can be related to an increase in the efficiency of microbial digestion in the rumen, in the ingestibility of the feeds, or in the intake capacity of the cows. The effects on milk protein synthesis and on the intake capacity of the cows seem to be due to the supply of some essential amino acids, particularly methionine, but also to the supply of non-essential glucose precursor amino acids. More studies are needed on the mechanisms involved, on the long-term effects, and on the secondary effects on reproduction and health.     

非蛋白氮在家禽日粮中的应用

本文综述了家禽日粮中添加非蛋白氮(NPN)的效果,并分析影响使用效果的主要因素。家禽利用非蛋白氮的机理目前尚无定论,本文推测可能存在3种机制:利用非蛋白氮合成非必需氨基酸(NEAA)、代谢产物负反馈抑制原理和微生物转化利用。家禽日粮中添加非蛋白氮效果很不稳定,影响因素复杂,实际生产中难以把握,现阶段不宜推广使用。     

反刍动物小肠氨基酸调控

反刍动物小肠氨基酸调控是反刍动物营养研究的重要课题。反刍动物小肠氨基酸的调控是以反刍动物氨基酸的需要为基础,有目的地通过各种途径使小肠吸收氨基酸含量达到动物的生产需要。反刍动物小肠氨基酸调控主要有以下几方面:通过瘤胃蛋白质保护、改变饲料在瘤胃中停留时间和添加生物制剂调节日粮过瘤胃蛋白质;通过日粮可发酵能、能氮平衡和瘤胃微生物环境控调微生物蛋白质;通过瘤胃保护氨基酸(RPAA)调控小肠氨基酸。     

Small intestinal digestibility of microbial and endogenous amino acids in dairy cows

The small intestinal digestibility of microbial amino acids and the apparent re-absorption of endogenous amino acids were estimated in three ruminal, duodenal and ileal fistulated lactating dairy cows. The cows were assigned to a 3 × 3 Latin square and fed diets low in amino acids, composed of straw, starch, molasses and urea. The treatments were three straw to concentrate ratios. The digestibilities and re-absorptions were estimated from duodenal and ileal flows of amino acids from feed, microbial and endogenous sources. The duodenal distribution of amino acids between different origins was determined by the difference method and by the amino acid profile method. The ileal distribution was estimated by a simple method where the feed fraction was estimated by the mobile bag method, the endogenous fraction as the water soluble fraction and the microbial fraction as the rest. In ileal samples, 8.0 ± 1.1, 52.2 ± 2.9 and 39.8 ± 2.6% of total amino acid nitrogen (AAN) were of feed, microbial and endogenous origin, respectively, compared with 5.1 ± 0.9, 61.6 ± 6.6 and 32.7 ± 6.9% in duodenal samples. The small intestinal digestibility of microbial AAN was estimated to be 75.1 ± 1.8% and the apparent re-absorption of endogenous AAN to be 62.3 ± 11.1%.