中链脂肪酸在畜牧业上应用的研究进展

中链脂肪酸(MCFA)是指含有6~12个碳原子组成碳链的脂肪酸,在动物体内,它们的消化、吸收、转运、氧化等都具特点。表现出特殊的生理活性功能,能迅速有效地为幼小动物提供能量的需要,对病原菌具有独特的抑菌以及调整动物肠道结构等的作用,具有显著的抗菌、促生长和提高饲料转化率等功效。文章综述了MCFA的代谢特点与作用机制以及在现代畜牧业中的运用研究进展。     

中链脂肪酸在动物生产中的应用效果及其影响因素研究进展

中链脂肪酸（MCFA）是一类具有特殊生理功能的能源物质，与长链脂肪酸（LCFA）相比，MCFA的碳链更短，到达肝脏的速度更快，MCFA可直接经门静脉运输至肝脏，且无需肉碱脂酰转移酶的转运即可直接进入肝细胞线粒体进行β氧化。因此，MCFA被动物吸收的更直接、更快速，供能也更直接。MCFA不但可为动物机体提供能量，还具有超出其能量价值之外的特殊生理功能，包括抑制细菌的生长和改善肠道微生态及结构，参与动物机体的免疫调节和激素调节等。MCFA的营养特点和生理功能为其在动物生产上的应用提供了依据，在动物生产应用方面，MCFA可提高动物生长性能，减少反刍动物瘤胃甲烷的排放，预防动物疾病，延长畜禽产品货架期，有效控制蚊蝇对家畜的侵扰，MCFA与一些其他饲料添加剂联合使用，不仅存在协同效应，还可克服其在实际生产应用中的缺点。近年来，使用安全、绿色的饲料添加剂替代动物饲料中抗生素的呼声越来越高，MCFA也逐渐受到大众的关注。然而，MCFA在研究和生产应用中存在效果差异，究其原因可能与MCFA的种类、添加水平、添加方式等因素有关。文章对MCFA的营养特点、生理功能、应用于动物生产的效果及其影响因素进行了综述，旨在为MCFA的深入开发与合理利用提供理论依据。     

中链脂肪酸在动物生产中的应用效果及其影响因素研究进展

中链脂肪酸(MCFA)是一类具有特殊生理功能的能源物质,与长链脂肪酸(LCFA)相比,MCFA的碳链更短,到达肝脏的速度更快,MCFA可直接经门静脉运输至肝脏,且无需肉碱脂酰转移酶的转运即可直接进入肝细胞线粒体进行β氧化。因此,MCFA被动物吸收的更直接、更快速,供能也更直接。MCFA不但可为动物机体提供能量,还具有超出其能量价值之外的特殊生理功能,包括抑制细菌的生长和改善肠道微生态及结构,参与动物机体的免疫调节和激素调节等。MCFA的营养特点和生理功能为其在动物生产上的应用提供了依据,在动物生产应用方面,MCFA可提高动物生长性能,减少反刍动物瘤胃甲烷的排放,预防动物疾病,延长畜禽产品货架期,有效控制蚊蝇对家畜的侵扰,MCFA与一些其他饲料添加剂联合使用,不仅存在协同效应,还可克服其在实际生产应用中的缺点。近年来,使用安全、绿色的饲料添加剂替代动物饲料中抗生素的呼声越来越高,MCFA也逐渐受到大众的关注。然而,MCFA在研究和生产应用中存在效果差异,究其原因可能与MCFA的种类、添加水平、添加方式等因素有关。文章对MCFA的营养特点、生理功能、应用于动物生产的效果及其影响因素进行了综述,旨在为MCFA的深入开发与合理利用提供理论依据。     

中链脂肪酸的生化及代谢特征与其在畜禽生产中应用的研究进展

中链脂肪酸（medium chain fatty acids,MCFA）是指碳原子数为6～12的一类脂肪酸,所有天然存在的脂肪酸均由C2单元（乙酰辅酶a）组成,因此碳原子数为偶数（如己酸C6、辛酸C8、癸酸C10、月桂酸C12）。MCFA不仅可以作为能源物质,还具有抗菌、调节免疫、维护肠道健康、防治疾病以及提高动物生长性能等作用,因而也可作为替抗产品。文章对MCFA的生物学功能和作用机制进行了简述,概述其在畜禽生产方面的应用,旨为MCFA在养殖业中的进一步应用提供参考。     

中链脂肪酸甘油三酯在养猪业中的应用

正中链脂肪酸(MCFA)是指链长为6~12C的饱和脂肪酸,其具备特殊的生理活性功能,能够快速为幼小动物供应能量,抑制细菌调节肠道结构,不仅促进生长提高饲料转化率,还能提高母猪的繁殖性能等。本文简单介绍了中链脂肪酸酯化形成甘油三酯(MCT)后的理化性质、代谢特点、生产工艺等,同时综述了其在养猪业中的应用与进展。脂肪是猪体组织的主要成分,也是其饲粮的重要成分。近年来对脂肪的研究不断深入,同时也推动了更多     

有机酸和中链脂肪酸对断奶仔猪胃肠道健康的影响

本研究评估了饲喂不同组合有机酸（OA）和中链脂肪酸（MCFA）日粮的断奶仔猪胃肠道菌群的变化。将96头25日龄断奶的阉割公猪随机分饲4种日粮。4种日粮为没有添加剂（对照）、添加OA（富马酸和乳酸）、添加MCFA（辛酸和癸酸）与OA和MC—FA组合。在小肠上部检出延胡索酸浓度范围低，     

维持猪群肠道健康的自然方法

不同脂肪酸的抗菌活性在实践中是众所周知的。脂肪酸和其他物质的靶向组合可以广泛改善动物肠道健康,减少抗生素的使用。由于法律法规要求在畜牧业生产中要减少抗生素的使用,不同的脂肪酸在动物营养中发挥着越来越重要的作用。由于中链脂肪酸(MCFA)具有很强的抗菌活性和能量供应成分,因此在猪生产中,寻找抗生素的替代品激发了人们对MCFA的兴趣。其不但可促进肠道绒毛的生长,还可增加饲料的消化率,也可以改善断奶后仔猪的肠道发育。     

"养鸡生产中沙门氏菌病的预防与控制策略"专栏(八)利用饲料添加剂"多重阻断法"预防禽沙门氏菌

用于控制家禽沙门氏菌的"多重阻断"(multi-hurdle)型饲料添加剂新概念具有广阔的应用前景.此类添加剂是由有机酸、中链脂肪酸(MCFA)、丁酸盐和甘露二糖组成的混合物,可显著降低盲肠中的肠炎沙门氏菌(S.Enteritidis).该方法的原理是将对沙门氏菌在肉鸡肠道增殖、黏附或侵袭具有控制或阻断作用的添加剂复合在一起同时使用.     

PIG PROGRESS维持猪群肠道健康的自然方法

不同脂肪酸的抗菌活性在实践中是众所周知的.脂肪酸和其他物质的靶向组合可以广泛改善动物肠道健康,减少抗生素的使用.由于法律法规要求在畜牧业生产中要减少抗生素的使用,不同的脂肪酸在动物营养中发挥着越来越重要的作用.由于中链脂肪酸(MCFA)具有很强的抗菌活性和能量供应成分,因此在猪生产中,寻找抗生素的替代品激发了人们对MC...     

利用饲料添加剂“多重阻断法”预防禽沙门氏菌

用于控制家禽沙门氏菌的＂多重阻断＂（multi-hurdle）型饲料添加剂新概念具有广阔的应用前景。此类添加剂是由有机酸、中链脂肪酸（MCFA）、丁酸盐和甘露二糖组成的混合物,可显著降低盲肠中的肠炎沙门氏菌（S.Enteritidis）。该方法的原理是将对沙门氏菌在肉鸡肠道增殖、黏附或侵袭具有控制或阻断作用的添加剂复合在一起同时使用。欧盟已经制订了明确的家禽沙门氏菌防控目标,而     

Effect of coated and non-coated fatty acid supplementation on broiler chickens experimentally infected with Campylobacter jejuni

The aim of this study was to examine whether and to what extent the supplementation of feed with a coated or non-coated mixture of fatty acids (caprylic and capric acid) affects broiler chickens experimentally infected with Campylobacter jejuni. The study was carried out using 48 chickens divided into four experimental groups. Throughout the whole rearing period (1-42 days), the chickens were fed a diet supplemented with 0.25% caprylic and capric acid (1:1), coated or non-coated. At the age of 14 and 28 days, chickens were orally challenged with C. jejuni. At regular time intervals post-inoculation, the shedding of C. jejuni was assayed using quantitative real-time PCR. Both supplements significantly decreased faecal C. jejuni counts by 1.2-4.1 log(10) CFU/g 4 days post-inoculation; after this time period, the effect of medium-chain fatty acids (MCFA) was less pronounced or absent. Campylobacter jejuni counts in excreta samples were significantly lower in chickens fed coated MCFA than in those fed non-coated MCFA. No effect of MCFA on feed intake or growth of chickens was observed. In conclusion, (i) MCFA are active against C. jejuni and (ii) the encapsulation enhanced the efficacy of the acids. These results allow the recommendation of using MCFA as feed additives in chickens, preferably 2-3 days before slaughter.     

Coated fatty acids alter virulence properties of Salmonella Typhimurium and decrease intestinal colonization of pigs

Salmonella Typhimurium infections in pigs are a major source of human foodborne salmonellosis. To reduce the number of infected pigs, acidification of feed or drinking water is a common practice. The aim of the present study was to determine whether some frequently used short- (SCFA) and medium-chain fatty acids (MCFA) are able to alter virulence gene expression and to decrease Salmonella Typhimurium colonization and shedding in pigs using well established and controlled in vitro and in vivo assays. Minimal inhibitory concentrations (MIC) of 4 SCFA (formic acid, acetic acid, propionic acid and butyric acid) and 2 MCFA (caproic and caprylic acid) were determined using 54 porcine Salmonella Typhimurium field strains. MIC values increased at increasing pH-values and were two to eight times lower for MCFA than for SCFA. Expression of virulence gene fimA was significantly lower when bacteria were grown in LB-broth supplemented with sub-MIC concentrations of caproic or caprylic acid (2 mM). Expression of hilA and invasion in porcine intestinal epithelial cells was significantly lower when bacteria were grown in LB-broth containing sub-MIC concentrations of butyric acid or propionic acid (10 mM) and caproic or caprylic acid (2 mM). When given as feed supplement to pigs experimentally infected with Salmonella Typhimurium, coated butyric acid decreased the levels of faecal shedding and intestinal colonization, but had no influence on the colonization of tonsils, spleen and liver. Uncoated fatty acids, however, did not influence fecal shedding, intestinal or tonsillar colonization in pigs. In conclusion, supplementing feed with certain coated fatty acids, such as butyric acid, may help to reduce the Salmonella load in pigs.     

The effects of dietary medium-chain fatty acids on ruminal methanogenesis and fermentation in vitro and in vivo: A meta-analysis

The efficacy of methane (CH₄) suppression using medium-chain fatty acids (MCFA) remains inconclusive, despite a number of studies on this topic are available. We thus carried out a meta-analysis to integrate the published data on different concentrations and types of MCFA such as lauric acid and myristic acid, which investigated ruminal methanogenesis and fermentation in in vitro and in vivo experiments. In vitro MCFA sources were classified either as pure MCFA (lauric acid, myristic acid and their combinations) or as natural MCFA-rich oils (canola oil enriched with lauric acids, coconut oil, krabok oil and palm kernel oil). The MCFA sources used in the in vivo studies were coconut oil, lauric acid, myristic acid and the combination of lauric and myristic acids. A total of 41 studies (20 in vitro and 21 in vivo studies) were compiled in our database, which included the data on CH₄ emission, digestibility, ruminal fermentation products and microbial populations. The results showed that the amount of CH₄ production per unit of digested organic matter decreased linearly under in vitro conditions (p < .01) and tended to decrease quadratically under in vivo conditions (p < .07) with increasing doses of MCFA. Populations of protozoa (p < .01) in both in vitro and in vivo responded negatively in a linear manner, whereas Archaea population diminished quadratically (p = .04) only in the in vitro conditions with increasing doses of MCFA. Increasing dietary MCFA concentrations also reduced the fibre digestibility linearly (p < .05) in both in vitro and in vivo conditions. CH₄ production for different sources of MCFA decreased in following order: coconut oil > lauric acid > myristic acid > mixed lauric and myristic acids > palm kernel oil > canola oil enriched with lauric acids > krabok oil. It can be concluded that the effect of MCFA on ruminal methanogenesis depends on the amount and type of MCFA.     

Effect of prebiotic fructans and organic acids on mineral retention in laying hens

Abstract

The aim of the study was to evaluate the effect of organic acids and prebiotic fructans added to the layer's diet on balance of calcium, phosphorus, and zinc. The basal experimental diet contained 3.30% Ca and 0.60% P, and was either unsupplemented or supplemented with additives as follows: 0.75% inulin, 0.75% oligofructose; 0.50% short-chain fatty acids (SCFA); 0.25% medium-chain fatty acid (MCFA); 0.30% SCFA+0.20% MCFA; and 0.75% inulin+0.50% SCFA. It was concluded that some additives used in the experiment had a positive effect on the mineral balance in hens. Inulin significantly improved retention of Ca, P, and Zn, SCFA – retention of Ca, SCFA+MCFA – retention of Zn, inulin+SCFA – retention of P and Zn.     

中链脂肪酸对体外发酵甲烷产量的影响

利用人工瘤胃体外产气法研究不同精粗比(0:1和1:1)日粮类型时中链脂肪酸对甲烷产量的影响。结果显示,体外培养24h,添加脂肪酸对甲烷产量的抑制作用不受日粮类型的影响(P>0.05);与不添加酸的对照相比,添加50mg未酯化月桂酸(C12:0)及月桂酸和肉豆蔻酸(C14:0)以3:2的比例组成的混合物(50mg)可分别抑制甲烷产量的22.2%(P<0.01)和11.8%(P<0.05);添加50 mg未酯化C14:0使甲烷产量降低3.4%(P>0.05);不同日粮类型上饲料产气量、瘤胃液pH值和氨氮浓度差异显著(P<0.01)。     

Influence of medium‐chain fatty acids and short‐chain organic acids on jejunal morphology and intra‐epithelial immune cells in weaned piglets

Medium‐chain fatty acids (MCFA) and short‐chain organic acids (SOA) are often used as feed additives in piglet diets. There are limited studies in pigs describing the impact of MCFA or SOA on gut morphology and the local immune system. The aim of this study was to investigate whether the supplementation of SOA (0.41% fumaric acid and 0.32% lactic acid), or the combination of SOA with MCFA (0.15% caprylic and capric acid) would have effects on gut morphology and intestinal immune cells in weaned piglets. A total number of 72 weaned piglets were randomly allocated into three experimental groups. Tissue samples of six animals per group were used to investigate the potential impact of the feed additives on villus length and crypt depth of the jejunum and to quantify intra‐epithelial lymphocytes (IEL). CD3‐positive IEL were determined via immunohistochemistry (IHC) and flow cytometry (FC), whereas CD2?, CD5?, CD8β?, CD16? and γδ TCR‐positive IEL were only analysed by FC. The supplementation of MCFA and SOA did not significantly affect morphometric data. The FC data indicated that SOA significantly increased the quantity of CD2^?CD8^? γδ T cells in the jejunum epithelium. Both IHC and FC analyses of pig jejunum confirmed that the majority of IEL expressed the surface marker CD3 and could be classified as cytotoxic T lymphocytes. In conclusion, the data indicated that SOA increased the proportion of CD2^?CD8^? γδ T cells in the jejunal epithelium. Thus, SOA might enable a beneficial effect on the local immunity by increasing the constitutive number of potential effector cells to defeat infectious diseases.     

Testing the efficacy of medium chain fatty acids against rabbit colibacillosis

Enteropathogenic Escherichia coli (EPEC) represents a major cause of lethal diarrhea in young mammals. Although the pathogenicity mechanisms of EPEC are now well understood, the intrinsic and environmental factors that control the expression of EPEC virulence remain largely unknown. In the rabbit, suckling reduces pups' sensitivity to EPEC infection. Hence, we have hypothesized that uncharacterized factors present in doe milk may mediate this protection. Medium chain fatty acids (MCFA), known to possess antimicrobial properties, are highly abundant in doe milk. We demonstrate that caprylic acid exhibits a clear bacteriostatic effect in vitro against the rabbit EPEC strain E22 (O103:H2:K-), in a dose-dependent manner. In vivo, the dietary inclusion of triglycerides of MCFA did not however reduce the sensitivity of young rabbits challenged with this EPEC strain. The mortality and fecal excretion of EPEC were not reduced, and the bacterial adhesion to ileum was not inhibited. Amount of MCFA reaching the ileal level might have been too low and/or their association to other milk antimicrobials may have been required to observe a positive effect on disease evolution in a context of a highly virulent challenge.     

Inhibition of African swine fever virus in liquid and feed by medium-chain fatty acids and glycerol monolaurate

Background: The ongoing African swine fever virus(ASFv) epidemic has had a major impact on pig production globally and biosecurity efforts to curb ASFv infectivity and transmission are a high priority. It has been recently identified that feed and feed ingredients, along with drinking water, can serve as transmission vehicles and might facilitate transboundary spread of ASFv. Thus, it is important to test the antiviral activity of regulatory compatible,antiviral feed additives that might inhibit ASFv infectivity in feed. One promising group of feed additive candidates includes medium-chain fatty acids(MCFA) and monoglyceride derivatives, which are known to disrupt the lipid membrane surrounding certain enveloped viruses and bacteria.Results: The antiviral activities of selected MCFA, namely caprylic, capric, and lauric acids, and a related monoglyceride, glycerol monolaurate(GML), to inhibit ASFv in liquid and feed conditions were investigated and suitable compounds and inclusion rates were identified that might be useful for mitigating ASFv in feed environments. Antiviral assays showed that all tested MCFA and GML inhibit ASFv. GML was more potent than MCFA because it worked at a lower concentration and inhibited ASFv due to direct virucidal activity along with one or more other antiviral mechanisms. Dose-dependent feed experiments further showed that sufficiently high GML doses can significantly reduce ASFv infectivity in feed in a linear manner in periods as short as 30 min, as determined by infectious viral titer measurements. Enzyme-linked immunosorbent assay(ELISA) experiments revealed that GML treatment also hinders antibody recognition of the membrane-associated ASFv p72 structural protein, which likely relates to protein conformational changes arising from viral membrane disruption.Conclusion: Together, the findings in this study indicate that MCFA and GML inhibit ASFv in liquid conditions and that GML is also able to reduce ASFv infectivity in feed, which may help to curb disease transmission.     

Effects of medium-chain fatty acids on performance,carcass characteristics,blood biochemical parameters and immune response in Japanese quail

1. This study had the aim of evaluating the effects of medium-chain fatty acids (MCFA) on performance, carcass characteristics, some blood parameters and antibody titre against sheep red blood cells (SRBC) in quail.

2. A total of 240 quail chicks were allotted to 4 treatments consisting of respectively 0, 1, 2 and 4 g/kg dietary MCFA.

3. There were no significant differences in body weight, feed intake and feed conversion ratio among treatments at different stages of the experiment.

4. MCFAs had no significant effect on breast, thigh, liver, spleen and bursa of Fabricius weight ratios. However, the relative weight of abdominal fat significantly decreased in quail receiving 0.2 and 0.4 MCFA as compared to other treatments.

5. Concentrations of low-density lipoprotein-cholesterol (LDL), triglycerides and total cholesterol were decreased and high-density lipoprotein (HDL)-cholesterol was increased in quail chicks receiving MCFA compared with control quail chicks. The concentrations of SRBC antibody were not statistically different among treatments.

6. It is concluded that MCFA significantly decreased LDL, triglycerides, cholesterol and abdominal fat and increased HDL in quail chicks.