日粮纤维在猪生产应用中的研究

日粮纤维水平对不同猪种肠道物理屏障和微生物的影响作者：王欢李平华牛清杜陶然蒲广范丽娟牛培培吴承武周五朵黄瑞华来源：《江苏农业学报》2020年第03期摘要：为研究日粮纤维水平对不同品种猪肠道形态、通透性和微生物的影响，按照2×4双因子设计，选择体质量约40 kg的健康二花脸猪和与二花脸猪相同生理阶段约65 kg的大白猪各24头随机分为4个处理组，分别饲喂基础日粮和7%、14%、21%麸皮替代基础日粮，每组6个重复，使用奥饲本全自动生产性能测定系统进行饲喂，每个重复1头猪。

正试期28 d，试验结束时采集血液样品，分离血清用于血清内毒素、二胺氧化酶（DAO）和D-乳酸含量测定;屠宰采集盲肠和结肠中段样品进行形态学观察，采集空肠和结肠黏膜进行微生物16S rRNA基因拷贝数测定。

结果表明：猪品种对血清内毒素含量、D-乳酸含量、空肠双歧杆菌丰度、盲肠隐窝深度、盲肠肠壁厚度、结肠肠壁厚度、结肠肌层厚度、结肠大肠杆菌和结肠乳酸杆菌丰度有显著影响（P关键词：二花脸猪;大白猪;日粮纤维;麸皮;肠道通透性;肠道形态;肠道微生物中图分类号：S828.8文献标识码：A文章编号：1000-4440（2020）03-0639-09Effects of dietary fiber levels on intestinal physical barrier and microbiota in different pig breedsWANG Huan1，2，LI Ping-hua1，2，3，NIU Qing1，2，DU Tao-ran1，2，PU Guang1，2，FAN Li-juan1，2，NIU Pei-pei2，WU Cheng-wu1，2，ZHOU Wu-duo1，3，HUANG Rui-hua1，2，3（1.Institute of Swine Science， Nanjing Agricultural University， Nanjing 210095，China;2.Huai′an Academy， Nanjing Agricultural University，Huai′an 223001，China;3.Integration Innovation Center of Jiangsu Modern Agricultural （Pig′s） Industrial Technology System， Nanjing 210095， China）Abstract： The aim of this experiment was to study the effects of dietary fiber levels on intestinal morphology， permeability and microbiota in different pig breeds. Based on 2×4 two-factor design，twenty-four Erhualian pigs （approximately 40 kg） and twenty-four Large White pigs （the same physiological stage as the Erhualian pig， approximately 65 kg） were selected and randomly divided into four treatment groups including control diet group， 7%， 14% and 21% wheat bran replaced basal diet with six replicates in each group and one pig per replicate. The pigs were fed by the Osborne testing stations system. After the 28-d trial， blood samples were collected and the serum was collected for analyses of endotoxin， diamine oxidase （DAO） and D-lactate. The middle sections of the cecum and colon were collected for histological analysis. Mucosal scrapings from the jejunum and colon were prepared for the detemination of 16S rRNA gene copy number. The results showed that pig breeds had significant effects on serum endotoxin content， D-lactate content， the abundance of Bifidobacterium in the jejunum， cecal crypt depth， intestinal wall thickness in the cecum， intestinal wall thickness in the colon， muscle thickness in the colon， the abundance of Escherichia coli and Lactobacillus in the colon （P<0.05）. The level of wheat bran had significant effects on serum DAO content， D-lactate content and the abundance of Escherichia coli in the colon （P<0.05）. For Erhualian pig， compared with the control group， 7% and 14% wheat bran significantly increased D-lactate content （P<0.05）， 21% wheat bran significantly increased DAO content （P<0.05）， 7% wheat bran significantly increased the muscle thickness in the cecum（P<0.05）， 21% wheat bran significantly decreased intestinal wall thickness in the cecum（P<0.05）， 7% wheat bran significantly increased the abundance of Lactobacillus， 14% wheat bran decreased the abundance of Escherichia coli in the colon （P<0.05）. For Large White pig，compared with control group， 14% wheat bran significantly increased DAO content （P<0.05），14% and 21% wheat bran significantly increased the intestinal wall thickness in the cecum（P<0.05）， 7% wheat bran significantly decreased the abundance of Bifidobacterium in the jejunum （P<0.05）， 14% wheat bran significantly decreased the abundance of Bifidobacterium in the jejunum and the abundance of Lactobacillus in the colon （P<0.05）. In conclusion， there were differences between Erhualian pig and Large White pig in large intestine morphology， intestinal permeability， the abundance of Bifidobacterium in the jejunum， the abundance of Escherichia coli in the color， the abundance of Lactobacillus in the colon. The level of wheat bran affected the abundance of Escherichia coli in the colon. The 7% wheat bran increased intestinal permeability in Erhualian pigs. However， muscle thickness in the cecum was increased to odapt to the digestion of fiber， and the abundance of Lactobacillus in the colon was increased to improve intestinal health. The 14% wheat bran increased intestinal permeability and intestinal wall thickness in the cecum，and decreased the abundance of Bifidobacterium in the jejunum and Lactobacillus in the colon.Key words：Erhualian pig;Large White pig;dietary fiber;wheat bran;intestinal permeability;intestinal morphology;intestinal microbiota中国是养猪大国，养猪历史悠久。

农业工程技术·综合版 2022年5月刊86畜禽与水产工程日粮中纤维对猪群生长发育造成的不良影响主要取决于生猪的生长阶段。

生长阶段的猪群如果日粮中的纤维含量过高，将会影响能量获取；但对妊娠母猪的影响相对较小，能够大大提高妊娠母猪的饱腹感，妊娠后期适量增加纤维能够有效解决母猪过肥的问题。

与年龄较小的仔猪相比，成年猪群发育状态良好，消化纤维和分解纤维的能力更强。

二、日粮纤维对猪生长的影响1、日粮纤维对生猪生长性能的影响日粮当中的纤维一定程度上能够有效改善胃肠道功能，增强胃肠道的蠕动能力，间接影响猪群的饲料消化利用率。

如果饲料配方中高纤维饲料种类较多或添加量超标，会影响机体的正常生长发育。

日粮中的纤维在进入肠道后能够被大肠杆菌进一步发酵，在多种微生物的分解作用下，分解成多种脂肪酸被机体利用。

综合性把控粗纤维日粮的添加量，不仅不会对育肥猪的生长发育产生危害，而且能够大大提升瘦肉比率。

如果日粮中的纤维含量相对较多，通过适当延长饲料投喂时间能够保证猪群更好地适应饲料中的粗纤维。

进入育肥后期后，粗纤维能够阻碍体内脂肪的过量沉积，大大提升瘦肉率，减少饲料采食量，从而降低经济成本。

饲料的采食多少与日粮中能量饲料的添加量密切相关，添加适量粗纤维日粮，能够有效稀释改善能量浓度，保证能量饲料更好地被消化和利用。

2、日粮纤维对猪营养代谢的影响日粮纤维会影响蛋白质代谢、脂肪代谢以及矿物质代谢。

如果日粮中的纤维含量显著升高，会刺激消化道黏膜，加速胃肠道蠕动，有助于养分吸收。

但是，日粮纤维具有一定的吸水性，添加过多会影响到机体的消化功能，造成消化不良。

（1）影响蛋白质代谢生猪养殖不同阶段通过添加适量高纤维饲料，会对猪群体内蛋白质的分解利用产生一定影响。

如果高纤维饲料添加过多会导致肠道中的营养物质供给不足，猪群出现生长发育不良。

短时间内摄入大量高纤维饲料，会影响肠道上皮细胞的正常繁殖，使细胞大量脱落。

添加量超过一定标准后，还会影响机体对氨基酸的消化利用，要严格控制添加量。

Engineering 3 (2017) 716–725ResearchAnimal Nutrition and Feed Science—ReviewNutritional and Metabolic Consequences of Feeding High-Fiber Diets to Swine: A ReviewAtta K. Agyekum a , C. Martin Nyachoti b ,*a Prairie Swine Center Inc., Saskatoon, SK S7H 5N9, CanadabDepartment of Animal Science, University of Manitoba, Winnipeg, MB R3T 2N2, Canadaa r t i c l e i n f oa b s t r a c tArticle history:Received 1 March 2017Revised 18 April 2017Accepted 20 April 2017Available online 24 May 2017At present, substantial amounts of low-cost, fibrous co-products are incorporated into pig diets to reduce the cost of raising swine. However, diets that are rich in fiber are of low nutritive value because pigs cannot degrade dietary fiber. In addition, high-fiber diets have been associated with reduced nutrient utilization and pig performance. However, recent reports are often contradictory and the negative effects of high-fiber diets are influenced by the fiber source, type, and inclusion level. In addition, the effects of dietary fiber on pig growth and physiological responses are often confounded by the many analytical methods that are used to measure dietary fiber and its components. Several strategies have been employed to ameliorate the negative effects associated with the ingestion of high-fiber diets in pigs and to improve the nutritive value of such diets. Exogenous fiber-degrading enzymes are widely used to improve nutrient utilization and pig per-formance. However, the results of research reports have not been consistent and there is a need to elucidate the mode of action of exogenous enzymes on the metabolic and physiological responses in pigs that are fed high-fiber diets. On the other hand, dietary fiber is increasingly used as a means of promoting pig gut health and gestating sow welfare. In this review, dietary fiber and its effects on pig nutrition, gut physiology, and sow welfare are discussed. In addition, areas that need further research are suggested to gain more insight into dietary fiber and into the use of exogenous enzymes to improve the utilization of high-fiber diets by pigs.© 2017 THE AUTHORS. Published by Elsevier LTD on behalf of the Chinese Academy of Engineering andHigher Education Press Limited Company. This is an open access article under the CC BY-NC-NDlicense (/licenses/by-nc-nd/4.0/).Keywords:Gut physiology High-fiber diets Nutrient utilization PigsSow welfare1. IntroductionConventional swine diets contain substantial amounts of cere-al grains (e.g., corn and wheat) and protein supplements such as soybean meal to provide pigs with the energy and nutrients they require. However, recent trends in the demand and supply of these conventional feedstuffs require swine producers around the world to seek low-cost alternatives such as cereal co-products from the bio f uel and milling industries to feed their pigs, in order to reduce feed costs [1]. The majority of these co-products have a high en-ergy and nutrient content but are fibrous in nature. When fibrous co-products are incorporated into pig diets, the carbohydrate com-position inevitably changes from a high-starch diet toward a diet containing less starch and more non-starch polysaccharides, which are the major component of dietary fiber.In general, diets that are rich in dietary fiber have a lower nutri-tive value for monogastric animals, including pigs, because these animals’ digestive enzymes are not suited to degrading non-starch polysaccharides [2]. The ingestion of high-fiber diets also has the potential to adversely affect energy and nutrient utilization and consequently result in lower pig performance [3–6]. Therefore, only a minimal level of fiber is typically included in diets fed to swine. However, dietary fiber has received a considerable amount of atten-tion in recent years because some fiber components have beneficial effects on pigs when fermented in the intestine [7,8], and can also affect satiety and animal behavior [9,10].This review discusses dietary fiber, its effects in pig nutrition, and the mechanisms involved in its utilization. Furthermore, the effects* Corresponding author.E-mail address: martin_nyachoti@umanitoba.ca/10.1016/J.ENG.2017.03.0102095-8099/© 2017 THE AUTHORS. Published by Elsevier LTD on behalf of the Chinese Academy of Engineering and Higher Education Press Limited Company.This is an open access article under the CC BY-NC-ND license (/licenses/by-nc-nd/4.0/).Contents lists available at ScienceDirectjo ur n al h om e pag e: w w /locate/engEngineering717 A.K. Agyekum, C.M. Nyachoti / Engineering 3 (2017) 716–725of dietary fiber on pig gut health and sow welfare are discussed. Finally, areas that require further research to expand our knowledge on fiber and some of the strategies used to improve fiber utilization in pigs are outlined.2. Dietary fiber2.1. Definition and classificationPlant carbohydrates can be classified as sugars, disaccharides, oligosaccharides, or polysaccharides (i.e., starch and non-starch polysaccharides). Sugars, oligosaccharides, and starch are found in the interior of the plant cell, whereas non-starch polysaccharides, together with lignin, are the main constituents of the plant cell walls, and are called dietary fiber. The term “dietary fiber” has sev-eral definitions; however, all these definitions have limitations be-cause plant cell wall components are variable and complex in their chemical and physical composition and in their metabolic effects. The initial definition of dietary fiber as “the sum of lignin and cell wall polysaccharides that are resistant to enzymatic hydrolysis in the digestive system of man” was coined by Trowell et al. [11] in re-lation to human medicine. However, this definition of dietary fiber is also applicable to other monogastric animals, such as pigs [12]. The Codex Alimentarius Commission [13] finalized the definition of dietary fiber as “carbohydrate polymers with 10 or more mono-meric units, which are not hydrolyzed by the endogenous enzymes in the small intestine of humans.” Dietary fiber also includes any polysaccharides that reach the hindgut, such as resistant starch and oligosaccharides, which constitute plant cell contents and include fructo-oligosaccharides. The main constituents of the plant cell wall polysaccharides are cellulose, hemicellulose, and pectin.Cellulose is a linear polymer of glucose units with β-(1→4) link-ages, whereas pectin consists mainly of glucuronic acid units joined in chains by α-(1→4) glycosidic linkages. The most abundant organic substrate on earth, cellulose forms the main structural component of plant cell walls. Hemicelluloses are a complex matrix of polysac-charides that include xylose, arabinose, galactose, mannose, glucu-ronic acid, and β-glucans. Lignin is a phenolic polymer that anchors the cell wall polysaccharides and is not digested or fermented by porcine intestinal enzymes or bacteria, respectively [2,7,8,14].Non-starch polysaccharides can be classified as insoluble or sol-uble based on their solubility in water or weak alkali [12]. Insoluble non-starch polysaccharides include cellulose and some hemicellulo-ses, and soluble non-starch polysaccharides include pectins, gums, and β-glucans. Soluble non-starch polysaccharides are more rapidly fermented in the gastrointestinal tract of the pig than insoluble non-starch polysaccharides [7,12]. For insoluble non-starch polysac-charides, little or no fermentation occurs in the upper gut; rather, fermentation remains low in the hindgut of pigs [15].Dietary fiber (or non-starch polysaccharide fractions) is currently classified based on physicochemical properties in order to provide more information on its metabolic and physiological activities. The physicochemical properties of dietary fiber that are relevant to pig nutrition include viscosity, hydration, and fermentability. Viscosi-ty describes the dissociation of non-starch polysaccharides in the gastrointestinal tract to form high molecular weight viscous aggre-gates. Soluble fibers such as β-glucans, gums, or pectins increase digesta viscosity when ingested by pigs. Fermentability describes the ability of non-starch polysaccharides to be fermented by the microflora harbored in the intestine. Soluble fiber is generally more fermentable than insoluble fiber. The hydration properties are swell-ing capacity, solubility, water-holding capacity, and water-binding capacity [16]. The water-holding capacity of a fiber affects its fer-mentability. Thus, when physicochemical parameters are incorpo-rated into pig feed formulation, they may provide nutritionists with a better control of the fermentation process that takes place in the pig’s gut and could assist nutritionists in predicting the energy con-tribution and prebiotic effect of a diet or feedstuff.2.2. Analytical methods for characterizing dietary fiberSeveral methods exist for characterizing the dietary fiber com-ponent of feeds and feedstuffs; the choice of an analytical method depends on the aims of the investigator [12,17,18]. Based on how the fibrous remnants are isolated and measured, dietary fiber analyti-cal methods are classified into three groups: chemical-gravimetric, enzymatic-gravimetric, and enzymatic-chemical methods. The numerous fiber analytical methods and the variability among these methods and among the obtained results make it rather difficult to compare information from different studies [19]. However, methods that categorize dietary fiber into soluble and insoluble components seem to provide the most accurate interpretation of study results. In what follows, the analytical methods most commonly used for measuring dietary fiber are briefly discussed.2.2.1. Crude fiber methodCrude fiber analysis is a chemical-gravimetric method that is part of the Weende proximate analysis used for feed ingredients [19]. It was introduced to differentiate between carbohydrate that is “avail-able” and carbohydrate that is “unavailable” for digestion. The aim of crude fiber analysis is to mimic the digestive actions of the gastric and pancreatic secretions by boiling a feed with dilute acid followed by a dilute alkali solution [19]. The crude fiber analytical method is very robust and reproducible within and among laboratories; how-ever, there is incomplete recovery of cellulose, hemicellulose, and lignin. Therefore, crude fiber is not considered to be an acceptable definition for dietary fiber and is not suitable for characterizing the fiber component in pig feed. However, many regulatory agencies use crude fiber for quality control purposes and for regulating the mini-mum fiber content allowed in a feed.2.2.2. The detergent (Van Soest) methodsThe detergent methods, which are chemical-gravimetric proce-dures, were developed by Van Soest in the 1960s. These methods employ detergents to progressively extract neutral detergent fiber (NDF), acid detergent fiber (ADF), and acid detergent lignin (ADL) [18,19]. The NDF procedure recovers the insoluble components of di-etary fiber (i.e., cellulose, hemicellulose, and lignin) after digesting a feed or ingredient in a solution at a neutral pH. Thus, the nutritional advantages of the NDF procedure are that it is able to approximate the insoluble dietary fiber fraction of a feedstuff and that its results are reproducible [19]. The ADF procedure recovers mainly cellulose and lignin by digesting a diet or feedstuff in a solution at an acidic pH [18], whereas the ADL recovers lignin using sulfuric acid. A more accurate estimate of hemicellulose and cellulose is obtained when the NDF, ADF, and ADL are determined sequentially using the same sample [18].The detergent procedures, although an improvement over the crude fiber method, do not recover soluble dietary fiber (e.g., pec-tins, gum, and β-glucans) [19]. Therefore, these procedures can underestimate the total dietary fiber, especially for starchy feeds or ingredient samples, although probably not for cereal co-products, which have a high insoluble fiber concentration.2.2.3. Total dietary fiber methodThe total dietary fiber method was introduced to overcome some of the pitfalls of the detergent procedure. The total dietary fiber method is important for feedstocks intended for monogastric ani-mals, including pigs, with hindgut fermentation. This procedure em-ploys enzymes to simulate the processes that take place within the718 A.K. Agyekum, C.M. Nyachoti / Engineering 3 (2017) 716–725weight [4]. Increasing the inclusion rate of distillers dried grains with solubles from 0 to 20% in nursery pig diets [24] and from 0 to 30% in growing pig diets [5] linearly decreased pig body weight, al-though the diets were formulated to contain similar net energy and standard ileal digestibility amino acids. Results from some studies [25,26] suggest that the decline in pig growth rate that occurs when high-fiber diets are fed is generally limited to the growing period rather than the finishing period. Conversely, in some studies [27–29], high-fiber diets had no adverse effects on pig performance in the growing or finishing phases, compared with the control.The abovementioned studies reported on various types of feeds that were termed “high-fiber” diets, which contained varying amounts of ingredients (i.e., purified and natural fiber sources). This may partly explain the varying responses to high-fiber diets in terms of pig growth, because different inclusion rates of high-fiber ingredients and fiber types will elicit different responses. Further-more, the specific fiber components and analytical methods used to measure fiber differed in those studies. Thus, crude fiber, NDF, total dietary fiber, and non-starch polysaccharides cannot be used inter-changeably as equal measures of dietary fiber when assessing the effects of high fiber ingestion on pig performance.Diets that are bulky due to the addition of fibrous feedstuffs have been reported to depress feed intake in pigs due to gut fill [4,30,31]. In gestating sows, early satiety due to the intake of high-fiber diets prevents certain stereotypies and thus is paramount to sow welfare [10], whereas in growing pigs, reduced feed intake is detrimental to performance. However, in growing-finishing pigs, feed intake does not always decrease when the pigs are fed high-fiber diets. For ex-ample, feed intake did not decrease in growing-finishing pigs that were offered diets containing up to 30% cereal grain co-products from the ethanol industry in several experiments [5,6,32–34]. In pigs raised in a thermo-neutral environment, feed intake is typically influenced by the diets’ energy content rather than by the bulki-ness of the diet [35]. The addition of fibrous feedstuffs to pig diets dilutes the dietary energy content. Therefore, a decrease in dietary energy content is typically associated with increased feed intake to compensate for the energy required to support the maintenance and growth of pigs. Nonetheless, a period of adaptation to a fibrous diet is required before growing pigs are able to consume enough of a high-fiber diet to compensate for the dietary energy dilution [35].3.2. Effects of fiber on nutrient digestibilityPre-cecal and total tract nutrient digestibilities in pigs have been reported to be negatively affected by high-fiber diets. Several mech-anisms have been put forward to explain the negative impact of high-fiber diets on nutrient digestion. In this context, soluble fiber has been reported to increase digesta viscosity and thereby slow down the diffusion of the substrate and enzymes in the porcine small intestine, which hampers nutrient digestion and absorption [3]. Indeed, it has been reported that soluble fiber from diets based on purified guar gum, sugar beet pulp, oats, wheat, and barley in-creased digesta viscosity, leading to a reduction in nutrient digestion [4,12,36]. On the other hand, insoluble fiber reduces digesta passage rate, thereby allowing less mixing time for digestive enzymes and dietary components [3]. For example, insoluble fiber from wheat bran, corn bran, and cellulose reduced digesta transit time in several studies, leading to decreased nutrient digestibility [4,10,37,38]. How-ever, the fiber in distillers dried grains with solubles (predominately insoluble) had no effect on digesta transit time in the experiment by Urriola and Stein [39]. This suggests that the effect of insoluble fiber on digesta transit time may vary among studies, and probably depends on the presence of interfering factors that are likely to exist in fiber from natural feedstuffs. Nonetheless, insoluble non-starch polysaccharides have been reported to decrease digesta transit timedigestive tract [19], and may separate dietary fiber into soluble and insoluble fiber. The carbohydrates included in the definition of total dietary fiber include celluloses, hemicelluloses, oligosaccharides, lignin, pectins, and gums. Thus, total dietary fiber differs from non-starch polysaccharides because lignin is included in the definition. The total dietary fiber method recovers more of the fibrous compo-nents than the NDF method, although it does not recover oligosac-charides that are soluble in aqueous ethanol.There are two major methods to this procedure: enzymatic-gravi-metric and enzymatic-chemical methods. The enzymatic-gravimetric methods are used to measure both insoluble and soluble fractions of dietary fiber; the AOAC Official Method 985.29 is the final version of these methods [20]. This procedure includes treatment of the sample with enzymes to remove starch and protein, precipitation of soluble fiber with aqueous ethanol, isolation and weighing of the residue and, finally, correction for protein and ash in the resi-due [19,21]. The enzymatic-chemical methods also use enzymes to remove starch, followed by precipitation of the soluble non-starch polysaccharides with aqueous ethanol. Thereafter, the neutral sugars are quantified by gas-liquid chromatography or high-performance liquid chromatography, and uronic acid is quantified by colorimetry [19].The Uppsala and Englyst methods are the two most common enzymatic-chemical methods available. The Uppsala method quan-tifies the non-starch polysaccharides portion as the sum of amylase- resistant polysaccharides, uronic acid, and lignin, whereas the Eng-lyst method does not include lignin and resistant starch in the final value [22]. Although the total dietary fiber methods are an improve-ment over the detergent procedures, they are still time-consuming, laborious, and relatively expensive.3. Dietary fiber in pig nutritionStarch and non-starch polysaccharides differ not only in chem-ical structure but also in the type of nutrients they supply. Starch digestion in the upper gut results in glucose, whereas non-starch polysaccharide degradation in the lower gut results in volatile fatty acids [16,23]. In addition, pigs do not secrete the digestive enzymes required to break down non-starch polysaccharides, whereas they do secrete the enzymes required to hydrolyze starch. Furthermore, starch and non-starch polysaccharides differ in terms of their effects on other nutrients in the digestion process and on the performance of pigs [16,23]. Several authors have reviewed aspects of high-fiber diets in pig nutrition. Taken together, the available information sug-gests that dietary fiber has both positive and negative effects on the pig.Most of the information on dietary fiber in pig nutrition has been generated using purified fiber sources such as pectin, cellulose, and guar gum, along with partially identified fiber from sources such as wheat bran [12], as opposed to information generated using natural fibrous feedstuffs such as distillers dried grain with solubles. Natu-ral fibrous feedstuffs are usually composed of more than one fiber type; that is, they are composed of both soluble and insoluble fiber. Therefore, the effect of natural fibrous feedstuffs on the digestive physiology of pigs may not necessarily be similar to that of purified fiber. In the following sections, fiber effects on growing pigs are dis-cussed in the context of fiber that has been obtained from purified and natural sources.3.1. Effects of fiber on pig growth performanceThe effect of high-fiber ingestion has generally been to reduce pig growth rate. However, the reports obtained have often been con-tradictory. For example, feeding growing pigs diets containing either 7% guar gum or 7% cellulose reduced growth rate and final body719 A.K. Agyekum, C.M. Nyachoti / Engineering 3 (2017) 716–725in the hindgut, whereas digesta transit time in the small intestine is unaffected or reduced [3,37].Diets that are rich in non-starch polysaccharides encapsulate nu-trients and thereby hamper their accessibility to digestive enzymes for hydrolysis [3]. Ingestion of fibrous diets has been reported to reduce nutrient digestibility in pigs through increased endogenous intestinal nutrient losses [3,7,17,40,41]. In addition, ingestion of fi-brous diets leads to increased thickness of the unstirred water layer adjacent to the intestinal mucosa, which can impair nutrient diges-tion and absorption [42].3.2.1. Fiber effect on starch digestionAlthough endogenous carbohydrate-degrading enzyme activities may be reduced by fiber ingestion [43], several studies [36,44,45] have reported that starch digestibility in pigs is not affected by dietary fiber content, and that dietary starch is almost completely digested at the end of the small intestine. The lack of a fiber effect on starch digestibility is suggested to be due to the relatively long length of the small intestine, which ensures that starch is digest-ed efficiently before the end of the ileum [36]. However, Wenk [3] suggested that a fiber-rich diet may reduce digesta transit time and allow a greater amount of undigested starch to pass through the ile-um. Indeed, Gao et al. [46] and Agyekum et al. [47] recently observed that the addition of 5% inulin or 30% distillers dried grains with solubles to a corn-soybean meal-based diet fed to growing-finishing pigs reduced ileal starch digestibility, probably due to increased ileal starch flow. Nonetheless, although overall starch digestibility may not be affected by dietary fiber, the rate of starch digestion and ab-sorption decreases due to fiber ingestion [48,49].The decrease in the rate of starch digestion has been attributed to the luminal viscosity and nutrient-encapsulating effect of intact cell wall polysaccharides [48]. Soluble fiber appears to have a great-er impact on starch digestion and absorption than insoluble fiber [49,50]. The reduction in starch absorption that occurs when pigs are fed fiber-rich diets may also be due to the decreased dietary starch load, in comparison with low-fiber diets, which are typically rich in starch.3.2.2. Fiber effect on protein digestionThe literature contains a plethora of information on the effect of fiber on protein digestion in pigs. In general terms, ingestion of a fibrous diet reduces both ileal and total tract protein digestibility. The reduction in ileal protein and amino acid digestibility due to fiber ingestion has been reported to be associated with increased endogenous and exogenous nitrogen and amino acid losses, where-as increased microflora (bacterial protein) excretion in the feces is primarily responsible for the reduction in total tract protein digesti-bility observed in pigs [3,17,51].Endogenous ileal nitrogen and amino acid losses refer to the ni-trogen or amino acids that are present in endogenously synthesized proteins and that have not been digested and reabsorbed before reaching the end of the ileum [17,51]. These losses can be classified into basal loss, which is the minimum quantity of nitrogen and ami-no acids that is inevitably lost in all diets, and specific losses, which are influenced by dietary ingredient composition [51].Concerning diet-specific ileal endogenous nitrogen and amino acid losses, several studies have reported that ingestion of fibrous diets increases the secretion of digestive enzymes and juices to ac-commodate dietary fiber in the digestive tract. For example, Langlois et al. [52] reported that a diet containing 40% wheat bran increased pancreatic juice and enzyme secretion in growing pigs. Increases in bile juice, mucin, and sloughed epithelial cells have also been reported to be due to fiber ingestion in pigs [17,41,53]. Digestive juices, mucin, and sloughed epithelial cells are rich in nitrogen and amino acids. Therefore, when fiber ingestion causes an increase in their production and a decrease in their reabsorption before the end of the ileum, the result is decreased ileal nitrogen and amino acid digestibility. Dietary fiber can also adsorb amino acid and peptides, thereby withholding them from digestion in the small intestine [17] and leading to decreased ileal nitrogen and amino acid digestibility.3.2.3. Fiber effect on lipid digestionThe effect of fiber on lipid digestibility has been investigated extensively in pigs. Shi and Noblet [54] reported that ingestion of high-fiber diets decreased lipid digestibility in pigs. Similarly, feed-ing growing pigs cereal-based diets containing 20% or 40% wheat bran decreased lipid digestibility [37]. Dietary fiber depresses lipid digestibility through several mechanisms. For example, dietary fiber can increase digesta passage rate and thereby limit the time required by digestive enzymes to digest dietary lipids [55,56]. Alter-natively, dietary fiber can bind with bile salts in the duodenum and render bile salts unavailable for the emulsification of dietary lipids. This in turn requires the synthesis of additional bile salts from blood cholesterol and thereby lowers blood cholesterol [55,56].Reduction in lipid digestibility has been reported to be depend-ent on the type of fiber. Soluble fiber increases digesta viscosity and thereby prevents substrate-enzyme interaction and decreases lipid digestion, whereas insoluble fiber reduces digesta transit time in the digestive tract and thus increases lipid excretion in the feces [57]. However, not all studies have reported a negative effect of fiber-rich diets on lipid digestion. For example, the addition of wheat bran, corn bran, soybean hulls, and sugar beet pulp to increase the fiber content of diets fed to pigs did not affect lipid digestibility relative to the control diet [38]. Kil et al. [58] also observed that the dietary inclusion of purified NDF (from Solka-Floc) did not affect lipid di-gestibility relative to the control. Conversely, Högberg and Lindberg [45] reported that feeding growing pigs diets that contained the brans from oats, wheat, and rye increased lipid digestibility. Simi-larly, Gao et al. [46] reported that the addition of 5% inulin or 5% so-dium carboxymethylcellulose (CMC) increased lipid digestibility in growing pigs. Agyekum et al. [47] also reported that adding 30% dis-tillers dried grains with solubles to a growing pig diet had no effect on ileal lipid digestibility, whereas fecal lipid digestibility tended to increase. Fat or oil is typically added to fibrous diets to compensate for the energy-dilution effect of fiber. However, it has been shown that lipid digestibility increases when dietary lipid content increases [58]. Therefore, the above-mentioned studies showing that lipid di-gestibility increased irrespective of fiber content may be due to the increased dietary lipid content that was intended to compensate for the low energy content. Nonetheless, increasing dietary lipid con-tent has also been reported to depress fiber digestibility [57]. Addi-tional studies are warranted to establish the role of fiber (i.e., form and type) in lipid digestibility.Depression in lipid digestibility has been reported to be more pronounced at the fecal level than at the end of the ileum [57]. Therefore, the values for hindgut lipid fermentation (calculated as total tract digestibility – ileal digestibility) are usually negative, indicating that dietary fiber intake may increase endogenous lipid synthesis by microflora in the hindgut of pigs. However, not all of the studies mentioned above reported a net lipid synthesis in the hindgut of pigs due to fiber ingestion. Thus, fiber ingestion did not result in net lipid synthesis in the studies by Kil et al. [58] and Gao et al. [46], whereas increased fiber intake did result in net lipid synthe-sis in the studies by Shi and Noblet [54], Högberg and Lindberg [45], and Agyekum et al. [47]. Kil et al. [58] and Gao et al. [46] used puri-fied dietary fiber sources (i.e., CMC, inulin, and Solka-Floc), whereas Shi and Noblet [54], Högberg and Lindberg [45], and Agyekum et al.[47] used fiber from natural sources (i.e., cereal co-products) in their studies. Therefore, a possible reason for the discrepancy may be the fiber source used in the various studies.。

日粮纤维在母猪生产中的应用作者：杨淑芬，郭球松，方热军来源：《湖南饲料》 2016年第6期杨淑芬郭球松方热军（1．湖南农业大学动物科技学院，长沙410128；2．湖南畜禽安全生产协同创新中心，长沙410128）摘要：本文就日粮纤维在母猪生产中的应用进行综述。

关键词：日粮纤维；母猪；生产；应用目前我国母猪年产仔数在很大程度上落后于国外。

影响母猪产仔数的因素诸多，纤维含量是其中的营养因素之一。

日粮纤维独特的理化性质及其与营养学功能紧密联系，能有效控制母猪体况，减收刻板行为等等。

本文旨在阐述日粮纤维的简介、日粮纤维的理化性质及其在母猪中的应用及存在的问题。

1 日粮纤维的简介日粮纤维(Dietary fiber，简称DF)是指所有的植物性多糖和木质素，并且能够抑制人分泌的消化液分解，这个定义同时适用于非反刍动物．也包括猪。

其包括果胶、纤维素、阿拉伯木聚糖、果聚糖、低聚糖等。

根据其溶解度主要分为可溶性日粮纤维(Soluble diet fiber，SDF)和不溶性日粮纤维(Insoluble diet fiber，IDF)。

可溶性日粮纤维是指除去淀粉、脂肪、蛋白质后溶于水而不溶于80%的乙醇的多糖成分，主要有阿拉伯木聚糖、果胶类物质等。

不溶性日粮纤维是指不溶于水的纤维．主要包括纤维素、半纤维素、木质素等。

2 日粮纤维的理化性状日粮纤维的理化性质主要包括吸附作用和阳离子交换能力、溶解性、黏性、持水性以及发酵性等。

2.1吸附作用日粮纤维分子表面含有能吸附螯合胆固醇、胆汁酸、以及肠道内毒素以及外毒素等有机物的活性基团。

吸附作用与pH、渗透压、日粮纤维的组成等有关。

2.2阳离子交换能力日粮纤维含有多种侧链基团，比如羧基、羟基和氨基，因此DF具有弱酸性，可以阳离子进行可逆的交换，进而在一定程度上影响矿物质的吸收。

2.3可发酵性DF在动物中可以通过诸多微生物（产琥珀酸丝状杆菌、生黄瘤胃球菌、白色瘤胃球菌、溶纤维丁酸弧菌、栖瘤胃普雷沃菌）发酵降解为可吸收的挥发性脂肪酸供机体重新利用。

试验研究ＬＩＶＥＳＴＯＣＫＡＮＤＰＯＵＬＴＲＹＩＮＤＵＳＴＲＹＮｏ．９，２０１９日粮纤维对妊娠母猪行为和繁殖性能的影响吴志娟，焦福林，李文刚，闫益波，隋　超，任毅菲（山西省农业科学院畜牧兽医研究所，山西太原０３００３２）摘　要：妊娠母猪在妊娠前期通常限饲以避免母猪体况过肥，但限饲使母猪的采食需求被抑制，容易产生刻板行为，为提高限饲母猪的福利，研究人员多采用增加日粮纤维含量的方法提高母猪的饱腹感，减少刻板行为发生。

在妊娠母猪饲粮中适量添加粗纤维可控制妊娠母猪体况，使其繁殖性能提高。

针对日粮纤维对妊娠母猪刻板行为和母猪繁殖性能的影响展开论述。

关键词：纤维；妊娠母猪；繁殖性能；行为ＤＯＩ：１０．１９５６７／ｊ．ｃｎｋｉ．１００８－０４１４．２０１９．０９．００３基金项目：山西省科技攻关项目［２０１５０３１１０１８－２］　引言在规模化养猪生产中，母猪是猪场的核心群体，相对稳定健康的猪群和母猪良好的繁殖性能，是猪场生产和发展的基础，关系到养猪场的养殖效益，母猪妊娠期的饲养管理尤为重要。

妊娠期母猪健康状况直接影响仔猪的生长及母猪的使用年限的长短，饲料、品种、营养和环境等因素，关系到妊娠母猪繁殖性能的高低，其中饲料因素更为关键。

母猪怀孕后，妊娠代谢加强，加上胎儿前期发育较慢，母猪体况不能太肥，否则分娩和泌乳会受影响，因此其日粮的营养水平在满足胎儿生长发育需要的基础上，母猪适当增重即可。

特别是在妊娠前期，母猪通常采取限饲的模式，采食量一般为其自身采食量的５０％～６０％，限饲提供的饲料量不能满足母猪的采食需求，从而导致母猪发生咬栏、舔地、空嚼等这些刻板行为，损害胎儿的发育，降低仔猪初生重和成活率，导致母猪的繁殖性能下降。

粗纤维饲料比重小，体积大，在胃肠中占据较大空间，在妊娠期给母猪喂含粗纤维较高的饲料，可降低母猪饥饿感，扩大胃肠容积，可刺激母猪消化道蠕动能力增强显著提高泌乳期的采食量和泌乳量，减少母猪泌乳期失重。

日粮纤维对生猪养殖及妊娠母猪的影响-种植技术随着人们对日粮纤维认识的深入,近年来有关妊娠母猪利用日粮纤维的研究已引起人们的极大学习。

下面就一起来具体来了解一下：日粮纤维对生猪养殖及妊娠母猪的影响。

1、日粮纤维的种类日粮纤维是结构性多糖、非结构性多糖、木质素，以及一部分细胞壁镶嵌蛋白质和矿物质等组成的不均一混合物，是非淀粉多糖(NSP)和木质素的总和。

NSP中的B一葡聚糖、阿拉伯木聚糖、果胶、甘露聚糖等以氢键松散地与纤维素、木质素及蛋白结合，溶于水，称水溶性非淀粉多糖或可溶性纤维，大多数NSP均为水溶性的淀粉多糖。

以酯键、酚键、阿魏酸、钙离子桥等共价键或离子键牢固的和其他成分结合称为不溶性非淀粉多糖，主要为纤维素。

碳水化合物中只有淀粉、二糖、戊糖和低聚糖可以被猪自身分泌的内源酶降解，NSP可以在猪的大肠被肠道微生物分解，而木质素在猪肠道内不可降解。

抗性淀粉和可溶性纤维( SF)可以被猪肠道微生物迅速分解，而不溶性纤维(IF)分解较慢。

2、猪利用日粮纤维的生理机制猪利用日粮纤维的生理基础是猪在长期生长发育进程中，为适应生存环境，形成了发达的大肠，尤其是结肠部分，并具有完整的微生物区系，包含所有的优势反刍纤维素分解菌。

猪的胃、小肠与其他单胃动物相似，主要是具有消化和吸收功能，但猪的大肠发达，具有类似瘤胃发酵罐的功能，这是猪的消化道结构的特点，也是优点。

猪大肠包含需氧微生物、厌氧微生物和兼氧微生物，其中专性厌氧微生物占优势。

其微生物区系包括高活性的反刍纤维分解菌属和半纤维素分解菌属，其中包括琥珀酸生成纤维菌、白瘤胃球菌、生黄瘤胃球菌、丁酸弧菌属及反刍类菌体，其中琥珀酸生成纤维菌和生黄瘤胃球菌属，在生长猪的大肠内也占优势地位。

猪的大肠内含有一种新型高活性的纤维分解菌属，即草食梭状芽胞杆菌，其降解细胞的能力相当或高于反刍纤维素分解菌。

初生猪的盲肠和结肠并无微生物存在，但随着开始采食植物性饲料，逐渐建立起微生物区系。

99PIGS TODAYMay 2021实践Practice饲料营养文 ⊙ 王晓佳 抚顺市农业特产学校广义上讲，膳食纤维是细胞壁化合物，不易被肠道酶水解的部分，例如纤维素、半纤维素、β-葡聚糖(βG)、果胶、树胶等。

非淀粉多糖、低聚糖和抗性淀粉也不被内源性酶水解，并可用作为肠中微生物发酵的基质，因此也属于可溶性膳食纤维。

本文从日粮中添加膳食纤维对母猪行为、繁殖性能、内分泌功能的影响等综述了膳食纤维的作用，为生产实践提供理论基础。

日粮中添加膳食纤维在母猪生产中的作用各种来源的膳食纤维是猪饲料的常见组成部分。

人们很早就认识到高纤维食物在产生饱腹感方面的价值。

饲粮中添加高纤维可以降低猪的采食量，这在生长猪或母猪哺乳期这类生产周期营养需求较高的阶段显然是有害的。

但最近研究表明添加膳食纤维可以改变肠道微生物群，从而减少对抗生素的需求，通过添加某些类型纤维还可以减少氮在环境中的残留，从而降低养猪生产的环境成本。

由此可见，膳食纤维可以增加养猪生产效益。

除此之外，膳食纤维浓缩物还具有特殊潜在价值能够作为“功能性”饲料添加剂，用以改善仔猪生长和福利，而提高母猪的繁殖效率则是应用高纤维饲料的最大优点。

1 日粮添加膳食纤维对母猪行为的影响膳食纤维作为饲料成分具有独特的理化特性，例如高膨胀性（SC）、粘度和水结合能力（WBC），对母猪行为和泌乳性能有长期影响，可减少母猪攻击性和相互斗殴。

攻击性的相互作用及其后果是导致仔猪福利不良的最重要原因。

在一些物种中，攻击行为可以被产前和分娩环境调节。

妊娠母猪经常受到食物限制，这可能会损害它们的福利。

高纤维饮食可以减轻饥饿感，可提高妊娠母猪福利和生产率，减少攻击性。

Huang S在不提供多余能量的情况下，在妊娠期母猪饲粮中添加膳食纤维是提高限制饲喂的母猪饱腹感和减少异常行为的一种方法。

研究表明妊娠期饲粮中添加5%膨胀性较大的抗性淀粉有利于提高母猪餐后饱腹感，缓解应激状态，减少异常行为，从而降低母猪死胎率。

日粮在养猪中的应用长期以来，我国养殖业面临着蛋白饲料资源紧缺、氮排放污染严重等问题。

豆粕是大豆提取豆油后产生的一种蛋白质含量较高的副产品。

作为主要植物蛋白饲料原料，豆粕的供应量和价格与大豆产量密切相关。

国际粮农组织数据显示，2020年我国大豆的产量为1960 万t，仅占世界产量的5.54％；进口大豆10032.71 万t，为大豆产量的5.11倍，占农产品进口的48.27％[1]；巴西和美国为我国的主要进口国，2020年1—7月农产品进口量分别占进口总量的36.99％、13.11％[2]。

随着中美贸易战的持续发展，我国加大了向其他国家进口大豆等蛋白饲料，同时加强了对低蛋白日粮技术的研究，以期减少对豆粕的需求，缓解美国大豆进口量降低带来的资源压力。

低蛋白日粮是指将日粮粗蛋白(CP)水平按猪营养需要(NRC)推荐标准降低2~4个百分点，然后通过适当添加赖氨酸(Lys)、蛋氨酸(Met)、苏氨酸(Thr)等必需氨基酸，使日粮中的各种氨基酸含量和比例与动物必需氨基酸的需求相吻合，达到理想氨基酸平衡，从而提高蛋白质利用率，降低排泄物中氮排放[3]。

我国农业农村部也大力倡导养殖业低氮减排绿色发展，研究饲料中豆粕减量替代方案，加强推广应用低蛋白日粮相关技术。

2020年，在我国农业农村部组织研究低蛋白日粮技术的基础上，全国饲料工业标准化技术委员会修订发布了《仔猪、生长育肥猪配合饲料》(GB/T5915-2020)[4]，其中育肥猪全程饲料平均CP水平最低为12.6％、最高为_应用提供参考。

1低蛋白日粮在养猪生产中的应用1.1 低蛋白日粮对母猪生产性能的影响母猪在不同生理阶段对CP和氨基酸需求有所不同，适当降低日粮CP水平能提高母猪采食量，从而影响其生产性能[6]。

对于妊娠母猪，其氨基酸需要量与胎儿、乳腺组织、胎盘(包括与之相关的绒毛尿囊液、子宫)、体蛋白沉积及能量摄入量密切相关(NRC2012)。

在妊娠中后期，饲喂含15％CP 日粮的母猪每天至少消耗20g 可消化赖氨酸(SIDLys)，而饲喂12％CP 日粮的母猪则消耗18.4g/d[7]。