The production of short chain fatty acid and colonic development in weaning piglets

Weaning process widely affects the small intestinal structure and function in piglets, while the responses of large intestine to weaning stress are still obscure. The purpose of this study was to determine the developmental changes (i.e., short chain fatty acids (SCFAs) concentrations, growth parameters, crypt‐related indices and antioxidant capacity) in colon of piglet during weaning. Forty piglets were weaned at day 21 and euthanized to collect colonic tissues and digesta samples on day 0, 1, 3, 7 and 14 post‐weaning (n = 8). Piglet growth performance was improved (p < .001) on day 7 and 14 post‐weaning. The concentrations of acetate, propionate, butyrate, valerate, isobutyrate, isovalerate and total SCFAs were higher (p < .001) during the late post‐weaning period. The mRNA abundances of SCFAs transporters were greater (p < .001) on day 7 and 14. The absolute and relative weights, absolute length and perimeter of colon were greater (p < .001) on day 7 and 14. Similarly, post‐weaning increases (p < .001) in colonic crypt depth and Ki67 positive cells numbers per crypt were observed during the same period. Colonic crypt fission indices decreased (p < .01), while total crypt numbers increased (p < .001) on day 14 after weaning. Moreover, total SCFAs concentration was significantly associated with colonic growth parameters and Ki67 cells/crypt (p < .001). In addition, catalase content was decreased on day 3, 7, and 14, whereas, the concentrations of total superoxide dismutase (T‐SOD) and manganese‐containing superoxide dismutase (MnSOD) were higher (p < .05) on day 1 and 3 post‐weaning. These results showed that weaning process has a significant effect on colonic growth and development, which might be associated with the change of SCFAs concentrations in colon.     

Fermentation characteristics of resistant starch,arabinoxylan, and β-glucan and their effects on the gut microbial ecology of pigs: A review

Dietary fibers (DF) contain an abundant amount of energy, although the mammalian genome does not encode most of the enzymes required to degrade them. However, a mutual dependence is developed between the host and symbiotic microbes, which has the potential to extract the energy present in these DF. Dietary fibers escape digestion in the foregut and are fermented in the hindgut, producing short-chain fatty acids (SCFA) that alter the microbial ecology in the gastrointestinal tract (GIT) of pigs. Most of the carbohydrates are fermented in the proximal part, allowing protein fermentation in the distal part, resulting in colonic diseases. The structures of resistant starch (RS), arabinoxylan (AX), and β-glucan (βG) are complex; hence, makes their way into the hindgut where these are fermented and provide energy substrates for the colonic epithelial cells. Different microbes have different preferences of binding to different substrates. The RS, AX and βG act as a unique substrate for the microbes and modify the relative composition of the gut microbial community. The granule dimension and surface area of each substrate are different, which influences the penetration capacity of microbes. Arabinose and xylan are 2 different hemicelluloses, but arabinose is substituted on the xylan backbone and occurs in the form of AX. Fermentation of xylan produces butyrate primarily in the small intestine, whereas arabinose produces butyrate in the large intestine. Types of RS and forms of βG also exert beneficial effects by producing different metabolites and modulating the intestinal microbiota. Therefore, it is important to have information of different types of RS, AX and βG and their roles in microbial modulation to get the optimum benefits of fiber fermentation in the gut. This review provides relevant information on the similarities and differences that exist in the way RS, AX, and βG are fermented, and their positive and negative effects on SCFA production and gut microbial ecology of pigs. These insights will help nutritionists to develop dietary strategies that can modulate specific SCFA production and promote beneficial microbiota in the GIT of swine.     

The absorption of lactic acid is more synchronized with the absorption of glucose than with the absorption of short-chain fatty acids — A study with sows fed diets varying in dietary fibre

Sows were fed one of three diets varying in level and type of dietary fibre (DF). A low DF diet (LF; 17% DF) based on wheat and barley and two generic high DF diets (HF1, high in soluble DF and HF2, high in insoluble DF;  41% DF) where the cereals were substituted with co-products (sugar beet pulp, potato pulp, pectin residue, pea hull, brewer's spent grain and seed residue (ray grass)) from the vegetable food and agro industries. Six sows were fitted with a catheter in the portal vein and the mesenteric artery and a flow probe around the portal vein. The sows were fed 2 kg/d of the three experimental diets in a repeated 3 × 3 crossover design. Blood samples were collected the last day in each period at − 120, − 60, 0, 15, 30, 45, 60, 90, 120 and then at 60-min intervals up to 600 min after feeding. Although lactic acid (LA) is formed by microbial fermentation, the absorption profile of LA was more comparable with the absorption profile of glucose than with that of other SCFA.     

断奶对仔猪肠道屏障的影响及营养调控

在集约化养殖中,3~4周龄早期断奶是仔猪生命周期中一个非常紧张的时期,此时仔猪胃肠道还未发育成熟。肠道屏障由上皮、免疫和肠神经系统组成,这些系统控制上皮屏障的完整性以及肠道功能,包括肠腔营养物质、水和电解质的运输。早期断奶导致肠道通透性增加,出现胃肠功能紊乱的情况,可能对猪只一生产生长期的影响。因此,仔猪断奶饲粮需要正确水平的营养素、营养源和高质量的添加剂,鼓励仔猪快速进食,减轻或消除断奶应激综合症,降低死亡率和发病率。养猪就是养肠道,合理使用功能性氨基酸、植物化学物质和有机酸等添加剂,能够修复由于断奶应激综合症导致的肠道屏障功能障碍。     

Effect of rearing environment and age on gut development of piglets at weaning

Outdoor reared pigs are reported to be larger at weaning than indoor reared pigs and respond better to the weaning process. This may be due to enhanced gut development associated with increased size. Eighty sows were allocated to either indoor or outdoor farrowing on the basis of size, parity and past performance. Resulting litters were weaned at either 4 or 6 weeks of age. On days 26 and 40 of age, 40 (10/treatment) and 20 piglets (10/treatment still unweaned) were killed to measure intestinal morphology. Data were analysed as a 2 × 2 factorial using the GLM procedures of Minitab 12.2. Pigs reared outdoors were larger than those reared indoors at both weaning ages, pigs weaned at 6 weeks were heavier than those weaned at 4 weeks, 8.4 versus 7.4 kg at 4 weeks and 12.9 versus 10.5 kg at 6 weeks respectively (± 0.25, P ≤ 0.001). There were no differences in small intestine size relative to body weight due to rearing environment and no differences in gut morphology. When corrected for body weight, 6 week pigs had heavier small intestines than 4 week pigs, 0.39 (± 0.010) versus 0.34 (± 0.007) g/cm length, respectively (P ≤ 0.001). Six week unweaned pigs had similar villus heights to 4 week unweaned pigs but wider villi (P < 0.05) and deeper crypts, for example, at the 25% site crypt depths were 236 and 193 μm (± 7.7/5.5) respectively (P < 0.001). Hence increased piglet size due to outdoor rearing did not advance gut maturation whereas increased piglet size due to age did influence maturation of gut structure.     

Resistant starch for weaning pigs — Effect on concentration of short chain fatty acids in digesta and intestinal morphology

We investigated the effect of potato starch, a source of resistant starch (RS), in diets for newly weaned pigs on production of short chain fatty acids (SCFA) and intestinal morphology. At weaning, at 4 weeks of age, 24 pigs were divided into 3 groups and fed diets containing 0 (C), 80 (P80) or 160 (P160) g raw potato starch per kg feed for 12 days. Pigs fed P160 had the longest villi whereas pigs fed P80 had the deepest crypts. Villous height at the mid-small intestine and average daily gain were positively correlated (r = 0.59, P < 0.01). The daily gain tended to be lower (P = 0.08) for pigs fed P80 than for pigs fed C or P160. The colon weight increased in pigs fed RS which coincided with an increased crypt depth in the colon. The concentration of SCFA increased in the large intestine with increasing amount of RS. The proportion of acetic acid decreased and the proportion of butyric acid increased in pigs fed P80 and P160. The increased SCFA production, especially of butyrate, may explain the colonic growth.     

Effect of cooking and fermentation of a pig diet on gut environment and digestibility in growing pigs

The effect of pre-feeding treatment of a pig diet on gut environment and digestibility was studied in a double 3 × 3 Latin-square experiment using growing castrated PVTC cannulated male pigs. The diets were based on local feed resources and were fed raw (R), cooked (C) or naturally fermented (F). There were no differences (P > 0.05) in pH and butyric acid concentration of ileal digesta between diets. However, on diet F concentrations of acetic, lactic and propionic acid in ileal digesta were higher (P < 0.05) than on diets R and C. The relative proportions of individual organic acids in ileal digesta were not a reflection of the fermentation profile found in diet F. The ileal apparent digestibility of crude protein, crude fiber and NDF were higher (P < 0.05) on diet F than on diets R and C. The total tract apparent digestibility of crude protein was higher (P < 0.05) on diet F diet than on diets R and C, while there were no differences in total tract apparent digestibility between diets for any other dietary component. In conclusion, when compared with a pig diet in the raw form, fermentation influenced the gut environment and improved the digestibility of some dietary component, while cooking prior to feeding had no measurable effects.     

Body composition and muscle glycogen contents of piglets of sows fed diets differing in fatty acids profile and contents

To study the influence of sow dietary fat on piglet body characteristics, multiparous sows were allocated to one of four different dietary treatments: a conventional low fat (3%) diet (LF) and three high fat (6%) diets; high fat saturated (HFS), high fat oats (HFO), and high fat linseed (HFL). All sows were fed the allocated diet from weaning of the preceding litter until the day after farrowing. At farrowing, one liveborn piglet per litter (NB), was sacrificed and dissected immediately after birth. The heaviest (H) and the lightest (L) piglets in the litter were killed and dissected in the same manner at one day of age. Measurement of body length and circumference, organ weight, body chemical composition and muscle glycogen content were determined. Body measurements were adjusted to the mean body weight (1.67 kg). Dietary treatment did not have any significant influence on body components or carcass traits except for lung weight, being lower in HFO and HFL than in LF piglets. Piglet category affected almost all parameters considered, showing the lowest values for NB piglets, except for lung and circumference that were higher in NB than in L and H piglets; and length which was lower in NB than in L piglets. NB piglets had the highest amount of muscle glycogen content, no difference was found between H and L piglets. Dietary treatments influenced piglet chemical composition, showing the highest overall values of dry matter (DM), protein, and fat for the HFL piglets' carcasses. The present data provide additional information on the depletion of energy reserves; it would appear that sow dietary fat has relatively little effect on progeny since only body chemical composition was significantly influenced by HFL diet.     

Exogenous infusion of short-chain fatty acids can improve intestinal functions independently of the gut microbiota

The present experiment was conducted to investigate the effects of exogenously infused short-chain fatty acids (SCFAs) on the growth development and intestinal functions in a germ-free (GF) pig model. Twelve hysterectomy-derived newborn piglets were reared in six sterile isolators. All piglets were hand-fed Co60-γ-irradiated sterile milk powder for 21 d and then were switched to sterile feed for another 21 d. During the second 21-d period, GF piglets (n = 6) were orally infused with 25 mL/kg sterile saline per day, and SCFA piglets (n = 6) were orally infused with 25 mL/kg SCFAs mixture (acetic, propionic, and butyric acids, 45, 15, and 11 mM, respectively) per day. We observed the concentrations of SCFAs in serum and intestine, and the messenger ribonucleic acid (mRNA) abundance of G-protein-coupled receptor-43 in the ileum was increased (P < 0.05) in the SCFA group. Meanwhile, oral infusion of SCFAs enhanced (P < 0.05) the contents of glucagon-like peptide-2 in the jejunum and serum and tended to increase the villi height in the ileum (P < 0.10). Besides, the activities of lipase, trypsin, sucrase, lactase, Na⁺-K⁺-adenosine triphosphatase ([ATPase] P < 0.05), and Ca²⁺-Mg²⁺-ATPase (P < 0.10) were stimulated and the mRNA expressions of solute carrier family 7 (SLC₇A₁) and regeneration protein (REG)-ΙΙΙ γ in the jejunum (P < 0.05) were upregulated in the SCFA group. Additionally, SCFAs infusion downregulated the mRNA abundances of interleukin (IL)-1β and IL-6 in the jejunum, ileum, or colon (P < 0.05) and increased the counts of white blood cell, neutrophils, and lymphocyte in the blood (P < 0.05). Collectively, exogenous infusion of SCFAs might improve intestinal health through promoting intestinal development and absorption function, and enhancing intestinal immune function, and these effects were occur independently of the gut microbiota.     

短链脂肪酸的生理功能及其在仔猪生产中的应用

断奶应激会给养猪生产带来许多问题,抗生素是解决仔猪断奶应激问题的手段之一。长期使用抗生素会引起耐药菌产生、降低机体免疫力,故我国决定在2020年开始全面禁止抗生素在饲料中的使用。而短链脂肪酸是一种具有多种生理功能的添加剂,并且没有毒副作用,是一种绿色无污染的抗生素替代品,或将在养猪生产中起到重要作用。本文综述了短链脂肪酸在动物机体内的吸收代谢过程及其参与能量代谢、改善消化道微生态和提高机体免疫等生理功能,并介绍了部分短链脂肪酸在仔猪生产上的应用效果,旨在响应国家禁抗政策的同时,为生产中提高仔猪生长性能和替代抗生素的使用提供新思路。     

短链脂肪酸在生猪产业的研究与应用

短链脂肪酸是肠道微生物发酵产物,其对机体健康的影响已被广泛研究。本文就短链脂肪酸在国内外的研究进展,综述了其对猪肠道健康和代谢健康的有益影响以及在生猪养殖中的应用,旨在为新型饲料添加剂的开发与利用提供应用和理论依据。     

Effect of dietary non-starch polysaccharide solubility and inclusion level on gut health and the risk of post weaning enteric disorders in newly weaned piglets

The objective of this experiment was to investigate the effect of non-starch polysaccharide (NSP) solubility and inclusion rate on gut health and development, performance and risk of post weaning enteric disorders (PWED) using NSP sources known not to affect digesta viscosity. The experiment consisted of a 2 × 3 factorial combination of NSP type (sNSP vs insoluble NSP (iNSP); inulin vs purified cellulose) and inclusion level (50 vs 100 vs 150 g/kg). Piglets were weaned at 28 days (day 0) and fed ad libitum until slaughter on day 14. There were no incidences of PWED. NSP solubility had little effect on performance, but sNSP diets resulted in lower caecal and colonic pH and higher colonic Lactobacilli to coliform ratio compared to iNSP diets. Increasing NSP levels significantly reduced caecal and colonic pH but decreased empty body weight percentage (P = 0.067). These results suggest that gut health may benefit most from diets containing appropriate sources of predominantly sNSP rather than iNSP. The optimal level of such sNSP will likely depend upon the level of risk of PWED in order to balance the trade off between maximising performance and improving gut health. Effects of NSP feeding under a higher infectious pressure remains to be assessed.     

Short-chain fatty acid administration via water acidifier improves feed efficiency and modulates fecal microbiota in weaned piglets

This study examined the effect of a water acidifier containing free and buffered short-chain fatty acids (SCFA-WA) on growth performance and microbiota of weaned piglets. In total, 192 male piglets, approximately 4 wk of age, were allocated to 24 pens (12 per treatment) with 8 piglets per pen. The piglets received either regular drinking water (negative control) or drinking water with the acidifier supplied at 2 L/1,000 L. Body weight and feed intake were measured weekly on pen level. During the first 2 wk, daily visual assessment and scoring of the feces was conducted. Fecal samples of three piglets per pen were collected on days 14 and 42 for high-throughput sequencing analysis of the microbiota. Piglets offered SCFA-WA had significantly improved feed efficiency in the third week (P = 0.025) and over the whole study period (days 0 to 42, P = 0.042) compared with piglets in the negative control group, with a strong tendency observed during the first feeding phase (days 0 to 21, P = 0.055). Furthermore, the water acidifier group had a higher water intake than piglets provided with control water during the second feeding phase (days 21 to 42, P = 0.028) and over the whole study period (days 0 to 42, P = 0.043). There was no significant difference in body weight, average daily gain, or average daily feed intake (days 0 to 21, 21 to 42, 0 to 42). Furthermore, there was no overall significant difference in fecal scoring between the treatments. In terms of the fecal microbiota response, piglets offered the water acidifier showed a significantly higher relative abundance (RA) of genus Clostridium sensu stricto 1 and a lower RA of genus Streptococcus compared to the control. Furthermore, the redundancy analysis showed a positive association between improved feed efficiency and daily weight gain and RA of Butyricicoccus and Faecalibacterium. In conclusion, consumption of the water acidifier containing free and buffered SCFA modulated the microbiota and improved feed efficiency in piglets.     

The relationship between appetite and plasma non-esterified fatty acid levels in housed calves

Non-esterified fatty acid (NEFA) levels in housed, 3-month-old calves were monitored in two experiments designed to establish (i) the effect of diet and time of sampling in relation to feeding on blood levels; and (ii) the relationship between appetite and plasma NEFA in animals on chopped hay. In the first experiment, a significant drop in NEFA levels was recorded after feeding. Furthermore, the NEFA levels of calves maintained on concentrate were significantly lower than those on hay throughout the post-feeding period. In the second study, a significant negative correlation was established between NEFA levels and intake of chopped hay in (i) ad-lib-fed calves infected with the abomasal nematode Ostertagia ostertagi; (ii) worm-free animals pair-fed with those in group (i); and (iii) ad-lib-fed worm-free calves. Regression analysis of raw and transformed data from all three groups combined also yielded significant correlations. It is suggested that the measurement of blood NEFA may be a useful indirect indicator of feed intake in conditioned housed calves offered hay diets.     

饲粮中添加不同水平葡萄糖酸对仔猪生长性能和肠道食糜中短链脂肪酸含量的影响

文章旨在研究饲粮中添加葡萄糖酸对仔猪生长性能和肠道食糜中短链脂肪酸含量的影响。试验选取28日龄断奶的三元杂交仔猪100头,饲喂基础饲粮7 d后随机分为4组,各组仔猪体重接近,性别比例一致。试验1、2、3组分别在对照组饲粮中添加0.4%、0.8%、1.2%的葡萄糖酸,处理42 d。试验结果:与对照组相比,试验1、2组仔猪平均末重分别显著增加6.7%、7.7%(P <0.05),平均日增重显著增加10.1%、11.9%(P <0.05),料肉比较对照组显著降低6.3%、7.1%(P <0.05);试验1、2、3组仔猪空肠食糜中乙酸浓度显著增加99.2%、125.6%、45.7%(P <0.05),丙酸浓度显著增加44.4%、38.9%、25.4%(P <0.05),总短链脂肪酸显著增加33.1%、21.6%、14.7%(P <0.05),此外,试验1、2、3组仔猪盲肠食糜中丙酸浓度较对照组分别增加33.5%、45.3%、26.9%(P <0.05),丁酸浓度增加38.2%、59.3%、64.0%(P <0.05),总短链脂肪酸浓度增加10.6%、17.7%、14.2%(P <0.05)。结果表明,饲粮中添加葡萄糖酸显著提高仔猪生长性能及肠道食糜中短链脂肪酸浓度,添加量为0.8%时效果最好。     

脂肪酸对基因表达的影响及调控

脂肪酸是一类重要的营养物质,是动物体内的能量来源,同时也是生物膜的组成成分,在细胞生化过程中也同样起着重要作用。研究发现,脂肪酸可通过对基因表达的影响,对代谢、生长发育以及细胞分化发挥重要的调控作用。真核生物基因表达的调控大致可分为转录前、转录、转录后、翻译和翻译后等5个阶段的调控。脂肪酸通过细胞膜受体信号途径和转录因子活化途径调节基因表达,而多不饱和脂肪酸主要从基因转录和mRNA的稳定性两个方面调节基因表达。文章综述了脂肪酸,尤其是多不饱和脂肪酸对基因表达的影响及调控机制。     

The effect of PHA-lectins and diet composition on performance and intestinal development in weaning piglets

Anti-nutritional factors such as PHA-lectins (phytohaemagglutinin) in piglet diets can compromise piglet's performance and health by gut damage, which is especially important at weaning. Two trials were conducted to investigate the effect of PHA and fermentable carbohydrates on performance, gut morphology, physiology and microbiology in piglets weaned at 26 days.

We studied dietary PHA as a model to standardize gut damage and its effect on intestinal morphology and microbiology in piglets until 2 weeks post weaning. In general, significant lower values were observed on day 7 compared to day 14 post weaning (d7 vs. d14: 358 vs. 442 μm villus height; 42.1 vs. 108.7 U/g protein sucrase-isomaltase), indicating gut maturation. We observed very few changes between day of weaning to day 7 post weaning, lactobacilli counts being most affected (8.9, 6.9, 7.4 cfu/g for d0, d7, d14). Apart from these marked time effects the effect of PHA was negligible and thus a less suitable model to standardize gut damage in this setup.

Furthermore we studied the effect of PHA in combination with rapid or slow fermentable carbohydrates (CHO) on performance and physiological parameters. We observed a dramatic effect on performance (ADG g/d: 245 no PHA + low CHO, 111 PHA + low CHO, 132 PHA + rapid CHO, 105 PHA + slow CHO), which was less clearly reflected in the physiological parameters.