Methodology and application of Escherichia coli F4 and F18 encoding infection models in post-weaning pigs

The enterotoxigenic Escherichia coli (ETEC) expressing F4 and F18 fimbriae are the two main pathogens associated with post-weaning diarrhea (PWD) in piglets.The growing global concern regarding antimicrobial resistance (AMR) has encouraged research into the development of nutritional and feeding strategies as well as vaccination protocols in order to counteract the PWD due to ETEC.A valid approach to researching effective strategies is to implement piglet in vivo challenge models with ETEC infection.Thus,the proper application and standardization of ETEC F4 and F18 challenge models represent an urgent priority.The current review provides an overview regarding the current piglet ETEC F4 and F18 challenge models;it highlights the key points for setting the challenge protocols and the most important indicators which should be included in research studies to verify the effectiveness of the ETEC challenge.Based on the current review,it is recommended that the setting of the model correctly assesses the choice and preconditioning of pigs,and the timing and dosage of the ETEC inoculation.Furthermore,the evaluation of the ETEC challenge response should include both clinical parameters (such as the occurrence of diarrhea,rectal temperature and bacterial fecal shedding) and biomarkers for the specific expression of ETEC F4/F18 (such as antibody production,specific F4/F18 immunoglobulins (lgs),ETEC F4/F18 fecal enumeration and analysis of the F4/F18 receptors expression in the intestinal brush borders).On the basis of the review,the piglets' response upon F4 or F18 inoculation differed in terms of the timing and intensity of the diarrhea development,on ETEC fecal shedding and in the piglets' immunological antibody response.This information was considered to be relevant to correctly define the experimental protocol,the data recording and the sample collections.Appropriate challenge settings and evaluation of the response parameters will allow future research studies to comply with the replacement,reduction and refinement (3R) approach,and to be able to evaluate the efficiency of a given feeding,nutritional or vaccination intervention in order to combat ETEC infection.

Tannic acid prevents post-weaning diarrhea by improving intestinal barrier integrity and function in weaned piglets

Background:Tannic acid(TA)is potential to reduce diarrhea in weaning pigs,but knowledge about the influence of TA on intestinal barrier integrity and function is still scarce.This experiment was conducted to investigate the effects of dietary TA supplementation on growth performance,diarrhea rate,intestinal barrier integrity and function of weaned pigs.Methods:A total of 108 crossbred(Duroc×Landrace×Yorkshire)piglets,with an initial average body weight of 6.60±0.27 kg,were allotted to 3 groups(6 pigs/pen and 6 replicates/group)in a randomized complete block design according to their gender and body weight.Piglets were fed the basal diet with 0(control,CON),0.2%and 1.0%TA,respectively.The trial lasted for 28 d.Results:Compared with the CON group,dietary 0.2%and 1.0%TA supplementation didn’t affect ADFI,ADG and F:G(P>0.05),but reduced diarrhea rate,diarrhea index and diarrhea score of piglets(P<0.05),reduced diamine oxidase(DAO)activity and D-lactic acid concentration in serum(P<0.01).The higher occludin expression and localization were observed in the duodenum,jejunum and ileum after supplementation with 0.2%or 1.0%TA(P<0.05).Adding 0.2%TA to diet significantly decreased crypt depth,increased villus height/crypt depth ratio in the duodenum(P<0.05),and dietary 1.0%TA tended to decrease crypt depth(P<0.10)and significantly decreased villus height(P<0.05)of the ileum.Moreover,lower malondialdehyde content in the ileum was detected in the pigs fed 1.0%TA(P<0.05).In the duodenum,both 0.2%and 1.0%TA groups had higher occludin(OCLN)mRNA and 0.2%TA group had higher zonula occludens-2(ZO-2)level(P<0.05).Meanwhile,dietary 1.0%TA supplementation tended to up-regulate OCLN mRNA levels in the jejunum(P<0.10)and 0.2%TA supplementation tended to up-regulate zonula occludens-1(ZO-1)mRNA levels in the ileum(P<0.10).Conclusion:In conclusion,dietary supplementation of 0.2%or 1.0%TA could effectively alleviate postweaning diarrhea without altering growth performance in weaned piglets,which might be achieved by improving intestinal barrier integrity and function.

Sow performance in response to natural betaine fed during lactation and post-weaning during summer and non-summer months

Background: Two studies were conducted to evaluate the effects of dietary natural betaine on sow reproductive performance during summer(Exp. 1) and non-summer months(Exp. 2). Treatments were designed as a 2 × 2 factorial arrangement with factors including dietary betaine(0 or 0.2%) and period of supplementation(lactation or post-weaning until 35 days post-insemination). In Exp. 1, 322 and 327 sows and in Exp. 2, 300 and 327 sows representing young(parity 1 and 2) and mature(parity 3 to 6) sows, respectively, were used.Results: In Exp. 1, supplementation of betaine during lactation increased sow body weight losses(-11.95 vs.-14.63 kg;P = 0.024), reduced feed intake(4.12 vs. 4.28 kg/d;P = 0.052), and tended to reduce percentage of no-value pigs(P = 0.071). Betaine fed post-weaning reduced weaning-to-estrus interval(5.75 vs. 6.68 days;P = 0.054) and farrowing rate(86.74% vs. 91.36%;P = 0.060), regardless of parity group. Post-hoc analysis with sows clustered into 3 parity groups(1, 2 and 3, and 4+) indicated that betaine fed in lactation to parity 4+ sows(P = 0.026) and betaine fed post-weaning to parity 1 sows increased the number of pigs born in the subsequent cycle(P ≤ 0.05). In Exp. 2, betaine fed during lactation tended to reduce the weaning-to-estrus interval(6.64 vs. 7.50 days;P = 0.077) and farrowing rate(88.23% vs.83.54%;P = 0.089), regardless of parity group. Feeding betaine post-weaning reduced number of pigs born(13.00 vs.13.64;P = 0.04) and pigs born alive(12.30 vs. 12.82;P = 0.075), regardless of parity group.Conclusions: Using 0.2% betaine during the non-summer months did not benefit sow performance. During the summer, betaine supplementation in lactation increased subsequent litter size in parity 4+ sows. Betaine fed during the post-weaning period reduced the wean-to-estrus interval and farrowing rate, increased total number of pigs born for parity 1 sows and reduced total number of pigs born to parity 4+ sows. Further research is needed to determine if the detrimental effects on feed intake and farrowing rate may be correlated and depend on dietary betaine level.

Tannic acid extracted from gallnut prevents post-weaning diarrhea and improves intestinal health of weaned piglets

This experiment was conducted to evaluate the effects of different levels of tannic acid(TA)on growth performance,diarrhea rate,nutrient digestibility and intestinal health in weaned piglets.A total of 180 weaned piglets(Duroc×Landrace×Yorkshire,24 d of age,initial average BW=7.77±0.17 kg)were allotted to 5 groups(6 pigs/pen and 6 replicates/group)in a randomized complete block design according to their gender and body weight.Piglets were fed a basal diet,or the basal diet supplemented with 0.05%,0.1%,0.2%or 0.4%TA for 28 d.The supplementary levels of TA in the diets were obtained by adding tannalbin containing 51%TA and 40.17%protein.The results showed that,compared with the CON group,dietary TA did not affect ADFI,ADG or F:G,and linearly reduced(P<0.01)the diarrhea rate and diarrhea index of piglets.There were no significant effects on apparent total tract digestibility(ATTD)in the 0.05%,0.1%and 0.2%TA groups,while negative effects(P<0.05)on apparent digestibility of crude protein and gross energy were observed in the 0.4%TA group.In addition,the nutrient digestibility of dry matter,crude protein and gross energy linearly decreased(P<0.01)with the increase of TA dosage.Supplementation of TA increased(P<0.05)the villus height of the duodenum and jejunum,as well as increased(P<0.05)catalase(CAT)activity in serum.Dietary TA improved(P<0.05)the Bacillus counts in cecal digesta.Further,TA significantly improved(P<0.05)Bacillus counts and reduced(P<0.05)the Escherichia coli counts in colonic digesta.The concentration of acetic acid,pro pionic acid,butyric acid and isovaleric acid in cecal digesta were significantly increased(P<0.05).The mRNA expression level of zonula occludens-1(Z0-1),zonula occludens-2(ZI-2),and claudin-2(CLDN-2)in the jejunum were greater(P<0.05)in TA supplemented groups.The study showed that,compared to the control,TA prevented post-weaning diarrhea and improved intestinal health of weaned piglets,and the appropriate level of TA supplementation would be from 0.1%to 0.2%.

Lower abundance of Bacteroides and metabolic dysfunction are highly associated with the post-weaning diarrhea in piglets

Growing evidences show a direct link between diarrhea and disorders of gut microbiota in pigs.However,whether there are microbial markers associated with post-weaning diarrhea remains unknown.In the current study,we compared the microbial community,functions and metabolites between healthy weaned piglets(group H,n=7)and piglets with post-weaning diarrhea(group D,n=7),in order to find out diarrhea associated microbial markers.Each of 7 fecal samples was collected from H and D piglets(weaned at 21 d and sampled at 26 d).The metagenomic and untargeted metabolomic analysis revealed that the microbial composition,function and metabolic profile in D pigs was considerably reshaped,including the reduced abundance and number of Bacteroides,which significantly correlated with the diarrhea status of host.The carbohydrate metabolism,biosynthesis and metabolism,lipid metabolism,amino acid metabolism,and the activity of glycan and carbohydrates digestion related enzymes showed extensively down-regulated in D pigs compared with H pigs.Diarrhea significantly changed the metabolic profiles of fecal microbiota,and most of the altered metabolites were negatively or positively correlated with the change in the abundance of Bacteroides.In conclusion,the lower abundance of Bacteroides and its associated metabolic dysfunction may be regarded as microbial markers of physiological post-weaning diarrhea in piglets.

Dietary glutamine,glutamate,and aspartate supplementation improves hepatic lipid metabolism in post-weaning piglets

A previous study has demonstrated that early weaning significantly suppressed hepatic glucose metabolism in piglets.Glutamate(Glu),aspartate(Asp)and glutamine(Gln)are major metabolic fuels for the small intestine and can alleviate weaning stress,and therefore might improve hepatic energy metabolism.The objective of this study was to investigate the effects of administration of Glu,Asp and Gln on the expression of hepatic genes and proteins involved in lipid metabolism in post-weaning piglets.Thirty-six weaned piglets were assigned to the following treatments:control diet(Control;basal diet+15.90 g/kg alanine);Asp,Gln and Glu-supplemented diet(Control+AA;basal diet+1.00 g/kg Asp+5.00 g/kg Glu+10.00 g/kg Gln);and the energy-restricted diet supplemented with Asp,Gln and Glu(Energy^-+AA;energy deficient diet+1.00 g/kg Asp+5.00 g/kg Glu+10.00 g/kg Gln),Liver samples were obtained on d 5 and 21 post-weaning.Piglets fed Energy^-+AA diet had higher liver mRNA abundances of acyl-CoA oxidase 1(ACOX1),succinate dehydrogenase(SDH),mitochondrial transcription factor A(TFAM)and sirtuin 1(SIRT1),as well as higher protein expression of serine/threonine protein kinase 11(LKB1),phosphor-acetyl-CoA carboxylase(P-ACC)and SIRT1 compared with piglets fed control diet(P<0.05)on d 5 post-weaning.Control+AA diet increased liver malic enzyme 1(ME1)and SIRT1 mRNA levels,as well as protein expression of LKBl and P-ACC on d 5 post-weaning(P<0.05).On d 21 post-weaning,compared to control group,Glu,Gln and Asp supplementation up-regulated the mRNA levels of ACOX1,ME1 and SIRT1(P<0.05).These findings indicated that dietary Glu,Gln and Asp supplementation could improve hepatic lipid metabolism to some extent,which may provide nutritional intervention for the insufficient energy intake after weaning in piglets.

Dietary inclusion of multispecies probiotics to reduce the severity of post-weaning diarrhea caused by Escherichia coli F18+ in pigs

This study was aimed to determine the efficacy of multispecies probiotics in reducing the severity of post-weaning diarrhea caused by enterotoxigenic Escherichia coli(ETEC)F18+on newly weaned pigs.Thirty-two pigs(16 barrows and 16 gilts,BW=6.99±0.33 kg)at 21 d of age were individually allotted in a randomized complete block design with 2×2 factorial arrangement of treatments.Pigs were selected from sows not infected previously and not vaccinated against ETEC.Pigs were fed experimental diets for 25 d based on 10 d phase 1 and 15 d phase 2.The factors were ETEC challenge(oral inoculation of saline solution or E.coli F18+at 2×109 CFU)and probiotics(none or multispecies probiotics 0.15%and 0.10%for phase 1 and 2,respectively).Body weight and feed intake were measured on d 5,9,13,19,and 25.Fecal scores were measured daily.Blood samples were taken on d 19 and 24.On d 25,all pigs were euthanized to obtain samples of digesta,intestinal tissues,and spleen.The tumor necrosis factor alpha(TNFα),malondialdehyde(MDA),peptide YY(PYY),and neuropeptide Y(NPY)were measured in serum and intestinal tissue.Data were analyzed using the MIXED procedure of SAS.The fecal score of pigs was increased(P<0.05)by ETEC challenge at the post-challenge period.The ETEC challenge decreased(P<0.05)jejunal villus height and crypt depth,tended to increase(P=0.056)jejunal TNFα,increased(P<0.05)ileal crypt depth,and decreased(P<0.05)serum NPY.The probiotics decreased(P<0.05)serum TNFα,tended to reduce(P=0.064)jejunal MDA,tended to increase(P=0.092)serum PYY,and increased(P<0.05)jejunal villus height,and especially villus height-to-crypt depth ratio in challenged pigs.Growth performance of pigs were not affected by ETEC challenge,whereas the probiotics increased(P<0.05)ADG and ADFI and tended to increase(P-0.069)G:F ratio.In conclusion,ETEC F18+challenge caused diarrhea,intestinal inflammation and morphological damages without affecting the growth performance.The multispecies probiotics enhanced growth performance by reducing intestinal inflammation,oxidative stress,morphological damages.

Effects of early postnatal gastric and colonic microbiota transplantation on piglet gut health

Background Diarrhea is a major cause of reduced growth and mortality in piglets during the suckling and weaning periods and poses a major threat to the global pig industry.Diarrhea and gut dysbiosis may in part be prevented via improved early postnatal microbial colonization of the gut.To secure better postnatal gut colonization,we hypothesized that transplantation of colonic or gastric content from healthy donors to newborn recipients would prevent diarrhea in the recipients in the post-weaning period.Our objective was to examine the impact of transplanting colonic or gastric content on health and growth parameters and paraclinical parameters in recipient single-housed piglets exposed to a weaning transition and challenged with enterotoxigenic Escherichia coli(ETEC).Methods Seventy-two 1-day-old piglets were randomized to four groups:colonic microbiota transplantation(CMT,n=18),colonic content filtrate transplantation(CcFT,n=18),gastric microbiota transplantation(GMT,n=18),or saline(CON,n=18).Inoculations were given on d 2 and 3 of life,and all piglets were milk-fed until weaning(d 20)and shortly after challenged with ETEC(d 24).We assessed growth,diarrhea prevalence,ETEC concentration,organ weight,blood parameters,small intestinal morphology and histology,gut mucosal function,and microbiota composition and diversity.Results Episodes of diarrhea were seen in all groups during both the milk-and the solid-feeding phase,possibly due to stress associated with single housing.However,CcFT showed lower diarrhea prevalence on d 27,28,and 29 compared to CON(all P<0.05).CcFT also showed a lower ETEC prevalence on d 27(P<0.05).CMT showed a higher alpha diversity and a difference in beta diversity compared to CON(P<0.05).Growth and other paraclinical endpoints were similar across groups.Conclusion In conclusion,only CcFT reduced ETEC-related post-weaning diarrhea.However,the protective effect was marginal,suggesting that higher doses,more effective modalities of administration,longer treatment periods,and better donor quality should be explored by future research to optimize the protective effects of transplantation.

Phytogenic feed additives alleviate pathogenic Escherichia coli-induced intestinal damage through improving barrier integrity and inhibiting inflammation in weaned pigs

Background:This study was conducted to investigate the effects of each phytogenic feed additive(PFA;PFA1,bitter citrus extract;PFA2,a microencapsulated blend of thymol and carvacrol;PFA3,a mixture of bitter citrus extract,thymol,and carvacrol;PFA4,a premixture of grape seed,grape marc extract,green tea,and hops;PFA5,fenugreek seed powder)on the growth performance,nutrient digestibility,intestinal morphology,and immune response in weaned pigs infected with Escherichia coli(E.coli).Results:A total of 634-week-old weaned pigs were placed in individual metabolic cages and assigned to seven treatment groups.The seven treatments were as follows:1)NC;basal diet without E.coli challenge,2)PC;basal diet with E.coli challenge,3)T1;PC+0.04%PFA1,4)T2;PC+0.01%PFA2,5)T3;PC+0.10%PFA3,6)T4;PC+0.04%PFA4,7)T5;PC+0.10%PFA5.The experiments lasted in 21 d,including 7 d before and 14 d after the first E.coli challenge.In the E.coli challenge treatments,all pigs were orally inoculated by dividing a total of 10 mL of E.coli F18 for 3 consecutive days.The PFA-added groups significantly increased(P<0.05)average daily gain and feed efficiency and decreased(P<0.05)the fecal score at d 0 to 14 post-inoculation(PI).Tumor necrosis factorαwas significantly lower(P<0.05)in the PFA-added groups except for T1 in d 14 PI compared to the PC treatment.The T3 had a higher(P<0.05)immunoglobulin G and immunoglobulin A concentration compared to the PC treatment at d 7 PI.Also,T3 showed significantly higher(P<0.05)villus height:crypt depth and claudin 1 expression in ileal mucosa,and significantly downregulated(P<0.05)the expression of calprotectin compared to the PC treatment.Conclusions:Supplementation of PFA in weaned pigs challenged with E.coli alleviated the negative effects of E.coli and improved growth performance.Among them,the mixed additive of bitter citrus extract,thymol,and carvacrol showed the most effective results,improving immune response,intestinal morphology,and expression of tight junctions.

Productive and physiological implications of top-dress addition of branched-chain amino acids and arginine on lactating sows and offspring

Background Branched-chain amino acids(BCAAs),including L-leucine(L-Leu),L-isoleucine(L-Ile),L-valine(L-Val),and L-arginine(L-Arg),play a crucial role in mammary gland development,secretion of milk and regulation of the catabolic state and immune response of lactating sows.Furthermore,it has recently been suggested that free amino acids(AAs)can also act as microbial modulators.This study aimed at evaluating whether the supplementation of lactating sows with BCAAs(9,4.5 and 9 g/d/sow of L-Val,L-Ile and L-Leu,respectively)and/or L-Arg(22.5 g/d/sow),above the estimated nutritional requirement,could influence the physiological and immunological parameters,microbial profile,colostrum and milk composition and performance of sows and their offspring.Results At d 41,piglets born from the sows supplemented with the AAs were heavier(P=0.03).The BCAAs increased glucose and prolactin(P<0.05)in the sows’serum at d 27,tended to increase immunoglobulin A(IgA)and IgM in the colostrum(P=0.06),increased the IgA(P=0.004)in the milk at d 20 and tended to increase lymphocyte%in the sows’blood at d 27(P=0.07).Furthermore,the BCAAs tended to reduce the Chao1 and Shannon microbial indices(P<0.10)in the sows’faeces.The BCAA group was discriminated by Prevotellaceae_UCG-004,Erysipelatoclostridiaceae UCG-004,the Rikenellaceae_RC9_gut_group and Treponemaberlinense.Arginine reduced piglet mortality pre-(d 7,d 14)and post-weaning(d 41)(P<0.05).Furthermore,Arg increased the IgM in the sow serum at d 10(P=0.05),glucose and prolactin(P<0.05)in the sow serum at d 27 and the monocyte percentage in the piglet blood at d 27(P=0.025)and their jejunal expression of NFKB2(P=0.035)while it reduced the expression of GPX-2(P=0.024).The faecal microbiota of the sows in Arg group was discriminated by Bacteroidales.The combination of BCAAs and Arg tended to increase spermine at d 27(P=0.099),tended to increase the Igs(IgA and IgG,P<0.10)at d 20 in the milk,favoured the faecal colonisation of Oscillospiraceae UCG-005 and improved piglet growth.Conclusion Feeding Arg and BCAAs above the estimated requirements for milk production may be a strategy to improve sow productive performance in terms of piglet average daily gain(ADG),immune competence and survivability via modulation of the metabolism,colostrum and milk compositions and intestinal microbiota of the sows.The synergistic effect between these AAs,noticeable by the increase of Igs and spermine in the milk and in the improvement of the performance of the piglets,deserves additional investigation.

Feed- and feed additives-related aspects of gut health and development in weanling pigs

The development of new/different management and feeding strategies to stimulate gut development and health in newly-weaned pigs, in order to improve growth performance while minimizing the use of antimicrobial compounds such as antibiotic growth promotants （AGP） and heavy mineral compounds, is essential for the long-term sustainability of the pig industry. Factors including the sub-optimal intake of nutrients and energy, inappropriate microbiota biomass and （or） balance, immature and compromised immune function, and psychosomatic factors caused by weaning can compromise both the efficiency of digestion and absorption and intestinal barrier function through mucosal damage and alteration of tight junction integrity. As a consequence, pigs at weaning are highly susceptible to pathogenic enteric conditions such as post-weaning diarrhea that may be caused by serotypes of enterotoxigenic Escherichia coil Many dietary components, e.g., protein, fiber, feed additives and minerals, are known to influence microbial growth in the gastrointestinal tract that in turn can impact upon pig growth and health, although the relationships between these are sometimes not necessarily apparent or obvious. In a world climate of increased scrutiny over the use of antibiotics per se in pig production, certain feed additives are seen as alternatives/replacements to antibiotics, and have evolved in some cases to have important roles in everyday commercial pig nutrition. Nevertheless and in general, there remains inconsistency and variability in the efficacy of some feed additives and in cases of severe disease outbreaks, for example, therapeutic antibiotics and/or heavy minerals such as zinc oxide （ZnO） are generally relied upon. If feed ingredients and （or） feed additives are to be used with greater regularity and reliability, then it is necessary to better understand the mechanisms whereby antibiotics and minerals such as ZnO influence animal physiology, in conjunction with the use of appropriate challenge models and in vitro and in vivo techniques.

Bacillus sp. probiotic supplementation diminish the Escherichia coli F4ac infection in susceptible weaned pigs by influencing the intestinal immune response, intestinal microbiota and blood metabolomics

Background:Probiosis is considered a potential strategy to reduce antibiotics use and prevent postweaning diarrhea(PWD).This study investigated the effect of Bacillus amyloliquefaciens DSM25840 or Bacillus subtilis DSM25841 supplementation on growth,health,immunity,intestinal functionality and microbial profile of post-weaning pigs after enterotoxigenic E.coli(ETEC)F4 challenge.Methods:Sixty-four post-weaning piglets(7748 g±643 g)were randomly al ocated to four groups:control basal diet(CO);CO+1.28×10~6 CFU/g of B.amyloliquefaciens(BAA);CO+1.28×10~6 CFU/g feed of B.subtilis(BAS);CO+1 g colistin/kg of feed(AB).At day(d)7,animals were chal enged with 10~5 CFU/m L of ETEC F4 ac O149 and then fol owed for fecal score and performance until d 21.Blood was col ected at d 6,d 12 and d 21 for immunoglobulins,at d 8 for acute phase proteins,at d 8 and d 21 for metabolomics analysis.Jejunum was sampled for morphometry,quantification of apoptosis,cel proliferation,neutral and acid mucine and Ig A secretory cel s,and microarray analysis at d 21.Jejunum and cecum contents were col ected for microbiota at d 21.Results:AB and BAS reduced the fecal score impairment compared to CO(P<0.05)at d 14.Body weight(BW),average daily weight gain(ADWG),average daily feed intake(ADFI)and gain to feed ratio(G:F)did not differ between Bacil us groups and CO.AB improved BW at d 7,d 14 and d 21,ADWG ADFI and G:F from d 0 to d 7(P<0.05).At d 8,CO had higher plasma arginine,lysine,ornithine,glycine,serine and threonine than other groups,and higher haptoglobin than AB(P<0.05).At d 21,CO had lower blood glycine,glutamine and Ig A than BAS.Morphology,cel s apoptosis and mucins did not differ.BAS and AB increased the vil us mitotic index.Transcriptome profile of BAS and AB were more similar than CO.Gene sets related to adaptive immune response were enriched in BAA,BAS and AB.CO had enriched gene set for nuclear structure and RNA processing.CO had a trend of higher Enterobacteriaceae in cecum than the other groups(P=0.06).Conclusion:Bacil us subtilis DSM25841 treatment may reduce ETEC F4ac infection in weaned piglets,decreasing diarrhea and influencing mucosal transcriptomic profile.

Recent Advances in Epidemiology of Porcine Circovirus Type 2 and Diagnosis of Porcine Circovirus-Associated Diseases

Porcine cimovirus （PCV） is the smallest animal virus so far and has two serotypes. PCV1 is nonpathogenic, but PCV2 is pathogenic and causes post-weaning multisystemic wasting syndrome （ PMWS）. Factors to induce PMWS include immunity and infection status of sows, infec- tion time, mixed infection, PCV2 variants, physical status of gilts, and feeding management. For final diagnosis, histopathological changes and ex- istence of PCV2 in lymphoid tissues are professional standards, because fluorescence quantitative RT-PCR is not enough specific or sensitive. The commemial PCV2 vaccines can reduce occurrence of PMWS and PCV-related diseases. This paper reviews recent advances in epidemiology of PCV2 as well as diagnosis and control of PMWS.

Targeting mitochondria with antioxidant nutrients for the prevention and treatment of postweaning diarrhea in piglets

Post-weaning diarrhea(PWD)in piglets poses a significant challenge and presents a grave threat to the global swine industry,resulting in considerable financial losses and compromising the welfare of animals.PWD is commonly associated with gut homeostatic imbalance,including oxidative stress,excessive inflammation,and microbiota dysbiosis.Antibiotic use has historically been a common initiative to combat PWD,but concerns about the development of antibiotic resistance have led to increased interest in alternative strategies.Mitochondria are key players in maintaining cellular homeostasis,and their dysfunction is intricately linked to the onset and progression of PWD.Accumulating evidence suggests that targeting mitochondrial function using antioxidant nutrients,such as vitamins,minerals and polyphenolic compounds,may represent a promising approach for preventing and treating PWD.Moreover,nutrients based on antioxidant strategies have been shown to improve mitochondrial function,restore intestinal redox balance,and reduce oxidative damage,which is a key driver of PWD.The present review begins with an overview of the potential interplay between mitochondria and gut homeostasis in the pathogenesis of PWD in piglets.Subsequently,alternative strategies to prevent and treat PWD using antioxidant nutrients to target mitochondria are described and discussed.Ultimately,we delve into potential limitations and suggest future research directions in this field for further advancement.Overall,targeting mitochondria using antioxidant nutrients may be a promising approach to combat PWD and provides a potential nutrition intervention strategy for regulating gut homeostasis of weaned piglets.

Effects of varying dietary folic acid during weaning stress of piglets

The present study was conducted to evaluate the effect of dietary folic acid on the growth performance,intestinal morphology,and intestinal epithelial cells renewal in post-weaning piglets.Twenty-eight piglets(weaned at day 21,initial body weight of 6.73±0.62 kg)were randomly allotted to 4 treat-ments with 7 pens per diet and 1 piglet per pen.The piglets were fed the same antibiotic-free and zinc oxide-free basal diets supplemented with folic acid at 0,3,9,and 18 mg/kg for 14 days.The results showed that dietary supplementation with folic acid increased villus height(VH)(P=0.003;linear,P=0.001),VH-to-crypt depth(VH:CD)ratio(P=0.002;linear,P=0.001),villus surface area(VSA)(P=0.026;linear,P=0.010).The analyzed parameters ADG,serum urea nitrogen(BUN)content,VH,VSA,and serum folate(SF)concentration responded linearly to the dietary folic acid concentration when the dietary folic acid concentration was below 4.42,5.26,4.79,3.47,and 3.53 mg/kg respectively(R2=0.995,0.995,0.999,0.999,0.872,P=0.09,0.07,0.09,0.09,0.36,respectively),as assessed by a two-linear broken-line regression.Above these breakpoints,the response of ADG,VH,VSA,and SF plateaued in response to changes in dietary folic acid concentration.Moreover,dietary supplementation with folic acid significantly increased the lactase(P=0.001;linear,P=0.001)and sucrase activities(P=0.021;linear,P=0.010)in the jejunal mucosa of weaned piglets.The mRNA expression of solute carrier family 6 member 19(SLC6a19),solute carrier family 1 member 1(SLC7a1),tumor necrosis factor-α(TNF-α),the number of Ki67 positive cells,and cell shedding rate had a significant linear contrast(P=0.023,0.021,0.038,0.049,and 0.008,respectively)in dietary folic acid groups.In conclusion,our results indicate that folic acid supplementation can improve the growth performance and intestinal morphology of weaned piglets by maintaining the balance of epithelial cell renewal.