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1.
Strains of hemolytic E. coli are implicated in edema disease and enteritis of swine. Immunological experiments were conducted to determine the specific role played by hemolytic E. coli in the etiology of these diseases. When cell-free extracts prepared from a frequently isolated E. coli — 0139:K82(B) were injected 48 hours apart into a healthy pig, symptoms of edema disease were produced on both occasions. Similar symptoms were produced when this extract was injected into a colostrum-deprived pig raised in isolation. The Schultz-Dale reaction revealed no difference between the contractions of the ilea of sensitized and non-sensitized guinea-pigs. In vitro treatment of a single non-sensitized guinea-pig uterus with extracts of five different strains of hemolytic E. coli produced sharp contractions in every trial. A similar treatment with extracts of four non-hemolytic E. coli strains also stimulated the non-sensitized guinea-pig uterus but the magnitude of the contractions was much less. These studies indicated that the cell-free extracts of hemolytic E. coli produced a marked nonspecific toxic reaction. 相似文献
2.
Strains of enterobacteria (nine Escherichia coli and two Salmonella) isolated from primary or secondary infections in the dog, cat, pig, calf and kangaroo were studied for the presence of extrachromosomal drug resistance factors (R factors). Seven strains of E. coli and two strains of Salmonella transferred resistance involving the following antibiotics: streptomycin, ampicillin, chloramphenicol, neomycin and tetracycline. All strains harboring R factors transferred streptomycin resistance and the identified resistance patterns were as follows: Sm Am, Sm Te, Sm Neo, Sm Am Te, Sm CI Neo and Sm Am CI Te. The levels of resistance observed were comparable for all donor strains and their converted recipients. Strains of E. coli harboring R factors were isolated from three dogs that had died of either otitis (followed by a generalized infection), enteritis or bronchopneumonia — secondary to distemper. The bacteria isolated from cats were recovered at the necropsy of animals that had died of purulent pleuresy and feline panleukopenia. The other strains (two Salmonella and one E. coli were isolated from fatal enteric diseases in the pig, calf and kangaroo. 相似文献
3.
Four gnotobiotic pigs were infected with an enteropathogenic strain of Escherichia coli, and 4 were infected with a nonenteropathogenic strain of E. coli. Pigs killed in pairs at 6, 12, 24, and 48 hours PI. Four pigs were maintained as germfree controls. The discussions were based on the results of 1) clinical observations, 2) necropsy observations, 3) counts of viable E. coli in segments of the small intestine, 4) attempts to isolate E. coli from the heart, liver, and bile, 5) microscopic examination of fixed intestinal sections to determine the location of E. coli and morphologic evidence of the host response, and (6) determinations of the pH of the contents of the various portions of the gastrointestinal tract. No diarrhea, fluid accumulation, or impairment of the digestive capacity were noted in the pigs infected with the nonenteropathogenic strain of E. coli. The number of viable E. coli detected in the respective segments of the homogenized small intestine was similar in pigs infected with either strain. Diarrhea occurred continuously starting 18 hours PI in the pigs infected with the enteropathogenic strain and killed 24 or 48 hours PI. The pH of the contents of the cecum and colon became markedly more alkaline simultaneously with the increase in the heterogeneity and fluid content of the cecum and colon and thus appeared to correlate well with the onset of the clinical diarrhea. No enteritis was detected grossly or microscopically. The characteristics that determine the enteropathogenicity of a strain of E. coli could not be defined from the results, but it was noted that the host response appeared to be quite similar to that of infant rabbits experimentally infected with Vibrio cholera. 相似文献
4.
Milk whey from immunized sows increased the survival time of gnotobiotic piglets infected with Escherichia coli. The survival time of infected piglets fed milk whey from non-vaccinated sow's was the same as that of similar pigs fed condensed cow milk. The significance of milk antibodies in immune protection against E. coli enteritis is discussed and compared with that of absorbed colostral antibodies. From calculations presented it would appear that seven day old piglets receive approximately 1 g of gamma globulin daily from milk and that this is equal to the piglets total serum gamma globulin content. After seven days of age the gamma globulin content of piglet serum falls, whereas that of milk remains constant; milk is, therefore, potentially a major source of immunoglobulins with protective activity against E. coli associated enteritides. 相似文献
5.
Nine gnotobiotic pigs derived from one gilt were fed bacteria-free filtrates prepared from: 1) cultures of an enteropathogenic strain of Escherichia coli 09:K·:NM (Strain 340), 2) cultures of a nonenteropathogenic strain of E. coli 08.K·.H16 (Strain CDC-1466-56), and 3) uninoculated culture medium. Diarrhea was observed initially two to four hours after feeding the filtrate prepared from the enteropathogenic E. coli. The duration of diarrhea was five to ten hours. No diarrhea was observed after feeding filtrate prepared from uninoculated medium or cultures of nonenteropathogenic E. coli. The pH values of the feces increased with the onset of diarrhea and decreased to normal after diarrhea stopped. No histopathological lesions were found. 相似文献
6.
A comparison was made between segments of pig and rabbit small intestine in their response to heat-labile (LT) and heat-stable (ST) preparations from porcine enteropathogenic Escherichia coli. Either whole cell lysates or dialysed broth culture supernatants were used as sources of LT and soft agar culture fluids as a source of ST. Whole cell lysates of all thirteen LT-producing E. coli strains tested regularly elicited fluid accumulation in rabbit gut loops. Whole cell lysates of certain E. coli strains considered to be nonenteropathogenic in pigs could also elicit a positive response in rabbit gut loops. When graded doses of LT were tested in pig and rabbit gut loops, the rabbit was more sensitive and is therefore considered preferable to the pig for quantitation of LT. In the rabbit, upper (jejunal) and lower (ileal) small intestine were compared for their response to LT and it was found that ileal loops were twice as sensitive but more prone to false positive reactions. When soft agar culture fluids of several enteropathogenic E. coli strains were tested in the rabbit, the response was inconsistent, and it was concluded that the rabbit is unsuitable for the assay of the heat-stable enterotoxin. 相似文献
7.
A study was undertaken to evaluate the response of different test systems to preparations of heat-stable enterotoxin (ST) derived from Eschericihia coli strains recovered from diarrheal disease of humans, pigs and calves. Sterile broth culture supernatants of enterotoxigenic strains of E. coli were heated at 65°C for 30 minutes and tested for the presence of heat-stable enterotoxin. Three test systems, namely, ligated intestine of weaned pigs, ligated intestine of rabbits and the infant mouse test were used in attempts to detect ST in the culture supernatants. Two patterns of reaction were observed in response to ST-containing preparations: either the preparation elicited a response in the three tests or the preparation elicited a reaction only in the ligated pig intestine. A response in all three tests were observed for 5/5 human ST-producing E. coli, 5/5 bovine enterotoxigenic E. coli, 5/5 “atypical” porcine enterotoxigenic E. coli, 3/3 St +LT - porcine E. coli of serogroup O138:K81 and 4/24 LT +ST + porcine E. coli. A response only in the ligated pig intestine was obtained with 5/5 ST +LT - porcine E. coli belonging to serogroups other than O138:K81 and to 20/24 ST +LT + E. coli from pigs. The results are consistent with the view that there are two kinds of ST, one of which (ST1) reacts in all three tests and the other (ST2) which reacts only in the ligated pig intestine. The findings underscore the limitations of the infant mouse test as a means of detecting ST in porcine isolates of E. coli, since the test fails to detect ST produced by a large number of these E. coli strains. There appeared to be a relationship between kind(s) of ST produced and the animal species from which the producing organism was recovered. 相似文献
8.
Chicks two, three and four weeks of age respond well serologically to endotoxin given intravenously, with the older chicks giving a better response. The induced immunity against live organism challenge produced by homologous endotoxin from Escherichia coli or Salmonella typhimurium is specific between these two organisms, however, cross-immunity occurs between E. coli 045 and E. coli 0109 and between Salmonella enteritidis and S. typhimcrium and further, endotoxins from different organisms may be combined to provide immunity against the homologous organisms. Endotoxoid administered to chicks rendered them more susceptible to live organism challenge for five days, following which some immunity developed. 相似文献
9.
Three hundred and seventy strains of fecal Escherichia coli were isolated from pigs in one barn and 475, 539 and 490 strains were isolated at each of three successive samplings in another barn. The majority of the E. coli isolates obtained at any one sampling belonged to a small number of E. coli types. Three repeated samplings in one barn indicated that the dominant E. coli types harboured by pigs in this barn were constantly changing. The results also suggested that, within a particular barn, a successive batch of pigs could experience the same sequence of E. coli types. Colicin production appeared to be associated with dominant strains and the proportion of colicin producers in different investigations ranged from 36 to 68%. 相似文献
10.
Minimum inhibitory concentrations (MICs) were determined for 1570 bacteria from eight geographic locations (1204 Escherichia coli, 231 other enteric gram-negative bacilli [including Citrobacter spp., Enterobacter spp., Klebsiella spp., Proteus spp., and Salmonella spp.], 31 Pseudomonas spp., 18 coagulase-positive staphylococci, 26 coagulase-negative staphylococci, and 55 streptococci and enterococci) by the National Committee for Clinical Laboratory Standards broth microdilution procedure. Antimicrobial agents tested included ampicillin, ceftiofur, enrofloxacin, erythromycin, florfenicol, gentamicin, neomycin, spectinomycin, sulfamethazine, tetracycline, and trimethoprim/sulfadiazine. Against the E. coli strains tested, ceftiofur, enrofloxacin, gentamicin, and trimethoprim/sulfadiazine were the most active compounds with MIC at which 50% of the strains are at or below (MIC50) = 0.5, < or = 0.03, 0.5, and 0.13 microg/ml, respectively, and MIC at which 90% of the strains are at or below (MIC90) = 1.0, 0.13, 32.0, and 2.0 microg/ml, respectively. Ampicillin, florfenicol, neomycin, and spectinomycin were the next most active compounds against the E. coli strains, with MIC50 = 4.0, 4.0, 16.0, and 16.0 microg/ml, respectively. MIC90 values for these compounds against E. coli strains were > 32.0, 8.0, 512.0, and > 128.0 microg/ml, respectively. The remaining compounds exhibited limited, strain-dependent activity against the E. coli strains tested. As with the E. coli, enrofloxacin, ceftiofur, and trimethoprim/sulfadiazine were also the most active compounds against the 231 other enteric organisms tested, with MIC50 < or = 1.0 microg/ml for all of these genera. The remaining compounds exhibited limited activity against these genera. Against the gram-positive cocci tested, ampicillin, enrofloxacin, ceftiofur, and trimethoprim/sulfadiazine were most active, whereas the remaining compounds exhibited strain-dependent activity. When MIC data for E. coli were summarized separately, differences were observed between the geographic locations for the various antimicrobial agents. In conclusion, ceftiofur, enrofloxacin, and trimethoprim/sulfadiazine were the most active of the compounds tested against all of the bacterial strains. 相似文献
11.
This study was initiated to determine the etiologic and pathogenic significance of an American strain of bovine viral diarrhea (BVD) virus (strain NADL-MD) in enteritis of neonatal calves (calf scours). Three colostrum-fed calves from dams exposed intravenously to BVD virus at 6, 16 and 25 days prepartum, respectively, had moderate diarrhea persisting until the eighth day of life. The BVD virus was isolated from all 3 calves and persisted up to 93 days in 1 calf, indicating either that BVD was transmitted in utero or via the dam's milk. Three specific pathogen free (SPF) calves permitted dams' colostrum for the first 4 feedings and then given milk replacer were exposed orally on the day of birth to BVD virus. One calf died of neonatal enteritis 28 hours post-exposure and at necropsy the BVD virus was isolated from several of its organs. The remaining 2 calves had a mild diarrhea persisting to the eighth day of age. Two calves permitted dams' colostrum ad lib. for 72 hours, and then weaned, were exposed orally to BVD virus. Both calves had a mild persistent diarrhea and BVD virus was isolated from their blood for 56 days post-exposure. Of 13 SPF, colostrum-deprived calves exposed orally or intranasally at birth to the BVD virus, 4 had severe diarrhea and died of neonatal enteritis from 38 hours to 13 days postexposure. Isolations of BVD virus were made from several of the organs of the calves at necropsy. All of the 9 surviving calves had a moderate to severe diarrhea frequently persisting for 7 to 10 days, and BVD virus was isolated from the survivors up to 103 days postexposure. Several strains of Escherichia coli were isolated from calves after the second day of life, but were neither pathogenic for mice, nor serologically related to strains of E. coli usually associated with outbreaks of calf scours. Four colostrum-deprived SPF calves were exposed orally at birth to a strain of E. coli isolated from the intestine of the calf with the most acute symptoms and fatal neonatal enteritis. None of the four calves receiving the E. coli had diarrhea. One calf, however, had respiratory distress and died on day 5. Two SPF colostrum-deprived control calves had neither diarrhea nor respiratory distress. The above findings support the conclusion that BVD virus should not be overlooked as a primary cause of the neonatal calf enteritis complex. 相似文献
12.
Prevalence of antimicrobial drug resistance among over 3000 clinical isolates of animal pathogens in Ontario during 1971-72 has been studied. A high number of multiple resistance patterns is prevalent among members of Enterobacteriaceae, especially Escherichia coli and Salmonella typhimurium. The most common resistance pattern among bovine strains was against not less than six drugs in common use. Among different animal species the bovine population was found to be the source of a high percentage of chloramphenicol resistant E. coli and S. typhimurium organisms. All the isolates resistant to this drug were in addition resistant to three or more other antibiotics of established therapeutic value. All the multiple resistant isolates of S. typhimurium tested had R factors and they transferred most of the resistance determinants including that for chloramphenicol to a recipient E. coli in vitro.Penicillin resistance among Staphylococcus aureus of bovine mammary origin did not appear to be high. Antimicrobial drug susceptibility patterns of staphylococci, streptococci and Corynebacterium sp indicate effective in vitro activity with many antimicrobial agents. 相似文献
13.
Escherichia coli O157:H7 and Salmonella are widely recognized as important agents of foodborne disease with worldwide distribution. The use of ionophores in feeding growing ruminants is widespread in the United States and has attracted recent interest due to the apparent temporal relationship between initial ionophore use and the increase in human E. coli O157:H7 cases. Two experiments were conducted to evaluate the effects of short-term feeding of ionophores on fecal shedding, intestinal concentrations, and antimicrobial susceptibility of E. coli O157:H7 and S. typhimurium in growing lambs. Sixteen lambs were used in each experiment, four lambs per treatment group: monensin, laidlomycin propionate, bambermycin, and a control treatment. Lambs were fed a grain and hay (50:50) diet with their respective ionophore for 12 d before experimental inoculation with E. coli O157:H7 or S. typhimurium. Animals were maintained on their respective diets an additional 12 d, and fecal shedding of inoculated pathogens was monitored daily. Lambs were killed and tissues and contents were sampled from the rumen, cecum, and rectum. No differences (P > 0.05) in fecal shedding of Salmonella or E. coli O157:H7 were observed due to treatment. Occurrence of Salmonella or E. coli in luminal contents and tissue samples from the rumen, cecum, and rectum did not differ (P > 0.05) among treatments. Feeding monensin decreased (P < 0.05) the incidence of scours in sheep infected with Salmonella compared with the other treatments. No differences in antimicrobial susceptibility were found in any of Salmonella or E. coli O157:H7 isolates. Results from these studies indicate that short-term ionophore feeding had very limited effects on E. coli and Salmonella shedding or on antimicrobial susceptibility in experimentally infected lambs. 相似文献
14.
Bacteriostatic doses of 5-methyltryptophan and of 7-azatryptophan exert a complete inhibition on the in vitro production of filtrable hemolysin by Escherichia coli. This inhibition is readily overcome by L-tryptophan, and does not seem to be specific but secondary to an interference with de novo protein synthesis and cell multiplication as is observed with chloramphenicol in sensitive strains. Although the influence of the two tryptophan analogs on hemolysin production and cell multiplication is similar, their mechanism of action at the molecular level appears to be different. The addition of 50 µg/ml 7-azatryptophan which causes an unbalanced growth characterized by an arrest of the cellular division and an increase of cell size, blocks the production of an active hemolysin. Exposure to 4 µg/ml 5-methyltryptophan also prevents cell multiplication and hemolysin production but no sign of unbalanced growth is evident. Mitomycin C in concentrations sufficient to prevent increase in the number of viable units provokes an extreme elongation of E. coli cells and, apparently, does not stop the synthesis of hemolysin. In blocking the production of hemolysin the three inhibitors of protein synthesis used in this study were more effective than mitomycin C an agent known to affect deoxyribonucleic acid synthesis and to induce extrachromosomic genetic factors. Results of conjugation experiments also described here support the finding of other workers that the genetic factor that controls the production of the filtrable hemolysin in E. coli can be transmitted by conjugation. Acridine orange eliminated the hemolytic property from a large proportion of the population of a hemolytic strain which did not carry the R factor, but was little effective in the strains which had received both the R factor and the hemolytic character by conjugation. 相似文献
15.
The aim of the study was to compare the resistance patterns of Escherichia coli isolates from pig herds with or without prophylactic use of anti‐microbial substances. The presented pig units received either antibiotics or oregano as preventive feed additives. The trial was performed from April to October 2001, in the large ‘country‐corner’, Hungary–Rumania–Serbia. Thirty of 39 evaluated herds suffered E. coli O139 K88 ac or ad LT STb caused losses, the remaining were negative for E. coli O139. Thirteen of the selected 30 herds produced with oregano feed supplementation (Oregpig ® Pecs, Hungary) antibiotic‐free pigs. These units had no history of prophylactic antibiotic use since 1995. The remaining 17 herds routinely used prophylactic antibiotic feed supplementation. In each herd, pigs of four different age groups (suckling piglets, weaners, fattening swine and breeding sows), showing the clinical symptoms of wasting, were investigated. E. coli O139 K88 ac or ad LT STb were tested for their resistance to antibiotics, available in this region. Oregano‐fed herds demonstrated high significantly ( P < 0.001) lower MICs ( μg/ml) for ampicillin, doxycyclin, enrofloxacin, gentamycin, oxytetracyclin and sulfamethacin compared to herds with prophylactic use of antibiotics. Resistance to ceftiofur revealed significant ( P < 0.05) differences between the antibiotic‐ or oregano‐treated units. The present results confirm literature data, that prophylactic use of antibiotics likely plays a role in inducing resistance of E. coli and other intestinal bacteria. Thus, imposing greater restrictions on antibiotic use in animal agriculture is likely to reduce but not eliminate the occurrence of resistant isolates. 相似文献
16.
The effects of orally and/or parenterally administered immune serums were evaluated in 36 gnotobiotic pigs infected with an enteropathogenic strain of Escherichia coli. Pigs were euthanatized at predetermined time intervals between 6 and 48 hours prostinfection. The results were evaluated on the basis of: 1) clinical observations, 2) necropsy observations, 3) counts of viable E. coli in segments of the small intestine, 4) attempts to isolate E. coli from the heart, liver, and bile, 5) microscopic examination of fixed intestinal sections to determine the location of E. coli and morphologic evidence of the host response, and 6) determination of the pH of the various portions portions of the gastrointestinal tract. 相似文献
17.
To examine and compare the pathogenicity of cytotoxic necrotising factor (CNF)-producing Escherichia coli, two litters of piglets were infected orally with 10 10E coli O88 or 10 10E coli O32 strains. Of the six piglets infected with E coli O88, two died within 24 hours and three developed blood-stained diarrhoea. The other piglets were killed one, five, six and eight days after infection, when bacterial cultures indicated an overwhelming bacteraemic infection with E coli O88 in the early stages followed by clearance through the large intestine. The pathological changes consisted of an early enteritis, progressing to enterocolitis and a bacteraemic spread to the lungs. The histopathological changes were characteristic of toxaemic effects in brain, heart, liver and kidney, and characterised by congestion, oedema and exudation. Infection with E coli O32 produced a milder but similar enterocolitis, also with bacterial colonisation in the lungs. The histopathological findings again reflected a toxaemia. The enteritis was more persistent after E coli O32 infection and the strain persisted in large numbers in the intestine. No evidence of bacterial adherence to the intestinal mucosa was found with either strain. Enteroinvasion was only evident in one E coli O884-nfected piglet, but the consistent occurrence of interstitial pneumonia showed the predilection of these organisms for the lung. The results confirm the toxigenic properties of CNF +E coli and suggest an important role for this organism in enteric infection of young pigs. 相似文献
18.
The significance of enterotoxin production and proliferative ability of Escherichia coli in the intestinal tract as related to porcine enteric colibacillosis was studied in 68 gnotobiotic pigs. The animals were monocontaminated at seven to ten days of age with eight selected strains of E. coli. The strains were two naturally occurring porcine enteropathogens — P155 (0149:K91;K88a,c:H10) and P307 (08:K87;K88a,b:H19), two nonenteropathogenic strains — P104 (0139:K82:H1) and F11 (018-ab:K?:H14), and four enterotoxigenic derivatives of the above strains — P104(P155), P104(P307), F11(P155) and F11(P307). The response of the animals was evaluated on the basis of clinical observations and necropsy lesions 22 hours after exposure to the organisms. E.coli counts were determined at seven different levels of the intestinal tract. Cell free extracts of the intestinal contents were examined for enterotoxic activity by the ligated pig intestine loop test. All of the strains possessing the enterotoxin plasmid produced enterotoxin in the pig's intestine and were capable of causing diarrhea. The nonenteropathogenic E. coli failed to do so. The strains possessing the P155 enterotoxin plasmid were more virulent than the corresponding derivatives with the P307 enterotoxin plasmid. Strains P155, P307 and P104(P155) proliferated in the upper small intestine at a greater rate and were more virulent than the other strains. The numbers attained in the upper small intestine by the other enterotoxigenic derivatives were comparable to those of their nonenteropathogenic parent strains. It was considered that enterotoxin produced by E. coli was the essential factor for causing a diarrheic response in gnotobiotic pigs. The virulence of each of the tested strains appeared to be governed by the degree of enterotoxicity associated with a particular enterotoxin plasmid, the numbers attained by these organisms in the upper small intestine, (but not in the lower small intestine or in the colon), and by other undetermined factors. 相似文献
19.
In a study of the response of gnotobiotic pigs to coliform infections, 45 one-week-old germfree pigs were divided into five groups and each group was inoculated orally with a different strain of Escherichia coli. Three of these were enteropathogenic swine strains, P307[08:K87(B), K88 a,b (L):H19]; P570 [0138:K81]; P568[0141:K85a,b(B), K88a,b(L):H4], one was a virulent human strain, H224, [026:K60(B6)], and one was a non-enteropathogenic swine strain, P581[OX13:K68]. It was attempted to protect a portion of the pigs with orally administered specific antisera and sera from non-immunized specific pathogenfree (SPF) pigs. Observations were made on the clinical response, bacterial counts of feces and intestinal contents, gross pathological changes, distribution of the organisms in organs and serum hemagglutinin titers. Infection with E. coli P307 resulted in diarrhea, dehydration and death, unless the pig was protected with specific antiserum. The pigs infected with E. coli P570 had a transient diarrhea but retained their appetites and recovered. Those infected with the other three strains remained healthy throughout. No circulating hemagglutinating antibody against the test strains of E. coli could be detected in any of the pigs seven days or earlier post-inoculation. Relationship could not be established between the numbers of viable E. coli in the feces and the presence of clinical colibacillosis. Orally administered specific antiserum afforded protection against strain P307, but did not reduce the number of E. coli in the gut or alter their distribution in the internal organs. This suggested that the protective effect of specific antibody in the intestine was due to its action on a metabolite (enterotoxin) produced by E. coli P307 rather than the organism itself. 相似文献
20.
In this study, we investigated the effects of probiotic, acidifier and synbiotic supplementation on growth performance, mortality rate, intestinal gene expressions, fecal shedding, and organs colonization induced by Escherichia coli in broiler chickens. Six experimental groups were included; negative control group (NC), positive control group (PC), probiotic group (PR), acidifier group (AC), synbiotic group (SY) and colistin sulfate group (CS). Chickens in groups NC and PC were fed a basal diet, while chickens in groups PR, AC, SY, and CS were fed a basal diet containing probiotic, acidifier, synbiotic and colistin sulfate, respectively from the 1st day to the 28th day of age. At 7 days of age, all groups (not NC) were orally challenged with 0.5 ml (1.0?×?109 CFU/ml) E. coli O78. The dietary supplementation of acidifier and synbiotic were sufficient to quell the devastating effects of E. coli infection in broilers. Growth performances represented by body weight gain, feed intake and feed conversion ratio were significantly improved as well as, mortalities were prevented whilst the ileal pro-inflammatory gene expressions (IL-6, IL-8, IL-13, TLR-4, IFN-γ, LITAF, AvBD-2, and AvBD-9) were significantly downregulated and the anti-inflammatory cytokine (IL-10) was significantly increased. In addition, E. coli fecal shedding and organs colonization was significantly diminished. It was concluded that the addition of both acidifier and synbiotic to the diet of broilers infected with E. coli could modulate the intestinal inflammatory responses induced by E. coli infection and minimized the inflammation-induced damage which resulted in improvement in growth performance, prevention of mortalities and reduction of E. coli environmental contamination. 相似文献
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