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1.
Necrotizing enteritis in piglets is caused by the spore-forming anaerobe Clostridium perfringens type C. The pathology is believed to be due to the production of beta-toxin by the agent and the infection tends to persist in affected herds despite appropriate hygiene measures. During the period 1989 to 2001, 35 outbreaks were observed in 15 herds in a limited geographic region in northwestern Switzerland in the canton of Fribourg. Initial outbreaks of acute disease were followed by chronic manifestations of necrotizing enteritis in eleven herds. Since clinical symptoms in case of chronic necrotizing enteritis and of mixed infections were rather non-specific, diagnosis in all herds was confirmed by gross pathological analysis, intestinal histology and bacteriological culture. After initial evaluation in 135 litters (1500 piglets), metaphylaxis consisted of penicillin for outbreaks of acute disease or of amoxycillin-clavulanic acid pending results of laboratory confirmation. Vaccination with a C. perfringens toxoid vaccine (Gletvax 6, also containing E. coli pilus antigens) together with penicillin chemoprophylaxis was used in 2400 litters (27,000 piglets). In 12 to 17% of litters disease recurred during this combined prophylaxis. Necrotizing enteritis persisted in all affected herds throughout the follow-up period.  相似文献   

2.
Pregnant gilts were vaccinated with two doses of alhydrogel adsorbed fimbrial antigens of Escherichia coli (K88ab, K88ac, K99 and 987P) supplemented with beta toxoid of Clostridium perfringens type C. Their piglets, and piglets of nonvaccinated gilts, were subsequently orogastrically challenged with one or other of the four fimbrial types of enteropathogenic E coli. Some of the vaccinated animals were reinjected with a single dose of the vaccine during second gestation and their piglets, and piglets of non-vaccinated sows, were challenged the same way as were litters of gilts. Blood serum and colostra were examined for antibodies to the four fimbrial antigens of E coli and for antitoxin to beta toxin of C perfringens type C. It was found that: (1) a highly significant reduction in mortality and morbidity was achieved in vaccinated litters against all four challenge strains of E coli; (2) excretion of K88ab and K88ac but not of K99 and 987P challenge strains was significantly reduced; (3) revaccination of sows by a single dose of the vaccine during second gestation conferred complete protection against mortality and highly significant protection against morbidity; (4) no correlation was noted between colostral or seroagglutinins to fimbrial antigens of E coli and mortality rates in litters challenged with homologous fimbrial types of E coli, but good correlation was found between colostral precipitins to K88 antigens and mortality rates in litters; (5) antitoxin value in 97 per cent of colostrum of vaccinated sows was 10 iu equivalent of C perfringens type C toxin or more per ml of colostrum.  相似文献   

3.
The aim of this study was to obtain prevalence estimates about the most important enteropathogenic bacteria: Lawsonia intracellularis, Brachyspira hyodysenteriae, Brachyspira pilosicoli, Salmonella enterica and Clostridium perfringens A and C in Hungarian farrow-to-finish pig herds. A total of 31 herds were selected, from where six pooled faecal samples, each containing three individual rectal faecal samples were collected from fattening pigs of 5-6 months of age. All 186 samples were examined by polymerase chain reaction (PCR) for the presence of the pathogens mentioned above. Lawsonia intracellularis was found in 29 herds (93.55%) and in 108 samples (58.06%); B. hyodysenteriae in 14 herds (45.16%) and in 23 samples (12.37%); B. pilosicoli in 19 herds (61.29%) and in 53 samples (28.49%); S. enterica in 17 herds (54.83%) and in 40 samples (21.50%). We detected the presence of C. perfringens A in 19 herds (61.29%) and in 46 samples (24.73%), while C. perfringens C was found in 8 herds (25.81%) and in 11 samples (5.91%). All examined herds were infected with one or more of these agents. Herds with diarrhoea in the mid- to late finishing phase had almost 10 times higher prevalence of B. hyodysenteriae than herds without such a history.  相似文献   

4.
Investigations were performed on shedding of C. perfringens in sows from four different pig farms. In two farms where no outbreaks of necrotizing enteritis had been observed, no strains of C. perfringens producing beta-toxin were detected in the faeces of sows. In contrast, C. perfringens strains producing beta-toxin were detected in sows on both farms suffering outbreaks of acute necrotizing enteritis. Strains of C. perfringens producing beta-toxin were invariably positive for the beta 2-toxin gene. However, strains carrying the beta 2-toxin gene only (i.e. negative for beta-toxin) were present in animals on all farms with roughly similar frequencies (mean 28.2% carriers). Some sows carried C. perfringens strains of both toxin genotypes simultaneously. Whereas these data further support the role of betatoxin as a cause of necrotizing enteritis, the role of beta 2-toxin in intestinal disease of piglets remains unclear. To establish the role of faecal shedding vs. environmental contamination as reservoirs of C. perfringens type C, strains were isolated from teats and feedlot trough swabs (toxin genotype beta/beta 2), as well as from fodder (genotype beta 2). However, sows carried this pathogen intermittently and in small numbers. This renders an individual, reliable diagnosis of carrier sows very difficult. Ribotyping of 34 C. perfringens isolates of different toxin genotypes showed five distinct profiles. Different toxin genotypes can belong to the same ribotype, and the same toxin genotype can be present in different ribotypes. Thus, even if a majority (79.4%) of strains investigated in a limited geographic region belonged to ribotype 1, ribotyping offered discrimination of strains beyond toxin typing.  相似文献   

5.
Field study of coccidial and rotaviral diarrhoea in unweaned piglets   总被引：1，自引：0，他引：1  
A study of diarrhoea in unweaned piglets was carried out in nine herds, with special reference to the enteropathogenic agents which could be demonstrated. Coccidial (Isospora suis) and rotaviral infections were both identified, either singly or in combination. More extensive studies of I suis infection were undertaken in two of the herds and it was found that diarrhoea occurred most commonly in five- to 14-day-old piglets. Piglets with I suis infection were not necessarily diarrhoeic but grew poorly compared to uninfected piglets. I suis infection in litters correlated with oocyst excretion in sows. In herds with I suis infection, amprolium and monensin were used in the sow ration to achieve control, and in one herd oral dosing of piglets with amprolium in the first three or four days of life was carried out.  相似文献   

6.
Clostridium perfringens isolated from lambs with dysentery (n=117) were analysed by a DNA amplification technique, the polymerase chain reaction (PCR), in order to determine the prevalence of the alpha-, beta-, beta 2-, epsilon-, iota- and enterotoxin genes. The most prevalent toxin type of C. perfringens found was type B, containing the alpha-, beta-, and epsilon-toxin genes, representing 46% of the cases with clostridial dysentery. C. perfringens type C containing the alpha-, and beta-toxin genes was isolated in 20% and type D, which is characterized by the alpha- and epsilon-toxin genes, was isolated in 28% of all isolates. The recently discovered, not yet assigned beta 2-toxigenic type of C. perfringens was represented in 6% of all isolates. No C. perfringens type A containing the alpha-toxin alone and no type E, which harbours the ADP-ribosylating iota-toxin, were found in the diseased animals. None of the samples contained the enterotoxin gene. Only one type of C. perfringens was found in a given herd, revealing the epidemiological use of PCR toxin gene typing of C. perfringens. The animals originated from 79 different herds with sizes ranging from 30 to 250 animals, bred in the area of northern Greece.  相似文献   

7.
Beta2 toxin, encoded by the cpb2 gene, has been implicated in the pathogenesis of porcine, equine and bovine enteritis by type A Clostridium perfringens. By incorporating primers to cpb2 into a multiplex genotyping PCR, we screened 3270 field isolates of C. perfringens. Of these, 37.2% were PCR positive for the cpb2 gene. The majority of isolates from cases of porcine enteritis were positive for cpb2 (>85%), and this was even more true for C. perfringens isolated from cases of porcine neonatal enteritis (91.8%). In contrast, isolates from normal pigs only contained cpb2 in 11.1% of cases. The correlation between enteritis in other animal species and the presence of cpb2 was not so strong. cpb2 was found in 21.4% of C. perfringens isolates from cattle with enteritis, and in 47.3% of isolates from calves with enteritis or abomastitis. The prevalence of cpb2 varied with genotype, with type A isolates being positive for this gene in 35.1% of cases. Furthermore, enterotoxigenic type D or type E strains almost always carried cpb2. We cloned a 6xHIS-tagged beta2 (HIS-beta2) and used this protein to raise antiserum against beta2. Culture supernatants from 68 cpb2-positive and 13 cpb2-negative strains were tested for the presence of beta2 by Western blotting. In cpb2-positive isolates of porcine origin, beta2 was almost always detected (96.9%). However, in cpb2-positive isolates from other animal species, only 50.0% expressed beta2 protein. The high rate of cpb2-positivity among strains from neonatal pigs with enteritis and the high correlation of genotype with phenotype, supports the contention that beta2 toxin plays a role in the pathogenesis of these infections. However, it may be important to consider the use of an additional method for the detection of beta2 toxin in non-porcine cpb2-positive isolates when making claims about the role of beta2 in enteritis in non-porcine species.  相似文献   

8.
Faecal samples from 684 litters of suckling piglets from 100 indoor swine herds from all regions of Norway were examined for the presence of Cryptosporidium and Giardia, using sucrose gradient flotation concentration and immunofluorescent staining. Thirty-one (31%) herds and 57 (8.3%) litters tested positive for Cryptosporidium, while 10 (1.5%) litters in 10 different herds (10%) tested positive for Giardia. Molecular characterisation of nine Cryptosporidium isolates demonstrated both C. suis and Cryptosporidium sp. pig genotype II. There was significantly more diarrhoea among the Cryptosporidium positive piglets than among the Cryptosporidium negative piglets. Diarrhoea was not observed amongst litters in which Cryptosporidium sp. pig genotype II was found. There was a significant difference in the Cryptosporidium prevalence between litters from different geographical areas of Norway. This study demonstrates that both Cryptosporidium (C. suis and Cryptosporidium sp. pig genotype II) and Giardia infections are prevalent among suckling piglets in Norway.  相似文献   

9.
Nineteen Clostridium perfringens Type C strains and ten foreign control strains of subtypes C1, C3, and C4 were tested for their toxin formation and spore resistance to heat. The 19 Type C strains had been isolated from unweaned piglets in the context of necrotising enteritis outbreaks in the GDR. The Clostridium perfringens Type C strains formed beta-toxin, but they failed to form epsilon-toxin or gamma-toxin, alpha-toxin was successfully recorded from 15 of the 19 strains tested from unweaned piglets. The minor-lethal toxin fractions were also tested, with delta-toxin being recorded from all strains, non-alpha-delta-theta-toxin from six, theta-toxin from five, and K-toxin from one. Tests for delta-toxin, lambda-toxin, and mu-toxin were negative. The Clostridium perfringens Type C strains isolated in the GDR from unweaned piglets with necrotising enteritis were, basically, identical with those described in Denmark by von Hogh (1967) with regard to toxin formation. Clostridium perfringens strains cultured in broilers with necrotising enteritis were characterised by regular toxin production in the context of alpha, theta, delta as well as non-alpha-delta-theta. They failed to form beta, epsilon, gamma and lambda, while mu-toxin was formed by them quite irregularly. They, consequently, are Type A strains. Resistance to chloramphenicol and/or oxytetracycline was exhibited by 78.5 per cent of 237 tested Clostridium perfringens strains which had been isolated from unweaned piglets and broilers with necrotosing enteritis. Multiple resistance was recorded from 33.9 per cent. All strains were susceptible to penicillin, nitrofurantoin, and erythromycin.  相似文献   

10.
This study comprised 48,931 litters in 89 sow herds. During the study (1976-82) weaning age decreased from approx. 42 days to approx. 30 days. The mean incidence of post-weaning diarrhoea was 6.0% of litters weaned, with little variation by year but with considerable variation among herds. Within the individual herd increased incidence occurred over limited periods, probably associated with specific infections. Litters with diarrhoea during the suckling period had increased risk of post-weaning diarrhoea. The incidence of post-weaning diarrhoea increased with litter size at weaning. Thus, a litter of 11-12 piglets at weaning had 1.2 times higher risk than litters with 8-10 piglets. In contrast to pre-weaning diarrhoea, there was no association between parity of the sow and diarrhoea in the litter after weaning. Litters weaned below 2 weeks of age had a 2-fold risk of developing diarrhoea after weaning and a 2.4-fold higher mortality rate than did litters weaned at 6-7 weeks. Similarly, litters weaned at an individual piglet weight below 3 kg bodyweight had a 3-fold higher risk of developing diarrhoea after weaning and a 5-fold higher mortality rate than did pigs from litters weaned at a bodyweight of 7-8 kg. The incidence of post-weaning diarrhoea decreased with increasing herd size. Piglets from litters with post-weaning diarrhoea had reduced weight gains after weaning and were 2.3 days older at 25 kg bodyweight than piglets from non-diarrhoeic litters. Likewise, diarrhoea after weaning was associated with an increased incidence of diseases of the skin and respiratory tract. Thus the risk of contracting respiratory disease was 4 times greater in diarrhoeic litters.  相似文献   

11.
OBJECTIVE: To determine the percentage of broodmares and foals that shed Clostridium perfringens in their feces and classify the genotypes of those isolates. DESIGN: Prospective cross-sectional study. ANIMALS: 128 broodmares and their foals on 6 equine premises. PROCEDURES: Anaerobic and aerobic bacteriologic cultures were performed on feces collected 3 times from broodmares and foals. All isolates of C. perfringens were genotyped. RESULTS: Clostridium perfringens was isolated from the feces of 90% of 3-day-old foals and 64% of foals at 8 to 12 hours of age. A lower percentage of broodmares and 1- to 2-month-old foals shed C. perfringens in their feces, compared with neonatal foals. Among samples with positive results, C. perfringens type A was the most common genotype identified (85%); C. perfringens type A with the beta2 toxin gene was identified in 12% of samples, C. perfringens type A with the enterotoxin gene was identified in 2.1% of samples, and C. perfringens type C was identified in < 1% of samples. CONCLUSIONS AND CLINICAL RELEVANCE: Clostridium perfringens was identified from the feces of all but 6 foals by 3 days of age and is likely part of the normal microflora of neonatal foals. Most isolates from broodmares and foals are C. perfringens type A; thus, the clinical relevance of culture results alone is questionable. Clostridium perfringens type C, which has been associated with neonatal enterocolitis, is rarely found in the feces of horses.  相似文献   

12.
A study was carried out in the South of Italy to assess the role of clostridia in neonatal diseases of lambs and kids. Eighty-seven lambs and 15 kids belonging to 25 flocks were examined and Clostridium perfringens was the microorganism most commonly identified. C. perfringens isolates were analysed by polymerase chain reaction (PCR), in order to determine the prevalence of the genes cpa, cpb, cpb2, etx, iap and cpe. The most prevalent toxin-type of C. perfringens was found to be type A found in 84% of the cases with clostridial enterotoxaemia. No C. perfringens type B, C or E were found. C. perfringens type D was isolated in 16% of the cases. About 24% of the isolates were cpb2 positive. The prevalence of cpb2 across the different C. perfringens types varied. The beta(2)-toxin gene cpb2 was detected in 4/21 (19%) type A isolates, in 1/2 type D isolates, and in 1/2 type DE (cpe-carrying type D) isolates. The high rate of positivity to cpb2 among the isolates suggests that a vaccine based on the beta(2)-toxin, should be included in the vaccination schedule of the animals to confer adequate protection and to prevent the disease.  相似文献   

13.
There was an epidemic of diarrhoea affecting pigs of all ages in Italy between May 2005 and June 2006. In 63 herds the cause was confirmed as porcine epidemic diarrhoea virus by electron microscopy, immunoelectron microscopy, pcr and serology. Watery diarrhoea without mucus and blood was usually associated with a reduction of feed consumption. In farrowing-to-weaning herds, diarrhoea affected the sows and suckling piglets, and the mortality in newborn piglets was up to 34 per cent. In growers and fatteners the morbidity ranged from 20 to 80 per cent, but there was either no mortality or it was very low. Depending on the size of the herd and the type of operation, the clinical disease lasted for weeks or months.  相似文献   

14.
At present neonatal coccidiosis caused by Isospora suis is known to be an important disease in piglets. The coccidium I. suis was diagnosed as the causative agent of diarrhoeic disease in piglets on a large pig farm with continuous farrowing operation. The diagnosis of coccidiosis was based on clinical history, gross lesions, histopathology, stained impression smears and aided by detection of oocysts in the faeces. Coccidiosis was associated with diarrhoea in piglets at the age of five to fourteen days. The disease was characterized by variable morbidity and only a portion of the litters was usually affected at one time. The piglets appeared listless, and suffered from yellow watery scours progressing to yellow pasty scours over a three- to five-day period. The lack of response to common antimicrobial therapy, and/or vaccination of sows for E. coli was observed. The prophylactic and therapeutic efficacy of tortrazuril (Baycox, Bayer) against coccidiosis was evaluated in naturally infected piglets. Tortrazuril at a dose of 20 mg/kg, given perorally to each piglet on days 6 and 8 of age, proved to be efficacious in preventing clinical coccidiosis in piglets. Tortrazuril fully controlled the oocyst output, prevented the development of diarrhoea but not improved the weight gains in three-week-old piglets if compared to the untreated controls. The prophylactic and therapeutic efficacy of tortrazuril was compared with another drug--amprolium (Amprovin, MSD). Amprolium at a dose of 100 mg/kg, given perorally to piglets from day 6 to 8 of age, was not efficacious in preventing clinical porcine neonatal coccidiosis. Amprolium reduced the oocyst output, but not prevented the development of diarrhoea. Tortrazuril (Baycox, Bayer) is clearly effective against porcine neonatal coccidiosis caused by I. suis.  相似文献   

15.
The prevalence of rotavirus infection was studied in 1090 litters from 26 sow herds. Samples of normal, semifluid and watery stools were examined for rotavirus by an ELISA-test on faeces. Rotavirus was detected in 77% of the herds and in 30.5% of the litters (prevalence rates). The highest prevalence rate was seen in piglets between 21 and 41 days of age. Gilts' litters had a very high prevalence during the first week of life. Apart from this, no difference was found between litters from gilts and older sows. Rotavirus was detected more frequently in semiliquid, loose stools than in normal or watery stools, and an association between virus detection and diarrhoea could not be demonstrated. However, litters which shedded rotavirus during the suckling period had lower weight gains and higher incidence rates of respiratory diseases than virus-free litters. Litters weaned at 2 weeks in battery cages had slightly increased risk of shedding rotavirus compared to litters weaned in more traditional systems. The study revealed that rotavirus is widespread in Danish swine herds. The findings give evidence to suggest that the type of mild diarrhoea in 3-week-old piglets known as steatorrhoea or "white scours" may be associated with rotavirus infection, possibly in combination with E. coli and other agents. The high prevalence in piglets weaned at 2 weeks plus the higher morbidity and mortality among such piglets sustain the conclusion that piglets should not be weaned before 3 weeks of age or below a body weight of 6-7 kg.  相似文献   

16.
The study comprised 70,796 litters in 104 sow herds, observed from 1976 through 1982. Weaning age decreased from approx. 42 days to approx. 30 days during the observation period. Diseases and symptoms were recorded together with production parameters (feeding, barn construction, economic returns etc.). The mean incidence rate of pre-weaning diarrhoea was 6.8% of litters, with considerable inter-herd differences (incidence rates from 0 to approx. 50%). There was a slight increase in incidence during the autumn (August through October). Incidence rates increased with litter size, with a peak incidence in litters of 11-13 piglets, and decreased with increasing parity of the sow. There was a positive association between occurrence of arthritis and pre-weaning diarrhoea in the litters, and litters from sows with post parturient disease (MMA complex) had 1.8 times higher risk of getting diarrhoea than litters from healthy sows. No important differences among breeds were found. Small herds (less than 200 farrowings per year) had higher incidence rates than large herds (400-499 farrowings per year). Herds with a gilt proportion above 30% had an incidence rate of 12.3%, i.e. nearly twice as high as the overall mean (6.8%). There was a trend towards a higher incidence rate in litters kept in traditional pens (i.e. large pens with solid floor and loose sows) than in intensive pens (i.e. small pens with slatted flooring and tethered sows). The overall pre-weaning mortality rate was 16.2% of pigs born, half of which was due to stillbirths (6.3%) and overlaid piglets (2.2%). In litters with pre-weaning diarrhoea, the mortality rate was 19%, compared to 13% in litters without occurrence of diarrhoea. This difference accounts for an excess loss of 0.6 piglets from birth to weaning in diarrhoeic vs. non-diarrhoeic litters. Piglets from litters with pre-weaning diarrhoea had reduced weight gain. Thus, on the average, they were 2.2 days older at 25 kg bodyweight and weighed 0.4 kg less at 30 days than piglets from non-diarrhoeic litters. Also, litters with pre-weaning diarrhoea had a significantly increased risk of post-weaning diarrhoea. The present information forms a basis for defining acceptable disease thresholds in suckling litters in intensively managed herds.  相似文献   

17.
Clostridial enteric infections in pigs.   总被引：1，自引：0，他引：1  
Clostridium perfringens types A and C and Clostridium difficile are the principal enteric clostridial pathogens of swine. History, clinical signs of disease, and gross and microscopic findings form the basis for a presumptive diagnosis of C. perfringens type-C enteritis. Confirmation is based on isolation of large numbers of type-C C. perfringens and/or detection of beta toxin in intestinal contents. Diagnosis of C. perfringens type-A infection, however, remains controversial, mostly because the condition has not been well defined and because type-A organisms and their most important major (alpha) toxin can be found in intestinal contents of healthy and diseased pigs. Isolation of large numbers of C. perfringens type A from intestinal contents, in the absence of other enteric pathogens, is the most reliable criterion on which to base a diagnosis. Recently, beta2 (CPB2) toxin-producing C. perfringens type A has been linked to disease in piglets and other animals. However, implication of CPB2 in pathogenesis of porcine infections is based principally on isolation of C. perfringens carrying cpb2, the gene encoding CPB2, and the specific role of CPB2 in enteric disease of pigs remains to be fully defined. Clostridium difficile can also be a normal inhabitant of the intestine of healthy pigs, and diagnosis of enteric infection with this microorganism is based on detection of its toxins in feces or intestinal contents.  相似文献   

18.
Potential risk factors for clinical signs of post-weaning multisystemic wasting syndrome (PMWS) and porcine dermatitis and nephropathy syndrome (PDNS) in pigs in the Netherlands were investigated in a matched case-control study using a questionnaire (personal interview). Eighty-two pig farmers were questioned about management, hygiene, husbandry systems, disease history, and preventive health care. In this study, 30 pig herds with (cases) and 30 pig herds without (controls) characteristic clinical signs of PMWS were compared. For PDNS, 11 pig herds with (cases) and II pig herds without (controls) characteristic clinical signs of PDNS were compared. Univariate analysis (P < 0.10) showed that the following occurred relatively more often in the PMWS case herds than in the control herds: 1) clinical signs of PDNS, porcine reproductive and respiratory syndrome (PRRS), porcine parvovirus (PPV) infections, meningitis, coccidiosis, and pre-weaning diarrhoea observed by the farmer; 2) vaccination against PRRS and mycoplasma; 3) non-optimal climatic conditions in the nursery rooms, a large variation in weaning age, a high occurrence of cross-fostering of piglets, a large number of sows with lactation problems, poor colostrum intake by piglets; and 4) (historical) use of breeding stock (including semen for artificial insemination) of Anglo-Saxon origin. In the final multivariate statistical model, one variable remained significantly associated with PMWS case herds, namely, the presence of clinical signs of PRRS (and/or the associated use of vaccination against PRRS). It should be noted that in almost all cases animals were vaccinated against PRRS because of clinical signs of PRRS that appeared a few months after the first occurrence of clinical signs of PMWS. This excludes PRRS vaccination as a primary factor in causing PMWS. Analysis of the PDNS case-control data showed comparable results with those of the PMWS study. In the final statistical model, the presence of clinical signs of PRRS (and/or the associated use of vaccination against PRRS) was significantly associated with PDNS case herds.  相似文献   

19.
The efficacy of a new vaccine against neonatal Escherichia coli diarrhoea in piglets containing purified F4ab, F4ac, F5 and F6 fimbriae and detoxified heat-labile toxin (LT) was tested in challenge experiments by the method described by the European Pharmacopoeia (3rd edn, EDQM, Council of Europe, Strasbourg, France). A group of 11 young sows from a herd without E. coli problems was vaccinated 6-8 and 2-4 weeks prior to expected farrowing and another group of nine young sows were non-vaccinated controls. Escherichia coli antibody titres were determined in serum samples taken from the sows before first vaccination and before farrowing and in colostrum samples. The newborn piglets were allowed to suckle colostrum from their mother immediately after birth. The piglets were marked with individually numbered ear tags. Approximately 12 h after birth, 118 piglets from vaccinated sows and 79 piglets from non-vaccinated control sows were challenged by oral instillation of 5 ml of a freshly prepared culture of one of the challenge strains [O8:K87:F4ab (LT+) or O149:K91:F4ac (LT+) or O9:K30:F5 or O9:K103:F6 respectively]. The challenge cultures contained as a mean 6.8x10(9) CFU/ml. After challenge the piglets were observed for 7 days and mortality and morbidity were recorded. Vaccinated sows developed significant levels of antibody titres in colostrum and serum. Control sows stayed at a low/seronegative level. The protective efficacy was excellent because 66.7-87.5% of the piglets from vaccinated sows remained without clinical signs after challenge. Only 0.0-28.0% of the piglets from non-vaccinated sows remained healthy and more than 47.1% of the piglets in this group died after challenge. It is concluded that the new vaccine is very effective in protection of piglets against neonatal E. coli diarrhoea.  相似文献   

20.
鸡卵黄抗体在防治仔猪大肠杆菌性腹泻中的应用   总被引：2，自引：0，他引：2  
仔猪大肠杆菌性腹泻病的致病过程主要与产肠毒素型大肠杆菌菌毛介导的粘附作用和产肠毒素密切相关，用禽菌毛抗原免疫产蛋母鸡制备卵黄抗体，在初生仔猪和断奶仔猪的人工感染实验中，口服卵黄抗体能降低腹泻程度和仔猪的死亡率；在商业性猪场的实验表明，卵黄抗体能降低提前断奶仔猪的腹泻发生率，并且有利于仔猪的增重，鸡卵黄抗体是仔猪大肠杆菌性腹泻病的一种新的防治方法，本文就国内外鸡卵黄抗体防治仔猪大肠杆菌腹泻的研究概况作了简要介绍。  相似文献   

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