Experimental exposure of young pigs using a pathogenic strain of Streptococcus suis serotype 2 and evaluation of this method for disease prevention.

Control of Streptococcus suis infections and associated disease have proven to be a difficult challenge under most farm conditions. The objective of this study was to experimentally expose young pigs with a pathogenic strain of S. suis serotype 2 as a means of controlling the disease in a commercial swine farm. Prior to the start of the study, the pathogenic S. suis strain responsible for mortality in the farm was identified and used to experimentally inoculate baby piglets. Over a 3-week period, groups of pigs were selected (100 pigs/wk) and divided into 2 groups: control (50 pigs/week) and experimentally exposed (50 pigs/week). Pigs in the experimentally exposed group were inoculated at 5 d old by tonsillar swabbing with the pathogenic S. suis farm isolate. The effect of exposure with this pathogenic strain was evaluated during the nursery and finishing stages and was based on: morbidity (pigs with central nervous signs (CNS) and/or lameness), mortality and number of treatments required by pigs that had either CNS or lameness. The relative risk (RR) of acquiring disease due to S. suis infection was also calculated. Results showed that morbidity in the experimentally exposed groups was lower than in the control group and these results were statistically different (P = 0.006). Experimentally exposed pigs also showed a statistically significant reduction in lameness problems (P = 0.012), but not in CNS (P = 0.20) or mortality (P = 0.59). Pigs in the control group had an increased RR of 4.76, 8.77 and 2.7 for morbidity, to have lameness or to have CNS signs, respectively. In conclusion, experimental exposure of young pigs with the farm's pathogenic S. suis strain at a young age, had a positive effect in reducing clinical signs characteristics of S. suis infection. This method constitutes a novel approach to the control of S. suis infections in swine farms.     

Efficacy of tiamulin against experimentally induced Streptococcus suis type-2 infection in swine

Eighteen 4-week-old pigs were used in a study to evaluate tiamulin in drinking water for control of experimentally induced Streptococcus suis type-2 infection. Pigs in groups A and B (n = 6 pigs/group) were aerosolized with a logarithmic-growth phase culture of S suis type 2, whereas pigs in group C (n = 6 pigs) served as noninfected and nonmedicated controls. After exposure to S suis, pigs in group B were given 180 mg of tiamulin/L of drinking water for 5 days. Pigs in group B consumed more feed (P = 0.009) and gained body weight faster (P = 0.02) than did pigs in group A. Pigs in group A had higher rectal temperature (P = 0.05) for up to 7 days after S suis exposure, higher clinical sign scores (P = 0.008), higher serum cortisol concentration on days 7 and 14, higher gross lesion scores (P = 0.03), and higher microscopic lesion scores (P = 0.01) than did pigs in groups B and C. Gross and microscopic lesions in pigs of groups A and B included meningitis, pneumonia, pleuritis, pericarditis, peritonitis, and synovitis of variable severity. Streptococcus suis type 2 was recovered from tissue specimens of 2 group-A pigs and 1 group-B pig. Data indicated that tiamulin administered via drinking water significantly reduced the effects of S suis type-2 infection.     

Effects of experimentally induced Streptococcus suis infection on the pharmacokinetics of penicillin G in pigs

The pharmacokinetics of potassium penicillin G were studied in both healthy (n = 8) and experimentally Streptococcus-suis-infected (n = 6) pigs following intramuscular administration (15,000 iu/kg). Streptococcus-suis infection was induced artificially in young cross-bred pigs by subcutaneous inoculation with 9 x 10(8) to 10(9) colony-forming units of S. suis. The rectal temperature of infected pigs was significantly increased (P less than 0.01) before penicillin G injection and this was maintained for 8 h after the drug was given. Other clinical symptoms were also present. The serum concentration-time data for penicillin were found to fit a one-compartment open model with first-order absorption in the two groups of pigs. Significant changes were not observed between healthy and diseased pigs in following parameters: A, Ka, Ke and Tmax. However, in diseased pigs, significant increases (P less than 0.01) were found in Vd and ClB, and significant decreases (P less than 0.01) in Cmax and AUC occurred. The increased body clearance (ClB) and greater apparent volume of distribution (Vd) of penicillin G could partly explain why the serum values of the drug were much lower in diseased pigs than in healthy pigs.     

Streptococcus suis serotypes associated with disease in weaned pigs

Streptococcus suis was recovered from 9 outbreaks of septicaemia and meningitis in weaned pigs between 1979 and 1983. Fifteen isolates from 7 outbreaks were identified as S. suis type 9, and 3 isolates from 2 outbreaks as S. suis type 2. Three further isolates of S. suis type 2 and an isolate of S. suis type 3 were recovered from cases of bronchopneumonia in weaned pigs from 4 other piggeries.     

Colonization of suckling pigs by Streptococcus suis with particular reference to pathogenic serotype 2 strains.

Three swine commercial farms with high mortality rates in nursery pigs due to Streptococcus suis serotype 2 were studied. Brain samples from diseased animals were collected for a period of 6 to 10 mo and used to isolate the strain that was responsible for the mortality (virulent strain) in each farm. Tonsil swabs from piglets at 5, 10 and 15 d were taken to assess both total colonization and colonization by the virulent strain. The effect of sow vaccination against S. suis on colonization was evaluated in 1 of the farms. All suspect tonsil isolates were identified biochemically and then tested against serotype 2. The genomic patterns of serotype 2 isolates were compared to that of the virulent strain using Rep-PCR. Results showed that total colonization by S. suis occurred very early in the pigs' life, with most animals being colonized by weaning age. Prevalence of colonization by serotype 2 strains was much lower than total colonization. After comparing serotype 2 isolates with the virulent strains, only 1 tonsillar isolate had the same genomic pattern as the virulent strain and it belonged to a 4-week-old weaned pig. The genomic pattern of the virulent strain was not found in any tonsillar isolate from 15-day-old or younger pigs. Although limited by sample size, sow vaccination against S. suis increased total colonization at the same time significantly decreasing colonization by serotype 2 strains. Even though most pigs are colonized early in age by S. suis, colonization by the virulent strain is of low prevalence and delayed in time. This could constitute a risk factor for developing the disease later in time, because animals would be colonized when maternal immunity is no longer present, allowing the organism to become systemic.     

Inoculation of pigs with Streptococcus suis type 2 alone or in combination with pseudorabies virus.

Pigs (9 [+/- 1] weeks old) were inoculated with Streptococcus suis type 2, pseudorabies virus (PRV), or both. For each pig of groups A, B, and C the inoculum of S suis was 10(9) colony-forming units. For each pig of groups A, B, and D the inoculum of PRV was 5 x 10(3) TCID50 of either PRV strain 4892 (group A, n = 9) or PRV isolate B (group B, n = 9). The PRV strain 4892 is a highly virulent strain; isolate B causes mild clinical signs of infection in inoculated pigs. Group-C pigs (n = 9) were given S suis alone, and group-D pigs (n = 3) were inoculated only with PRV isolate B. Clinical signs of infection and development of lesions were readily seen in pigs of groups A, B, and C. Duration and severity of clinical signs of disease and lesions were reduced in pigs of group C, compared with those of the other 2 groups. Lesions, such as polyarthritis and fibrinous pericarditis, were more abundant and acute in the groups of pigs given mixed challenge exposure, compared with pigs inoculated exclusively with S suis type 2 (group C). The group of pigs inoculated with PRV isolate B alone did not manifest clinical signs of disease or lesions. Average daily gain for group-C pigs was higher, compared with that of other groups; the difference was statistically significant at P less than 0.02 and P less than 0.05 for groups B and D, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)     

Influence of ampicillin, ceftiofur, attenuated live PRRSV vaccine, and reduced dose Streptococcus suis exposure on disease associated with PRRSV and S. suis coinfection

The objective of this research was to evaluate the efficacy of two antimicrobials (ampicillin and ceftiofur), a modified-live porcine reproductive and respiratory syndrome virus (PRRSV) vaccine, and low dose exposure to Streptococcus suis on disease associated with PRRSV/S. suis coinfection. Fifty-six, crossbred, PRRSV-free pigs were weaned at 10-12 days of age and randomly assigned to five treatment groups. All pigs were inoculated with 2ml of 10(6.4) TCID50/ml of high virulence PRRSV isolate VR-2385 intranasally at 29-31 days of age (day 0 of the study) followed 7 days later by intranasal inoculation with 2ml of 10(8.9)colony forming units(CFU)/ml S. suis type 2 isolate ISU VDL #40634/94. Pigs in group 1 (n=10) served as untreated infected positive controls. Pigs in group 2 (n=12) were treated with 5.0 mg/kg ceftiofur hydrochloride intramuscularly (IM) on days 8, 11, and 14. Pigs in group 3 (n=11) were treated with 11 mg/kg ampicillin IM on days 8-10. Pigs in group 4 (n=12) were vaccinated 14 days prior to PRRSV challenge with a commercial modified-live PRRSV vaccine. Pigs in group 5 (n=11) were exposed to a 1:100 dilution of the S. suis challenge inoculum 19 days prior to S. suis challenge. Mortality was 80, 25, 82, 83, and 36% in groups 1-5, respectively. The reduced dose S. suis exposure had some residual virulence, evidenced by S. suis induced meningitis in two pigs after exposure. Treatment with ceftiofur hydrochloride and reduced dose exposure to S. suis were the only treatments which significantly (P<0.05) reduced mortality associated with PRRSV/S. suis coinfection, significantly (P<0.05) reduced recovery of S. suis from tissues at necropsy, and significantly (P<0.05) reduced the severity of gross lung lesions.     

Passive immunization of pigs against experimental infection with Streptococcus suis serotype 2

The safety and protective efficacy of a horse antiserum raised against inactivated whole cell preparations of Streptococcus suis serotype 2 was investigated in pigs by experimental challenge. The antiserum was evaluated in two similar experiments each comprising 12 4-week-old pigs treated with 6 ml of antiserum the day before challenge and four pigs used as challenge controls. Pigs were infected by subcutaneous injection with approximately 10(11) colony forming units of S. suis serotype 2. Clinical disease in the pigs that could be attributed to infection with S. suis was reduced from 88 to 35% (P = 0.015). The percentage of pigs with lesions that could be associated with S. suis was reduced from 88 to 22% (P = 0.002) and isolation of S. suis serotype 2 was reduced from five (63%) out of eight pigs in the combined challenge control groups to 3 (13%) out of 23 pigs in the combined treatment groups. These results indicate that passive immunization of pigs may be a way to reduce or control S. suis serotype 2 infections in pigs.     

Rapid detection of Streptococcus suis serotype 2 in weaned pigs

A survey to detect Streptococcus suis serotype 2 in 1,716 weaned pigs was done in Quebec. Forty-nine sow herds were included in this survey: in 26 herds, S suis serotype 2 had been isolated during the preceding 12 months and in 23 herds (control), the organism had not been detected during a previous study. Swab specimens of the nasal cavity and tonsils of pigs were obtained for bacteriologic culture, and S suis serotype 2 was easily detected by the use of brain-heart infusion agar containing a Streptococcus-selective supplement and 5% goat antiserum raised against S suis serotype 2. After measurement of the diameter of the precipitation zone of 539 isolates, a slide agglutination test was performed to identify the S suis serotype 2 isolates. The mean precipitation zone diameter obtained for group S suis serotype 2 was larger (P less than 0.001) than that for the group designated as "others". With slide agglutination test results as reference and on the basis of discriminant analysis to stimulate detection of S suis serotype 2, 93.1% of all isolates were correctly classified, using the precipitation zone diameter as unique classification criterion. Relative specificity was 94.5% and relative sensitivity was 88.7%. Use of the precipitation zone diameter on a quantitative basis led to the proposal of a simple and reliable technique to screen swine herds for S suis serotype 2 in weaned pigs. Nasal and tonsillar swab specimens were obtained and analyzed concurrently for S suis serotype 2. The organism was found in both sites in only 20.4% of 103 carrier pigs.(ABSTRACT TRUNCATED AT 250 WORDS)     

Streptococcus suis type 2 infections in pigs in the Netherlands (Part two)

Since 1983 some pig breeding and fattening farms in the Netherlands have been faced with a considerable mortality in pigs due to Streptococcus suis type 2 infections. The most predominant clinical feature of S. suis type 2 infection is meningitis, although sudden deaths often occur. It was noted that some affected farms had imported breeding stock from the United Kingdom. Tonsils of slaughter pigs were collected from herds with and without a history of S. suis type 2 infections. Bacteriological examination was done by using an elective-selective medium. No significant difference was found in carrier rates of S. suis type 2 between clinically healthy and affected herds (38% vs. 45%). A cohort study was carried out by regular bacteriological examination of tonsil biopsies on a farm with a high incidence of streptococcal meningitis. Twenty-seven percent of the pigs were carriers of S. suis type 2 at nine weeks of age. Possible methods for disease control are discussed.     

Molecular characterization of Cryptosporidium isolates from pigs in Zaragoza (northeastern Spain)

A total of 142 stool specimens from pigs on 24 farms from the province of Zaragoza (northeastern Spain) were screened for Cryptosporidium spp. Samples were first analysed by routine techniques (formalin-ethyl acetate sedimentation method and modified Ziehl-Neelsen stain) selecting those microscopically positive for genetic characterization. Cryptosporidium species and genotypes were determined by a nested PCR-RFLP technique at the 18S ribosomal DNA locus and sequencing of the PCR-positive secondary products. Cryptosporidium oocysts were microscopically identified in the faeces of 32 pigs (22.5%) from 15 farms (62.5%). Infected animals included 23 weaned piglets (30.7%), 5 fattening pigs (11.9%) and 4 sows (16%). Diarrhoea was not detected in any of the infected pigs. The molecular characterization was successfully performed in 26 samples from 14 farms. Cryptosporidium suis was found in 10 specimens from 7 farms (nine weaned piglets and one sow) and the Cryptosporidium pig genotype II in 16 samples from 10 farms (13 weaned piglets and 3 fattening pigs). Both C. suis and the pig genotype II were concurrently detected on three farms.     

Efficacy of an in-feed preparation of ivermectin against endoparasites and scabies mites in swine.

In 2 trials, the efficacy of an in-feed preparation of ivermectin was evaluated in 40 pigs naturally infected with endoparasites and Sarcoptes scabiei var suis. Treated pigs (n = 10 in each trial) were fed a ration containing 2 ppm ivermectin for 7 days, followed by consumption of a nonmedicated ration for the remainder of the trial. Control pigs (n = 10 in each trial) were fed a complete, nonmedicated ration for the duration of the trial. Pigs in trial A were monitored for 14 days after treatment; those in trial B were monitored for 35 days after treatment. In trial A, treatment efficacy of ivermectin was 100% against Ascaris suum, Physocephalus sexalatus, Oesophagostomum dentatum, O brevicaudum, Metastrongylus spp; 99.8% against Ascarops strongylina; 90.9% against Trichuris suis; and 13.1% against Macracanthorhynchus hirudinaceus. At the terminus of the trial, statistically significant (P less than 0.05) differences were observed between numbers of treated and control pigs infected with A suum, Ascarops strongylina, and Oesophagostomum spp. On posttreatment day 14, S scabiei were not found in any scrapings taken from treated pigs, but were found in scrapings from 3 of 10 control pigs. The number of infested pigs in the treatment group was not statistically different from the number of infested pigs in the control group. In trial B, treatment efficacy was 100% for A suum and Metastrongylus spp; 96.9% for Ascarops strongylina; and 76.9% for M hirudinaceus. At the terminus of the trial, statistically significant (P less than 0.05) differences were evident between numbers of treated and control pigs infected with A suum, Ascarops strongylina, and Metastrongylus spp.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of experimentally induced Isospora suis infection on morbidity, mortality, and weight gains in nursing pigs

Forty-nine pigs from 6 litters were inoculated at 3 days of age with 300,000 sporulated oocysts of Isospora suis to determine the effects of neonatal coccidiosis on morbidity, mortality, and weight gain in nursing pigs. Fifty-one control pigs from 6 litters were not inoculated. Three to 5 days after inoculation, the inoculated pigs developed a nonhemorrhagic diarrhea, generally lasting 6 to 10 days, that lead to visible dehydration, loss of condition, and 20.4% mortality. Control pigs did not die or develop coccidiosis during the 3-week study and had significantly (P less than 0.05) greater body weights at 7, 14, and 21 days of age than did the inoculated pigs.     

Evaluation of a ceftiofur-washed whole cell Streptococcus suis bacterin in pigs

The efficacy of currently available washed whole cell Streptococcus suis bacterins is generally poor. We developed and tested the efficacy of a novel ceftiofur-washed whole cell bacterin. Sixty-six, 2-week-old specific pathogen free (SPF) pigs were randomly divided into 5 groups. Three groups were vaccinated 28 and 14 d prior to challenge. The 3 ceftiofur-washed whole cell bacterins each contained 1 of 3 different adjuvants (Montanide ISA 25, Montanide ISA 50, and Saponin). Pigs exhibiting severe central nervous system disease or severe joint swelling and lameness were euthanized immediately and necropsied. All remaining pigs were necropsied at 14 d post inoculation. The ceftiofur-washed whole cell S. suis bacterin with Montanide ISA 50 adjuvant significantly (P < 0.05) reduced bacteremia, meningitis, pneumonia, and mortality associated with S. suis challenge. Further work on this novel approach to bacterin production is warranted.     

Streptococcus suis type 2 infections in pigs in the Netherlands (part two)

Summary

Since 1983 some pig breeding and fattening farms in the Netherlands have been faced with a considerable mortality in pigs due to Streptococcus suis type 2 infections. The most predominant clinical feature of S. suis type 2 infection is meningitis, although sudden deaths often occur. It was noted that some affected farms had imported breeding stock from the United Kingdom.

Tonsils of slaughter pigs were collected from herds with and without a history of S. suis type 2 infections. Bacteriological examination was done by using an elective‐selective medium. No significant difference was found in carrier rates of S. suis type 2 between clinically healthy and affected herds (38% vs. 45%).

A cohort study was carried out by regular bacteriological examination of tonsil biopsies on a farm with a high incidence of streptococcal meningitis. Twenty‐seven percent of the pigs were carriers of S. suis type 2 at nine weeks of age. Possible methods for disease control are discussed.     

Pathogenesis of porcine reproductive and respiratory syndrome virus-induced increase in susceptibility to Streptococcus suis infection

Eighty 3-week-old crossbred pigs were randomly assigned to six groups (13-14 pigs/group). Group 1 pigs served as uninoculated controls, group 2 pigs were inoculated intranasally (i.n.) with Streptococcus suis serotype 2, group 3 pigs were inoculated i.n. with a modified live porcine reproductive and respiratory syndrome virus (PRRSV) vaccine, group 4 pigs were inoculated i.n. with the same vaccine and with S. suis, group 5 pigs were inoculated i.n. with VR-2385 (a high-virulence strain of PRRSV), and group 6 pigs were inoculated i.n. with VR-2385 and S. suis. Pigs exposed to both PRRSV and S. suis were inoculated with PRRSV 7 days prior to S. suis inoculation. The pigs were 26 days old when inoculated with S. suis. Respiratory disease was significantly more severe in groups 5 and 6. Mortality rate was the highest in group 6 (87.5%). This rate was significantly higher than that observed in all other groups except group 4 (37.5%). The mortality rate in group 2, inoculated with S. suis alone, was 14.3%. No pigs from groups 1, 3, or 5 died prior to the scheduled necropsies at 10 and 28 days postinoculation with PRRSV (DPI). To study the effect of PRRSV and/or S. suis on pulmonary clearance by pulmonary intravascular macrophages, six pigs from each group were intravenously infused with 3% copper phthalocyanine tetrasulfonic acid in saline prior to necropsy at 10 DPI. Mean copper levels in the lungs of pigs in groups 2, 5, and 6 were significantly lower than those in control pigs. The mean percentage of lung tissue grossly affected by pneumonia at 10 DPI was 0%, 1%, 0%, 3%, 64%, and 62% for groups 1-6, respectively. Both gross and microscopic interstitial pneumonia lesions were significantly more severe in the VR2385-inoculated groups (5 and 6). PRRSV was isolated from bronchoalveolar lavage fluid collected at necropsy from 100% of the pigs in groups 5 and 6, 71.4% of pigs in group 4, 38.5% of pigs in group 3, and none of the pigs in groups 1 or 2. Streptococcus suis serotype 2 was cultured from the internal tissues of 7.7%, 28.6%, and 78.6% of the pigs in groups 2, 4, and 6, respectively. Streptococcus suis serotype 2 was isolated from whole blood at necropsy from 7.7%, 35.7%, and 78.6% of pigs in groups 2, 4, and 6, respectively. Significantly more pigs in group 6 had S. suis isolated from whole blood and internal tissues. In summary, both high-virulence PRRSV and S. suis decreased copper clearance, and the incidence of isolation of S. suis and PRRSV was higher in dually inoculated pigs. PRRSV-induced suppression of pulmonary intravascular macrophage function may in part explain PRRSV-associated increased susceptibility to S. suis infection.     

Effect of pyrantel tartrate and carbadox on acquisition of the swine kidneyworm (Stephanurus dentatus) and other parasites by pigs on contaminated lots.

A combination of pyrantel tartrate (106 mg/kg of body weight) and carbadox (55 mg/kg of body weight) in ground feed was fed to 20 weaned pigs (av wt, 14.4 kg) for 42 days. Another group of 20 pigs included nontreated controls. The pigs were farrowed and suckled in a slat-floored farrowing house and had minimal exposure to the small intestinal threadworm (Stronglyoides ransomi) until they were placed on severely contaminated dirt lots at the start of the experiment. Five pigs from each of the two groups were necropsied on day 42. Carbadox was withheld from the feed for the 15 remaining treated pigs. All other pigs were necropsied when they attained market weight, 72 to 83 days layer. Treated pigs killed at market weight had 44% fewer (P less than 0.10) kidneyworms (Stephanurus dentatus) than did control pigs. A 17% increase (P less than 0.01) in the weights of livers of control pigs when compared with treated market-weight pigs was associated with an increase of fibrotic hepatic tissue of control pigs. Worm infections were reduced in the treated market-weight pigs: by 96% (P less than 0.05) for the large roundworm (Ascaris suum), 77% (P less than 0.01) for nodular worms (Oesophagostomum spp), and 64% (P less than 0.01) for the intestinal threadworm. There was some evidence for prophylaxis in market-weight pigs (P less than 0.10) against lungworms (Metastrongylus spp), but none against the whipworm (Trichuris suis) or thick stomach worms (Ascarops strongylina and Physocephalus sexalatus). Pigs given the pyrantel tartrate in feed until attaining market weight maintained a feed-to-gain ratio superior (7.1%) to that of nontreated pigs.     

Controlling Salmonella infection in weanling pigs through water delivery of direct-fed microbials or organic acids: Part II. Effects on intestinal histology and active nutrient transport

The objective of this study was to evaluate the effects of water-delivered, direct-fed microbials (DFM) or organic acids on intestinal morphology and active nutrient absorption in weanling pigs after deliberate Salmonella infection. Pigs (n = 88) were weaned at 19 ± 2 d of age and assigned to 1 of the following treatments, which were administered for 14 d: 1) control diet; 2) control diet + DFM (Enterococcus faecium, Bacillus subtilis, and Bacillus licheniformis) in drinking water at 10(9) cfu/L for each strain of bacteria; 3) control diet + organic acid-based blend (predominantly propionic, acetic, and benzoic acids) in drinking water at 2.58 mL/L; and 4) control diet + 55 mg/kg carbadox. Pigs were challenged with 10(10) cfu Salmonella enterica var Typhimurium 6 d after commencement of treatments. Pigs (n = 22/d) were harvested before Salmonella challenge and on d 2, 4, and 8 after challenge. Duodenal, jejunal, and ileal mucosal tissues were sampled for measurement of villus height and crypt depth. Jejunal tissue was sampled for determination of active nutrient absorption in modified Ussing chambers. Duodenal villus height was greater in pigs fed in-feed antibiotic before infection (P < 0.05). Jejunal crypts were deeper in DFM- and acid-treated pigs on d 4 after infection compared with all other treatments (P < 0.05). Salmonella infection resulted in a linear decrease in phosphorus (P < 0.001) and glucose (P < 0.05) active transport, and an increase (P < 0.001) in glutamine uptake immediately after challenge. Salmonella infection reduced basal short-circuit current (I(sc)); however, water-delivered DFM or organic acid treatments caused greater basal I(sc) on d 2 after challenge than did carbadox. Carbachol-induced chloride ion secretion was greatest in negative control pigs before infection (P < 0.01) and DFM-treated pigs (P < 0.05) after infection. In conclusion, both the DFM and acidification treatments induced increases in basal active ion movement and jejunal crypt depth, which could be interpreted as responses consistent with increased Salmonella pathology, but none of the additives markedly affected intestinal absorptive and secretory function in response to Salmonella challenge.     

Characterization of microbial populations and volatile fatty acid concentrations in the jejunum,ileum, and cecum of pigs weaned at 17 vs 24 days of age

In a series of five 17-d replicate trials, a total of 54 cannulated and 12 noncannulated pigs were used to determine the effects of weaning age (17 d or 24 d) on pH, dry matter percentage, aerobic and anaerobic microflora, lactate, and volatile fatty acid (VFA) concentrations in the jejunum, ileum, and cecum of weanling pigs. At -14 d of age, cannulated pigs were surgically fitted with T-cannulas in the jejunum (n = 20), ileum (n = 18), or cecum (n = 16). Upon weaning, cannulated pigs were individually caged in an environmentally controlled room with ad libitum access to a phase starter diet and water. Noncannulated pigs were killed at weaning and samples were collected from the jejunum, ileum, and cecum. Digesta and fecal swabs from cannulated pigs were collected twice weekly. The pH of cecal contents was lower (P < 0.05) and dry matter percentage was greater (P < 0.05) than those ofjejunal or ileal contents. Pigs weaned at 24 d of age had increased (P < 0.05) E. coli populations 3 d postweaning compared to preweaning populations, regardless of site of collection, whereas this increase was not observed in pigs weaned at 17 d of age. Unweaned pigs maintained higher (P < 0.05) lactobacilli populations compared to weaned pigs; however, populations declined (P < 0.05) in both groups by 3 d postweaning, with pigs weaned at 24 d of age having lactobacilli populations greater than pigs weaned at 17 d of age. Fecal populations of E. coli and lactobacilli declined (P < 0.05), whereas fecal bifidobacteria populations increased (P < 0.05) postweaning, regardless of weaning age. Concentrations of total fecal anaerobes declined (P < 0.05) in pigs weaned at 17 d of age but were maintained in pigs weaned at 24 d of age. Volatile fatty acid concentrations were greater (P < 0.05) in the cecum than in the jejunum or ileum, and acetic acid concentrations decreased (P < 0.05) postweaning regardless of weaning age. A tendency for L+ lactate concentrations to be greater (P < 0.07) in the ileum and jejunum vs the cecum was observed. Results indicate that weaning and weaning age have significant effects on microbial populations and VFA concentrations.     

The effect of Eperythrozoon suis infection on the osmotic fragility of erythrocytes]

Osmotic fragility of erythrocytes was tested in weaned pigs experimentally infected with Eperythrozoon (E.) suis. Acute eperythrozoonosis of splenectomized pigs led to an increase of osmotic fragility. It is supposed that E. suis infection causes a structural change in erythrocyte membrane. Possible mechanisms of this cell membrane injury are discussed.