Nutrient digestibility, organ morphometry and performance in vaccinated or non-vaccinated Lawsonia intracellularis infected piglets.

BACKGROUND: Lawsonia intracellularis is one of the world's most important infectious diseases in pork production with regard to economic losses. So far, studies are missing that describe the effects of a natural infection of piglets on the digestibility of nutrients, possible effects on performance and the morphometrics of the intestine depending on whether piglets are vaccinated, clinically healthy or clinically affected with regard to Lawsonia intracellularis induced diarrhoea. RESULTS: Digestibility studies were performed on a total of 27 eight-week-old piglets with naturally occurring Lawsonia intracellularis infection in a trial with three repetitions. Nine out of 27 animals were vaccinated as suckling pigs with a commercial Lawsonia intracellularis vaccine (vac; Enterisol®Ileitis). Half of the remaining 18 animals were without clinical signs of infection (non-vac/cs-), half showed moderate clinical signs of Lawsonia intracellularis induced diarrhoea (non-vac/cs+). All three groups were fed one identical complete diet ad libitum. Faecal shedding of Lawsonia intracellularis was found in all groups (25 out of 27 animals). Numerically, the mean excretion in the group non-vac/cs + (7.69 ± 1.65 log10 copies/ g faeces) was higher in comparison to the group non-vac/cs- (5.83 ± 2.35 log10 copies/ g faeces) and vaccinated animals (vac: 6.00 ± 2.89log10 copies/ g faeces). The average daily weight gain (ADG; Ø 8.66 day period) differed significantly (vac: 894a ± 73.3, non-vac/cs-: 857ab ± 86.3, non-vac/cs+: 785b ± 137 g/day). The apparent total tract digestibility (ATTD) of nitrogen was significantly lower in clinically affected animals (vac: 83.0a ± 1.72, non-vac/cs-: 83.9a ± 2.03, non-vac/cs+: 80.7b ± 2.57).The total length of the small intestine in clinically affected animals increased significantly (vac: 15.9ab ± 1.57, non-vac/cs-: 14.6b ± 1.12, non-vac/cs+: 16.2a ± 1.37 m). The relative body weight depending on the length of the small intestine was lower for clinically affected animals (vac: 1.72a ± 0.21, non-vac/cs-: 1.83a ± 0.17, non-vac/cs+: 1.56b ± 0.12 kg/m). CONCLUSION: These studies show that clinically moderate L. intracellularis infections lead to significantly lower ADGs in comparison to vaccinated animals. The disease is also found in altered intestinal morphometry and reduced total N digestibility if clinical signs occur.

Spread of an Experimental Salmonella Derby Infection in Antibiotic-Treated or Lawsonia intracellularis Vaccinated Piglets.

Lawsonia intracellularis infections are a common reason for antibiotic treatment in pig production. Experimental studies in animals naturally infected with Lawsonia intracellularis comparing the course of an experimental Salmonella infection in piglets previously treated with tylosin or vaccinated against Lawsonia intracellularis are scarce. A total of 72 seven-week-old Salmonella-free pigs were taken from a herd with a Lawsonia intracellularis history in piglet rearing. The pigs were divided into two groups with three replicates each. Animals had either been previously treated with tylosin (10 mg/kg body weight) for seven days (AB⁺VAC-) or had been vaccinated as suckling pigs by drenching (Enterisol®Ileitis; AB-VAC⁺). Two animals per replicate were primarily infected with Salmonella Derby (1.04 × 108 colony-forming units per animal). The detection of Salmonella in faeces (p < 0.0001, odds ratio: 3.8364) and in the ileocaecal lymph nodes (p = 0.0295, odds ratio: 3.5043) was significantly more frequent in AB⁺VAC- animals. Overall, the odds ratio for detecting Salmonella in any substrate or organ was significantly higher in the AB⁺VAC- group animals (p = 0.0004, odds ratio: 5.9091). Treatment with tylosin can significantly increase the spread of a Salmonella infection, which is not observed after early Lawsonia intracellularis vaccination.

Experimental studies on effects of diet on Lawsonia intracellularis infections in fattening boars in a natural infection model.

BACKGROUND: Lawsonia intracellularis is one of the most economically important pathogens in swine production. This study tested the hypothesis that the composition of diets for pigs has an impact on the excretion of L. intracellularis in a natural infection model. RESULTS: Fifty boars (~ 90 kg BW) from a SPF-farm with a strict hygiene and management regime for reducing the spread of an L. intracellularis infection up to the beginning of the final fattening period were transported, regrouped and randomly allotted to groups of five animals each at the research facility. After a 1-week acclimatisation period groups were fed one of five diets 4 weeks before slaughter. These were either a finely ground pelleted diet (FP) or a coarsely ground meal diet (CM), both consisting of wheat (40.0%), barley (39.3%), soybean meal (16.0%), soybean oil (2.0%) and minor components. In the other meal diets parts of wheat, barley and soybean meal were substituted either with 22% cracked corn (CORN), 16.9% dried whey (WHEY) or 30% raw potato starch (RPS). The animals had a comparable serological status in a blocking-ELISA immediately before the start and at the end of the feeding experiment. Values increased significantly during the trial. In all subgroups (FP/CM/CORN/WHEY/RPS), shedding was detected in week 0 (genome equivalents = GE; log10 GE L. intracellularis/g faeces: 2.46 ± 2.64/3.58 ± 2.54/3.43 ± 2.37/2.30 ± 3.16/2.58 ± 2.73). The average number of L. intracellularis microbes in faeces during the trial period did not differ between the groups (log10 GE L. intracellularis/g faeces: 3.40 ± 1.53/3.01 ± 1.41/3.80 ± 1.71/3.98 ± 2.20/4.08 ± 2.13). In animals fed the WHEY-diet, significantly lower counts of L. intracellularis were found in the caecal content. The acetate content in the caecum was negatively correlated with the serological results at the end of the trial (r = - 0.36; P = 0.010). Butyrate concentrations in the caecal content were negatively correlated with the number of L. intracellularis in the caecum (r = - 0.32; P = 0.023). CONCLUSION: Therefore, this study provides preliminary evidence that there might be specific dietary effects on the course of a L. intracellularis infection.