Dietary approaches reducing boar taint-Importance of Lawsonia intracellularis colonisation for interpreting results.

In the fattening of male pigs, boar odour is a major problem with regard to the acceptance of the meat by consumers. Skatole can be one cause. Tryptophan from non-digested feed ingredients and intestinal cell debris can be the precursor in skatole formation. Lawsonia intracellularis, one of the most widespread pathogens in swine, promotes the epithelial cell turnover and might favour the tryptophan influx into the hindgut. Therefore, the question arises how far the severity of a Lawsonia intracellularis infection has an effect on results of dietary experiments with specific issues. Fifty finishing boars from a specific pathogen-free farm were randomly allotted to ten boxes in five feeding groups. Natural developing Lawsonia intracellularis colonisation was monitored serologically (twice individually) and molecular biologically (weekly individually). Over 4 weeks, animals were fed either a finely ground pelleted diet (FP), a coarsely ground meal diet (CM), a meal diet either with 22% cracked corn (CORN), 16.9% dried whey (WHEY) or 30% raw potato starch (RPS). Fifty % of animals showing lower differences in serological Lawsonia intracellularis values between the start and the end of the trial were characterised by a higher dry matter content in faeces (256 ± 29.4 vs. 239 ± 23.6 g/kg). Lawsonia intracellularis-negative caecal samples showed the highest butyrate concentrations (27.2 ± 7.53 mmol/kg). Lawsonia intracellularis-negative faecal samples of group FP showed the highest DM levels in faeces (neg: 290 ± 46.1/pos: 250 ± 52.2 g/kg); negative samples from group RPS had the lowest values (217 ± 24.4 g/kg). Lawsonia intracellularis-negative faecal samples from the group CM were lower in skatole than positive samples (82.8 ± 32.8 vs. 119 ± 29.3 µg/g DM). RPS group samples without pathogen detection had the lowest skatole concentrations (30.5 ± 36.3 µg/g DM). This study provides first evidence that clinically unremarkable colonisation with intestinal pathogens might influence the results of dietary approaches.

Reduction of Salmonella prevalence at slaughter in Lawsonia intracellularis co-infected swine herds by Enterisol® Ileitis vaccination.

Salmonella spp. remains a wide-spread pathogen among pig herds and its control has major impact on food borne Salmonella infections in humans. The objective of the study was to investigate the influence of an Enterisol® Ileitis vaccination on Salmonella seroprevalence in Lawsonia intracellularis (L. intracellularis) and Salmonella spp. co-infected pig herds under field conditions. This study compared vaccinated and non-vaccinated pigs of consecutive piglet batches, housed on four different finishing units. Prior to study start, endemic field infections of L. intracellularis and Salmonella spp. were confirmed by serology in the nursery and in all finishing units. Field infection of L. intracellularis occurred at the middle of the nursery phase. In total twenty-five batches of finishing pigs were included in the study, pigs were investigated for four (non-vaccinated group, n = 9) or six months (vaccinated group, n = 16). The primary outcome parameter was Salmonella serology (antibody titers) at the end of fattening. Secondary parameters comprised serology for L. intracellularis and performance parameters, including average daily weight gain (g), duration of fattening period (days), feed conversion (kg/kg) and mortality (%). A total of 709 blood samples were assessed, deriving from vaccinated (n = 439) and non-vaccinated finishing pigs (n = 270). Evaluation of the antibody titers demonstrated that vaccination significantly reduced the Salmonella seroprevalence in the finishing pigs on all four farms. The average OD% values were reduced from 32.7% to 13.4% in addition to a reduced variability in the vaccinated pigs compared to the control group. The Salmonella category of all finishing farms improved by at least one category in accordance with the German Salmonella monitoring program. In addition, vaccination had a positive tendency on the average daily weight gain, fattening duration and reduced mortality. In conclusion, this study demonstrates that vaccination with Enterisol® Ileitis has a positive and direct impact on reduction of Salmonella infection in co-infected herds.