Correlation between detection of enteropathogenic bacteria and health and productive parameters in finishing pigs in Argentina

Enteric infections cause economic losses in pig production. Increases in costs are associated with reduced average daily gain (ADG), increased mortality rate and increased in use of antibiotics. Porcine proliferative enteropathies (PPE), swine dysentery (SD), porcine spirochetosis and salmonellosis are enteric diseases caused by L. intracellularis (LI), B. hyodysenteriae (BH), B. pilosicoli (BP) and Salmonella enterica (SE) respectively. The above mentioned infections have been reported world-wide, however in Argentina their impact on productive parameters were not studied. This study analyzes the relationship between enteric infections and health and productive parameters.

Eight farms between 80 to 2500 sows were studied. From each, 120 samples of feces of 8, 14, 17, 20 and 24 weeks-old pigs were collected. DNA was extracted (ZR Fecal DNA MiniPrep, Zymo Research, CA, USA) and was analyzed by multiplex PCR assay to identify LI, BH and BP. For SP, pooled samples were cultures using standard methods. Productive, health and biosecurity information were obtained by an ad-hoc survey form. Spearman correlation was applied in order to analyze the association of each pathogen with ADG, weight at 70 days, nursery and fattening mortality, biosecurity practices, and herd size and production system.

Lawsonia intracellularis, BH and SE were identified in 16.22% (153/943), 1.38% (13/943) and, 6.3% (9/144) of the samples, respectively. All samples were negative to BP. All farms were positive to LI, 2 to BH and 5 to SE. Detection BH was positively associated with mortality rate (r =0.82, p= 0.04) and negatively with ADG (r = -0.8, p= 0.04). The weight of pigs at 70 days showed a negative correlation with nursery and fattening mortality (r=-1.0 p=0.01; r=0.86 p=0.03) respectively. Biosecurity practices showed a negative correlation with weight at 70 days and negative correlation nursery mortality (r=-0.9 p=0.03; r=0.9 p=0.03) respectively. No correlation with SE, LI, number of sows and production system were found.

- In the study, BH affected productive performance and mortality in grower-finisher pigs. Losses were associated with high mortality and low ADG. Herds with good biosecurity practices have a lower risk of infection, mortality rate and higher ADG.

- A high prevalence of LI in Argentinean herds was found, however no statistically association was found between PPE and decreased ADG. It seems that under the conditions of this study, infection with LI might need of cofactors to impact negatively on the growth rate.

Disclosure of Interest: None Declared.