Abstract
BackgroundPorcine post-weaning diarrhea (PWD) has reemerged as an important topic in pig production, as common control strategies based on prophylactic use of antimicrobials and zinc oxide have been deemed unsustainable. The objectives of this study were to estimate the cumulative incidence of porcine post-weaning diarrhea with different etiologies in production systems weaning without zinc oxide and prophylactic antimicrobials, to assess risk factors for post-weaning diarrhea, and to estimate the impact of post-weaning diarrhea on growth rate. A cohort study was conducted at two commercial indoor producers weaning without medicinal zinc oxide and prophylactic antimicrobials.ResultsPiglets were included at birth (n = 300) and 272 survived until weaning. After insertion to the nursery units, the piglets were clinically examined every day for 14 days, and rectal swabs were collected and analyzed for enterotoxigenic Escherichia coli (ETEC) and rotavirus A. The cumulative incidences of PWD the first 14 days after insertion to the nursery units were 41.8% (CI 33.6, 50.4) and 51.1% (CI 42.3, 60.0) at the two producers, respectively. We found a low incidence of cases associated to ETEC, and detected a substantial proportion of cases associated to rotavirus. We observed a biphasic pattern in the assumed etiology with rotavirus occurring first, and then a shift towards cases associated to ETEC/non-ETEC hemolytic E. coli. Being offspring of older sows was a protective factor for the development of PWD (Hazard ratio = 0.88 [CI 0.78, 0.99] per unit increase in parity of the dam). Low birth weight reduced the post-weaning growth rate (− 5.2 g/day [CI − 7.5, − 2.9] per 100 g decrease in birthweight) and increased the hazard of developing PWD (Hazard ratio for birthweight below 1100 g: 2.30 [CI 1.41–3.74]). The combined effect of having diarrhea for 2 days or more and receiving antimicrobial treatment was associated with an increased average daily weight gain.ConclusionsThis study suggests novel insights regarding pathogen dynamics and risk factors for PWD in productions not using prophylactic antimicrobials and medicinal zinc. The findings may have important implications for both antimicrobial usage and prevention strategies.
Highlights
Weaning of pigs is a delicate process where suckling is terminated and solid food replaces the milk-based diet
This study estimated the cumulative incidences of diarrhea associated with E. coli and rotavirus A during the first 14 days after insertion to the nursery units in two Danish intensive indoor productions weaning without medicinal zinc oxide
Interpretation of findings Assumed etiologies and pathogen dynamics The present study demonstrated two interesting cases of infection dynamics in post-weaning diarrhea (PWD) outbreaks in pigs where neither antibiotics nor medicinal zinc were used as a preventive measure
Summary
Weaning of pigs is a delicate process where suckling is terminated and solid food replaces the milk-based diet. Under common Danish and European intensive production schemes, piglets are removed from the sow and weaned to special nursery units at 3–5 weeks of age. At this age the colostrogenic immunity is declining and the lactogenic immunity is lost from the discontinued suckling [2, 3]. The gut health might be further compromised by the stressful events during weaning [8, 9], and the new environment where surface contamination and pen mates might introduce the piglets to new pathogens. A cohort study was conducted at two commercial indoor producers weaning without medicinal zinc oxide and prophylactic antimicrobials
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