Table 3.

Description of data charting items for relevant journal articles, technical reports, proceedings, or theses.

Variable	Description of items
General study characteristics
Study design	Clinical trial (i.e., experimental or field-based trial under conditions of natural exposure), challenge trial (i.e., deliberate exposure to a pathogen or antigen under the control of the investigator), observational study
Study location	Country and region where the study was conducted as stated in the article or if not stated, first author address
Year of publication	Year of publication or year of proceeding
Farm setting	Population farm setting (i.e., experimental research farm, commercial farm, or unclear)
Detailed trial or observational study characteristics
Specific pig population in which the intervention was given	Specific population based on production stage included dams, suckling piglets, nursery pigs
Purposea of the intervention as stated in the title or objective statement	Disease prevention (i.e., no pre-existing health problems or known exposures), disease treatment (i.e., individual pigs or groups in whole or part or the farm were known to have clinical disease or exposure to viral or bacterial pathogens. In addition, some studies included performance (e.g., feed intake, growth or body weight, feed efficiency)
Non-antibiotic interventions in the form of a product or management practice or risk factor studied	Products: Piglet vaccines, maternal vaccination, non-antibiotic feed or water additive including the addition of specific dietary components, non-antibiotic medication (e.g., any medication, vitamin, mineral, antibodies, etc. administered directly to an individual). Combination products used as interventions that contained both an antibiotic [e.g., Zinc Oxide (ZnO) plus an antibiotic] were excluded. Management: Feeding regime as amount or schedule (e.g., protein level, creep feeding, restricted feeding); diet type or format (e.g., pelleted vs. mash, fermented feeds, complexity of feeds); weaning method or weaning stage as defined by the authors (e.g., early vs. late); biosecurity (e.g., comingling, mixing, introductions, animal movements); housing, flooring or feeders (e.g., animal density, feed troughs and water supply factors, flooring); air quality; producer education
Comparison groups	No treatment or conventional practice comparison, placebo or sham, different level or form of treatment, antibiotic and/or ZnOb
Health outcomes of interest reported	Mortality (i.e., piglet deaths in absolute terms, deaths per time period, excess deaths, or other metric); clinical diarrhea (e.g., scours, fecal consistency, or fecal score); clinical respiratory disease; non-diarrheal, non-respiratory non-specific morbidity (e.g., fever, removals or unthriftiness) or other morbidities such as lameness; treatment for illnesses or antibiotic use; pathology or lesions; fecal shedding of specific swine pathogens; measures of specific and non-specific immunity and infection (i.e., serology, cell mediated immunity, viremia, PCR, immune markers such as acute-phase proteins, or tumor necrosis factor (TNF)
Other outcomes measured	None, performance outcomes (i.e., feed intake, growth or body weight, or feed efficiency), farm economics or treatment costs, diet digestibility, gastrointestinal microflora, gastrointestinal morphology
Study size	Number of study subjects in each study at the hierarchical level of the analysis (e.g., individual, pen or group, herd or farm)

^aStudies in which the purpose included both prevention and treatment were counted as disease control in results.

^bSome studies compared a non-antibiotic intervention group to a zinc oxide comparison group while other studies compared a zinc oxide treatment group to a no-treatment control group, antibiotic or other treatment comparison group.