Effects of Egg Yolk Antibodies on Weanling Pigs Challenged with Pathogenic Salmonella Typhimurium

An experiment was conducted to determine effects of anti-Salmonella egg yolk antibodies (ASEYA) on shedding and antibiotic resistance of Salmonella enterica Typhimurium and E. coli, growth performance and immunological parameters. Weaned pigs in two replicate trials (n = 132) were randomly assigned to six dietary treatments, including a control diet without additives, apramycin followed by carbadox, oxytetracycline (OXY), egg yolk powder containing ASEYA, egg yolk powder lacking ASEYA, or spray dried plasma protein (SDPP). Treatments were given to pigs on day 3 of the trial and all pigs were intranasally and orally challenged with Salmonella Typhimurium containing a nalidixic acid resistance marker on day 7. Fecal samples were collected on day 0, 7, 8, 12, 14, 21, 58, 88, and 118 for detection of Salmonella and E. coli to determine shedding and antibiotic resistance. Blood samples were collected and rectal temperatures (RT) were measured on day 0, 7, 8, 12, 14, 21, and 28. Blood was analyzed for white blood cell (WBC) counts and serum was analyzed for Salmonella antibody and interleukin-1β (IL-1β). The percentage of pigs shedding Salmonella was lower (P<0.05) for antibiotic treatments compared to other diets; however, resistance was greater (P<0.05) in E. coli from pigs fed antibiotics. Weight gains did not differ between treatments. Pigs fed OXY had lower RT compared to pigs fed SDPP and ASEYA (P<0.05); however, pigs in all groups had higher RT 24 h after challenge (P<0.05) and had decreasing RT by day 12. Concentrations of anti-Salmonellaa antibodies and WBC counts did not differ between treatment groups. Salmonella antibody concentrations increased in all groups beginning on day 14 and continued to increase through day 28 (P<0.05). IL-1β was generally below detection limits. These studies indicate that in-feed ASEYA may not be effective in controlling shedding of Salmonella or improving the performance or health status of pigs challenged with Salmonella likely because ASEYA cannot reach invasive Salmonella that move through routes outside of the GI tract and/or because ASEYA lose activity as a result of animal digestive processes.