Submitted to: American Society of Animal Science Southern Section Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 1/30/2003
Publication Date: 2/1/2003
Citation: Rudine, A., Dabovich, L., Dowd, S., Morrow, J., McGlone, J. 2003. Rearing pigs indoors or outdoors: effects on immunity and Salmonella shedding [abstract]. In: Proceedings of American Society of Animal Science, Southern Section Meeting, January 31 - February 4, 2003, Mobile, AL. Abstract No. 119. p. 31 Interpretive Summary:
Technical Abstract: Pig performance, health, and behavior may be influenced by the production system. A conventional indoor system was compared with an outdoor system for effects on pig immunity and Salmonella shedding. Contemporary litters were born indoors on slatted floors in farrowing crates or outdoors in the summer months on pasture. Indoor pigs were weaned into a conventional nursery with slatted flooring while outdoor pigs were weaned into pastures with alfalfa and a straw-bedded hut. After weaning, pigs were kept with 2 littermates per pen. A total of 6 replicate pens were evaluated per treatment. Pig dominance order was determined by a feed competition test during the post-weaning period. At 9 weeks of age, pigs were moved to a controlled facility where they were individually housed in biocontainment bubbles and dosed with Salmonella enterica typhimurium (SALM). Fecal samples were collected every 12 hours and cultured for SALM. Performance data were analyzed as a randomized complete block design with effects of production system, dominance status (dominant or submissive) and their interaction. Outdoor born and reared pigs had higher hemoglobin concentrations (P<0.01), neutrophil phagocytosis of latex beads (P<0.05), and increased antibody titer to sheep red blood cells (P=0.05) compared with indoor born and reared pigs. Dominant pigs had elevated lymphocyte proliferation to phytohemagglutinin (P<0.01), background titers to sheep red blood cells (P<0.02) and lower (P<0.05) increase in antibody titer to sheep red blood cells than submissive pigs. The interaction between production system and dominance status was not significant for any measure. Pigs born and reared outdoors had reduced (P<0.05) SALM shedding compared with indoor born and reared pigs (2.4 vs. 5.7, SEp=1.03, log colony forming units SALM). In conclusion, pigs in the outdoor production system had enhanced immunity and reduced bacterial shedding of Salmonella compared with pigs in the conventional indoor system.