Thermal Environmental Effects and Group Size on Growing Swine Immune Status

The effects of environmental conditions on the immune system of growing pigs (30-50 kg) were studied using T and B cell proliferation counts. Pigs were exposed to a constant 32°C ambient temperature versus a naturally occurring diurnal temperature variation during hot weather and a constant 10°C vs 21°C ambient temperature during cold weather. In addition, T and B cell proliferation counts were compared for pigs in single, 9 and 18 pigs/pen group sizes. Concancavalin A (ConA), Phytohemagglutinin (PHA) and Staphylococcal enterotoxin B (SEB) mitogens were used to determine T cell activation over time. Pokeweed (PWM), Lipopolysaccharide (LPS) and Salmonella typhimurium mitogen (STM) mitogens were used to determine B cell proliferation over time. ConA tests revealed significant (P\u3c0.01) increases in T cell proliferation over time for both temperature treatments during hot weather. No significant differences in B cell proliferation were noted during the hot weather trials. A general decline in T cell activation over time was noted in both temperature treatments during cold weather. Significant (P\u3c0.01) reductions in B cell activation were noted for all pigs in the cold weather trials. T and B cell proliferation comparisons for group size at all temperature treatments were non-significant. The objective of this experiment was to find what effects temperature and group size have on the capacity and function of a growing pig\u27s immune system