The objective of this swine study was to evaluate whether high levels of soybean meal (SBM) could modulate the pig’s response to a respiratory disease challenge by reducing systemic viral replication and modulating the immune system. A total of 2,112 pigs weighing about 6 kg were placed into two nursery rooms of 48 pens each (22 pigs/pen) under commercial conditions to evaluate the potential of SBM levels (low, medium, or high) in combination with phytase (560 or 1415 analyzed FTU/kg) to improve growth and health of weaned pigs originating from a porcine reproductive and respiratory syndrome (PRRS) affected sow farm.

Results indicated no significant treatment main effects or interactions (P › 0.05) for ADFI, ADG or gain: feed. The percentage of pigs pulled for medical treatment declined linearly with increasing SBM levels (11.09, 9.15, 8.42%; P= 0.04). However, there was no reduction in mortality or improvement in the percentage of full value pigs (97.3, 97.4, and 97.3%; P = 0.97). Stool firmness decreased with increasing SBM during day 1 to 5 (linear, P = 0.01) and tended to decrease for day 1 to 10 (P = 0.13). Phytase tended to improve stool score for day 1 to 5 (P = 0.06) and day 1 to 10 (P = 0.14). Soybean meal levels did not affect (P 0.31) viral load of PRRS when determined on day 20 or day 42. The researchers concluded that increased levels of SBM may be beneficial in health challenged pigs by reducing labor and cost associated with treatment for disease without impacting performance or viral load of PRRS. The tendency for high levels of SBM to cause stool looseness can be countered with a high phytase level.