Any of us that has ever had a sick animal has seen the results. They don't eat as much feed or even quit eating all together. They lose muscle mass and bloom. They grow slower and convert feed to gain at a slower rate.
Part of the reason for the decrease in performance is the animal's own immune response. When an animal mounts an immune response it produces what are termed acute phase proteins. One of the effects of these substances is to repartition energy away from growth to provide energy for the immune response.
It is important to understand that you do not have to detect a clinical illness in order for the performance robbing effects to happen.
Whenever you come home from a jackpot or your animal gets stressed these acute phase proteins go to work robbing your animal of performance.
Here are a few summaries of the work that has been done by researchers on the polysaccharides in TrueGlo
Dritz et al at Kansas State University Published a paper in a 1996 Journal of Animal Science that measured the immune response and performance in pigs. In this study they challenged pigs with endotoxin or LPS and measured performance. They found an increase in acute phase protein which are produced by the body and stimulate inflammatory response. They also measured significant (P< 0.01) decreases in performance by every measure.
They summarized their findings this way: "These data suggest that LPS immune challenge caused decreased growth by decreasing ADFI and altering nutrient partitioning and that growth responses to diet complexity are independent of immune challenge."
Dritz et al also published work on the B glucan polysaccharides that are in TrueGlo in The Journal of Animal Science 1995 and a Strep Suis challenge.
They found a significant (p < 0.01) improvement in the average daily gain and feed intake performance for pigs that were challenged and fed the polysaccharides compared to the challenge. They also found a significant decrease (p < 0.01) in the acute phase inflammatory proteins in pigs that were fed the B Glucan polysaccharides. In 2005 Mao et al published work in the Journal of Animal Science on the B glucan polysaccharides and demonstrated that when they are fed during an endotoxin challenge they decreased the inflammatory response and improved cell mediated immunity in pigs.
Yaun Et al published a paper in the Journal of Animal Science 2006 that confirms the prior work of both Dritz and Mao. (APS is the same B Glucan polysaccharide in TrueGlo.)
They summarized their work with this statement " In conclusion, the present study demonstrated that dietary supplementation of APS could improve ADG and profoundly affect the cellular immunity of pigs. Considering its advantages of natural origin, lack of drug residues, and low side effects, this natural-derived polysaccharide, APS, can be used as a potential immuno-modulating agent to improve growth and immune function of pigs."