Submitted to: Journal of Animal Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 2/16/2006
Publication Date: 11/27/2006
Citation: Mckee, C.A., Eicher, S.D., Carroll, J.A. 2006. Supplemental vitamin C and yeast cell-wall beta-glucan as growth enhancers in newborn pigs and as immunomodulators after an endotoxin challenge after weaning. Journal of Animal Science. 84:2352-2360. Interpretive Summary: Piglet mortality and morbidity is high following weaning due to disease and anorexia. To test a possible dietary immune modulator, thirty-two crossbred male pigs were given one of four dietary supplements in milk: an unsupplemented control, a yeast cell-wall product, vitamin C, or both the yeast cell wall product and vitamin C. Piglets receiving both had a greater weight gain after weaning. After weaning, piglets were given an intra venous (i.v.) injection of a bacterial cell wall product, lipopolysaccharide (LPS). The vitamin C alone decreased concentrations of cortisol (a stress hormone) and TNF protein (a communication protein that results in weight loss). The RNA analysis in the tissues was opposite the blood TNF (vitamin C fed pigs had greater expression of TNF in the intestine, lung, and liver samples). In contrast, the spleen cells had greater abundance of TNF expression with the yeast cell-wall product. The pigs fed vitamin C only, slept less at 40 to 50 minutes after the injection (when TNF was peaking). The early cell signal protein (interleukin-1, IL-1) was not different, but its receptor antagonist (IL-1Ra) was enhanced in several of the tissues with either vitamin C or the yeast cell-wall product, demonstrating a down regulation of immune responses by 2 hours post-challenge. The difference in the immune cell populations in each of the tissues, and the movement of the LPS to those tissues may explain the TNF and IL-1Ra differences. The blood cells would be the first to encounter the LPS that was delivered i.v. The yeast cell-wall product and the vitamin C may be affecting different immune cells and therefore the tissues differently, adding to the disparity of the results. This study showed enhanced growth occurred when the vitamin C and yeast cell-wall product were fed together. During the LPS challenge, the vitamin C alone appeared to have a greater immunosuppressive effect that was also demonstrated by reduced sleeping behavior. This study may impact the decisions made by the feed industries that are searching for antibiotic alternatives.
Technical Abstract: Piglet mortality and morbidity is high due to disease and anorexia following weaning. To test possible dietary immune modulators, thirty-two crossbred male pigs were given one of four dietary treatments (8 pigs per treatment): Control (CTL), beta-glucan (BG; Energy Plus ® at 2.5% of diet), vitamin C (VC; Stay C 35 ® at 75 ppm), and beta-glucan and vitamin C given together (2.5% and 75ppm respectively) called ImmunoGain (patent pending, IG). Supplements were given in whole milk within the first 36 hours of birth, and then daily for the first two weeks. Plasma ACTH, cortisol, and tumor necrosis factor-alpha (TNF) protein, relative abundance of interleukin (IL)-1, IL-1 receptor antagonist (Ra), and TNF (measured by real-time RT-PCR), differential cell counts, and behaviors were measured just prior to and after an i.v. lipopolysaccharide (LPS at 150 ug/kg) challenge. Growth response was recorded for the four weeks of feeding the diets prior to the challenge. The BG containing treatments enhanced gain compared to both the VC and CTL groups. ACTH was not different among treatments, but cortisol tended to be less in the VC pigs compared to the CTL (P=0.06) and cortisol concentrations showed an interaction of the beta-glucan and vitamin C (P < 0.05). Plasma TNF was lowest for the VC only pigs (beta-glucan by vitamin C interaction P=0.08). However, TNF RNA expression was greatest for VC and BG compared to CTL and IG intestine samples, and similarly the liver TNF expression was greatest (P<0.01) for the VC compared to CNT and IG, with a main effect of BG (P<0.01). Lung cells had greater TNF expression for VC groups (main effect P<0.01). In contrast, spleen cells of BG pigs had a greater relative abundance of TNF(P<0.01). Interleukin-1 expression tended to be greater for VC and BG and IL-1Ra expression was greater (P<0.05) for VC and BG compared to the CTL and IG supplemented groups. The liver IL-1 expression was not different among treatments, but the IL-1Ra was greatest for VC groups (main effect P<0.01). The spleen and lung cells did not have different IL-1 and IL-1Ra expression among treatments. Behavior only tended to be different among treatments, by 40 and 50 min post-challenge for the percentage of pigs sleeping, with the VC pigs tending to have fewer pigs sleeping at those times. These results show a complex interaction between vitamin C and this beta-glucan product following an LPS challenge, that are differentially expressed in the tissues by 2 hours after LPS injections. The advantage of the IG growth response was reflected by reduced TNF expression of the intestine and liver tissues, suggesting an important immunomodulatory role of the IG treatment.