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item Touchette, K
item Carroll, Jeffery - Jeff Carroll
item Allee, G
item Matteri, Robert - Bob
item Dyer, C
item Beausang, L
item Zannelli, M

Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/6/2001
Publication Date: N/A
Citation: N/A

Interpretive Summary: With increased public concern regarding the use of sub-therapeutic levels of antibiotics in livestock feed, there has been an increased effort by the scientific community to evaluate nutritional supplements which may enhance immune function in domestic animals. For the last few years, our laboratory has been investigating the use of spray-dried plasma as a nutritional supplement with the potential to alter immune function in the weaned pig. The objective of this study was to determine if supplementing the young pig's diet with spray-dried plasma would alter endocrine and immune responses of the young pig to an endotoxic challenge. We found that, when pigs were supplemented with spray-dried plasma for a period of 7 d post weaning, basal activation of the immune system was reduced. As a result of this reduction in basal immune function, there was an overactivation of the immune system to the endotoxin. Results from this study indicate that the enhanced growth associated with feeding spray-dried plasma most likely results from a reduction in the basal immune function. The potential downside is that feeding spray-dried plasma apparently results in a naive immune system which may not be beneficial when the pigs are exposed to pathogenic challenges within their environment. Results from this study demonstrate the significant impact nutritional supplements can have on the overall health and immune function of the young pig. These results will be of particular interest to swine producers, feed companies, and scientists working in the area of swine nutrition and immunology.

Technical Abstract: Twenty barrows (14d, 5kg) were used to determine the effect of spray-dried plasma (SDP) on the pig's immune response to a lipopolysaccharide (LPS) challenge. Pigs were fed a diet containing 0 or 7% SDP for 7 d. On d 6, all pigs were fitted with a jugular catheter. On d 7, the pigs were given an i.p. injection of either saline or LPS (150 ug/kg BW) followed by a 3-h blood collection every 15-min. Small intestine was collected for measurement of villous height, crypt depth, and villous height-to-crypt depth ratio (VCR) at three sites (25, 50, and 75% of the total length). Feeding SDP reduced expression of tumor necrosis factor(TNF)-alpha and interleukin-1(IL-1)beta mRNA in the adrenal gland, spleen, thymus, hypothalamus, pituitary, and liver. Expression of IL-6 mRNA was reduced in the adrenal gland, spleen, and pituitary for pigs fed SDP. For pigs fed the diet with SDP, LPS did not affect cytokine mRNA expression, while LPS reduced expression of TNF-alpha mRNA in the spleen and IL-1beta mRNA in th adrenal gland, spleen, and thymus for pigs fed the diet without SDP. For pigs fed the diet with SDP, LPS caused serum TNF-alpha to increase 150-fold compared to a 60-fold increase for pigs fed the diet without SDP. Similarly, IFN-gamma increased 110-fold for pigs fed the diet with SDP compared to a 16-fold increase for pigs fed the diet without SDP. For pigs fed the diet with SDP, LPS caused major villous atrophy, whereas for pigs fed the diet without SDP, LPS had no effect on intestinal morphology. Results indicate that basal activation of the immune system appeared to be less for pigs fed the diet with SDP. As a result of this decreased activation, there was an over-response of the immune system to the LPS, which resulted in major damage to the gastrointestinal tract.