Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: 7/28/2000
Publication Date: N/A
Technical Abstract: Previously, we reported that pigs fed spray-dried plasma (SDP) have greater hypothalamic-pituitary-adrenal (HPA) axis and immune system responses following a lipopolysaccharide (LPS) challenge than pigs fed a diet with no SDP. The objective of this study was to evaluate mRNA expression of hormones in tissues associated with the HPA axis. Twenty pigs (14 d, 5 kg) )were weaned to an isolated environment and allotted to 1 of 4 treatments i a 2x2 factorial arrangement, with two levels of SDP (0 vs 7%) and two i.p. injections (LPS vs saline). Diets were formulated to contain equal ME and digestible essential amino acids and fed for 7 d postweaning. On d 7, i.p. injections of LPS (150 ug/kg BW) or saline were given. After 3 h, pigs were sacrificed and tissue was collected for mRNA analysis. Tissue mRNA levels measured were not affected by LPS treatment. Pigs fed the diet with SDP had a lower level of hypothalamic CRH mRNA compared to pigs fed the diet without SDP (P<.05). Pigs fed the diet with SDP also had a lower level of CRH receptor mRNA in the pituitary compared to pigs fed the diet without SDP (P=.12). Dietary treatment did not affect POMC mRNA in the pituitary. Pigs fed the diet with SDP had a lower level of adrenal ACTH receptor mRNA compared to pigs fed the diet without SDP (P<.05). These results suggest that the HPA axis of pigs fed SDP after weaning may be less activated than that of pigs fed a diet without SDP. Considering the well-known effect of pathogen exposure as a stimulator of the HPA axis, our observation of a lower level of HPA activation may reflect a decreased immune activation as previously reported. Thus, feeding SDP may provide immunological protection for weaned pigs under typical production conditions and reduce basal activation of the HPA axis.