Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: October 22, 2003
Publication Date: October 22, 2003
Citation: Carroll, J.A. 2003. Enhancing neonatal swine performance: a multidisciplinary perspective [abstract]. Invited presentation at the University of Missouri. Technical Abstract: The information to be presented includes our efforts over the last several years to identify nutritional supplements which can be utilized to enhance the immune system of young pigs. Additionally, information on our more recent research activities evaluating the acute-phase immune response in pigs challenged with live bacteria, and our efforts in elucidating the appetite regulatory response in weaned pigs will be presented. Our research efforts on nutritional modulation of the immune system have focused primarily on the use of spray-dried animal plasma and fish oil as nutritional supplements which could provide immunological protection. We have demonstrated that the enhanced growth performance observed with the inclusion of spray-dried plasma in the diet of weaned pigs appears to be associated with immunological protection at the level of the intestinal mucosa. Providing this protection allows nutrients to be diverted away from maintenance of the immune system and towards growth, thus enhancing the overall productivity of the pig. With regard to the use of fish oil in the diets of weaned pigs, our data clearly demonstrate that fish oil supplementation reduces the secretion of various hormones and cytokines associated with the acute-phase immune response when pigs are challenged with an endotoxin. Therefore, these pigs appear to be better equipped to combat the detrimental effects associated with an endotoxin challenge. Collectively, the data from our studies provide evidence that nutritional supplements can be effectively used to enhance the immune capabilities of the young pig. Escherichia coli (E. coli) causes gastrointestinal disease in many species; however, the associated immune response has not been well defined. To address this issue, 22 crossbred pigs were assigned to blood collection (n=10) or rectal temperature measurement (n=12) groups. Blood-collection pigs were non-surgically cannulated one day prior to blood collection. At 0 h, all pigs received a 10 mL oral dose of 240 million colony-forming units of E. coli K88 via a nasogastric tube. Blood collection and rectal temperature monitoring occurred hourly from -1 to 5 h, every 30 minutes from 5 to 8 h, and at 24 h post-E. coli dosing. Serum concentrations of cortisol (CS), interferon-gamma (IFN), tumor necrosis factor-alpha (TNF), interleukin-1beta (IL-1), IL-4, IL-6, IL-8, IL-10, serum amyloid A (SAA), C-reactive protein (CRP), haptoglobin (HG), and lipopolysaccharide (LPS) increased (P < 0.0007) after E. coli administration. Serum concentrations of IL-4 and IL-8 did not change and serum concentrations of TNF were undetectable. While TNF was not associated with increased rectal temperature, positive correlations existed between rectal temperature and CS (r = 0.49; P < 0.0001), IFN (r = 0.29; P < 0.0009), IL-1 (r = 0.45; 0.0001), IL-6 (r = 0.31; P < 0.0003), IL-10 (r = 0.35; P < 0.0001), and LPS (r = 0.29; P < 0.0009). These data indicate that circulating TNF does not play an integral role in the febrile response in pigs challenged with E. coli; however, CS, IL-1, IL-6, IL-10, and IFN may play an important role in initiating and controlling fever. Low feed intake by pigs during weaning leads to a suppression of weight gain and may also increase susceptibility to diseases. Our objective was to characterize the hormonal changes that take place during a feed-deprivation period similar to that commonly observed during weaning in pigs. In Experiment 1, eight barrows were either fed on a continual basis (CON; n = 4) or were feed deprived for 24 h and then re-fed until 30 h (FD; n = 4). Relative serum concentrations of ghrelin tended to be lower in FD pigs at 12 h (P = 0.08) when compared to CON pigs, but greater than CON pigs at 24 and 30 h (P < 0.01). Serum IGF-I was lower in FD pigs from 12 to 30 h as compared to CON pigs (P < 0.05) and increased following re-feeding (P < 0.06). Experiment 2 included 32 pigs that were either fed (CON72 and CON96; n = 16), feed deprived for 72 h (FD72; n = 8), or FD72 and then re-fed from 72-96 h (FD72/RF24; n = 8). Ghrelin in the FD72 and FD72/RF24 groups was lower at 12 h (P < 0.03), but greater at 36 h and 48 h than CON pigs (P < 0.01). Serum IGF-I and leptin decreased following feed deprivation (P < 0.001) and remained low until re-feeding. Cortisol was elevated from 12 to 72 h during feed deprivation (P < 0.01), but was not different from CON96 pigs following re-feeding (P > 0.88). Expression of ghrelin mRNA tended to be lower in the FD72 pigs' stomachs, pituitary glands, and hypothalami (P = 0.06, 0.07, and 0.08, respectively) compared to CON pigs. These results provide evidence that feed deprivation is accompanied by multiple changes in the endocrine and neuroendocrine axis which influence feed intake, somatotrophic response, and HPA axis hormone concentrations. This information will be of particular interest to nutritional scientists, industry personnel, swine extension specialists, and swine producers.