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Title: EFFECTS OF FISH OIL SUPPLEMENTATION ON PERFORMANCE AS WELL AS IMMUNOLOGICAL, ADRENAL, AND SOMATOTROPHIC RESPONSES OF WEANED PIGS AFTER ESCHERICHIA COLI LIPOPOLYSACCHARIDE CHALLENGE

Author
item LIU, Y - CHINA AGRIC. UNIV.
item LI, D - CHINA AGRIC. UNIV.
item GONG, L - CHINA AGRIC. UNIV.
item GAINES, A - UNIV OF MISSOURI
item Carroll, Jeffery - Jeff Carroll

Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/17/2003
Publication Date: 11/20/2003
Citation: Lie, Y.L., Li, D.F., Gong, L.M., Gaines, A.M., Carroll, Jeffery A. Effects of fish oil supplementation on performance as well as immunological, adrenal, and somatotrophic responses of weaned pigs after escherichia coli lipopolysaccharide challenge. Journal of Animal Science. Nov 2003. v. 81. p. 2758-2765.

Interpretive Summary: We evaluated the immunological benefit of adding fish oil in a weaned pig's diet. For this study, we used 72 pigs that were 28 days of age and evaluated growth performance and immunological, adrenal, and somatotrophic responses following an immune challenge with an endotoxin (Escherichia coli lipopolysaccharide). Pigs were fed a diet that consisted of 7% corn oil or 7% fish oil for the 28-day experiment. On days 14 and 21, pigs were immunologically challenged and blood samples were collected to evaluate blood hormone responses to the endotoxin. The results demonstrated that adding fish oil improved average daily gain and average daily feed intake following the endotoxin challenge. Additionally, these results indicated that adding fish oil to the young pig's diet alters indices of the immune axis that may lead to improved pig performance during an immune challenge. Given that feeding sub-therapeutic levels of antibiotics has become a much-debated topic, information regarding the use of nutritional supplements to boost immune function will be of importance to all livestock production in the United States, as well as in other countries. This data will also be of interest to all individuals associated with swine production including scientists in academia, government, and industry.

Technical Abstract: Seventy-two crossbred pigs (7.58 +/- 0.3 kg BW) weaned at 28 days of age were used to investigate the effects of fish oil supplementation on pig performance and immunological, adrenal, and somatotropic responses following Escherichia coli lipopolysaccharide (LPS) challenge in a 2 x 2 factorial design. The main factors included diet (7% corn oil or 7% fish oil) and immunological challenge (LPS or saline). On days 14 and 21 postweaning, pigs were injected intraperitoneally with either 200 ug/kg BW of LPS or an equivalent amount of sterile saline. Blood samples were collected three hours post-injection for analysis of interleukin-1 beta, prostaglandin E2, cortisol, growth hormone, and insulin-like growth factor I. On day 2 after LPS challenge, lymphocytes were isolated from peripheral blood and incubated with 8 or 16 ug/mL concanavalin A to measure lymphocyte proliferation. Bovine serum albumin was injected intramuscularly two days after the first LPS injection and specific antibody production was measured on days 7 and 12 after bovine serum albumin administration. The results indicate that LPS challenge decreased ADG (P < 0.05) and ADFI (P < 0.05) from days 14 to 21, and depressed ADG (P < 0.10) from days 21 to 28. Fish oil improved ADG and ADFI during the first LPS challenge period between days 14 to 21 (P < 0.10). On day 14, LPS challenge x diet interactions were observed for plasma interleukin-1 beta (P < 0.10), prostaglandin E2 (P < 0.001), and cortisol (P < 0.05) such that these parameters responded to the LPS challenge to a lesser extent in pigs receiving the fish oil diet compared with pigs fed the corn oil diet. In contrast, among LPS treated pigs, pigs fed the fish oil diet had higher plasma insulin-like growth factor I (P < 0.10) compared with those fed the corn oil diet. On day 21, among LPS treated pigs, pigs fed fish oil had lower plasma interleukin-1 beta (P < 0.10) and cortisol (P < 0.05) compared with those fed corn oil. Pigs fed fish oil had lower plasma prostaglandin E2 (P < 0.05) and higher plasma insulin-like growth factor I (P < 0.10) compared with those fed corn oil. Lipopolysaccharide challenge resulted in decreased plasma growth hormone (P < 0.05) on day 14, whereas it had no effect on plasma growth hormone on day 21. During both the first and the second LPS challenge periods, LPS challenge resulted in increased blood lymphocyte proliferation when these cells were incubated with either 8 (P < 0.10) or 16 ug/mL (P < 0.05) concanavalin A. During the first challenge period, pigs fed fish oil had lower blood lymphocyte proliferation when incubated with 16 ug/mL concanavalin A (P < 0.10). Neither LPS challenge nor diet type affected serum antibody response to bovine serum albumin (P > 0.10). These results suggest that fish oil alters indices of the immune axis that may lead to improved pig performance during an inflammatory challenge.