Effects of dietary omega-3 polyunsaturated fatty acids on growth and immune response of weanling pigs
© Li et al.; licensee BioMed Central Ltd. 2014
Received: 31 May 2014
Accepted: 17 July 2014
Published: 24 July 2014
The recognition that omega-3 polyunsaturated fatty acids (n-3 PUFA) possess potent anti-inflammatory properties in human models has prompted studies investigating their efficacy for animal growth and immunity. This study examined the effect of feeding an n-3 PUFA-enriched diet on growth and immune response of weanling piglets. Newly weaned pigs (averaging 27 ± 2 days of age and 8.1 ± 0.7 kg of body weight) were assigned randomly to receive a control (3% vegetable oil, n = 20) or n-3 PUFA-supplemented (3% marine n-3 PUFA, n = 20) diet for 28 day after weaning. Female pigs consuming the n-3 PUFA-enriched diet were lighter at week 4 post-weaning than those fed the vegetable oil supplement. Weanling pigs gained more weight, consumed more feed and had better growth to feed ratios between days 14 and 28 than between days 0 and 14 post-weaning. Plasma insulin-like growth factor I (IGF-I) decreased between days 0 (87.2 ± 17.0 ng/mL) and 14 (68.3 ± 21.1 ng/mL) after weaning and then increased again by day 28 (155.2 ± 20.9 ng/mL). In piglets consuming the vegetable oil-enriched diet, plasma tumor necrosis factor alpha (TNF-α) increased from 37.6 ± 14.5 to 102.9 ± 16.6 pg/mL between days 0 and 14 post-weaning and remained high through day 28 (99.0 ± 17.2 pg/mL). The TNF-α increase detected in the piglets fed vegetable oil was not observed in the piglets fed n-3 PUFA. Results indicate that weaning induces considerable immune stress in piglets and that this stress can be mitigated by dietary supplementation of n-3 PUFA.
Keywordsn-3 PUFA Growth Immunity Pig
Nutritional, environmental and immune challenges associated with weaning may lead to considerable economic losses to pork producers. This period is generally characterized by decreased voluntary feed intake, altered gut integrity and increased concentrations of inflammatory cytokines in blood [1–3]. These nutritional and physiological abnormalities often result in diarrhea and depression of growth in newly weaned piglets. Restrictions of antibiotic usage in swine have compelled the industry to find alternatives that offer both performance enhancement and protection from disease [4, 5]. In this regard, Liu et al.  reported that dietary fish oil reduced the release of pro-inflammatory cytokines in weaned pigs challenged with Escherichia coli lipopolysaccharide. A more recent study indicated that prenatal exposure to long-chain n-3 PUFA increased postnatal glucose absorption in piglets . Although exact mechanisms by which dietary n-3 PUFA modulate immune and metabolic functions in pigs are yet to be fully elucidated, the above study would indicate that dietary n-3 PUFA may help the piglets adapt quickly to the rapidly changing diet at weaning .
Currently, there is very little information regarding the use of n-3 PUFA in the diets of pigs raised under minimal disease and stress conditions. To test the hypothesis that nutritional management strategies that attenuate intestinal inflammation may partition nutrients to skeletal muscle for optimal growth, this study was designed to examine the effects of dietary n-3 PUFA on growth and immune response of weanling pigs raised without an added bacterial or environmental challenge.
Results and discussion
Tumor necrosis factor-α, a cytokine produced primarily by monocytes and macrophages, is thought to be one of the principal mediators of inflammation . In the present study, plasma TNF-α concentrations were lower in weanling piglets supplemented with n-3 PUFA than those fed the vegetable oil supplement (Figure 3). These findings are consistent with previous in vitro [21–23] and in vivo [11, 24, 25] studies and suggest that n-3 PUFA inclusion in the diet could mitigate the immune stress in weanling pigs. Whereas exact mechanisms of n-3 PUFA suppression of TNF-α are yet to be fully elucidated, we speculate that suppression of TNF- α production by n-3 PUFA may be attributed, in part, to their inhibitory effects on NF-κB activation and or translocation to the nucleus [9, 22, 23]. Nuclear factor-κB are normally confined in the cytoplasm through their association with IκΒ. When cells are activated by inflammatory stimuli, the IκΒ are rapidly phosphorylated and degraded to free the NF-κΒ. The free NF-κΒ then migrate to the nucleus where they bind to cognate DNA binding sites and activate inflammatory gene transcription . Any factor that prevents IκΒ phosphorylation and, thus, NF-κΒ activation, will decrease pro-inflammatory gene expression in the nucleus. Additionally, long-chain PUFA serve as ligands for peroxisome proliferator-activated receptors (PPAR), which are known to inhibit nuclear translocation of NF-κΒ . Thus, activation of PPAR may be another intracellular mechanism by which marine n-3 PUFA regulate NF-κΒ activation and TNF-α production in animal models .
Hematological traits of weanling pigs fed diets with vegetable oil or long-chain omega -3 fatty acids a
WBCd × 103/mm3
RBCe × 103/mm3
Platelets × 103/mm3
In the pig, the period following weaning is generally characterized by sub-optimal growth, deteriorated feed efficiency, and a high incidence of diarrhea. Results of this study provided no evidence for n-3 PUFA modulation of growth of male weanling pigs raised in the absence of significant immunological and environmental challenges. The observation that female piglets consuming the n-3 PUFA-supplemented diet were lighter at week 4 post-weaning than those consuming the vegetable oil-enriched diet (Figure 2) may be indicative of a decrease in fat accretion at the expense of lean tissue. Additionally, dietary n-3 PUFA may improve the immune status of weanling pigs, as reflected by considerably lower plasma TNF-α in pigs consuming n-3 PUFA than those fed vegetable oil. The gradual increase in body weight, feed intake and feed efficiency following weaning likely reflects a progressive adaptation to post-weaning diets and a gradual improvement of the gastrointestinal microbiota.
Animals, diets and experimental design
Ingredient and calculated compositions of experimental diets
Soybean meal, %
Vegetable oil, %
Gromega Ultra 345, %
Min-Vit Premix, %
Fatty acid profile (g/100 g of total fat) of experimental diets a
∑n- 6 /∑n-3
Blood collection and analysis
On days 0, 14 and 28 of the experiment, jugular venous blood samples (8 ml from each experimental pig) were collected into evacuated heparinized tubes (BD Franklin Lakes, NJ) and centrifuged (3,000 × g for 15 min) to separate plasma. The plasma samples were stored at −80°C until analysis. Concentrations of IGF-I and TNF-α in plasma were analyzed using commercially available ELISA kits (R&D Systems, Inc., Minneapolis, MN). Hormone and cytokine analyses were performed in single assays and intra-assay CV were 4.0 and 4.7% for IGF-I and TNF-α, respectively. The least detectable concentrations were 0.06 ng/mL and 5.50 pg/ml. On day 27 of the experiment, additional blood samples were collected for complete blood cell counts, and hematological traits were determined as described by Quiroz-Rocha et al. .
Fecal consistency scores a of weanling pigs fed diets with vegetable oil or long-chain omega -3 fatty acids b
Effects of diets on growth, IGF-I, TNF-α and fecal characteristics were analyzed using the MIXED procedure of Statistical Analysis System (version 9.3) with repeated measures . For individual measurements (body weights), fixed effects included diet, gender, diet × gender interaction, week after weaning, diet × week interaction, gender × week interaction and diet × gender × week interaction. The pig, nested within gender and diet, was considered a random variable, and therefore the pig variance was used to test the effects of diet, gender, and diet x gender interaction. Initial weights were used as covariates in these analyses. A similar model was used to test the effect of diet on plasma IGF-I and TNF-α concentrations, except that week after weaning was replaced by day of blood sample collection. For collective measurements (feed intake, average daily gain, feed efficiency, and fecal consistency score), the statistical model included the effect of diets, pen (diet), week relative to weaning, diet × week interaction. In these models, pen was used as experimental unit to test the main effect of diet. Single blood samples were collected for complete blood cell counts, and, therefore, the statistical models for hematological traits contained only the main effect of diet. For all responses, significant differences between means were declared at P < 0.05.
Average daily feed intake
Average daily gain
F: Gain to feed ratio
Insulin-like growth factor I
Peroxisome proliferator-activated receptors
Red blood cells
Tumor necrosis factor alpha
White blood cells.
The authors thank JBS United, Inc (Sheridan, IN, USA) for kindly providing Gromega Ultra 345 for this research and the University of Florida Swine Unit crew for their help with the field work. The present study was supported partially by the Department of Animal Sciences of the University of Florida.
- Le Dividich J, Sève B: Effects of underfeeding during the weaning period on growth, metabolism, and hormonal adjustments in the piglet. Domest Anim Endocrinol. 2000, 19: 63-74.View ArticlePubMedGoogle Scholar
- Montagne L, Boudry G, Favier C, Le Huërou-Luron I, Lallès JP, Sève B: Main intestinal markers associated with the changes in gut architecture and function in piglets after weaning. Br J Nutr. 2007, 97: 45-57.View ArticlePubMedGoogle Scholar
- Pié S, Lallès JP, Blazy F, Laffitte J, Sève B, Oswald IP: Weaning is associated with an up-regulation of expression of inflammatory cytokines in the intestine of piglets. J Nutr. 2004, 134: 641-647.PubMedGoogle Scholar
- Cromwell GL: Why and how antibiotics are used in swine production. Anim Biotechnol. 2002, 13: 7-27.View ArticlePubMedGoogle Scholar
- Vondruskova H, Slamova R, Trckova M, Zraly Z, Pavlik I: Alternatives to antibiotic growth promoters in prevention of diarrhoea in weaned piglets: a review. Vet Medic. 2010, 5: 199-224.Google Scholar
- Liu YL, Li DF, Gong LM, Yi GF, Gaines AM, Carroll JA: Effects of fish oil supplementation on the performance and immunological, adrenal, and somatotropic responses of weaned pigs after an Escherichia coli lipopolysaccharide challenge. J Anim Sci. 2003, 81: 2758-2765.PubMedGoogle Scholar
- Gabler NK, Radcliffe JS, Spencer JD, Webel DM, Spurlock ME: Feeding long-chain n-3 polyunsaturated fatty acids during gestation increases intestinal glucose absorption potentially via the acute activation of AMPK. J Nutr Biochem. 2009, 20: 17-25.View ArticlePubMedGoogle Scholar
- Heo JM, Opapeju FO, Pluske JR, Kim JC, Hampson DJ, Nyachoti CM: Gastrointestinal health and function in weaned pigs: a review of feeding strategies to control post-weaning diarrhoea without using in-feed antimicrobial compounds. J Anim Physiol Anim Nutr. 2012, 97: 207-237.View ArticleGoogle Scholar
- Calder PC: Omega-3 fatty acids and inflammatory processes. Nutrients. 2010, 2: 355-374.View ArticlePubMedPubMed CentralGoogle Scholar
- Calder PC: Omega-3 polyunsaturated fatty acids and inflammatory processes: nutrition or pharmacology?. Br J Clin Pharmacol. 2012, 75: 645-662.Google Scholar
- Carroll JA, Gaines AM, Spencer JD, Allee GL, Kattesh HG, Roberts MP, Zannelli ME: Effect of menhaden fish oil supplementation and lipopolysaccharide exposure on nursery pigs. I. Effects on the immune axis when fed diets containing spray-dried plasma. Domest Anim Endocrinol. 2003, 24: 341-351.View ArticlePubMedGoogle Scholar
- Korver DR, Klasing KC: Dietary fish oil alters specific inflammatory immune responses in chicks. J Nutr. 1997, 127: 2039-2046.PubMedGoogle Scholar
- Eastwood L, Kish PR, Beaulieu AD, Leterme P: Nutritional value of flaxseed meal for swine and its effects on the fatty acid profile of the carcass. J Anim Sci. 2009, 87: 3607-3619.View ArticlePubMedGoogle Scholar
- Baillie RA, Takada R, Nakamura M, Clarke SD: Coordinate induction of peroxisomal acyl-CoA oxidase and UCP-3 by dietary fish oil: a mechanism for decreased body fat deposition. Prostaglandins Leukot Essent Fatty Acids. 1999, 60: 351-356.View ArticlePubMedGoogle Scholar
- Belzung F, Raclot T, Groscolas R: Fish oil n-3 fatty acids selectively limit the hypertrophy of abdominal fat depots in growing rats fed high-fat diets. Am J Physiol. 1993, 264: R1111-R1118.PubMedGoogle Scholar
- Hill JO, Peters JC, Lin D, Yakubu F, Greene H, Swift L: Lipid accumulation and body fat distribution is influenced by type of dietary fat fed to rats. Int J Obes Relat Metab Disord. 1993, 17: 223-236.PubMedGoogle Scholar
- Jump DB, Clark SD, Thelen A, Liimatta M: Coordinate regulation of glycolytic and lipogenic gene expression by polyunsaturated fatty acids. J Lipid Res. 1994, 35: 1076-1084.PubMedGoogle Scholar
- Noreen EE, Sass MJ, Crowe ML, Pabon VA, Brandauer J, Averill LK: Effects of supplemental fish oil on resting metabolic rate, body composition, and salivary cortisol in healthy adults. J Int Soc Sports Nutr. 2010, 7: 31-37.View ArticlePubMedPubMed CentralGoogle Scholar
- Thissen JP, Verniers J: Inhibition by interleukin-1β and tumor necrosis factor-α of the insulin-like growth factor I messenger ribonucleic acid response to growth hormone in rat hepatocyte primary culture. Endocrinology. 1997, 138: 1078-1084.PubMedGoogle Scholar
- Bemelmans MH, van Tits LJ, Buurman WA: Tumor necrosis factor: Function, release and clearance. Crit Rev Immunol. 1996, 16: 1-11.View ArticlePubMedGoogle Scholar
- Lo CJ, Chiu KC, Fu M, Lo R, Helton S: Fish oil decreases tumor necrosis factor gene transcription by altering the NF-κΒ activity. J Surg Res. 1999, 82: 216-221.View ArticlePubMedGoogle Scholar
- Novak TE, Babcock TA, Jho DH, Helton WS, Espat NJ: NF-κB inhibition by ώ-3 fatty acids modulates LPS-stimulated macrophage TNF-α transcription. Am J Physiol Lung Cell Mol Physiol. 2003, 284: L84-L89.View ArticlePubMedGoogle Scholar
- Zhao Y, Joshi-Barve S, Barve S, Chen LH: Eicosapentaenoic acid prevents LPS-induced TNF-α expression by preventing NF-kB activation. J Am Coll Nutr. 2004, 23: 71-78.View ArticlePubMedGoogle Scholar
- Gaines AM, Carroll JA, Yi GF, Allee GL, Zannelli ME: Effect of menhaden fish oil supplementation and lipopolysaccharide exposure on nursery pigs. II. Effects on the immune axis when fed simple or complex diets containing no spray-dried plasma. Domest Anim Endocrinol. 2003, 24: 353-365.View ArticlePubMedGoogle Scholar
- Malekshahi Moghadam A, Saedisomeolia A, Djalali M, Djazayery A, Pooya S, Sojoudi F: Efficacy of omega-3 fatty acid supplementation on serum levels of tumour necrosis factor-alpha, C-reactive protein and interleukin-2 in type 2 diabetes mellitus patients. Singapore Med J. 2012, 53: 615-619.PubMedGoogle Scholar
- Friendship RM, Lumsden JH, McMillan I, Wilson MR: Hematology and biochemistry reference values for Ontario swine. Can J Comp Med. 1984, 48: 390-393.PubMedPubMed CentralGoogle Scholar
- Wilson GD, Harvey DG, Snook CR: A review of factors affecting blood biochemistry in the pig. Br Vet J. 1972, 128: 596-610.PubMedGoogle Scholar
- Quiroz-Rocha GF, LeBlanc SJ, Duffield TF, Wood D, Leslie KE, Jacobs RM: Reference limits for biological and hematological analytes of dairy cows one week before and one week after parturition. Can Vet J. 2009, 50: 383-388.PubMedPubMed CentralGoogle Scholar
- Littell RC, Henry PR, Ammerman CB: Statistical analysis of repeated measures data using SAS procedures. J Anim Sci. 1998, 76: 1216-1231.PubMedGoogle Scholar
This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.