title: Response of older laying hens to an Escherichia coli lipopolysaccharide challenge when fed diets with or without supplemental folic acid.
abstract: Folic acid plays a key role in nucleic acids and protein synthesis, and has been associated with anti-inflammatory effects in LPS-induced infections. To this end, a study was conducted to investigate the effects of dietary folic acid (FA) supplementation in older laying hens (58 to 66 wk of age) challenged with Escherichia coli lipopolysaccharide (LPS). A total of 24 Shaver White laying hens at 58 wk were fed 2 diets. The diets were wheat-soybean-based, with either 0 or 4 mg of supplemental FA per kg of diet. After 8 wk of feeding and at 66 wk, the hens were injected intravenously with 8 mg of LPS or saline per kg of BW. Four hours after injection, blood was collected and hens were euthanized to obtain spleen and cecal tonsils. The T cell subsets in the blood and the spleen (CD4+ and CD8+), total IgG, and biochemical constituents (total protein, albumin, globulin, and fibrinogen) were not influenced (P > 0.05) by dietary FA supplementation. However, LPS injection decreased (P < 0.05) biochemical constituents, CD4+, and CD8+ cells in the blood, whereas CD4+:CD8+ ratio and total IgG increased (P < 0.05), and fibrinogen was not influenced. Gene expression in the spleen and cecal tonsils was not influenced by dietary FA supplementation except a diet × challenge interaction for interleukin (IL)-8 in the spleen; IL-8 decreased in FA-fed hens that were treated with LPS. Also, FA supplementation decreased the expression of IL-8 in cecal tonsils. Relative to saline-injected hens, expression of IL-1β, interferon-γ, and IL-10 increased in the LPS-injected hens in the spleen and cecal tonsils, IL-8 increased in LPS-injected hens only in the cecal tonsils, whereas Toll-like receptor 4, IL-4, IL-17, and IL-18 increased in the LPS-injected hens only in the spleen; however, LPS decreased expression of IL-13 in the cecal tonsils. In conclusion, FA did not affect inflammatory responses in older laying hens; more studies are required to investigate possible protective effects of FA in laying hens.
authors.affiliation: Department of Animal Science, University of Manitoba, Winnipeg, Manitoba, Canada R3T 2N2.
authors.forename: P M
authors.initials: PM
authors.lastname: Munyaka
authors.forename: G
authors.initials: G
authors.lastname: Tactacan
authors.forename: M
authors.initials: M
authors.lastname: Jing
authors.forename: Karmin
authors.initials: K
authors.lastname: O
authors.forename: J D
authors.initials: JD
authors.lastname: House
authors.forename: Michael
authors.initials: M
authors.lastname: St Paul
authors.forename: Shayan
authors.initials: S
authors.lastname: Sharif
authors.forename: J C
authors.initials: JC
authors.lastname: Rodriguez-Lecompte
mesh_terms: D000375:Aging / Q000276:immunology*; D000821:Animal Feed / Q000032:analysis; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D002432:Cecum / Q000276:immunology; D002645:Chickens; D004032:Diet / Q000662:veterinary*; D019587:Dietary Supplements; D004926:Escherichia coli / Q000737:chemistry*; D005260:Female; D005492:Folic Acid / Q000494:pharmacology*; D005786:Gene Expression Regulation / Q000187:drug effects / Q000276:immunology; D007074:Immunoglobulin G; D008070:Lipopolysaccharides / Q000737:chemistry / Q000276:immunology*; D014066:Palatine Tonsil / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D013154:Spleen / Q000166:cytology; D016176:T-Lymphocyte Subsets
chemical_list: D007074:Immunoglobulin G; D008070:Lipopolysaccharides; D005492:Folic Acid