title: No protective effects of high-dosage dietary zinc oxide on weaned pigs infected with Salmonella enterica serovar typhimurium DT104.
abstract: Twenty-eight-day-old weaned pigs were fed diets with a low (LZn), medium (MZn), or high (MZn) Zn concentration (50 to 80, 150, or 2,500 mg Zn/kg of diet, respectively) provided as zinc oxide (ZnO)(24 pigs per group). They were infected orally with Salmonella enterica serovar Typhimurium DT104 on day 32. Salmonellae were cultivated from feces (up to 42 days postinfection [dpi]) and organs (2 and 42 dpi). Activation of the adaptive systemic and mucosal immune systems was investigated by recording anti-Salmonella IgG levels and levels of B and T lymphocyte subpopulations in blood and gut-associated lymphatic tissue. Growth performance was recorded as well. Salmonellae were shed at higher levels and for longer periods in the HZn group (P < 0.05), with no differences in the tissues. At 2 dpi, the relative percentages of CD4(+) T helper cells (P < 0.01) and of CD2(+) T and NK cells (P < 0.01) in blood were reduced from the relative cell counts obtained at 0 dpi, irrespective of the Zn group. The lowest percentage of cytotoxic T cells was found 14 dpi in the HZn group relative to the MZn (P < 0.05) and LZn (P < 0.01) groups. Supplementation of the feed with 2,500 mg Zn/kg of diet immediately after weaning could positively affect the immune responses of piglets infected with Salmonella Typhimurium, but for a short period only. After 2 weeks, all positive effects disappeared, and rather negative effects, such as higher shedding of salmonellae, lower T cell frequencies, and worse performance, occurred. Thus, supplementation with ZnO at high levels in the pig industry should be limited to 2 to 3 weeks.
authors: Federal Institute for Risk Assessment, Department of Biological Safety, Unit Molecular Diagnostics and Genetics, Berlin, Germany. pawel_janczyk@t-online.de
authors: Pawel
authors: P
authors: Janczyk
authors: Susanne
authors: S
authors: Kreuzer
authors: Jens
authors: J
authors: Assmus
authors: Karsten
authors: K
authors: Nöckler
authors: Gudrun A
authors: GA
authors: Brockmann
mesh_terms: D056704:Adaptive Immunity / Q000187:drug effects; D000821:Animal Feed; D000818:Animals; D000907:Antibodies, Bacterial / Q000187:drug effects / Q000276:immunology; D001402:B-Lymphocytes / Q000187:drug effects / Q000276:immunology; D057138:Bacterial Shedding; D019587:Dietary Supplements; D004305:Dose-Response Relationship, Drug; D005243:Feces / Q000382:microbiology; D005260:Female; D056724:Immunity, Humoral / Q000187:drug effects; D007074:Immunoglobulin G / Q000187:drug effects / Q000276:immunology; D008297:Male; D011897:Random Allocation; D012481:Salmonella Infections, Animal / Q000276:immunology / Q000382:microbiology / Q000517:prevention & control*; D012486:Salmonella typhimurium / Q000187:drug effects / Q000254:growth & development*; D013552:Swine; D013553:Swine Diseases / Q000276:immunology / Q000382:microbiology / Q000517:prevention & control*; D013601:T-Lymphocytes / Q000187:drug effects / Q000276:immunology; D013997:Time Factors; D014886:Weaning; D015034:Zinc Oxide / Q000008:administration & dosage / Q000494:pharmacology*
chemical_list: D000907:Antibodies, Bacterial; D007074:Immunoglobulin G; D015034:Zinc Oxide