title: Effects of direct-fed microbials on growth performance, gut morphometry, and immune characteristics in broiler chickens.
abstract: This study was conducted to compare growth performance, gut morphometry, and parameters of local and systemic immunity in broiler chickens fed for 22 consecutive days with a diet supplemented with Bacillus spp. as direct-fed microbials (DFM), a commercial product incorporating 3 DFM, or a nonsupplemented diet. Direct-fed microbials did not significantly modify BW gain and most failed to affect serum antibody levels in response to immunization with a recombinant Eimeria protein. However, altered intestinal morphometric measurements were readily apparent in DFM-fed chickens as revealed by increased villus height and crypt depth compared with non-DFM-fed controls. In addition, serum levels of alpha-1-acid glycoprotein as an inflammatory marker were reduced in DFM-fed birds, whereas splenic lymphocyte proliferation, intestine intraepithelial lymphocyte subpopulations, and cytokine mRNA levels in intraepithelial lymphocytes were increased, decreased, or unchanged compared with controls depending on the DFM used. These results provide a rational scientific basis for future studies to investigate DFM as immunomodulating agents to enhance host protective immunity against enteric pathogens in broiler chickens.
authors.affiliation: Animal Parasitic Diseases Laboratory, Animal and Natural Resources Institute, Agricultural Research Service, USDA, Beltsville, MD 20705, USA.
authors.forename: K W
authors.initials: KW
authors.lastname: Lee
authors.forename: S H
authors.initials: SH
authors.lastname: Lee
authors.forename: H S
authors.initials: HS
authors.lastname: Lillehoj
authors.forename: G X
authors.initials: GX
authors.lastname: Li
authors.forename: S I
authors.initials: SI
authors.lastname: Jang
authors.forename: U S
authors.initials: US
authors.lastname: Babu
authors.forename: M S
authors.initials: MS
authors.lastname: Park
authors.forename: D K
authors.initials: DK
authors.lastname: Kim
authors.forename: E P
authors.initials: EP
authors.lastname: Lillehoj
authors.forename: A P
authors.initials: AP
authors.lastname: Neumann
authors.forename: T G
authors.initials: TG
authors.lastname: Rehberger
authors.forename: G R
authors.initials: GR
authors.lastname: Siragusa
mesh_terms: D000821:Animal Feed; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D001412:Bacillus subtilis; D049109:Cell Proliferation; D002645:Chickens / Q000254:growth & development*; D004032:Diet / Q000662:veterinary*; D019587:Dietary Supplements; D041981:Gastrointestinal Tract / Q000033:anatomy & histology* / Q000276:immunology / Q000382:microbiology / Q000502:physiology*; D008214:Lymphocytes / Q000166:cytology / Q000502:physiology; D009961:Orosomucoid / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D013154:Spleen / Q000166:cytology; D015430:Weight Gain
chemical_list: D009961:Orosomucoid; D012333:RNA, Messenger