Relationship of Dietary Antimicrobial Drug Administration with Broiler Performance, Decreased Population Levels of Lactobacillus salivarius, and Reduced Bile Salt Deconjugation in the Ileum of Broiler Chickens

• Published in: Poultry science 2006-12, Vol.85 (12), p.2186-2194
• Main Authors: Guban, J, Korver, D.R, Allison, G.E, Tannock, G.W
• Format: Article
• Language: English
• Subjects: Animal Feed - analysis; Animal Nutritional Physiological Phenomena; animal performance; Animals; Anti-Bacterial Agents - administration & dosage; Anti-Bacterial Agents - chemistry; Anti-Bacterial Agents - pharmacology; bacitracin; Bacitracin - administration & dosage; Bile Acids and Salts - metabolism; bile salts; body weight; broiler chickens; broiler feeding; Chickens - growth & development; Diet - veterinary; dietary fat; Dietary Fats; digesta; digestibility; Digestion - drug effects; Drug Therapy, Combination; feed additives; feed conversion; feed intake; Female; ileum; Ileum - metabolism; Ileum - microbiology; intestinal microorganisms; Lactobacillus - drug effects; Lactobacillus salivarius; liveweight gain; Male; medicated feeds; monensin; Monensin - administration & dosage; poultry housing
• ISSN: 0032-5791; 1525-3171
• DOI: 10.1093/ps/85.12.2186

Straight-run broiler chickens were raised either in floor pens or wire-floored cages (trial 1) or in floor pens only (trials 2, 3, and 4). Birds raised in floor pens had lower BW and feed intakes than those raised in cages. The administration of bacitracin in the feed increased feed intake from d 12 to d 35, decreased the feed conversion ratio during the same period in trial 2, and improved the weight gain of broilers from d 0 to 10 in trial 3. The concentrations of conjugated bile salts (taurocholic and taurochenodeoxycholic acids) were higher in the ileal contents of broilers administered the antimicrobials compared with untreated birds. Supplementation of the feed with monensin increased fat digestibility in the ileum of the birds. Although total numbers of bacteria in ileal contents were the same regardless of whether antimicrobials were administered or not, the bacterial community differed qualitatively. Populations of Lactobacillus salivarius were reduced in birds fed antimicrobials relative to untreated broilers. A representative ileal isolate of L. salivarius deconjugated bile salts in pure culture in the laboratory and in the ileal contents of ex-Lactobacillus-free chickens maintained in a protective environment and colonized by the Lactobacillus isolate. These observations provide a link between bile salt deconjugation in the ileum by L. salivarius and decreased weight gain of broilers. Lactobacillus salivarius populations could be targeted in future studies aimed at modification of the ileal bacterial community to achieve growth promotion of broilers without the administration of antimicrobial drugs.