Related Experiment Video
Updated: Jun 19, 2026
05:51
Production of Germ-Free Fast-Growing Broilers from a Commercial Line for Microbiota Studies
Published on: June 18, 2020
THE MODE OF ACTION OF ANTIBIOTICS IN STIMULATING GROWTH OF CHICKS
1Department of Microbiology, Rega Institute for Medical Research, University of Louvain, Louvain, Belgium.
The Journal of Experimental Medicine
|October 30, 2009
Summary
Antibiotics like virginiamycin improve chick growth by combating gut bacteria that hinder nutrient absorption. This effect is most significant around the 8th day of life, especially with sucrose-based diets.
Area of Science:
- Animal Science
- Microbiology
- Nutritional Science
Background:
- Chicks fed an antibiotic-free diet exhibit a temporary malabsorption syndrome around day 8.
- This syndrome impairs feed utilization and weight gain.
Purpose of the Study:
- To investigate the effect of virginiamycin on chick growth and nutrient absorption.
- To understand the role of gut microbiota and dietary carbohydrates in antibiotic efficacy.
Main Methods:
- Chicks were fed casein-sucrose or casein-cornstarch diets.
- Virginiamycin was administered at 20 ppm.
- Chicks were housed in old or new disinfected quarters.
- Fecal transfer was used to introduce specific gut flora.
Main Results:
- Virginiamycin suppressed malabsorption, improving feed conversion and weight gain in chicks in old quarters.
- The antibiotic's growth-promoting effect was diet-dependent, most pronounced with sucrose.
- In disinfected quarters, virginiamycin showed no significant growth benefits, indicating the importance of gut microbiota.
Conclusions:
- Antibiotics stimulate chick growth primarily through antibacterial action against Gram-positive bacteria interfering with nutrient absorption.
- The growth-promoting effect of virginiamycin is transient and linked to specific dietary conditions and the presence of a growth-depressing microflora.
Related Concept Videos
00:57Antibiotic Selection
Overview
01:23Inhibitors of Gram-positive Cell Wall Synthesis
Bacterial cell walls are typically rigid structures composed mainly of peptidoglycan, a mesh-like polymer that provides mechanical strength and maintains cell shape. The synthesis of peptidoglycan is a crucial process in bacterial growth and serves as a primary target for many antibiotics.Mechanism of Action of Beta-Lactam AntibioticsBeta-lactam antibiotics, such as penicillin, inhibit peptidoglycan synthesis in actively growing cells. These antibiotics share a characteristic four-membered...
01:27Production of Antibiotics
Penicillin, one of the earliest and most widely used antibiotics, is produced industrially by the filamentous fungus Penicillium chrysogenum. Large stirred-tank bioreactors ranging from tens to hundreds of thousands of liters maintain tightly controlled temperature, pH, and dissolved oxygen conditions to support fungal metabolism and maximize antibiotic yield. Penicillin is a secondary metabolite, synthesized primarily during the stationary growth phase, which requires a carefully managed...
01:25Inhibitors of Bacterial Protein Synthesis
Aminoglycosides constitute a highly potent class of bactericidal antibiotics that exert their antimicrobial effects by targeting the bacterial ribosome, specifically disrupting protein synthesis. These polycationic molecules consist of amino-modified sugars linked via glycosidic bonds to an aminocyclitol core such as 2-deoxystreptamine or streptamine. Their strong positive charges facilitate tight binding to the negatively charged phosphate backbone of ribosomal RNA (rRNA), primarily at the 16S...
01:21Microbiota Modulation by Antibiotics
Antibiotics have revolutionized modern medicine by saving countless lives from bacterial infections. However, their widespread use has inadvertently harmed the delicate balance of the human gut microbiota. The gut microbiota, a complex community of bacteria, archaea, viruses, and fungi, plays a vital role in regulating metabolism, immune responses, and maintaining intestinal health. Antibiotics, especially broad-spectrum types, disrupt this ecosystem by eradicating both harmful and beneficial...
01:23Antimicrobial Proteins
Antimicrobial proteins are important components of the immune system. They aid the body in combating pathogens by either killing them directly or hindering their replication processes. Four main types of antimicrobial substances are interferons, the complement system, iron-binding proteins, and antimicrobial proteins.
Interferons
Interferons (IFNs) are proteins produced by lymphocytes, macrophages, and fibroblasts infected with viruses. While IFNs cannot prevent viruses from entering and...
Interferons
Interferons (IFNs) are proteins produced by lymphocytes, macrophages, and fibroblasts infected with viruses. While IFNs cannot prevent viruses from entering and...