Increased productivity in poultry birds by sub-lethal dose of antibiotics is arbitrated by selective enrichment of gut microbiota, particularly short-chain fatty acid producers

Abstract

Antibiotics are widely used at sub-lethal concentrations as a feed supplement to enhance poultry productivity. To understand antibiotic-induced temporal changes in the structure and function of gut microbiota of chicken, two flocks were maintained for six weeks on a carbohydrate- and protein-rich diet. The feed in the conventional diet (CD) group was supplemented with sub-lethal doses of chlorotetracycline, virginiamycin and amoxicillin, while the organic diet (OD) had no such addition. Antibiotic-fed birds were more productive, with a lower feed conversion ratio (FCR). Their faecal samples also had higher total heterotrophic bacterial load and antibiotic resistance capability. Deep sequencing of 16S rDNA V1-V2 amplicons revealed Firmicutes as the most dominant phylum at all time points, with the predominant presence of Lactobacillales members in the OD group. The productivity indicator, i.e. higher Firmicutes:Bacteroidetes ratio, particularly in the late growth phase, was more marked in CD amplicon sequences, which was supported by culture-based enumerations on selective media. CD datasets also showed the prevalence of known butyrate-producing genera such as Faecalibacterium, Ruminococcus, Blautia, Coprococcus and Bacteroides, which correlates closely with their higher PICRUSt-based in silico predicted 'glycan biosynthesis and metabolism'-related Kyoto Encyclopedia of Genes and Genomes (KEGG) orthologues. Semi-quantitative end-point PCR targeting of the butyryl-CoA: acetate CoA-transferase gene also confirmed butyrate producers as being late colonizers, particularly in antibiotic-fed birds in both the CD flocks and commercial rearing farms. Thus, antibiotics preferentially enrich bacterial populations, particularly short-chain fatty acid producers that can efficiently metabolize hitherto undigestable feed material such as glycans, thereby increasing the energy budget of the host and its productivity.

Gut Microbiota, Blood Metabolites, and Spleen Immunity in Broiler Chickens Fed Berry Pomaces and Phenolic-Enriched Extractives

“…Besides, iron-chelating activities of pomace compounds such as tannin could induce iron-poor conditions, which are favorable to Lactobacillus , as these bacteria do not require iron for growth ( 60 ). Accordingly, data of the present study showed an increase of butyrate-producing genera such as Ruminococcus and Coprococcus in cranberry pomace–fed broiler ceca similar to what was observed in broiler chickens fed chlortetracycline, virginiamycin, and amoxicillin prophylactically for growth promotion ( 61 ). The above changes induced by tested products in this study could explain, at least in part, the low prevalence of subclinical NE caused by C. perfringens and coccidiosis due to Eimeria species.…”

Soybean Oligosaccharides Supplementation Attenuates the Fecal Odor Compounds by Modulate the Cecal Microbiota of Broilers

“…These results are consistent with earlier observations that in-feed antibiotic preferentially enriched butyrate-producing bacteria [19], SBO inhibited the growth of pathogenic microbes, and reduced the production of odor compounds [3,14,30]. Previous studies have found that supplementation of broiler diets with a mixture of chlortetracycline and other antibiotic increased both Ruminococcaceae and Lachnospiraceae [34]. It is known that both Lachnospiraceae and Ruminococcaceae produce butyrate [19,35,36].…”

Extended antibiotic treatment in salmon farms select multiresistant gut bacteria with a high prevalence of antibiotic resistance genes

“…The ingestion of medicated feed implicates that the intestinal microbiota of these animals is strongly affected. Antibiotics substantially change the bacterial diversity of gut microbiota in farmed animals [ 53 ], which, often, can result in functional and growth problems [ 57 ]. Another effect caused by the high use of the medicated food on the intestinal microbiota is that the feces could contain resistant bacteria, which could be easily dispersed in the environment [ 58 , 59 ].…”