Antibiotic effect minor on older bird’s gut

21-07-2017 | |
Minor effect of antibiotics on gut health in older birds. Photo: Shutterstock
Minor effect of antibiotics on gut health in older birds. Photo: Shutterstock

What is the effect on gut health when antibiotics are supplied in older broilers? Dutch researchers put this to the test.

The study was done by scientists from Wageningen Bioveterinary Research and Wageningen Livestock Research in the Netherlands. The results have been published in the Journal of Poultry Science.

Gut health is a hot topic and it is known that animal health benefits from a stable intestinal homeostasis, for which proper development and functioning of the intestinal microbiota and immune system are essential. Changes in microbial colonisation in early life (the first 2 weeks post hatch) impacts the functioning of the adult gut and the associated crosstalk between microbiota and intestinal mucosal cells.

Antibiotics in drinking water tested

But is this also the case in older birds? The aim of the present study was therefore to investigate the effect of the administration of antibiotics later in life (day 15 to 20 post hatch) on microbiota and immune parameters. For this purpose, chickens received from 15 days post hatch during 5 days amoxicillin or enrofloxacin through their drinking water. Before and at 6, 16, and 27 days after start of the administration of antibiotics, the composition of the microbiota in the jejunum was determined using a 16S ribosomal RNA gene-targeted DNA microarray, the CHICKChip.

Read also: All About Feed published a special edition on gut health for animal species.

Gut affected, but small changes

It was shown that at 6 days after the start of the administration of the antibiotics, the composition and diversity of the microbiota were affected significantly (P < 0.05), but this change was small and observed only temporarily since differences disappeared at 16 days after initiating treatment with amoxillin and at 27 days after starting treatment with enrofloxacin. Intestinal morphology and development were not visibly affected since there were no differences between villus/crypt ratios and numbers of PAS+ and PCNA+ cells in the duodenum and jejunum at any time point. At 16 days after the start of antibiotic administration, the number of CD4+T-cells and CD8+ T-cells in the duodenum was lower compared to the control animals; however, this difference was not significant. At some time points, significant differences (P < 0.05) were observed among the groups to locally expressed IL-8, IL-1β, IFN-γ, IL-2, and IL-4 mRNA. However, this effect was not long lasting, as differences that were observed at 16 days after starting the treatment had disappeared at 27 days after treatment was started.


The results of this study indicate that later in the broiler’s life, antibiotics only temporarily affect intestinal microbial and immune parameters.

Source: Poultry Science

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Emmy Koeleman Freelance editor