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Early life modulation of the gut microbiota and antibiotic resistance in calves fed oregano essential oil.

P. P. Ray

Events

06-22-2020

Abstract:

109
Early life modulation of the gut microbiota and antibiotic resistance in calves fed oregano essential oil.
P. P. Ray*1, C. Rymer1, D. Wilde2, E. F. Lund2, A. C. Singer3. 1Department of Animal Sciences, School of Agriculture, Policy and Development, University of Reading Reading, United Kingdom, 2Anpario plc Worksop, United Kingdom, 3NERC Centre for Ecology and Hydrology Wallingford, United Kingdom.

This study aimed to investigate the modulation in the gut microbiota and associated changes in antibiotic resistance in calves fed Oregano essential oil (EO). Ten Holstein bull calves were divided into 2 groups (5 calves/group) and assigned to 1 of 2 dietary treatments: control (fed waste milk) and EO (Orego-Stim Liquid, Anpario plc, UK; fed waste milk with EO for the first 10 d of the study) within 48 h after birth. Fecal grab samples were collected on d 0, 3, 10, 21 and at weaning. Replica plating technique was used to determine the proportion of E. coli colonies resistant to a 4th generation cephalosporin (cefquinome). Genomic DNA was extracted, 16S rRNA (V3-V4) was amplified and sequenced using Illumina MiSeq platform. Data were processed in R using DADA2 Pipeline and analyzed using Minitab. Firmicutes and Actinobacteria were 2 most predominant phyla across all samples. While fecal abundance of Firmicutes was higher in control calves compared with EO-fed calves (66 vs 44%; P = 0.01), Actinobacteria was more abundant in EO-fed calves than in control calves (39 vs 15%; P = 0.05). Relative abundance of genus Butyricicoccus in the feces was higher in control calves compared with EO-fed calves (19 vs 9%; P = 0.04). Arthrobacter and Escherichia tended to be less abundant (3.8 vs 3.9%; P = 0.10; 0.4 vs 0.6%; P = 0.05) and Ruminococcus tended to be more abundant in EO-fed calves compared with control calves (2.1 vs 1.5%; P = 0.05). Feeding EO did not influence overall species richness and evenness. However, both richness and evenness were greater in control calves compared with EO-fed calves on d 3 and 10, but not after d 10. Relative abundance of Arthrobacter was positively correlated to the fecal abundance of cefquinome resistant E. coli (ρ = 0.56; P < 0.01). Fecal count of Cryptosporidium eggs tended to increase with increasing abundance of Arthrobacter (ρ = 0.40; P = 0.09) and decreasing abundance of Ruminococcus (ρ = 0.40; P = 0.10). Feeding EO to young calves could modulate the gut microbiota such that growth of antibiotic resistant bacteria and parasite colonization is reduced.

Keywords: calves, antibiotic resistance, essential oil.