Abstract
Anthelmintic treatment of adult ewes is widely practiced to remove parasite burdens in the expectation of increased ruminant productivity. However, the broad activity spectra of many anthelmintic compounds raises the possibility of impacts on the rumen microbiota. To investigate this, 300 grazing ewes were allocated to treatment groups that included a 100-day controlled release capsule (CRC) containing albendazole and abamectin, a long-acting moxidectin injection (LAI), and a non-treated control group (CON). Rumen bacterial, archaeal and protozoal communities at day 0 were analysed to identify 36 sheep per treatment with similar starting compositions. Microbiota profiles, including those for the rumen fungi, were then generated for the selected sheep at days 0, 35 and 77. The CRC treatment significantly impacted the archaeal community, and was associated with increased relative abundances of Methanobrevibacter ruminantium, Methanosphaera sp. ISO3-F5, and Methanomassiliicoccaceae Group 12 sp. ISO4-H5 compared to the control group. In contrast, the LAI treatment increased the relative abundances of members of the Veillonellaceae and resulted in minor changes to the bacterial and fungal communities by day 77. Overall, the anthelmintic treatments resulted in few, but highly significant, changes to the rumen microbiota composition.
Highlights
Anthelmintic treatment of adult ewes is widely practiced to remove parasite burdens in the expectation of increased ruminant productivity
The ewes in one group were treated with a 100-day rumen in-dwelling controlled release capsule (CRC) containing albendazole and abamectin; those in the second with a long-acting injection (LAI) of moxidectin, given subcutaneously; and the third group was a non-treated control (CON) group
Rumen content samples were taken from all ewes just prior to administration of anthelmintic treatments on day 0, and the bacterial, archaeal and protozoal community structures in these were analysed
Summary
Anthelmintic treatment of adult ewes is widely practiced to remove parasite burdens in the expectation of increased ruminant productivity. Archaeal and protozoal communities at day 0 were analysed to identify 36 sheep per treatment with similar starting compositions. The LAI treatment increased the relative abundances of members of the Veillonellaceae and resulted in minor changes to the bacterial and fungal communities by day 77. Albendazole was shown to have little impact on the gut bacterial communities of helminth-free subjects, but in parasite-infected subjects, interactions between treatments and infection level on the microbiota were apparent[13]. In this study we examined the impact of two commercially available long-acting anthelmintic products on the rumen microbiota of sheep, as our first step to investigate these interactions and understand the observed variability in response associated with anthelmintic treatments
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