Evaluación del microbioma de sólidos de estiércol reciclado suplementados con biocarbón como lecho para vacas

The intensification of dairy production with animal confinement generates a large quantity of manure that, when poorly managed, can have undesirable environmental impacts. An attractive alternative that has emerged for recycling these substantial amounts of animal manure produced daily in dairy farms, is the use of Recycled Manure Solids (RMS) as bedding material. However, this ecological strategy that has several advantages, such as its reduced costs and high availability, as well as the fact that its use has been associated with increased cow well-being, is not without its risks. In fact, being the solid fraction of cows’ manure, RMS can present high levels of pathogenic bacteria and be responsible for an increase in mastitis cases or contribute to the dissemination of antimicrobial resistant bacteria and genes, which poses a risk to farm personnel, animals, and the environment. To tackle this problem, one innovative strategy that has emerged for manure reuse and recycling is the use of biochar, an inorganic char coproduct obtained from thermochemical processing of biomass that may eliminate relevant bacterial species when added to animal waste.

In this line of thought, the objective of our work was to evaluate the potential of RMS supplemented with a pine biochar produced in Portugal as a new cow bedding material. In particular, an incubation experiment was designed and conducted to assess the effect of biochar addition on the microbiome of RMS. For that, fresh RMS samples were collected on a commercial dairy farm after liquid-solid fraction separation, and placed in naturally-ventilated containers, which were then incubated in conditions as similar as possible to those found during regular farm husbandry. Triplicate containers were prepared for 4 different conditions: 1–non-supplemented RMS (kept as a negative control); 2-RMS supplemented with 2.5% (w/w) of biochar; 3-RMS supplemented with 5% (w/w) of biochar; and 4-RMS supplemented with 10% (w/w) of biochar. This experiment was performed during two distinct periods: April-May (humid season) and June-July (dry season). Composite RMS samples from each condition (10 g of bedding material), collected at four timepoints (days 0, 5, 15, 30) from different locations in the containers, had their microbiome profile determined by performing 16S rRNA amplicon sequencing using Nanopore PromethION platform.

In general, the results obtained showed that biochar supplementation had a clear impact in the microbiome of RMS, affecting not only those populations’ diversity but also the relative abundance of relevant pathogenic bacteria. In particular, long-term storage (30 days) was found to be more beneficial than short-term storage, for both seasons. That effect was also more evident for samples supplemented with 2.5% biochar. For samples collected in the dry season, RMS supplementation with 2.5% biochar led to decreased microbiome diversity and reduced abundance of the Enterobacteriaceae and Staphylococcaceae families (by 38% and 80% when compared with the negative control, respectively), which include several known agents of mastitis in dairy cows. In the humid season, under these same conditions, a 23% decrease was found for the relative abundance of members of the Enterobacteriaceae family, while biochar supplementation also led to undetectable levels of species of the Enterococcaceae family. Unexpectedly, under those conditions, we also observed an increase in the abundance of the Brucellaceae family (of 50% and 160% in the dry and humid seasons, respectively), which includes important infectious agents, highlighting the need for caution when using this type of approach as the changes induced by biochar treatment are complex and should be analyzed as a whole to ensure the safe and sustainable use of this environmental-friendly resource in animal production.

  • vetoquinol
  • analítica veterinaria
  • delaval
  • innogando
  • Secure Cattle
  • hifarmax
  • DML Datamars Livestock
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