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16:00 - "Microbiota dynamics in dairy cows around calving and its associations with health"
Microbiota dynamics in dairy cows around calving and its associations with health
Abstract:
The transition period (± 3 weeks around calving) is critical for the health and productivity of dairy cows. During this phase, significant physiological and metabolic changes occur, including reduced feed intake and an increased energy demand for lactogenesis. This renders cows more susceptible to metabolic and infectious diseases. The role of the gut microbiota in shaping immunity in the gut and systemically through host–microbiota interactions has been investigated in human biology, but little is known about this in dairy cattle.
My primary objective was to enhance the description and understanding of the faecal microbiota composition in dairy cows, and its relationship with general health and immunity during the transition period. To do so, several datasets were analysed, relying on a large diversity of analytical methods. First, a thorough meta-analysis of existing faecal microbiota data of lactating Holstein cows was conducted, including more than 2,000 samples. Notwithstanding the challenges posed by inconsistent data quality and methodological heterogeneity, three microbial profiles were established. The findings of this study provide a robust baseline for future comparative research. Second, an experiment was conducted on 25 commercial dairy farms in Brittany (France) to investigate changes in 411 dairy cows during the periparturient period. Shifts in microbial composition were observed within the short timeframe surrounding calving. Finally, we studied the relationship between microbiota and immune parameters, with a particular focus on the cytokine expression and inflammatory response during the transition period. Four immunological profiles were established during this period. Despite the lack of a clear link between these four immune profiles and microbial composition, we found that the variability in cytokine expression could be partly (<10%) explained by the presence of several taxa. Although these associations are exploratory in nature, they have generated specific hypotheses linking host physiology during the periparturient period to microbial ecology. Altogether, this work is part of more global efforts to improve animal welfare, enhance farm profitability, and promote sustainable agriculture from a One Health perspective, which combines animal, environmental, and human health.