(F09) Fecal Microbiota Dynamics in Calves During the First 24 Days in a Veal Unit

Abstract:

Background: The intestinal microbiota plays a crucial role in health, with early-life disruptions potentially affecting long-term outcomes. Various factors influence its composition, particularly during critical periods such as veal calf rearing.

Objectives: To evaluate fecal microbiota changes in calves during the first 24 days after entering a veal rearing unit. Animals: Fifty male calves (8–14 days old) purchased from a single auction market but originating from different farms.

Methods: Fecal samples were collected at arrival (D0) and on days 4, 10, and 24. Fecal scores and antibiotic use were recorded. Microbiota composition was analyzed via 16S rRNA sequencing (V4 region). ANOVA and PERMANOVA tests (p < 0.05) determined statistical significance.

Results: Richness and diversity were lowest at arrival and changed significantly over time (p < 0.001). However, microbiota composition was not associated with diarrhea incidence or antibiotic treatment. Specific bacterial taxa were linked to each time point (e.g., Bifidobacterium and Veillonella at D0, Lactobacillus and Bacteroides at D10). Diarrhea occurrence remained stable over time (p = 0.0037). Conclusions and Clinical Importance: Significant microbiota shifts occurred over time, independent of diarrhea or antibiotic use, suggesting a strong environmental influence. Stress, transportation, dietary transitions, and housing conditions likely contributed to these changes. Further research is needed to determine the long-term impact on calf health and performance and to identify microbiota modulation strategies during early rearing.