Airborne microbial load and diversity: impact of climatic conditions in loose cattle housing systems

Airborne microbes from animal confinement facilities not only amplify the risk of disease spread among livestock but also pose substantial health threats to animals and farm workers. The objective of this study was to investigate the microbial counts in cattle sheds and their relationship with meteorological factors, including temperature, relative humidity, and air velocity, as well as microbial diversity. Sampling was carried out both indoors and outdoors of two cattle sheds throughout three seasons (summer, rainy, and winter), at fortnightly intervals. Results showed that bacterial and fungi counts ranged from 0.0 to 1.60 × 10³ CFU/m³ inside the sheds and from 0.0 to 1.08 × 10³ CFU/m³ outside, with significant variation between areas and seasons. The predominant microbial count was mesophilic bacteria followed by staphylococci, fungi and Enterobacteriaceae. The mesophilic bacteria, Enterobacteriaceae and fungi showed statistically significant positive correlation with air temperature while air velocity with Enterobacteriaceae bacteria. No significant correlation exists between relative humidity and microbial concentration. The bacterial families Staphylococcaceae and Bacillaceae from the mesophilic group of bacteria were identified as the most prevalent, whereas the dominant fungi taxa in the cattle sheds were Aspergillus spp. and Penicillium spp. The microbial environment within cattle sheds under loose housing systems was found to be well-regulated, with airborne bacteria and fungi levels remaining within recommended limits.