In the scorching heat and high humidity of northeastern Tamil Nadu, dairy cattle face significant challenges to their comfort and milk production. A new study reveals how different cattle housing systems create varying microclimates, offering scientific guidance for local dairy farmers.
Research Methodology
Researchers conducted field studies in Vellore and Virudhunagar districts, important dairy farming regions characterized by semi-arid climates with annual rainfall between 800-1400 mm. Average temperatures range from 19.5°C to 38.9°C. The team surveyed 139 dairy farmers and selected 30 farms (each with ≥5 cattle) representing five common housing types differentiated by roofing materials:
• Thatched roofs
• Tiled roofs
• Metal roofs
• Cement concrete roofs
• Open housing systems
Using maximum-minimum thermometers and digital hygrometers, researchers recorded key parameters including maximum/minimum temperatures, 8 AM/2 PM temperatures, and temperature-humidity index (THI) values at both morning and afternoon readings. Data collection spanned a full year, divided into four seasons according to India Meteorological Department classifications.
Key Findings
During the southwest monsoon season (June-August), cement concrete roofs recorded the highest 8 AM temperatures (26.71±1.13°C) and THI values (77.23±1.76), while thatched roofs maintained the coolest conditions (24.83±1.17°C and 74.54±1.72 THI). Similar patterns emerged during the northeast monsoon (September-November), with cement roofs again showing the warmest measurements.
The study found that only during cold seasons (December-February) did all housing systems maintain morning THI below the critical 72 threshold, indicating cattle experienced no significant heat stress during early hours. However, THI values consistently exceeded recommended levels during other periods, suggesting cattle faced environmental stress through most of the day.
While minimum temperatures across all seasons remained within optimal comfort ranges for dairy production, afternoon temperatures in all housing systems exceeded recommended maximums, highlighting the need for supplemental cooling measures.
Performance Comparison
Thatched roofs demonstrated superior thermal performance across multiple metrics:
- Recorded lowest morning and afternoon temperatures during northeast monsoons
- Maintained lowest THI during southwest monsoons
- Showed lowest maximum temperatures and THI during cold seasons
Tiled roofs emerged as the second-best option, maintaining the second-lowest maximum temperatures year-round and recording the lowest afternoon THI during summer months.
Metal roofs ranked third in thermal performance, while cement concrete roofs consistently showed the poorest results across all measured parameters. Open housing systems, though maintaining the lowest minimum temperatures, recorded afternoon temperatures second only to cement roofs, making them unsuitable without supplemental shading.
Industry Implications
The findings confirm that dairy cattle in northeastern Tamil Nadu experience prolonged heat stress, with THI values exceeding critical thresholds during most daylight hours, even in monsoon seasons. This aligns with previous research showing similar thermal challenges for crossbred calves.
The study provides the first direct comparison of locally prevalent housing systems, offering region-specific recommendations beyond generic roofing material evaluations. Researchers emphasize the importance of selecting housing types based on local climate conditions, particularly as climate change intensifies thermal challenges.
While thatched and tiled roofs prove most suitable for the region's microclimate, the study notes that even these systems require additional afternoon cooling measures to ensure optimal cattle comfort and milk production. The findings offer valuable guidance for sustainable dairy development across Tamil Nadu and similar climatic regions in India.
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