Avaliação do desempenho térmico de estruturas de sombreamento para áreas de pastejo de galinhas poedeiras

Abstract

The free-range system has gained prominence for providing improved welfare conditions for laying hens, allowing the expression of natural behaviors. However, direct exposure to the environmental elements in paddocks can impair the health and productivity, highlighting the need for effective shading strategies. This study aimed to evaluate the thermal performance of artificial shading structures built with different roofing materials in paddocks for free-range laying hens’ systems. A systematic and bibliometric reviews were first conducted to identify research gaps, followed by the construction of prototypes using different roof materials (aluminum roofing, 70% polyethylene mesh, 6 mm corrugated fiber-cement roofing painted white on the external surface and with four-layer Tetra Pak® roof insulation blanket, commercial ecological roofing, treated roundwood, treated roundwood with green roof, and treated whole bamboo). The structures were assessed through morphological characterization of the roofing materials using Scanning Electron Microscopy (SEM), alongside microclimatic variables and thermal comfort indices. The systematic and bibliometric reviews underscored Brazil's leading role in research on roofing materials, emphasizing the need for further research on sustainable materials. SEM analysis allowed detailed material characterization and helped explain the observed thermal responses. Results indicated that 70% polyethylene mesh exhibited the poorest thermal performance, whereas green roofs, treated roundwood, and painted fibercement with underlayment showed fewer limitations. Among these, shading structures with green roofs, treated roundwood, and painted fiber-cement with roof insulation blanket were the most effective for reducing thermal discomfort under artificial shading structures located in the free-range paddocks; nevertheless, no were sufficient to ensure thermal comfort during peak heat periods. These findings provide insights for enhancing paddock microclimates in alternative laying-hen systems, supporting the development of more sustainable and ethically responsible production practices.