Use of alternative tiles in the free-range broilers rearing: thermal environment, productive performance and physiological responses

Industrial poultry in Brazil has been growing every year, keeping the country among the main producers and as the largest chicken meat exporter in the world (ABPA 2020). Parallel to this market, there is the alternative production of birds, which has been conquering its space, becoming a relevant activity for small and medium producers, from different regions of the country, both for subsistence and for commercial production. Despite the high power of production and commercialization of industrial broiler meat, there is still a portion of the population that identifies itself better with a diet coming from productions understood as more natural, where the growth of birds is much less intense, the welfare of birds it is more respected and the use of growth stimulants is not practiced (Cavalcanti 2019). In the free-range breeding, own lines of slow growth are used, adapted to semi-intensive management. However, in tropical and subtropical climates, as is the case in Brazil, high temperatures and relative humidity are among the main factors that can interfere negatively in the creation, significantly altering the productivity of these birds. Their exposure to heat stress conditions causes decreased food consumption, impairing growth, carcass yield and meat quality, in addition to promoting production energy expenditure for heat loss, increasing respiratory rate and cloacal temperature (Amaral et al 2011; Cassuce et al 2013). Once proven that the ability of birds in thermal exchange with the environment is strongly affected by the facilities (Abreu e Abreu 2011; Nascimento et al 2014), producers have been looking for alternatives that aim to improve the thermal conditions of the environment in which the animal is in order to reduce the negative effects of these environmental factors on production. From a bioclimatic point of view, roofs are one of the main factors that significantly influence the thermal environment of the installation, mainly due to the materials used in their manufacture (Silva and Sevegnani 2001). Various types of tiles are available on the market, made from materials ranging from the most common, such as clay and fiber cement, to innovative ones, such as ecological tiles, each with its specific characteristics. However, due to the cost of these tiles, some research has been carried out with alternative materials such as vegetable tile, Tetra Pak packaging, waste from toothpaste tubes and others (Fiorelli et al 2010; Cardoso et al 2011; Silva et al 2015 Abstract The physiological parameters and the productive performance of free-range broilers submitted to installations with different materials of tile composition were evaluated. 320 male broilers of the Vermelho Pesadão lineage were used, with an initial age of 35 days, distributed among the following treatments: 1) Fiber cement tile painted white on the outside; 2) Cardboard tile coated with double-sided canvas black for the interior and white for the exterior; 3) Tetra Pak® box tile; 4) Tile of Tetra Pak® boxes covered with PET bottles. A completely randomized design was used, with 4 replicates per treatment and 20 broilers per experimental unit. The climatic environment was evaluated daily at 8, 10, 12, 14 and 16 hours. The productive and physiological parameters were evaluated every 7 days, the last ones being collected at 9 and 15 hours. In the afternoon, the highest values of air temperature and black globe temperature index and humidity were recorded, regardless of the materials evaluated. Fiber cement tiles and cardboard tiles coated with double-sided canvas showed the lowest values of climatic variables. There was no difference between the types of tile for the variables of productive performance and physiological parameters. It was concluded that the fiber-cement tiles painted white on the outside, and the cardboard coated with light canvas on the outside provided a better thermal environment inside the aviaries, which can be indicated for use in shelters for the creation of free-range broilers.