ABSTRACT The correct use of tyres on agricultural tractors, in respect of the terrain and the type and internal pressure of the tyre, are factors that influence the performance of the tractor. The aim of the present study was to evaluate the operating performance of an agricultural tractor fitted with two types of traction device (radial and diagonal tyres) at different pressures, and operating on soil with two levels of moisture. The experiment was conducted on a dystrophic Red Yellow Argisol, with tests to evaluate the performance of the tyres under specific working conditions. Tractive power and tractive force, wheel slip and fuel consumption were evaluated. For each of the conditions under evaluation, the radial configuration showed better performance than the diagonal configuration, the effect being more significant at the lower pressure and under low soil moisture. The use of radial tyres led to an increase in traction capacity and drawbar power, with a reduction in fuel consumption, especially at higher slip rates. tractors tyre pressures moisture Argisol force evaluated evaluation rates

As condições térmicas no interior de instalações para frangos de corte tem importância vital para o sucesso desta atividade. Desta forma, deve-se buscar o conforto térmico para as aves com o mínimo custo em materiais, equipamentos e energia. Baseado nisto foi desenvolvido um trabalho com o objetivo de avaliar o efeito de três sistemas de resfriamento evaporativo no desempenho de frangos de corte. Para isso, utilizou-se um galpão dividido em quatro partes nas quais foram instaladas os tratamentos: ventilador associado a nebulização (VNB), ventilador de alta rotação associado a nebulização (VNA), nebulização (NEB) e nebulização acoplada ao ventilador (NEV). Foi registrado o consumo de ração, o ganho de peso e a mortalidade, obtendo-se assim a conversão alimentar. Os sistemas de resfriamento evaporativo (VNA e VNB) proporcionaram os melhores resultados com os maiores valores de ganho de peso por ave e os menores valores de conversão alimentar e mortalidade. Resultados menos satisfatórios foram observados no NEV, com os menores valores de ganho de peso por ave e maiores valores de conversão alimentar e mortalidade.

The thermal conditions inside poultry houses are very important for the success of this business. It is however necessary to have an adequate animal thermal confort and a minimum cost of material, equipment and energy. This experiment was carried to verify the effect of evaporative cooling systems on the performance of poultry. The building was divided in four equal sectors. The treatments consisted of ventilator and spraying system (VNB), high rotation ventilator and spraying system (VNA), spraying system (NEB), and spraying system connected to the ventilator (NEV). Feed intake, weight gain, mortality of poultry were recorded and the food conversion calculated. It is shown the evaporative cooling systems (VNA e VNB) presented the best results, increasing weight gain with lower values of food conversion and mortalily. The worst results were found for the spraying system connected to the ventilator (NEV).