Ambiência e termorregulação de novilhas leiteiras em sistema silvipastoril durante o verão e inverno

Abstract

Heat stress is a major factor of economic impact on the dairy herd, bringing negative effects on the development of dairy females, especially in heifers phase. Based on this problem, the objective of this study was to evaluate the influence of bioclimatic aspects of silvopastoral system in the ambience and thermoregulation of dairy heifers in different seasons. The research was conducted on a dairy farm in the county of Realeza, in Paraná southwestern. Two treatments were used, these being, one outdoor and one with shading provided by silvopastoral system of Eucalyptus grandis. The treatments were five dairy heifers each, randomly. The dry bulb temperature, relative humidity, light and wind speed to ambience analysis variables were taken for eight consecutive days in each treatment and to obtain the thermoregulation data were measured respiratory rate and mean surface temperature. With all the information collected obtained a comparison between the conventional system of creation and silvopastoral system. Environmental conditions in the silvopastoral system were lower than those presents in the conventional breeding system. The respiratory rate and surface temperature values were lower in animals that were shading (P <0.05). There was a positive correlation between elevated respiratory rate and surface temperature as rising air temperatures. Through the results concluded in this research that the silvopastoral system provides better thermal comfort for the dairy heifers.