Automação do sistema de resfriamento adiabático evaporativo na pré-ordenha de vacas girolando e seus efeitos na produção de leite

• Autor(a) principal: SILVA, Irenilson Machado da
• Data de Publicação: 2011
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UFRPE
• Texto Completo: http://www.tede2.ufrpe.br:8080/tede2/handle/tede2/5584
• topic: Bovino de leite; Conforto térmico; Sistema de resfriamento; Produção de leite; CIENCIAS AGRARIAS::ENGENHARIA AGRICOLA

The objective of this study was to develop a system for monitoring and control of actuators in quanti-qualification of the effects of cooling system in the pre-milking for caw on milk production, physiological state and the efficiency of the thermal conditioning system with the use of geostatistics in a semi-intensive system of milk production. The research was conducted on a dairy farm producing type B milk located in the state of Pernambuco, 8°36'33" S, 36°37'30" W and altitude of 733 m, in January-February of 2010. The development of the controller system of the environmental variables (temperature, ºC and relative humidity of the air, RH%), comprised the steps of assembly, test and laboratory calibration and after that the validation of the equipment carried in the field. The validation step showed that the results obtained allowed that the system can be used safely, which granted the degree of automation required for the intermittent operation of cooling system in the pre-milking. The equipment showed the lower cost (R$ 325.76), when compared to other middle market (R$ 450.00). In the experimental step of the study, 16 cows producing 20 kg milk d-1 were used, adopting the Latin square design 4 x 4 and comparison between means by Tukey test (P<0.05). Different times were considered of exposure of the animals in pre-milking to the adiabatic evaporative cooling system (AECS) automated, 0, 20, 30 and 40 min. The dry bulb temperature (Tbs) and relative humidity of air (RH) were recorded every minute, which allowed determining the temperature and humidity index (THI) and the enthalpy (h). The respiratory rate (RR), rectal temperature (RT) and temperature of coat (TC) were measured before and after cooling system. The exposure of animals to 40 min of the cooling system maintained the environmental variables and the indices of comfort between the recommended limits. The physiological variables (RR, RT and TC) showed lower values when the animals were exposed to AECS for 40 min., with 3.66% increase in the milk production. The investment promoted increase in the monthly revenue of R$ 1,992.67, with a time of return on invested capital of 40 days. Knowledge of spatial variability of air temperature and the construction of maps of kriging allowed checking that the use of geostatistics has defined specific areas in the stable waiting pen (pre-milking) that were above the critical limit of animal thermal comfort. The time of exposure to cooling system for 40 min ensured the stabilization of air temperature within the thermal comfort condition for lactating cows.