Investimento em climatização na pré-ordenha de vacas girolando e seus efeitos na produção de leite Investment in system in the pre-milking of girolando cows and its effects on milk production

Abstract

Objetivou-se, com este trabalho, avaliar os efeitos da climatização na pré-ordenha sobre o acondicionamento térmico, fisiologia, produção de leite e relação custo/benefício do sistema de resfriamento adiabático evaporativo (SRAE). Utilizaram- -se 16 vacas com produção de 18 kg de leite d-1, adotando-se delineamento em quadrado latino 4 x 4 e comparação entre as médias pelo teste de Tukey (P The objective of this study was to evaluate the effects of cooling of pre-milking cows on production, physiology, thermal conditioning and the cost-benefit of the Adiabatic Evaporative Cooling System (AECS). Sixteen cows were used with an average daily milk production of 18 kg, distributed in 4 x 4 Latin square design. The Tukey test (P<0.05) was utilized for comparison of means. The treatments (0, 10, 20 and 30 min.) consisted of exposure of pre-milking cows to the AECS. The dry bulb temperature (DBT, ºC) and relative humidity (RH, %) were recorded every minute, which allowed the determination of the efficiency of the AECS through the temperature and humidity Index (THI) and enthalpy (h). The respiratory rate (RR), rectal temperature (RT) and temperature of the coat (TC) were measured before and after cooling. The 30 min. treatment kept the environmental variables and the comfort indexes within recommended limits. The physiological variables (RR, RT and TC) were lower in the 30 min treatment and reflected positively on milk production, which increased 4.35% compared to the control treatment (0 min). The investment was profitable having a 58 day return on investment and a monthly revenue increase of R$ 1,266.84.

Keywords

• bem-estar animal
• bovinocultura de leite
• conforto térmico
• resfriamento evaporativo
• animal welfare
• dairy cattle
• thermal comfort
• evaporative cooling system