Resumo

GHIANO, J et al. Mitigacion del estrés calórico en vacas lecheras  en un clima subhumedo. FAVE. Secc. Cienc. agrar. [online]. 2016, vol.15, n.1. ISSN 1666-7719.

The aim of the study was to evaluate the effect of frequency refreshed during the summer on the production of milk and physiological markers associated with heat stress in Holstein cows. During January and February 2014 cows were locked from 06:00 to 17:00 in pens with artificial shade, free access to food and water bowl, and from 17:00 until 04:00 had access to a strip grazing alfalfa. Cows were assigned to treatments: comfort: 3 refreshed daily, one at 11:00 am and the other 2 prior to milking (C; n = 15) and traditional, just 2 prior to milking (T cooled; n = 15 ). Milk production (PL) was recorded daily, while the rectal temperature (RT), respiratory rate (RR) and behavioral behaviors were measured weekly. The ambient temperature and relative humidity were recorded daily. -humidity Temperature index (ITH) was calculated, no significant differences in PL obtained. In FR significant difference was found between treatments. The C group had 18% fewer FR that T. An interaction between treatment and was detected to date in FR (p <0.05) on days whose ITH was> 84. The animals in group C remained 10% less time in the shade that predominate T behavior was to stop. The animals in the traditional group were 60% longer than the comfort panting.

Palavras-chave : Refreshed; Behavior; Milk production; Respiratory rate.