Parâmetros fisiológicos, comportamentais e produção de leite de vacas F1 Holândes/Zebu

Abstract

This work was conducted with the aim of evaluating the effects of thermal environment on the milk production, physiological and behavioral parameters in crossbred cows rose on pasture, in the feedlot and during milking, based on the collection of data in two different seasons and throughout the day. The data collection occurred at the Experimental Farm of the EPAMIG, in the city of Felixlândia/MG. They were used 50 cows F1 Holstein / Zebu in milk, originated from crosses of Nelore, Gir, Dutch, Zebu and Guzerat. During the experimental period were carried out daily measurements of environmental variables: dry bulb temperature, relative humidity and black globe temperature and then calculated the values of IGTH for all times of the day. The physiological parameters: rectal temperature, body temperature, breathing and heart rate were measured before and after the milking in the morning and in the evening daily for 12 days. The behavioral parameters were observed in three different conditions: pasture, feedlot and milking parlor at "Focal Sampling" method. The milk production was obtained by daily weighing and note during the two periods of the experiment. The design used was completely randomized, in factorial scheme 5 x 2 (5 genotypes and 2 times of the year) and the averages were compared by the Scott-Knott test at 5% of probability. There were no differences among the genetic groups for the most physiological parameters studied, being these higher in the spring season and in the afternoon. Animal behavior was affected by the season and by time of day. The environmental variables observed in the two seasons of the year studied did not promote changes in physiological parameters of the animals, indicative of the adaptation of the crossing to the various climatic conditions.