Physiological response to heat stress and ingestive behavior of lactating Jersey cows in silvopasture and conventional pasture grazing systems in a Brazilian subtropical climate zone

The aim of this study was to evaluate the physiological response to heat stress and ingestive behavior of Jersey cows in silvopasture and conventional pasture grazing systems. The experiment was carried out during the warm season, spanning spring, summer, and fall seasons in the Brazilian subtropical climate zone. Twelve lactating Jersey cows were observed in rotational grazing on Cynodon nlemfuensis Vanderyst and Panicum maximum Jacq. Treatments were composed of different grazing systems (silvopasture and conventional pasture). The silvopasture grazing system had eucalyptus trees (Eucalyptus grandis Hill ex Maiden) with an average height of ≈ 10 m and row spacing of 20 m. In the conventional pasture grazing system, there were no rows of eucalyptus and no other type of tree or structure to provide shade to the animals. During the summer and fall periods of evaluation, the silvopasture animals presented a lower respiratory rate, whereas during the spring and fall evaluation periods, these animals presented a lower rectal temperature. Cattle in the silvopasture showed longer grazing times at night (+21.65 min) and overall (+36.00 min) and remained lying down (ruminating and resting) for longer (+ 73.07 min) than conventional pasture grazing system animals. In addition, the animals in the silvopasture had a lower water intake (3.12 L/100 kg BW). The silvopasture grazing system improved the welfare of the grazing Jersey cows, as evidenced by the improvement in physiological response to heat stress, increased grazing time and decreased standing time (resting + ruminanting) when compared to cows in the conventional pasture grazing system.