Objective:

To assess the diurnal behavioral response of beef cattle in feedlot in the dry tropics.

Materials and Methods:

During fall, a prospective observational study was carried out for 42 days. At 8:00, 12:00 and 16:00 h, behavioral patterns, temperature and relative humidity were recorded, and the temperature and humidity index were calculated. Cattle were housed in pens provided with polypropylene shade and pens without shade.

Results:

At 8:00 h, the cattle under shade and cattle without access to shade were subjected to environmental conditions of thermal comfort category (p<0.01); but at 12:00 h cattle under shade were in thermal danger and thermal alert at 16:00 h. For cattle without access to shade at 12:00 and 16:00 h, the thermal danger persisted (p<0.01). Feed access was inhibited at 8:00 and 12:00 h and increased at 16:00 h, but rumination decreased at 8:00 and 16:00 h and increased at 12:00 h (p<0.01). Rest indicators were mostly observed in danger and thermal alert (p<0.01). The agonist indicators were inhibited at 8:00 and 12:00 h (p≤0.04). Social behavior was mostly manifest at 16:00 h (p<0.001).

Conclusions:

The diurnal expression of bovine behavior related to the climatic factor and the provision of shade, can be inhibited in the hours of highest caloric load expressed as the Temperature and Humidity Index.

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