Orientação e sombreamento do confinamento na temperatura da superfície do pelame de bovinos

Abstract

The study evaluated the effect of shading on haircoat surface temperature (HST) of cattle from five genetic groups: 4 ½ Limousin + ½ Nellore (L), 8 ½ Limousin + ¼ Nellore + ¼ RedAngus (LR), 4 ½ Limousin + ¼ Nellore + ¼ Simmental (LS), 2 ½ Marchigiana + ¼ Nellore + ¼ Simmental (MS) and 4 ¾ RedAngus + ¼ Nellore + ¼ Guzerá (RG). The cattle were 20 months old and had an average weight of 300 kg. They were housed at individual 10 m2-pens, with half covered with zinc tiles. The diet was isoproteic and isoenergetic, with a 67:33 roughage concentrate ratio. There was no difference (p > 0.05) in HST among genetic groups during daytime on Side 1 (S1) of the feedlot, while on Side 2 (S2) the lowest HST (29.48oC) (p < 0.05) was observed for MS. At night, the HST for Side 1 was higher (p < 0.05) for RG (30.32oC) and did not differ (p > 0.05) among the others. On Side 2, the highest HST (p < 0.05) occurred for RG (30.63oC) and the lowest (p < 0.05) for MS (28.07oC). The building orientation showed no effect on HST of animals, which was influenced by time of day, direct reflex action of thermal radiation intensity on zinc tiles and on the concrete floor.