The effect of artificial or natural shade on respiration rate, behaviour and performance of grazing steers

A study was carried out in Uruguay (latitude 33° 14′S, longitude 54° 15′W) to assess the impact of shade on climatic conditions and on grazing cattle during summer. Three treatments (no shade, artificial shade provided by cloth and natural shade provided by trees) were assigned to 30 steers. The provision of shade significantly reduced the black globe temperature but did not affect either air temperature or relative humidity. Respiration rate (RR)±standard deviation averaged 74±22, 67±18 and 61±12 breaths per minute in no shade, artificial and natural shade treatments, respectively (P<0.05). Diurnal grazing time (473 min) and overall average daily gain (914 g/animal) were not affected by treatments (P>0.05). The amount of time the steers spent in shade was strongly related to air temperature with a threshold around 25°C. Provision of artificial or natural shade was successful as a method of reducing RR of grazing steers without affecting grazing time or animal performance.