A note on an apparent copper deficiency in cattle in central coastal New South Wales

Abstract

Hereford-type steers were grazed at 1.5, 2.0, 2.5 and 3.0 ha-1 on a Paspalum dilatatum dominant pasture for three years at Bringelly, New South Wales. There were large differences in mean daily liveweight gain between replicates; sometimes steers at the lowest stocking rate had a lower mean daily liveweight gain than those run at higher stocking rates. The mean plasma copper concentration varied from 0.28 to 0.41 ¦g ml-1 for the steers on the plots having a low liveweight gain and 0.50 to 0.87 for steers a with higher daily gain. The mean liver copper content varied from 11 to 46 mg kg-1. The copper concentration in the pasture ranged from 7 to 16 mg kg-1. The range in molybdenum concentration was from 0.08 to 0.38 mg kg-1. The plasma and liver copper data suggest that some of the poorer performance may have been due to copper deficiency in the animals but this was not caused by the low levels of copper in the pasture nor induced by high levels of molybdenum.