An evaluation of the efficacy of orally administered copper glycine complex, copper amino acid chelate, copper sulphate, a copper oxide wire particle bolus and a copper edetate injection in New Zealand dairy cows : a thesis presented in partial fulfillment of the requirements for the degree of Masters in Animal Science, Massey University, Palmerston North, New Zealand

This thesis set out to examine the difference in efficacy of the most commonly used copper supplements in New Zealand dairy herds. There is limited information on copper supplementation in New Zealand dairy cattle in the area of chelated (organic) verses sulphated (inorganic) supplements and this study was designed to provide more information to the New Zealand dairy industry. Sixty non-pregnant mixed age Friesian dairy cows, on the basis of liver copper concentrations, were randomized into 6 groups of 10 animals so that each group had the same mean liver copper concentration. The treatments were Group 1, non-supplemented control; Group 2, 150mg copper/day as copper glycine chelate drench; Group 3, 150mg copper/day as copper amino acid chelate drench; Group 4, 150mg copper/day as copper sulphate drench; Group 5, 20g copper oxide wire particles administered as a bolus and Group 6, l00mg of copper, as calcium copper edetate, administered as a subcutaneous injection on days 1 and 58. The duration of the study was 116 days and the cows were fed baleage, with limited access to pasture. On days -5, 14, 28, 58, 86, and 116 after supplementation, liver samples were obtained by a biopsy technique and blood from the coccygeal vein for copper determinations. The mean initial copper concentration in the liver of the cows used in this study was 827 (SE 109) μmol/kg fresh weight (FW). The mean liver copper concentration of the cows in the control group decreased significantly (P<0.05), from 827 (SE 109) μmol/kg FW on day 1 to 554 (SE 114) μmol/kg FW on day 116. Over days 58 to 116 the mean liver copper concentration of the copper glycine chelate, copper amino acid chelate, and copper sulphate groups where significantly (P<0.05) greater than the non-supplemented control group. The combined means over the 6 sampling events showed that the group supplemented with the copper glycine chelate had significantly (P<0.05) greater liver copper concentration than the group supplemented with copper sulphate (1064 versus 910