Influence of Level of Dietary Inorganic and Organic Copper and Energy Level on the Performance and Nutrient Utilization of Broiler Chickens (Report‪)‬

INTRODUCTION The essentiality of copper for poultry and livestock is well documented (Davis and Mertz, 1987). Cu is an essential mineral which serves as co-factor in many enzyme systems in the body. Cu-sulfate (CuS[O.sub.4]5[H.sub.2]O) is the most commonly used dietary Cu supplement. Copper in the form of Cu-sulfate improves growth rate and feed efficiency in broilers (Choi and Paik, 1989; Baker et al., 1991) and in pigs (Roof and Mahan, 1982; Edmonds et al., 1985; Cromwell et al., 1989) at supernormal level (125 to 250 mg/kg). Growth promoting effect of dietary Cu has been attributed to its antimicrobial action (Fuller at el., 1960; Bunch et al., 1961; Burnell et al., 1988). Improved availability of Cu from organic Cu complexes compared with the commonly used Cu salts recently has been suggested. Chelates, complexes or proteinates are the organic form of Cu and are usually considered for use in animal diet as alternatives to inorganic Cu source. More bioavailability of Cu is probably due to better absorption, which enhances its efficiency (Downs et al., 2000; Yu et al., 2000; Guo et al., 2001). Baker and Ammerman (1995) reported that relative bioavailability estimate of organic Cu sources ranged from 88% to 147% of the response to cupric sulfate in poultry, Swine, sheep and cattle. Improvements in the digestibility of proteins (Braude, 1965; Castell and Bowland, 1968) and retention of nitrogen (Braude, 1965) have been reported in young pigs fed diet containing added Cu. Studies by Dove and Haydon (1992) and Dove (1995) have indicated that addition of 250 mg Cu/kg improved digestibility and utilization of the fat of weaned pigs, but results have limited and inconclusive for chickens when Cu added to the feed fortified with oil.