the use of copper supplementation to improve growth performance and claw health in young holstein bulls

this study was performed to determine the effect of copper on growth performance, blood metabolites and claw health in young holstein bulls in a humid area in north of iran. one hundred and two young holstein bulls (initial body weight= 377.3±17.1 kg) were randomly allocated to two treatments in a completely randomized design for 56 days. the treatment groups received: (1) the basal diet of no supplemental cu (control; n= 50); (2) basal diet plus 30 mg of cu kg-1 of dry matter (dm) as cuso4 (n= 52). animals received fresh total mixed ration for ad libitum feeding allowing 10% refusals. the groups’ dry matter intake (dmi) was assessed daily. the body weights (bw) were recorded and jugular blood samples collected on days 0, 28 and 56. all claws of young bulls were examined every two weeks for an identification of claw lesions. copper supplementation improved average daily gain (adg) and gain:feed (g:f;p < 0.05). serum cholesterol decreased with cu supplementation (p< 0.001). serum zn, cu, and urea n were not affected by supplementation of cu; however, plasma total protein (p< 0.001), and albumin (p< 0.001) were increased by a supplementation of cu. the prevalence of lameness was 19.6% and control group had the highest odds ratio (or= 2.43). as a result, it is concluded that supplemental cu might improve growth performance in the finishing bulls and decrease the prevalence of lameness.