اثرات مس، روي و كلرتتراسايكلين بر ميزان رشد و بروز لنگش گوساله هاي نر پرواري هلشتاين

The effects of supplemental copper, zinc, and chlortetracycline on growth and claw health in young Holstein bulls

Three hundred eighteen young Holstein bulls (initial BW=375±17.5 kg) were randomly allocated to one of six treatments in a completely randomized design. Dietary treatments consisted of the basal diet; basal diet plus 30 mg of Cu/kg of DM as CuS04; basal diet plus 150 mg of Zn/kg of DM as ZnS04; basal diet plus Chlortetracycline (200 mg/bull/d; CTC); basal diet plus 30 mg of Cu/kg of DM + CTC (200 mg/bull/d); and basal diet plus 150 mg of Zn/kg of DM + CTC (200 mg/bull/d). The effect of treatments on average daily gain, group dry matter intake, feed efficiency (gain:feed), dry matter digestibility, and lameness prevalence was measured. Feed efficiency in Cu + CTC received group was more than control group while in Zn received groups feed efficiency considerably decreased (P0.001). The prevalence of lameness was 12.89% and statistically, the effect of treatments on lameness was significant (P<0.011). Results showed that Cu + CTC receiving young bulls had the best average daily gain and gain:feed and also, had less lameness prevalence.