Hepatic copper status and performance of dairy cows fed copper sulphate or a copper containingrumen bolus either without or with added sulphur and molybdenum

摘要

Implications Antagonists to Cu absorption and metabolism decrease intake in diets containing 0.5 of the forage DM asgrass silage and rapidly deplete liver Cu reserves, although provision of a Cu bolus may reduce the rate of decline.Introduction Copper (Cu) is one of the most important trace elements for normal health and performance in dairy cattle(Suttle, 2010). Clinical symptoms in dairy cows are rarely caused by a dietary deficiency of Cu but more often related tointeractions with antagonists such as sulphur (S) and molybdenum (Mo) which form thiomolybdates in the rumen andadversely affect absorption and normal Cu metabolism (Suttle, 2010). Previous research has identified that theseantagonists have a more pronounced effect in diets based on grass than maize silage (Sinclair et al., 2013), although theeffect of form of Cu is unclear. The objectives of the current study were to determine the effect of Cu source (CuSO4 vs.bolus) fed either without or with added S and Mo on indicators of Cu status and performance in dairy cows.