Decrease lysyl oxidase activity in hearts of copper-deficient bovines

•This is the first report that determined lysyl oxidase activity in bovine heart of copper deficient animals.•The commercial kit used to measure lysyl oxidase activity for the first time in bovines, was successful.•Cardiac pathology in Cu-deficient cattle may be associated, at least in part, to a decrease in LOX enzymatic activity. Lysyl oxidase (LOX) is a metalloenzyme that requires Cu as a cofactor and it is responsible for the formation of collagen and elastin cross-linking. The objective of this work was to measure the LOX enzyme activity in the heart of bovines with Cu deficiency induced by high molybdenum and sulfur levels in the diet. Eighteen myocardial samples were obtained from Cu-deficient (n = 9) and control (n = 9) Holstein bovines during two similar assays. The samples were frozen in liquid nitrogen and stored at −70 °C to measure enzymatic activity. A commercial kit was used, following producer instructions. The results showed that LOX activity from the hearts of Cu-deficient bovines is 29 % lower than the ones of control bovines, being this difference statistically significant (p = 0.03). To our knowledge, this is the first report that determined LOX enzymatic activity in bovine heart of Cu-deficient animals. The microscopic alterations found in these animals in our previous work, could be explained by a diminished LOX activity. The results are in agreement with other authors, who found a relationship between LOX activity and dietary Cu intake. The information provided by this work could help to clarify the pathogenesis of cardiac lesions in cattle with dietary Cu deficiency.