[The effect of Rumensin on mineral metabolism and on the conversion of nutrients in feedlot cattle].

A study on mineral metabolism and conversion of nutrients by applying sodium monensinate, 125 mg per head and day, in cattle fattening was performed. This experiment was realized under production conditions in the fattening station of pavillion type for 367 days and included 985 bulls of Bohemian Spotted cattle. The feed ration consisted of maize silage with addition of dried poultry bedding and concentrates. At the beginning of the experiment the appetite antipathy was observed, the adaptation period lasted 4 weeks. During the adaptation period the weight gains decreased; after adaptation of animals to monensin the weight gain not only counter-poised, but in comparison with the control it increased. Throughout the experiment no health disorders connected with the applied additive were observed. In the rumen fluid the content of calcium, magnesium, phosphorus, zinc, copper and iron was followed. In the blood plasma the levels of sodium, potassium, calcium, magnesium, phosphorus, zinc, copper and iron were followed. The application of sodium monensinate did not affect the followed parameters of mineral metabolism. The experiment was aimed at the evaluation of production and operational parameters with a view to the weight gain and feed conversion. In the experimental group the weight gain was higher by 3.85%. The saving of maize silage in the experimental group amounted to 5.8%, by using of this additive the saving of concentrates amounted to 1.35%. In the experimental group the feed conversion converted to dry matter increased by 7.12%. Sodium monensinate at the dose of 125 mg per head and day had positive effect on the followed production and economic parameters.