Activity of Dehydrogenases and Enzymes of Nitrogen Metabolism in Cardiac Tissue and Skeletal Muscle of Steers Fed Monensin

Abstract

Kala~njuk G. I., M. Marounek, L.G.Kala~njuk, M. G. Gerasymiv, O. G. S a v k a : Activity of Dehydrogenases and Enzymes of Nitrogen Metabolism in Cardiac Tissue and Skeletal Muscle of Steers fed Monensin. Acta vet. Brno 1995, 64: 157-161. Activites of lactate dehydrogenase (E.C. 1.1.1.27), malate dehydrogenase (E.C. 1. 1. 1.40), 2-oxoglutarate dehydrogenase, (E.C.1.2.4.2) glutamate dehydrogenase (E.C.1.4.1.3), glutamin synthetase (E.C.6.3.1.2), arginase (E.C.3.5.3.1), ornithine carbamoyltransferase (E.C.2.1.3.3), aspartate aminotransferase (E.C.2.6.1.1) and alanine aminotransferase (E.C.2.6.1.2) were measured in cardic and skeletal muscles of steers fed ration with or without monensin. Steers, 9 months old at the beginning, were fed concentrate, molasses, grass, lucerne and maize chaff. Five steers received monensin in amount of 0.5 mg per 1 kg of live body mass per day. Control ration, without monensin was fed to the other five steers. After 10 months steers were slaughtered and activity of enzymes assayed in the mitochondrial and cytoplasmic fraction of cells. Monensin increased activity of 2-oxoglutarate dehydrogenase and decreased activity of glutamate dehydrogenase in both fractions of the skeletal muscle tissue. Enzymatic activities found in heart mitochondria were higher in monensin-fed steers than in control steers. Steers given monensin gained 8.23 % more than control steers (263 vs 243 kg). Monensin, enzyme, heart, muscle Feed antibiotics, including monensin, have the ability to improve perfonnance and feed efficiency in ruminants. It is known that monensin is absorbed from the alimentary tract (D a vis 0 n 1983; Don 0 h 01984) and several authors demonstrated its influence on intermediary metabolism of ruminants (Armstrong and Spears 1988; Benz et al.1989;Marounek et al. 1989). Little is known about the effect of monensin on activity of tissue enzymes in ruminants. K a I a c n j uk et al. (1993) measured activity of various enzymes in rumen mucosa and liver of steers fed monensin at recommended level. Authors found no consistent effect of monensin on enzymes of both tissues. In this paper we report data on activity of nine enzymes in cardiac and skeletal muscles of steers fed ration with or without monensin for ten months. Cardiac and skeletal muscles are primary target tissues at high intake of monensin (T 0 d d et al. 1984; Van V lee t et al. 1985) and, presumably, also during long-term supplementation of rations under normal feeding conditions. ' Materials and Methods Ten crossbred steers, 9 months old at the beginning of experiment, were divided into two groups, according to feed additive treatment. Steers were individually housed and kept on a diet consisting of concentrate (I kg per 100 kg of the live weight), molasses (0.5 1.0 kg) and grass, lucerne and maize chaff ad libitum. In winter, the roughage portion of the diet consisted of maize silage and beet ad libitum. Concentrate contained ground barley (63%), dried poultry litter from broilers which did not receive a ionophore in their diet (20%), grass meal (15%) and zeolite (2%).