[Activity of carbohydrate-metabolizing enzymes and content of carbohydrate and nitrogen compounds in muscles of young cattle depending on breed and sex].

The activity of glycolysis and glyconeogenesis enzymes, content of carbohydrate and nitrogen compounds were studied in muscles of 15-month cattle of different sex of the black-piebald breed and its crosses with bulls of two meat breeds Hereford and Limousine. In the muscles of bulls the activity of phosphoglucomutase, phosphohexoisomerase, aldolase and fructose-1,6-diphosphatase is considerably higher (except of the activity of phosphoglucomutase and phosphohexoisomerase in the muscles of pure-bred black-piebald animals for which difference is not statistically reliable) and the content of glycogen, glucose, fructose, lactic acid, free and phosphorylated pentoses of nonadenylic compounds is essentially lower than in the muscle tissue of heifers of analogous breed groups. A higher activity of carbohydrate metabolism enzymes (especially aldolase and fructose-1,6-diphosphate) and a higher content of total pentoses, the adenylic system pentoses, ATP phosphorus in the muscles of the cross Limousine and Hereford bulls and Limousine heifers as compared to the pure-bred black-piebald animals of the corresponding sex coincide with a greater increase in the muscular tissue and more intensive synthesis of proteins in it. A considerably lower level of glycogen, glucose, fructose and a relatively high activity of carbohydrate metabolism enzymes in the muscles of cross young cattle show that disintegration of these carbohydrates is in excess of their synthesis, that is due to an increase in the energy demand connected with a more intensive synthesis of proteins in the muscular tissue. Therefore, in the authors opinion the performed kill of the cross Limousine and Hereford bulls as well as Limousine heifers, is somewhat untimely and unreasonable. At the same time the activity of all the studied enzymes in the muscles of the cross Hereford heifers, vice versa, is considerably lower as compared to the black-piebald heifers and coincides with a low gain in live weight and muscular tissue, a more rapid accumulation of glycogen and lipids and a more delayed--of proteins in the muscular tissue, that evidences for their early maturity. Therefore the further raising of the cross Hereford heifers in the farm for obtaining meat is economically less profitable. The data obtained give grounds to recommend determination of the activity of carbohydrate metabolism enzymes, especially of aldolase and fructose-1,6-diphosphate, as a test for checking the muscular tissue growth and for prognosing the meat productivity in the growing pure-bred and cross young cattle of different sex.