ENERGY USE IN LACTATING COWS WITH DIFFERENT LEVELS OF ENERGY-PROTEIN RATIO IN THE DIET
The article is focused on the influence of standard rations with different levels of energy-protein ratio (EPR) on the use of fodder energy by the Black-Spotted cows. The experiment was conducted on the Shevchenko farm, Tashlinsky district, Orenburg region, on the background of winter and summer rations usually used in the dry-steppe zone of South Urals. The cow rations consisted of fodders produced on the farm and balanced in accordance with lactation periods. The level of EPR was regulated by introduction of sunflower cakes to substitute the mixture of concentrated feeds (by the periods of lactation). The results of the studies showed that the use of metabolic energy in the organisms of lactating cows depended, to a great extent, on the composition of the ration, the balance of energy and protein in it, daily milk yields and energy value. The effectiveness of energy use for milk synthesis has been increased with the EPR optimization (0.17–0.18).