NUTRIENT DIGESTIBILITY AND NITROGEN UTILIZATION OF LACTATING COWS WHEN RECEIVING A FOOD MIXTURE WITH MINERAL SUPPLEMENTS

Abstract

The article presents results of studies on giving natural mineral additives from the deposits of Oryol (Stimulus) and Bryansk regions (smectite tripoli) in the composition of the feed mixture to lactating cows of the second lactation of the black-and-white breed in the agricultural enterprise OOO "Mololchnoye" of Bryansk region. A comparative analysis of the effect of two dosages of their inclusion in the ration - 3 and 4% of the dry matter without changing their energy nutritional value on productivity, digestibility of nutrients and nitrogen usage in the organism of lactating cows was carried out. A positive effect on the level of milk productivity of both natural mineral additives was found, however, more significant changes in protein and lipid metabolism occurred in the body of cows who received smectite tripol as part of the feed mixture at a dose of 4% of the dry matter of the ration. Thus, the dry matter digestibility coefficients, including organic matter, as well as protein and crude fat digestibility coefficients of lactating cows that received smectite tripoli (4%) significantly exceeded similar parameters in all experimental groups. Based on the results of the balance experiment, a positive nitrogen balance of lactating cows of all groups was established. Concurrently, a redistribution of digested nitrogen with a higher transformation into products was noted, which is confirmed by a large percentage of its transition into milk (10.3%). This redistribution of nitrogen in the body of lactating cows of the experimental groups became possible due to its lower retention in the body (by 5.9% due to "Stimulus" additive and by 11.0% - smectite tripoli). Therefore, based on the obtained experimental data, it is possible to recommend to include smectite tripoli natural mineral additive at a dose of 4% of the dry matter of the ration into the feed mixture for lactating cows.