Solving the problem of food security, including adequate provision of Ukraine's population with quality, ecologically clean food products of animal origin is possible only if the creation of a full stable fodder for the livestock industry, rational use of land resources, energy conservation and environmental protection. In this concern an important place is given to the scientific investigations in order to increase the quality, effective use of silage, haylage which are now in the composition of the diet of cattle occupy on nutritional power 40–50 % and sometimes more.

Silage has long occupied a firm place in the feed production and proved that the feeding value of silage yields little green forage, retaining most of the nutrients. While it is no secret that non-compliance with the total number of technologies silage nutrient losses can be high.

The use of low-quality forages dramatically increases energy consumption on the physiological functions of the body and reduces the efficiency of the meat synthesis. As a result of reduced animal productivity and feed costs per unit increase 1.5–2 times.

In this regard, the use of new preservatives for silage green mass is an urgent problem for today. Improve the quality of silage preservation and promote various preservatives that are currently used in small quantities.

Currently, much attention is paid in the farms of Ukraine to biological preservatives that have properties to stabilize and preserve the nutrients in the silage fodders. One of such preserve means is biopreservative 11S33, DuPontPioneer company, which is a bacterial concentrate containing in its composition different strains of lactic acid bacteria.

However, there are few data in the available literature on the use of new biological preservative in harvesting corn silage and its use in diets of calves for fattening and they need to be studied in deep.

The objective of the research was to investigate the impact of feeding corn silage harvested using microbial drug 11S33 on fattening performance of young cattle.

Studies conducted in the private agricultural enterprise "Heysyske" Stavyshche District, Kyiv Region.

Before the experiments there were harvested two types of corn silage: one without preservatives (control), the other – with the use of silage ferments DuPontPioneer (inoculant 11S33).

To study the fattening parameters were selected bulls-24 counterparts, two groups of animals were formed (control and experimental).

Analyzing the nature of the changes of live weight of calves at cultivation it should be noted that at the beginning of the experiment, the animals from the control and experimental groups in body weight were not significantly different. In subsequent age periods marked a definite advantage over the bulls from experimental group and control group counterparts.

The analysis of indicators of live weight of calves of Ukrainian Black and White dairy cattle at different ages it was found that animals from the research group ranging from 9 months of age dominated by analogue control.

Animals from the research group at 12 and 15 months statistically significantly (P < 0.05) were 12.7 kg and 17.3 kg of live weight more than their peers in the control group.

Thus using silage in feeding bulls harvested with microbial drug 11S33 provides increasing live weight for the period of growing by 15 months of age by 4.3 % (P < 0.05).

The cost of feed for 1 kg increase in body weight were lower in the experimental group of calves at 6.07 %, compared to the control group counterparts.

Assessing the rate of growth in the growing animal it should be noted that the average daily live weight of calves had their experimental features.

Analyzing the dynamics of average increases bulls of Ukrainian Black and White dairy breeds it was found that in the period up to 9 months of age calves from the experimental group according to the intensity of growth did not significantly differ among themselves, although the trend of increase occurred in animals fed silage procured from microbial inoculants (research group).

Feeding silage harvested using microbial drug 11S33 significantly increased the rate of growth of calves from the research group in 6–9 months at 5.05% in 9–12 months on 6.95 % in 12–15 months on 7.00 % (P < 0.05) compared with their peers in the control group.

During the period from 6 to 15 months bulls of Ukrainian Black and White dairy cattle from the research group in terms of average daily increments bulls dominated the control group on 6.31 % (P < 0.05).

Increasing the intensity of bulls growth apparently passed through better conservation of nutrients and their digestibility.

Thus, biological preservative 11S33 at a dose of 1 g / t in the silage corn in the phase of milky ripeness of grain contributes to better preserve nutrients feed and feeding corn silage, in the commercial diet significantly increases average daily gain of calves while reducing the cost of feed for production products.

The prospect of further research is to study the impact of feeding corn silage fed with microbial drug 11S33, the digestibility of nutrients and their absorption.

Key words: forage production, microbial ferment, silage preservative inoculant, the increase in body weight, diet.