In two scientific-field experiments with broiler chicken cross-breeding ”Кобб-500", the goal was set to learn the influence of different dosages, forms and types of feeding the acidifier FRA LBB DRY onto the contents of the microflora of intestine, retention and productivity of broiler chickens.

The first experiment was done using three groups-analogs of broiler chickens, 46 birds per group. The broiler chickens of the first group were the control group. This group was fed a regular mixed feed. The second and third groups were fed the same mixed feed with an addition of the acidifier of FRA LBB DRY feed added; 3kg per ton of feed for the 2-nd, and 5 kg per ton for the third group.

The second experiment was done using 6 similar groups-analogs of broiler chickens, 100 birds per group, with an equal ratio of male to female chicken. Throw-out the experiment all six groups were fed the same amount of fully nutritional mixed feed, in accordance with their age growth groups. As far as drinking went, the groups were hydrated differently. Birds of the first group were getting plain water, broiler chickens of the 2, 3, 4, and 5 groups were getting a mix of FRA LBB DRY acidifier in the quantities of 1,0; 1,33; 1,66 and 2,0 ml/L accordingly. The last group, group 6, was getting a dose of liquid Norfolk antibiotic in the quantity of 1 ml/L.

As the bacteriological experiments have shown, after 7 days of feeding different doses of dry acidifier, the stool sample of the second and third groups of broiler chickens, when compared to the first group, had shown to contain less undesirable microflora in particular Escherichia coli – by 26,7 and 29,0 %, enterococcus by 21,4 and 24,7 % with a high probability of difference (P<0,01). At the same time the test samples contained higher concentration of useful microflora such as Bifidobacterium and lacto bacteria. The difference, when compared to the- test sample, was 18,3–24,1 % (P<0,01) and 16,5-17,8 % (P<0,05).

In the second experiment adding acidifier FRA LBB DRY to water for the 2, 3, 4, and 5-th groups by 1,0; 1,33; 1,66 and 2 ml/l of water had caused a decrease of escherichia coli by 12,7 % (P<0,05), 17,4 % (P<0,01), 18,8 % (P<0,01) and 16,0 % (P<0,05), enterococcus by 14,9; 20,9; 17,8; and 16,9 % with a high degree of probability (P<0,01), at the same time increasing the amount of bifidobacteria by 19,1; 20,6; 17,9 and 21,3 %, (P<0,01) and lactobacteria by 14,4; 16,5; 15,8; 12,4 % (P<0,01).

The changes that had taken place in the contents of the microflora of intestine obviously had a positive effect on digestion and processing of nutrients, which, as a result, had improved the upkeep and productivity of the broiler chickens which were exposed to the acidifier. In the first experiment departure of the broiler chickens was almost three times less than that of a control group. In the second experiment the upkeep of broilers in test groups was larger than the control by 6–7 absolute percent.

Adding an acidifier into the mixed feed also increased the rate of growth in birds. Case in point, in the first experiment the growth of the body mass of one broiler of the 2-nd and 3-rd test groups was by 5,05 and 5,23 % larger than the control group. In the second experiment, both absolute and daily weight gains of 2–5-th groups were by 3,8-4,5 % larger than those of the control group.

As far as comparing the expenses in terms of quantities of food per 1 kg of gains, both experiments have shown that test groups 2–3 and 2–5 consumed 3,4 and 2,7–4,3 % less than the control group.

Among the objective measures that show the efficiency of the experiment, we can use the European efficiency index, which in first and second experiments was 37,8-38-6, and 32,0-50,1 points higher than the control group.

Alongside with the acidifier, the experiment was also set to text the effectiveness of the use of the Norfolk antibiotic, which was given to the birds in group 6 of the second experiment. The data had shown that by absolute and daily weight gain, feed conversion, livestock retention, and European efficiency index, the birds in the 6th group definitely surpassed the control group in all categories, but fell short of the other experiment groups in almost all categories. This data lets us conclude that there is a good possibility that we can exchange the antibiotics for acidifier, with little to no loss in productivity.

In summary, the data of this microbiological research shows that including acidifier into a fixed feed has a positive impact on the broiler chicken intestines microflora, which could quite possibly be one of the factors that improves the digestion and consumption process and an improved upkeep of the birds as a result.

By the general evaluation of the results of the experiment, the optimal dosage of dry and liquid acidifier FRA LBB DRY for the broiler chickens can be considered 3kg/tons of mixed feed or 1,33 –1,66 ml/l of water.

As a perspective of further development, the research might look into a search of acidifiers of a different biochemical nature and of a more potent action.

Key words: broiler chickens, acidifier, antibiotic, microflora of the intestines, productivity.