As it turned out that selenium activated the action of many enzymes and hormones and provides their physiology function, many scientists have lately bound the increase of bird’s productive qualities to the change of metabolism intensity in the body. It is well-proven today that selenium improves digestion of feed nutrients, laying and digesting of nitrogen, macro- and microelements what proves that in an organism not only the processes of breaking up of albumens, fats and carbonhydrates but also their synthesis and accumulation are more active. However, the relatd research was carried out mainly on laying hens and grown-up geese.

The purpose of research was a study of influence of additions of different selenium doses in the mixed fodders on the degree of nutrient digestion in the body of chicken broilers.

To carry out a physiology experiment which consisted of two periods (previous and basic), there waere selected young birds in 30-daily age, 5 heads from control and experimental groups each, at identical correlation in the groups of males and females.

During the experiment the mixed fodders for the bird of experimental groups were additionally added selenium in such amount, mg/kg: second group – 0,2; third – 0,3 and fourth – 0,4. The chickens of the first control group did not get selenium addition. Sodium selenite was used as a source of selenium.

As the analysis of physiology experiment results showed, digestion of nutrients of feed in birds of all experimental groups was high enough. However, chicken broilers of experimental groups fed with the selenium enriched mixed fodders had the best indicators of nutrient digestion.

So, the chickens of experimental groups advantageously differed by digestion of organic matters (73,0–73,8 %, against 72,9 % in the control group). However, statistically reliable (Р<0,001) difference appeared only in the third experimental group, with the birds exceeding the same age birds in the control group by 0,9 %.

More substantial difference was traced by digestion of raw protein. So, if for the chickens of control group it was digested by 84,7 %, then for the birds of experimental groups this index was for much higher (Р<0,001) by 1,4 %, 2,1 and by 2,0 %, accordingly.

The youngsters of the control group showed lower results than those of the experimental group by digestion of raw cellulose. The difference between the control and experimental groups (in favour of the last): in the second – 0,8 %, in the third – 2,8 (Р<0,001) and fourth – 1,8 % (Р<0,01). Low digestion of raw cellulose by experimental youngsters is explained (27,0–29,8 %) with the considerable thickness of hard hydrolyzing walls of plant cells which block access to the enzymes of digestive juices to the nutrients of corn components of the mixed fodders.

Additions of selenium in the mixed fodders for broiler chickens increased the digestion of raw fat. While in the control group this indicator was 68,4 %, then in the second experimental group it increased by 0,8 % (Р<0,05), the third – by 1,1 (Р<0,001) and the fourth – by 0,3 %.

As for BER digestion, the youngsters of the second and third experimental groups had insignificant increase of this index by 0,1 and 0,4 %, accordingly, and the youngsters of fourth experimental group – vice versa, the decline by 0,5 %, in comparison with the control group (78,6 %).

Thus, all doses of selenium introduction in the mixed fodders studied had though ambiguous, but positive influence on the digestion processes in the bird’s body. Thus, chicken broilers fed with the selenium enriched mixed fodders (0,3 mg/kg) had the greatest indicators of nutrient digestion.

Key words: mixed fodder, selenium, dose, chicken broiler, digestion, nutrients.