In recent years in Europe the molecular mechanisms of genetic regulation of adaptive capacity of farm animals is being studied. It was determined that the most sensitive to the stress is immune and reproductive function of the body, and it is preferable to prevent stress by feeding animals with recommended animal anti-stress premix. But drugs reduce the negative impact of stressors on the body just for a while. The selective way is perspective: descendants can inherit resistance to operational loads that always occurs in industrial technology.

The dependence performance of sperm bulls-inseminators based on their resistance to stress has not been clarified enough yet. Therefore, the study of adaptive capacity bulls-inseminators is a key issue.

The purpose and objective of the study was to assess the quality of the adaptive Holstein bulls-inseminators and the impact of this feature on the results of their tribal using. To determine the adaptive capacity of bulls-inseminators we have developed stress index type (ITSi) which is integrated in the concentration of cortisol, testosterone activity of creatine phosphokinase, alanine aminotransferase and aspartat aminotrasferase before and after prescribed method, the load on animals.

Among the 16 Holstein bulls-inseminators there were identified 9 and 7 animals of high- and low resistance to stress. In the third year of breeding use, usually there is a stabilization of reproductive function in bulls-inseminators. We have found out how it depends on their adaptive capacity.

During the third year of breeding bittern use with high resistance to stress found higher sperm activity by 0,9 points (12,8% for P<0,95), sperm concentration to 0,1 billion / ml (10,8% for P>0,95 ), the number of sperm in the ejaculate 1,0 billion (24,6% for P>0,95), a smaller percentage of sperm rejection by 4,4% (P<0,99), more sperm suitable for freezing 154 5 ml (51,8% for P<0,95), more quality spermodoz from one ejaculate 28,6 doses (37,3% for P>0,95) and higher and higher ability of sperm to insemination to 9,0% at P>0,95 compared with peers low resistance to stress.

We have identified correlations to confirm the data presented in the tables. In particular, the graph shows that animals resistant to stress are focused in the left column, that is, low stress index type is no reduction in the number of sperm in the ejaculate. While animals are not resistant to stress focused on the right side, indicating the reduction in the number of sperm in the ejaculate with increasing stress index type (r = - 0,427 ± 0,205 for P>0,95).

It has been found that for the third year in tribal use with reduced performance and more value in ITS bulls-inseminators, combined to increase the rate of rejected sperm (r = + 0,479 ± 0,193 for P>0,95) and reduced the number of quality spermodoz (r = - 0,494 ± 0,189 for P>0,95). A direct correlation between the magnitude of ITS and the ability of sperm to fertiliz
(r = - 0,661 ± 0,141) of the likely outcome (P>0,95).

Thus, it has been defined that the main indicators of sperm productivity and sperm quality significantly depend on the adaptive capacity of bulls-inseminators. The greatest impact of the type of stress showed the activity of sperm, percentage of rejected sperm, sperm number obtained suitable for freezing and the number of received quality spermodoz from one ejaculate (P>0,95), which must be considered in the selection and exploitation of animals in tribal enterprises.

Key words: bulls-inseminators, adaptive capacity, Holstein breed, semen quality, correlative variation.