The studies were being conducted from 2009 until 2013 in the agricultural cooperative "Vostok" conditions, Izium district, Kharkiv region. The primary data of zootechnique and pedigree records concerning 1492 Ukrainian Black Pied dairy breed cows were used for the analysis. Evaluation of milk production was carried out with the determination of daily milk yield by months of lactation. The type of lactation curve was determined. Productive longevity was defined as the period between the date the of first calving cows and the date of disposal of the flock. As an indication of the level of reproduction ability between the date of the first calving and the service period, the period between calving and first hunting (impedance period) and insemination index (number of inseminations per conception).

Biometric data processing was carried out by the methods of mathematical statistics.

The results presented the evaluation of productive longevity of black-motley Ukrainian dairy breed cows depending on the cause and type of disposal of the lactation curve. It was found that under the conditions of agricultural cooperative "Vostok" Kharkiv region between the productive use of cows averaged 1,039 days (2.8 lactation). More than 52 % of the animals were removed from the herd to fourth lactation. Cases of violation of the reproductive ability had the highest frequency among other causes of premature rejection
(> 37 %). Cows with stable type lactation curve were at more optimal level of signs of reproductive ability.

The age of animals significantly affect the ratio of the frequency of unplanned disposals cows for various reasons. More than 13% of first calving had been culled because of low productivity.

Deterioration of reproductive function was up to 45 % of the total number of retired animals characteristic for the second and third lactation.

The incidence of udder and limb reached a maximum after 5 calving. With an average milk yield in the first lactation of about 4400 kg, the highest productivity were animals characterized by functional disorders of the reproductive system.

Increasing milk production to a greater extent affected the increase in the index insemination than for the period from calving to first fixed hunting.

More than 30 % of the first calving had persistent type of lactation. Almost 64 % had unstable lactation function. After reaching the peak and decline of daily milk yield they were characterized by gradual increase in productivity, which led to the formation of two vertex lactation curve. More than 6 % of the animals after maximum performance marked a sharp downturn.

Level indicators of reproductive function in cows distribution by type of lactations proved the connection between the dynamics of daily milk yield and stress sensitivity animals. It has been proved to be one of the criteria reaction norms animals on environmental factors, and consequently, the level of adaptive capacity.

Frequency and value of disposals of animals for reasons of various diseases and functional disorders are caused by the age of the animal and the level of milk production.

Cows with stable type of activity differ lactation better indicator of reproductive ability.

Key words: cow, Ukrainian black-and-white dairy breed, productive longevity, functional impairment, type of lactation curve.