@article{Huculak_2020, title={Level of dairy productivity and reproductive function of holstina cows of different ages during long lactation }, url={https://snaubulletin.com.ua/index.php/ls/article/view/227}, DOI={10.32845/bsnau.lvst.2020.3.6}, abstractNote={<p><em>The duration of lactation of the experimental groups of animals ranged from 845.9 to 915.5 days, ie was quite long. Thus, in lactating experimental cows of I, II and III (control) groups, the duration of lactation, respectively, the first, second and third was not only long, but also had almost the same period, which averaged 681.1-681.5 days.</em> <em>At the same time, the fifth lactation period in group V animals was slightly longer, lasting an average of 629.4 days, while in group IV cows, the fourth lactation was 611.9 days.</em></p> <p><em>During the entire lactation period, cows of group I had the highest hopes, which averaged 18469.8 kg of milk. At the same time, relatively the lowest milk yield was characterized by cows of the IV group, in which this indicator did not exceed 15617.3 kg.</em></p> <p><em>Characterization of milking during 305 days of lactation allows a more objective assessment of milk production of animals. The results of this assessment show that the highest rate at this level was in cows of group IV, who lived an average of 11399.2 kg of milk. High productivity potential is also reflected in cows of group V, which hold 305 days of the fifth lactation of the population on average 10464.3 kg, which is only 8.93</em> <em>% (P &lt;0.05) less than in cows of group IV in the fourth lactation .</em></p> <p><em>Group I first-borns were characterized by relatively the lowest milk yield in 305 days of lactation, which averaged 8486.1 kg of milk, which was less than the group IV animals by 34.3</em> <em>% (P &lt;0.001).</em></p> <p><em>Thus, the very long lactation function of Holstein cows from the first to the fifth lactation is characterized by a fairly high level of milk productivity, which is highest in the firstborn and tends to decrease during the second, third and fourth lactations and a slight increase in the fifth. In contrast, the level of productivity of experimental cows, calculated at 305 days of lactation, indicates the lowest milk yield in the firstborn and its gradual increase until the fourth lactation and a slight decrease in the fifth.</em></p> <p><em>The high level of milk productivity of experimental cows, on the one hand, and insufficient or suppressed activity of the hypothalamic-pituitary-gonadal system of the body, on the other hand, led to low fertility from artificial insemination and high insemination index.</em></p&gt;}, number={3 (42)}, journal={Bulletin of Sumy National Agrarian University. The series: Livestock}, author={Huculak А.}, year={2020}, month={Nov.}, pages={33-37} }