THE INFLUENCE OF THE INTENSITY OF BREEDING OF HEIFERS OF UKRAINIAN BLACK-AND-WHITE DAIRY BREED IN DIFFERENT AGE PERIODS ON THE FUTURE DAIRY PRODUCTIVITY
Authors: Antonenko S. F. 
Published: June 2020

The scientific experiment was carried out in two stages at State enterprise pilot farm “Hontarivka”, Vovchansk district, Kharkiv region.
First stage. In a retrospective analysis of the rearing calf intensity from 3 to 6 months revealed that the highest live weight at 6-month age had animals of group III, .which is probably 47.0 kg or 34.6% and 23.0 kg or 14.4% (P < 0.001 in both comparison cases) outperformed peers I and II groups. A similar trend was observed in the analysis of live weight of heifers at 9 and 12-month age. Live weight at insemination in the higher growth group also had better rates of 4.0 and 3.7%, respectively, in animals of groups I and II (P < 0.001–0.05). It should be noted that the required live weight for insemination at heifers at growth rates of up to 500 g was reached in only 20.3 months, however, in the other two groups, the insemination age decreased by 1.5 and 1.7 months. Firstcalf heifers from group III also had the highest milk expectancy of 170.0 and 123.0 kg, or 3.1 and 2.3%, respectively, then animals in groups I and II.
In the age period from 6 to 9 months it was found that at 9-month age heifers of group III had a higher live weight against animals of I and II groups respectively by 39.0 and 16.0 kg or 18.8 and 7.0% (P < 0.001 in both comparison cases). Intergroup differences by this indicator at 12-month age hiefers decreased to 35.0 and 8.0 kg, respectively, or 13.0 and 2.7% (P < 0.001 in both cases of comparison), which provided an advantage for the live weight of group III over I and II groups during the first fruitful insemination. Whereas the age of first fruitfull insemination, on the contrary, was lower at heifers of group III at 49 and 34 days than at groups I and II heifers. The highest milk productivity was also found at firstcalf heifers of group III at 634 kg or 12.3% (P < 0.001) and at 137 kg or 2.5% against animal I and II groups.
The heifer live weight at the period from 9 to 12 months corresponded to the established differences at other age periods generally. And 12-month age calves of group III also significantly exceeded the analogues of group I by 38.0 kg or 14.0% (P < 0.001) and peers of group II – by 23.0 kg or 8.0% (P < 0.001). The live weight at fruitfull insemination of group III heifers was the largest and the difference compared with animals of group I was 21.0 kg or 5.3% (P < 0.01) and group II – 19.0 kg or 4.8% (P < 0.001). Group III animals also had the highest milk productivity, which is likely to be higher than group I peers by 751 kg or 14.5% (P < 0.001) and group II animals by 552 kg or 10.3% (P < 0.001).
Second stage. It was found that during the experiment, live weight of free-stall keeping heifers were outnumbered by peers. In particular, the live weight of group I animals at the first month of the experiment was less by 8.0 kg or 2.9%, the second by 15.0 kg or 4.7% (P < 0.05) and the third by 19.0 kg or 5.4% against peers of group II. A similar pattern was observed in the estimation of intensive growth of these animals. However, at the end of the experiment, the heifers of the experimental group were 7.0 cm or 5.9% (P < 0.001) higher in the withers, 7.0 cm or 5.6% (P < 0.001) in the back, and the sacrum – 6.0 cm or 4.7% (P < 0.001). They showed deeper breasts by 3.0 cm or 4.9% (P < 0.01), larger breast widths – by 2.0 cm or 5.4% (P < 0.01), width in macaques – by 2.0 cm or 4.9% (P < 0.01), oblique torso length – 8.0 cm or 5.8% (P < 0.001), chest circumference 9.0 cm or 5.6% (P < 0.001) and girth – 1.0 cm or 6.1% (P < 0.01).
It should be noted that from the second month of the research the animal number the free-stall keeping animal number, which ready for insemination, was more at 2.3 times or 5 goals than stall keeping heifers, and their live weight was more at 8 kg or 3.0%. With age, the differences between the groups gradually increased and by the third month reached 8 goals or 2.6 times and 19.0 kg or 5.7%.