GROWTH AND REPRODUCTIVE ABILITY OF HEIFERS AND FIRST-CALF COWS OF THE CREATED SIMМENTAL MEAT BREED
Authors: Dedova L. O. , Bashchenko M. I. , Vdovychenko Yu. V. 
Published: November 2020

Introduction. Four domestic meat breeds of cattle have already been created – Ukrainian, Volynian, Polessian and Southern. Now carry out the work to create another breed of cattle, the Simmental meat, based on local Simmental combined direction of productivity.
Now carry out the work with related groups of cattle of the created Simmental meat breed, which are the basis for the creation of further lines, but the economic and biological characteristics of animals of different related groups have not been sufficiently studied. This is especially touch of repair heifers, their raising.
Therefore, the study problems of growth, development and biological characteristics in the raising of repair heifers of different related groups had is not only theoretical but also practical importance.
The purpose of our researches was to study the dynamics of live weight and reproductive ability and their selection and genetic parameters of heifers and first-calf cows of different related groups of the created Simmental meat breed.
Research materials and methods. The researches was carried out on heifers and first-calf cows of different related groups of the created Simmental meat breed in PJSC "Dniprovske" of Boryspil district of Kyiv region. To analyze the growth and reproductive ability of heifers and cows were formed groups of animals depending on from that to which related group they belong: I group – Metz 5290; II – Achilles 369; III – Abricot 58311; IV – Huxle 19223; V – Hercules 8942 and VI – Signal 120.
Research results. We determine that heifers of the II group, which belong to the related group of Achilles 369, by live weight at all ages of periods surpass to peers. Thus, at 15 months of age, the advantage of heifers of the II group by live weight in comparison with peers of the I, III, IV, V and VI groups was 6.0; 1.2; 7.8; 17.3 (P > 0.90) and 12.8 kg.
In heifers of related groups Hercules 8942 and Signal 120, the coefficient of variability of live weight at birth in which was the lowest, and in subsequent age periods it little varied, therefore at 15 months of age in these heifers it was the highest, in comparison with analogues, and was 9.8.
When studying the age repeatability of live weight of heifers of different related groups, we determine, that in heifers of the related group of Signal 120 indicators of the coefficient of repeatability of live weight in all age periods were the highest and fluctuated from 0.75 to 0.95.
The longest duration of service and between calving periods was in cows of the II group, which belong to the related group of Achilles 369, they were 155.3 and 435.5 days, respectively.
The coefficient reproductive ability was highest in cows of the IV group, which belong to the related group of Huxle 19223, and was 0.92, and the lowest – in cows of the II group, which belong to the related group of Achilles 369 – 0.85.
An important indicator of the reproductive ability of animals is the index of fertility. In our researches, it was determine that the animals of the experimental groups generally had average fertility. Thus, their index of fertility fluctuated from 40.8 (II and V groups) to 42.4 (IV group).
When calculating the possible percent of calves on 100 cows, it was determine that the lowest this indicator was in cows of the II group, which belong to the related group of Achilles 369. They were inferior to animals of the I, III, IV, V and VI groups by 2.0; 1.7; 7.3; 2.2 and 4.0 goals.
Also, the coefficients of variation of indicators of reproductive ability of heifers and first-calf cows of different related groups were calculated. It was determine, that the heifers of the related group Huxle 19223 had the highest coefficient of variability in the duration of the service period, which was 47.8.
When calculating the correlation connexions between growth and reproductive ability of heifers of different related groups detected in all groups of animals a positive relationship between live weight at 7 months of age and index of fertility, between live weight at the first insemination and the age of the first insemination and between live weight at the first insemination and the age of the first calving.
Conclusions. It was determined, that the animals of the related group of Achilles 369 at all ages of periods had a large live weight in comparison with their analogues. The highest coefficient of variability of live weight at 15 months of age was in heifers of the related group Signal 120 and amounted to 9.8. Also, the heifers of this group had the highest the indicators of the coefficient of recurrence of live weight in all age periods and ranged from 0.75 to 0.95. The best indicators of reproduction were characterized by animals of the related group Haxle 19223. The coefficient of reproductive ability in them was 0.92, and the index of fertility was 42.4. Also, heifers of the related group Haxle 19223 had a highest coefficient of variability in the duration of the service period, which was 47.8. In animals of all groups was revealed a positive relationship between the live weight at 7 months of age and the index of fertility, which indicates the possibility of using this relationship in breeding work with the herd.