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The experiment is carried out on 3 groups of cows (1 - with productivity up to 7500 kg, 2 – from 7500 to 9000 kg and the 3rd group-9000 and above kg of milk for the previous lactation). Milk yield for 305 days of lactation of cows of group 3 averaged 9068 kg (P≤ 0,01), group 2-8682 (P≤ 0,05) and group 1 – 7940 kg of milk. Milk fat production in cows of group 3 - 369 kg (P≤ 0,05), group 2-351 and group 1 – 326 kg. The yield of milk protein from cows of group 3 is 285 kg (P≤ 0,01), group 2-270 (P≤ 0,05) and group 1-248 kg. A comparative analysis of the growth and development of heifers with mothers with different levels of productivity was carried out. At the 2nd month of growing, the weight of heifers of the 3rd group is 76 kg (P≤0,10), the 2nd - 72 kg (P≤0,10). The average daily growth of group 3 heifers at 6 months was 1244 g (P≤0,10), group 2 - 1127 and group 1-617 g.Group 3 Heifers at 9 months weighed 301,2 kg (P≤0,05), group 2 – 299,3 kg (P≤0,05). Heifers of group 3 at 12 months reached 380,6 kg (P≤0,05), group 2–378,5 (P≤0,05) and group 1 – 353,7 kg. The growth of experimental heifers of group 2 was 887,6 g (P≤0,05), group 3–829,6 and group 1 – 710 g per day. Monitoring of growth and development of heifers continues.

The aim of genetic improvement in cattle breeding is to create animals, which are characterised by high economic efficiency while maintaining the high breeding values for health and reproduction traits. In Russia dairy cattle industry the integrated approaches based on application of genomic methods for cows’ fertility and health traits along with milk production are being developed. However, their efficiency depends largely on the ability for multiple replicating outstanding individuals by embryo transfer. Therefore, the target of our research was to develop a strategy for the integrated genetic improvements of fertility and udder health traits towards the production of embryos with high estimated breeding values (EBV). We analysed the culling factors of more than 23,400 Black-and-White and Holstein cows of the Moscow region cattle population. Using the genotyping procedure by Illumina Bovine SNP50 BeadChip (Illumina Inc., San Diego, CA, USA), the regional training group consisted of 401 proven bulls and 60 pre-selected cows was formed. After the quality check based on Plink 1.90, we selected 39,631 single nucleotide polymorphisms for the analysis. The GBLUP methodology was used to calculate genomic EBV (GEBV). The cows were additionally tested by PCR or PCR-RFLP (restricted fragment length polymorphism) for LoF mutations in the genes FANCI, APAF1, SMC2, GART, ITGB2, SLC35A3, and APOB, associated with fertility haplotypes HH0, HH1, HH34, HH4, HHB, HHC, and HCD, respectively. The evaluation of genetic variances and EBV for days open (DO), breeding per conception (BC), calving ease (CE), somatic cell score (SCS), milk yield (MY), fat yield (FY), and protein yield (PY) was carried out using the BLUPF90 family of programs. Cows’ culling rate for reproductive traits was 21% and for udder diseases was 8%. The genetic correlations, rg, between SCS and cows’ fertility traits were rg = 0.132 for BC, rg = 0.067 for DO, and rg = –0.056 for CE that can be used as an indicator for the monitoring reproductive disorders at the different stages of lactation. The frequencies of fertility haplotypes’ carriers among the potential donor dams were 6.6, 1.1, 8.8, 0.0, 1.1, 0.0, and 4.4% for HH0, HH1, HH3, HH4, HHB, HHC, and HCD, respectively. Based on EBV and carrier status for LoF mutations, we selected 46 dams and 28 sires to produce embryos with high GEBV for MY (+633, ..., +884 kg), FY (+26 kg), PY (+18 kg), and SCS (106 points) and higher as population average GEBV for fertility and udder health traits. Genome-wide association study analysis by the reliability of Bonferroni correction test (P < 1.2 × 10−6) showed the presence of quantitative trait loci on BTA1, BTA5, BTA9, BTA11, BTA12, BTA27, and BTX. Our results will be used to construct Russian fitness index for dairy cattle and for implementing embryo production technology into the Russian breeding system. Research supported by the Russian Science Foundation within Project no. 15-16-00020.

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В нормализации продуктивного долголетия важно поддержание энергетического баланса организма коров в период новотельности. Достигается это оптимизацией технологических режимов эксплуатации, в том числе изменением кратности доения, что и являлось целью работы. Исследования проведены на молочном комплексе беспривязного содержания коров на 700 скотомест. Новотельных коров первой группы первые 20 дней после отела доили 2 раза в сутки с интервалом в 12 часов, а затем переводили на трехкратное доение до 90 дня лактации. Во второй группе применялось трехкратное доение с отела до 90 дня лактации. Все коровы с 91 дня лактации и до запуска доились двукратно. Выявлены достоверные различия по количеству дней от отела до окончания отечности вымени и его выраженности в баллах. В группе с двукратным доением коров продолжительность активной мобилизации жировых запасов тела составила 2 мес. со снижением упитанности на 0,47 балла, а у аналогов с трехкратным доением 3 мес. и 0,51 балла соответственно. Коровы и первотелки второй группы за начальный период лактации превосходили первую по удою на 539,7 кг (p0,001) и 225,4 (p0,05), а также по содержанию жира и белка, лактозы и сухого вещества. С применением технологического приема двукратного доения коров транзитного периода с переходом на трехкратное с 21 дня лактации в первые 100 дней лактации снижается молочная продуктивность, но нормализуется продолжительность и интенсивность использования тканевых резервов тела, а также удлиняется период послеотельной отечности вымени и, как следствие, возрастает количество соматических клеток в молоке.In the normalization of productive longevity of cows, it is important to maintain the energy balance of the body during the postpartum period. This achieved by optimizing the technological modes of operation, including changing the frequency of milking, which was the purpose of the work. On a dairy farm of loose cows on 700 places carried out researches. The fresh cows of the first group milked for the first 20 days after calving twice a day, at an interval of 12 hours, and then transferred to 3-times daily milking, to 90 days of lactation. In the second group, 3-times daily milking used from calving to 90 days of lactation, the interval between milking was 6 hours. All cows were milking twice from 91 days of lactation until the start. There were significant differences in the number of days from calving to the end of the udder edema and its severity in points. In the group with 2-times daily milking of cows, the duration of active mobilization of body fat reserves was 2 months with a decrease in fatness by 0.48 points, and for analogues with 3-times daily milking - 3 months and 0.52 points, respectively. The cows and 1st calving cows of the second group for the first lactation period exceed the first group of milk yield by 539.7 kg (p0.001) and 225,4 (p0,05), as well as by the content of fat and protein, lactose and dry matter. Thus, with the use of technological reception of 2-times daily milking cows transit period with the transition to 3-times daily milking from 21 days of lactation, the milk production decreases, but the duration and intensity of use of tissue reserves of the body is normalized and the period of udder edema is prolonged in postpartum, and as a result the number of somatic cells in milk.