The influence of the calving season on milk production was determined to be 0.9% for 305 days of lactation on average across all farms. In loose-housing, the influence of the season was smaller (0.4%) compared to stall housing (1.6-5.5%). Seasonal differences in the milk output of first calving cows for stall housing was equal to 437-816 kg, and for loose-housing 192-283 kg (р<0.05). In some farms animals of autumn and winter calving were distinguished by the best milk output, while in other farms spring-winter calving cows were more productive. It indicates a significant influence on the production of first-borns by the conditions of housing. The analysis of the indices of lactation constancy according to I. Johansen and A. Hanson indicates that the smallest decrease in milk output in the period of the next 14 weeks of lactation compared to the first 14 weeks of lactation was characterized by the first-borns of the experimental farm "Kutuzivka", and the largest by the animals of the experimental farm "Gontarivka". According to H. Turner's index, the differences between the peak monthly milk output and the milk output per lactation were the smallest in the first calving cows of the experimental farm "Stepne". Lactation curves of the cows that calved in the autumn-winter period had a steady character, which gradually decreased at maximum productivity for 3-4 months of lactation. In the first 3 months of lactation their herdmates of spring-summer calving also had an increase in milk output which fell dramatically in the following months when the animals were conveyed to winter-stall housing and a decrease in the completeness of feeding cows during this period. According to variance analysis, differences in daily milk output for each of the ten months of lactation were possible (p<0.001). The highest peak of daily output in all farms was obtained from first calving cows of spring calving which explained by the best conditions of housing and feeding during the calving period. Seasonal differences in the peak daily milk output of first calving cows ranged from 2.0 to 2.5 kg for stall housing and from 1.2 to 1.4 kg for loose-housing (p<0.001).

There were presented the results of heterosis level (hypothetical and true) and the degree of phenotypic dominance of the main economically valuable characteristics in hybrids of silkworm Bombyx Mori L. of the first generation. The crossing was conducted by full diallel scheme, including 16 variants (12 hybrids and 4 parental forms), 50 mg in triplicate replications. There were studied the types of heredity and the level of heterosis of the main economically valuable characteristics in F1 hybrids of silkworms. It was revealed that the heredity of caterpillars viability, average cocoon weight and male silkiness was mostly positive as regards to G2, G4, G6 and G7 lines, while the heredity of females was mostly depressed (negative superdominance). Determination of the effect of heterosis and the degree of phenotypic dominance made it possible to identify 7 best combinations in terms of caterpillar viability in comparison with parental forms, among them the best were hybrids G2×G6 and G6×G2 with high degree of phenotypic dominance (positive superdominance) -- 7.8 and 9.0, with hypothetical heterosis of 11.0% and 12.7% and true heterosis of 9.4% and 11.1% accordingly. The effect of heterosis (positive superdominance) was found in 8 hybrids according to cocoon weight out of 12 hybrid combinations, partial positive inheritance in 3 hybrids, and intermediate type of dominance in 1 hybrid. The hybrids G6×G4 (Ht=9.00 %, Hbt=8.30 %) and G6×G7 (Ht=1.68 %, Hbt=1.43 %), whose heredity was of the positive superdominance type, were distinguished by female silkiness with a high level of hypothetic and true heterosis (13, 92 and 6.80, accordingly), while hybrid depression was observed in 5 combinations, intermediate heredity in 3, and partial positive and negative dominance in one combination each. The 9 hybrids had positive overdominance type heredity for silkiness in males. Production of high-quality silkworm biomaterial contributes to extension of possibilities of its use in various spheres of human activity.

The production of high-quality silkworm biomaterial Bombyx mori L. contributes to the expansion of the possibilities of its use in various areas of human activity - in light and pharmacological industries, aviation, medicine, radio and electrical engineering, mill production, photography and cinematography, food industry.The economic efficiency of the technological process for the production of silkworm hybrids was determined using breeds marked by sex at the grena stage, based on the fact that there is no single standard method for calculating the cost of the sericulture production process. Costs and profits depend on many factors, both direct and indirect costs, on the general economic and political situation in the world, as well as on changing, unpredictable factors, such as natural and climatic conditions. Since the cultivation of hybrids took place under the same cultivation conditions, the economic effect was determined based on differences in the preparation of hybrid eggs. Cost-effectiveness calculations were made for the yield of cocoons from 1 standard box of caterpillar ants. The cost of production was different, since with the traditional weight method of obtaining hybrids, distribution by sex occurred at the cocoon stage, during the removal of cocoons from cocoons and their sorting, on 8–14 days from the day of mass pupation. The profitability of using hybrids based on sex-marked lines at the egg stage is almost 11% higher compared to hybrids obtained by the traditional weight method. The economic effect is to increase the viability of caterpillars - by 4%, the yield of cocoons from 1 box of ant caterpillars, kg - by 17-24 kg. Additional profit from the technological process of production of silkworm hybrids when using Mer.6.white and Mer.7.white lines is UAH 2020.08, and Bp.35 white and Bp.54 white - UAH 2023.30. The obtained indicators of the level of profitability are calculated for one-time rearing of hybrids, and with repeated rearing, the level of profitability increases significantly and ranges from 40% to 70% per year. Keywords: sericulture, breeds, sex marking, silkworm hybrids, economic effect, hybrid production technology.