PSVI-18 Efficiency of the use of ultrafine particles of silicon dioxide in the synchronization scheme of estrus of heifers

The intensification of the reproduction of a herd of cattle requires the use of highly effective synchronization schemes for estrus. All schemes available today give a low percentage of fertilization with frontal insemination. The aim of this study was to assess the effect of ultrafine particles of silicon dioxide on fertility and the level of sex hormones in heifers during synchronization of sexual heat with subsequent frontal insemination. Ultrafine particles of silicon dioxide were injected in isotonic sodium chloride solution. The synchronization scheme included two-fold application of prostaglandin preparations; blood was taken from under the tail vein to determine the hormonal status on days 1, 11, and 14 of the experiment. The results of the study showed that ultrafine particles of silicon dioxide had a positive effect on the level of sex hormones. Concerning progesterone, the difference between the values of increase in the level in the experimental and control groups was 112.1% (P ≤ 0.01) on the 11th day. On the 14th day of the experiment, the difference between the values of the decrease level was 19.6% (P ≤ 0.05). Follicle-stimulating hormone increased by 9.1% (P ≤ 0.05) by the 14th day of the experiment compared with the previous value. In the heifers of the experimental group, the excess was more significant, i.e.15.4% (P ≤ 0.05); the level of luteinizing hormone in the experimental group on the 14th day of the experiment exceeded the level of the control by 31.1% (P ≤ 0.05). According to the results of the examination for pregnancy, an increase in fertility was revealed by 20.0% in the experimental group in comparison with the control group. This study demonstrates the potential of using ultrafine silica particles in estrus synchronization schemes for heifers to increase heifer fertility. The research was carried out in accordance with the research plan for 2019–2021. FGBNU FSC BST RAS (No. 0761-2019-0006).

Improvements on Mechanical Property and Microstructure of Cementitious Composite Incorporated with Silica Fume and Carbon Nanotube

Nano-size fillers (ultrafine silica fume (USF) or/and multi-walled carbon nanotube (MWCT)) were incorporated into cement matrix to fabricate nano-fillers reinforced cementitious materials (NFRCs) with surfactant ultrasonic dispersion and subsequently mix cast process. The flexural and compressive strengths of four groups NFRCs with varied nano-filler loading were comprehensively investigated. Results show, there are positive effects on the flexural and compressive strength of NFRCs with nano-fillers loading, especially when USF and MWCT are incorporated simultaneously, and the correspondent maximal flexural and compressive strength can increase by above 17%, 28% with respect to the baseline, respectively. The pozzolan infilling effect of USF and the crack-bridging effect of dispersed MWCT result in the dense and integrated network microstructures of cured NFRC.

Analysis of efficiency of development of swine embryos outside the organism with use of nanobiomaterial

Aim. To study the effect of nanobiomaterial, synthesized on the basis of ultrafine silica modified by the sucrose (UFS/sucrose) on the effectiveness of meiotic maturation of swine oocytes and their subsequent embryonic development outside the organism. Methods. The oocyte-cumulus complexes (OCC) of pigs were divided into four groups: three experimental groups, in which cultivation was carried out in a medium containing 0.1, 0.01 and 0.001% UFS/sucrose and control group - without the addition of nanobiomaterial. Results. It has been established that the addition of 0.001% UFS/sucrose is the most effective for increasing the level of maturation, it provides 80.9% oocytes that have reached the stage of metaphase II meiosis. For the purpose of studying completeness of in vitro maturation of swine oocytes, they were fertilized by cryopreserved ejaculated spermatozoa. It was found, that in experimental groups with 0.1 and 0.01% UFS/sucrose concentration zygotes were formed outside the organism by 8.3% and 5.4% less than in the control group (11.3% ± 6.3), respectively. Higher by 12.2% level of embryo cleavage was observed in the group that matured with 0.001% UFS/sucrose, compared with control, and this figure was 23.5%. Conclusions. It was shown that the use of UFS/sucrose in the system of embryogenetic research contributes to the purposeful stimulation of biological processes in the oocytes. It has been proved that the addition of UFS/sucrose at a concentration of 0.001% to the medium composition for cultivation of OCC positively affects the maturation efficiency of swine oocytes and provides a higher level of embryo cleavage outside the organism (23.5%). Keywords: oocytes, in vitro cultivation, embryos, nanobiomaterial, ultrafine silica, sucrose.