Oxidative stress as a leading factor of male infertility requires correction with modern pharmacological agents, particularly redox-active nanoparticles, to improve sperm quality and hormonal balance. The current experimental study aimed to investigate the effect of orthovanadate nanoparticles of rare earth elements, particularly Gadolinium, with pronounced redox properties on the reproductive function of male rabbits under oxidative stress. A total of 36 mature male Hyla rabbits were divided into three groups of intact control (n = 12) and two experimental groups, including rabbits ubder oxidative stress (n = 12), induced by the introduction of tert-Butyl hydroperoxide, and those under oxidative stress plus hydrosol of gadolinium orthovanadate nanoparticles (NPs, n = 12) intake for 14 days. There were four rabbits per three replicates in each group. Animals of all groups were kept on the same diet and had free access to water. The use of NPs led to an improvement in sperm quality indicators. There was an improvement in motility and ejaculate volume indicators (by 14.6% and 39.2%, respectively), a reduction of the content of morphologically abnormal sperm by 26.7%; normalization of sex hormones, an increase in the level of total testosterone (by 113%) with a decrease in 17-β-estradiol (by 16.5%). This sex hormones improvement led to an increase in the androgen saturation of the rabbit’s body (free androgen index at the end of the experiment was 36.5%). The obtained changes were accompanied by a decrease in the oxidative load, as evidenced by a reduced content of diene conjugates and thio-barbituric acid-reactive compounds in the blood serum of rabbits by 30.4% and 26.8%, compared to the control. At the same time, there was an increase in the antioxidant potential, especially its glutathione link – the activity of glutathione peroxidase and glutathione reductase (by 42.5% and 34.2%, respectively), and the content of reduced glutathione increased by 62.3%, compared to the indicators before the introduction of NPs. The results of the study confirmed the effectiveness of using gadolinium orthovanadate NPs to correct the reproductive function of males under oxidative stress.

The substantiation of the use of antioxidant compounds to correct the reproductive capacity of males is an urgent problem of modern reproductive science. Some amino acids have pronounced antioxidant properties, including N-acetylcysteine (NAC). The work aimed to determine the effect of oral administration of NAC on sperm quality and hormonal balance in infertile boars. According to the results of andrological dispensation, three groups of animals were formed – I experimental groups (n = 5) and II (n = 5), with reduced reproductive capacity, and control (n = 5) with total reproductive capacity. The animals of the experimental groups were orally administered NAC at a dose of 75 mg/kg body weight (test I) and 50 mg/kg body weight (test II) for 30 days. With the introduction of different doses of NAC, an improvement in the quality of the ejaculates of the boars of the experimental groups was observed. In I experimental group, on the 120th day of the experiment, a probable increase in motility by 35.5 %, ejaculate volume by 8.7 %, and concentration by 5.1 % were established (P ˂ 0.05). On the other hand, the content of spermatozoa with morphological abnormalities probably decreased (by 22.7 %, P ˂ 0.01). Similar changes were obtained in boars of the II experimental group – the number of morphologically abnormal cells probably decreased – on the 90th and 120th day of the study by 17.7 % (P ˂ 0.05) and 24.7 % (P ˂ 0.01), respectively. Sperm motility and ejaculate volume increased significantly – by 28.1 % (P ˂ 0.01) and 7.9 % (P ˂ 0.05). The use of NAC contributed to the normalization of the endocrine function of the gonads, as a result of which an increase in the level of total testosterone in the blood serum of boars – an experimental group I was established by 16.3 % (P ˂ 0.05) on the 30th day of the study and by 33.7 % (P ˂ 0.001) on the 45th day. Similar changes were obtained in the animals of the II experimental group – an increase in testosterone level by 13.8 % and 29.8 % on the 30th and 45th day of the experiment, respectively (P ˂ 0.05–0.01). The estradiol level tended to decrease on the 30th day of the study. In contrast, on the 45th day, it was significantly lower than before administration by 13.6 % and 12.3 % in animals of I and II experimental groups, respectively (P ˂ 0.05). Testosterone-estradiol ratio up to 7.4–8.2 units on the 45th day of the study, which indicated the normalization of the balance of sex hormones in the body of boars. The obtained results recommend NAC as an effective means of correcting infertility in boars.

The objective of our experiment was to study the histrostructural changes in the ovaries of pregnant rabbits with previous reproductive cycles in artificial insemination without using further hormonal treatment to increase the reproductive function of rabbits. We have studied the ovaries of pregnant rabbits of the Hyla breed on the 7th day of pregnancy age, which were in the fifth reproductive cycle. The AI technique in rabbits needs an ovulation stimulator or inducer because female rabbits are induced ovulators. In our experiments, we used Surfagon for induction of ovulation by the method proposed by Lisin V. I., Sushko A.B., Institute of animal's science of the NAAS. The ovaries were fixed in 10%-neutral formalin solution. Paraffin histosections were made and coloured with hematoxylin and eosin according to the standard technique.The macroscopic and microscopic studies of the rabbit ovary of the 5th reproductive cycles indicate a high level of their luteinization. The results of the histological study show that the histostructural picture of the ovaries of pregnant rabbits reflects the nature of the course of the phases of the previous reproductive cycles typical for this animal species. In the ovary of pregnant rabbits of the fifth reproductive cycle, all generations of follicles were found. The predominant functional elements of the ovarian parenchyma were luteal structures: the corpus luteum of pregnancy, atretic bodies and interstitial glandular tissue. There were two types of follicular atresia: obliterating, which took place in the preantral (primary and secondary) follicles and cystic and the antral tertiary follicles. The formation of hemorrhagic follicles was a type of cystic atresia. The formation of atretic bodies occurred as a result of luteinization of primary and secondary follicles. In the ovaries of pregnant rabbits of the fifth reproductive cycle, yellow bodies of various generations were found, that is the evidence of their functioning for several reproductive cycles. The number and development of corpus luteum in the right and left ovaries was asynchronous, which indicates the asynchronous nature of ovulation in the preceding and current reproductive cycles. Interstitial glandular tissue was the predominant histological element in the ovaries of rabbits of the fifth reproductive cycle. Compared with the ovaries of other mammalian species, it was found not only in the cortical, but also in the medulla of the ovaries of pregnant rabbits.

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The article highlights the results of the reproductive capacity of different breeds of boar sires in the farms of eastern, southern, and central regions of Ukraine in dynamics over three years are given. It represented the influence of the year's season on sperm quality by estimating the ejaculate volume, concentration, and motility of sperm of boars-sires of the different breeds and their hybrids. Data were also calculated on the culling of ejaculates of boar sires of various breeds for the years 2019–2021 in the dynamics. In a comparative aspect, the indicators were analyzed by the following genotypes: Large White, Ukrainian Meat, Landrace, Duroc, Yorkshire, and synthetic line Makster. The reproductive capacity of boars was within the limits of the indicators for the elite and first classes. However, specific differences were observed between boars of different breeds, which were constant and took place during the three studied years. The difference in the concentration of sperm in the ejaculates of the Ukrainian Meat breed gradually decreased starting from 2019 and was the smallest in 2021. The highest ejaculate volume was found in boars of the Ukrainian meat breed (310.9 ± 113.2 cm3), and the sperm concentration was the highest in boar sires of the Large White breed (215.7 ± 83.5 million/cm3). On the other side, hybrids of the Large White breed had low indicators compared to other groups of animals (Large White × Yorkshire – 184.2 ± 68.5 million/cm3, Large White × Makster – 189.0 ± 59.7 million/cm3). Sperm motility did not undergo significant breed differences: the average annual indicator of motility was 7.6 ± 0.09 points, and it was the highest in the winter period (8.6 ± 0.11 points), however, for the established variances; the dilution was used 1.65–3.58 times and a high percentage of unusable sperm (15.4–29.4 % of the total amount) was established in a large number of samples. According to the results of the annual analysis of the sperm production of boars, a high degree of culling of ejaculates was established for various reasons (high level of sperm agglutination (52.3–74.0 %), low concentration of germ cells (14.5–29.8 %), presence of foreign impurities (5,8–12.4 %). The highest percentage of culling was in summer (20.3 %). Thus, the obtained results showed the breed and seasonal characteristics of the reproductive capacity of breeding boars.