Nasko Vasilev's research while affiliated with Trakia University and other places

Publications (26)

Article
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Background Determination of gestational age in goats was performed using ultrasound measurements of different fetal biometric parameters. There are no data showing quadratic and exponential dependence between fetal heart parameters and gestational age. Objectives The objective of the present study was to test the significance of the defined indica...
Article
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The aim of the present study was to determine the parameters characterising the blood flow velocity in the fetal heart and aorta in goats by Doppler ultrasonography. Twenty-four Bulgarian White milk goats, aged 4-6 years, weighing 45-51 kg were used in the study. Doppler ultrasound measurements of the blood flow velocity in fetal heart were done at...
Article
The goal of this review is to consider and discuss the scientific literature related to the effect of heat stress (HS) on reproductive performance in dairy cows and opportunities to reduce its effects. The information in literature shows that the HS topic in dairy cows began to be discussed in the 1970s. As genetic progress related to productivity...
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This study evaluates the phytochemical composition and ability of herbal preparation AyuFertin, supplemented shortly after calving, to resume the cyclic ovarian activity in postpartum Bulgarian Murrah buffaloes. In total, 13 healthy Bulgarian Murrah buffaloes at the age of 4–10 years, calved in March–April 2019 were involved in the experiment. Seve...
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Penev, T., Dimov, D., Vasilev, N., Mitev, J. & Miteva, Ch. (2020) Effect of heat stress on some reproductive traits in Holstein-Friesian cows under temperate continental climate. Bulg. J. Agric. Sci., 26 (Suppl. 1), 155-162 The aim of the present study was to determine the effect of heat stress (HS) on some reproductive traits in Holstein-Friesian...
Article
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Many drugs and toxic compounds are subjected to disposition and metabolism in bovine mammary epithelial cells (bMECs). For rapid investigation of different compounds and their possible interactions, validated in vitro models are needed. Therefore, the first objective of described experiments was to develop the techniques for cell isolation, purific...
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Nowadays, a modern trend of the animal husbandry is to increase the reproductive potential of livestock and poultry. There is a large interest worldwide in discovering new and safe non-hormonal biologically active substances obtained from natural sources, which could substitute the synthetic hormones. The positive influence on reproduction in lives...
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Systemic therapy with oxytetracycline is often used for treatment of clinical metritis although data about its penetration into the uterus and uterine secretion are lacking. Uterine secretions and milk from six cows with clinical metritis were collected for microbiological assay. The animals were treated intramuscularly with long-acting oxytetracyc...
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The purpose of this study was to determine the possibility of visualization of fetal and uterine structures in the second and third pregnancy trimester in goats through three-dimensional (3D) ultrasonography. Twenty Bulgarian local goats, aged between 2 and 4 years, weighing 46-52 kg with previously confirmed pregnancy were used in the study. Ultra...
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The purpose of the present study was to determine the fetal number in goats by using hormonal and ultrasonographic examinations. The experiments were conducted with 106 clinically healthy Bulgarian local goats, 1.5 to 7 years of age, weighing 35-52 kg. Hormonal examinations were performed on 24 goats. Serum progesterone concentrations were measured...
Article
The aim of the current study was to determine the gestational age in goats through measurement of some fetal and uterine structures. Twenty‐four pregnant Bulgarian local goats were submitted to ultrasound fetometry by transrectal and transabdominal approaches. Ultrasound measurement of studied parameters were done at 7‐day intervals during the firs...
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The aim of the present study was to determine plasma haptoglobin concentrations in cows in field conditions. Experiments were carried out a total of 106 cows, divided in 5 groups. The 1st group comprised 25 cows with low milk somatic cell counts (SCC), without microbiological findings used as controls; the IInd group -23 cows with untreated subclin...
Article
The aim of the present study was to evaluate the potential of colour Doppler and three-dimensional ultrasound for visualization of mammary gland structures in goats. Ten Bulgarian white milk goats, aged from 2 to 4 years, weighing 48-54 kg were used. Mammary gland scans were performed via the transcutaneous approach, using 11.0 MHz linear transduce...
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Hristov, K., P. Parvanov, N. Vasilev, I. Fasulkov & M. Karadaev, 2017. Effect of non-hormonal agents Tribestan and Lactina ® on the sexual behaviour and quality of semen in rams during non-breeding season. Bulg. J. Vet. Med., 20, Suppl. 1, 297-301. The aim of this study is to investigate the effects of non-hormonal agents Tribestan and Lactina® on...
Article
The purpose of the present study was to investigate the ultrasound and histopathological findings in experimentally induced Staphylococcus aureus mastitis in goats. The experiment was conducted using six clinically healthy goats, 2–4 years of age, weighing 48–54 kg. The experimental infection was done with stationary-phase culture of a field S. aur...
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The aim of the present study was to assess changes in acute phase proteins fibrinogen and haptoglobin, as well as hematological, blood biochemical, and microbiological alterations in local Bulgarian goats with experimentally induced Staphylococcus aureus mastitis. The experiments were conducted with 6 clinically healthy local Bulgarian goats, 2 to...
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The aim of the present study was to determine the features and size of teat structures in cows using ultrasonography. The experiment was conducted with 12 clinically healthy Black-and-White cows, 3 years of age, with body weight of 350–450 kg. Ultrasonography was performed on 48 teats using ultrasound SonoScape A5v (SonoScape, China) with multifreq...
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The present study aimed to compare three identification methods that are routinely used for the detection of Staphylococcus aureus as bovine mastitis agent. The evaluated methods were as followed: conventional biochemical method, commercial identification system BioLog (Gen III MicroPlate) and amplification of species-specific gene (nuc) by polymer...
Article
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Abstract. The study was performed at three dairy cattle farms from three districts in the country: Plovdiv, Bourgas, and Veliko Tarnovo. The cows housed at all three farms were of the Holstein-Friesian breed. A total of 150 cows were included, 50 from each farm. The rearing at the three farms was free with differences in some technological details....
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NEDELKOV, K., N. TODOROV and N. VASILEV, 2012. The possibility for oestrus synchronization by salt-free-salt diet in some sheep breeds reared in Bulgaria. Bulg. J. Agric. Sci., 18: 942-952 The purpose of these studies was to determine the effectiveness of the salt-free-salt diet, which is widely applied in Bul-garia as a non-hormonal method for oes...
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The purpose of this study was to examine the behaviour of dairy cows during the rest periods and their preferences to different bedding materials with limited amount of straw as well as the hygienic score of dairy cows. Thirty-six Holstein dairy cows at the first to fourth lactation with live weight 610±58 kg and milk yield of 7364±1202 liter for 3...
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Full-text available
The aim of the present research was to evaluate some of most important zoohygienic indicators on the basis of a preliminary technical and technological layout of a semi-open free-stall dairy barn for housing of 74 cows. The study was performed on a large dairy barn with longitudinal sidewalls replaced by retractable curtains, with three rows of cub...
Article
Important factors for spread of infections in rearing dairy cows are the buildings, rearing technology and the cleaning method. The exposure of the animals to dampness, mud and manure in the premises increases the percentage of subclinical and clinical mastitis. The objective of the study was to establish the relationship between the conditions in...

Citations

... The effect of high ambient temperature on the hypothalamic-pituitary-ovarian axis plays an important role in regulating hormonal secretion, behavior, follicular development and embryonic growth and survival in the uterus of animals. These changes alter key components of livestock breeding, such as the duration of the estrus, fertility and conception rate (Penev et al. 2021). Nutrition is widely known to regulate reproductive endocrine functioning in many species. ...
... There is no reasonable guarantee that BAA are absolutely safe, as there are many cases when undeclared substances such as hormones, analgesics, antidiabetic and other drugs are added to BAA to stimulate their effect, the long-term uncontrolled use of which is extremely hazardous (Peng et al. 2013;Mihaylova et al. 2020). ...
... Thus, ceftiofur administration to cows with postpartum metritis did not influence the number or type of bacteria present in the uterus but did reduce the number of days of elevated body temperature in these animals [42]. Oxytetracycline administered intramuscularly to cows with metritis resulted in penetration of the antibiotic into uterine secretions, but levels were below MIC values [43]. Therefore, apparently some antibiotics in the insemination dose can pass from the uterus to the bloodstream. ...
... Khan and Khan (2015) found that cows with more parities had higher scores for stature, chest width, body depth, angularity, rear legs-rear view, central ligament, teat length and rear udder width. Miteva et al. (2012) found a significant trend for set too close at the hocks in rear legs-rear view among cows with more parities (from the first to third). This was related to various reasons, such as increasing the capacity of the udder, gestations, type of floor, and others (Manske, 2002). ...
... The floor structure of cattle housing plays a significant role and must be comfortable enough to ensure adequate rest and welfare (Mitev et al. 2012) of the cows. In order to create a comfortable environment, bedding material must provide thermal comfort and softness, be durable, and have sufficient friction to prevent slipping when lying down (van Gastelen et al. 2011). ...
... In a previous study of ours (Karadaev et al., 2016), fetal heart rate was measured for the first time on gestational day 35 with an average value of 212.5 (±6.1) bpm. Although fetal structures with high correlation coefficient (Rš ≥ 0.90) are most frequently used to determine gestational age -embryo/fetus length (crown-rump length CRL), trunk diameter (TD), and biparietal diameter (BPD) (Abdelghafar et al., 2011;Karadaev et al., 2018), some authors (Serin et al., 2010) assume that monitoring fetal heart rate can be used to determine gestational age in Saanen goats and they reported correlation coefficient Rš = 0.77. Kahn (1989) established that fetal heart in cattle decreased with progression of pregnancy. ...
... Ultrasonography is a complementary means of diagnosis, widely used in different medical areas presenting the advantage of being non-invasive and easily transported. In goats, it has been used mainly at the scientific level, performed to visualize physiological and pathological changes occurring on the mammary gland structures [16,17]. There are studies related to milking and IMI diagnosis which have been carried out through the measurement of the different gland structures with the use of B-mode ultrasonography [18][19][20]. ...
... The specificity of the bird ontogenesis is that the development of an embryo takes place outside the mother's body, it occurs in the environment that has an influence on the postnatal development of the bird by abiotic and biological factors (feeds, temperature fluctuations, light, noise, microflora and others) (Garmata, 2018). The influence of different factors causes the changes of homeostasis, the processes of metabolism (Ayasan et al., 2006;Hristov et al., 2017), the reduction of resistance and productivity (Groza, 2014;Munez et al., 2015). ...
... Diagnostic ultrasonography has been employed to get the images of udder structures, including mammary glands with the mammary parenchyma, the lactiferous ducts, the mammary vessels, the teat (teat cistern and teat arteries), the supra-mammary lymph nodes, and the gland cistern (17). Several studies have investigated the relationship between the ultrasonography assessed mammary gland and SCC or mastitis (18)(19)(20). Ultrasound technology is considered an effective method for the rapid detection of mastitis. ...
... Haptoglobin belongs to a group of transporter plasma proteins that bind the free haemoglobin (45). This defines its bacteriostatic effect as well as antioxidant activity (26,45) Many studies have demonstrated the importance of Hp as a clinically helpful parameter for measuring the occurrence and severity of inflammatory responses in sheep with various infectious diseases (12,(46)(47)(48)(49)(50)(51)(52). Pepin et al. (46) investigated the changes in Hp concentrations in lambs experimentally infected by Corynebacterium pseudotuberculosis. ...