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Background: The current study aims to measure the effect of oxidative stress on the pregnancy rates of Bulgarian Murrah buffaloes during the breeding and non-breeding season. Methods: The study group consisted of 24 mature buffaloes more than 40 days after parturition. The following parameters were measured: Reactive Oxygen Species (ROS) products, Ascorbate radicals, Malondialdehyde (MDA), Nitric Oxide (NO), Super Oxide Dismutase (SOD), Glutathione peroxidase (GSH-Px), Protein Carbonyl Content (PPC), and total Nitric oxide. The Presynch/Ovsynch protocol was used for estrus synchronization. Results: A statistically significant increase in ROS products were measured in blood serum during the breeding season compared with the non-breeding season. The highest levels measured were in non-pregnant buffaloes during the breeding season. High levels of oxidative stress were registered due to low SOD activity in buffaloes during the breeding season compared to SOD activity during the non-breeding season. The highest SOD activity was observed in non-pregnant buffaloes during the summer season. The lowest GSH-Px levels were observed in non-pregnant buffaloes during both study periods. During the breeding season, concentrations of total NO and PPC were elevated. Conclusion: Comparing the obtained results for oxidative stress and antioxidant activity concerning pregnancy rate depending on the season showed that pregnancy in buffaloes during the breeding season was realized at higher values of NO and SOD. Increased oxidative stress was observed, resulting in a statistically significant increase in serum ROS products, as well as decreased SOD activity in buffaloes during the breeding season.

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 indicators (fetal heart rate, longitudinal and transverse fetal heart axes) for determining gestational age in local Bulgarian goats. Methods A total of 24 pregnant local Bulgarian goats, aged between 2 and 5 years, body weight 42–50 kg were included in the study. Ultrasonographic examinations were performed weekly on gestational days 21, 28, 35, 42 and 49. After gestational day 49 until parturition, scans were performed biweekly. The data from the measurements were subjected to linear (y = a + bx), quadratic (y = aх 2 + bх + c) and exponential (y = ax n) correlation. Results: Average fetal heart rate values decreased with pregnancy progression. The coefficient of determination (R2) and standard error of estimate (SEE) of the heart rate indicator were 0.72, 0.75, 0.58 and 15.1, 14.4, 19.2 days, respectively, for the three correlations. Longitudinal diameter (long axis) had the following values for R2 = 0.94, 0.96, 0.96 and for SEE = 7.0, 5.5, 5.5 days, for the linear, quadratic and exponential correlations, respectively, while the values of the fetal heart transverse diameter (short axis) were higher than those of the external one (R2 = 0.95, 0.97, 0.97). Simultaneously, SEE is lower (SEE = 6.1, 4.9, 5.0 days) compared to that found for the long heart fetal axis. Conclusions For precise estimation of gestational age, use of longitudinal (long) and transverse (short) axes is recommended. Fetal heart rate is not an exact indicator but can be used as a reference for gestational age along with changes in the heart size and echogenicity., The objective of this study is to determine gestational age in Bulgarian local goats through ultrasonographic measurements of some fetal heart indicators (heart rate, longitudinal and transverse heart axes). For precise estimation of gestational age, use of longitudinal (long) and transverse (short) axes is recommended. Fetal heart rate is not an exact indicator but can be used as a reference for gestational age along with changes in the heart size and echogenicity.

Background: The intensive reproductive management in the dairy farms requires inclusion of a large group of replacement heifers in the breeding program for a shorter period. In this aspect, a creation of effective estrus synchronization protocols with timed artificial insemination (TAI) by sexed semen and optimization of the current ones have a crucial role for obtaining high pregnancy rate. These protocols are beneficial, because they led to reduced interval to first AI, lack of need for estrus detection, and allow obtaining a large group of female calves for on time. Because of limited fertilizing potential of sexed spermatozoa this type of semen is applied mainly for heifers, as fertility is higher compared to lactating cows. The main objective of the present study was to investigate the effect of ovarian status on the reproductive performance in dairy heifers subjected to estrus synchronization and timed artificial insemination with sexed semen. Materials, Methods & Results: Forty-eight Holstein healthy heifers separated in 2 groups were subjected to PGF2α-GnRH pre-treatment and Ovsynch or PRID-5-day estrus synchronization protocol and timed artificial insemination (TAI) with sex-sorted semen, staring 6 days after end of the hormonal pre-treatment. The ovarian status (presence of follicles with or not a corpus luteum) of the heifers at the begin of the treatment, on day of TAI and pregnancy rate in different groups were determined and compared. Additionally, the ovarian status at the begin of the treatment, ovarian status and size of preovulatory follicle (PF) on day of TAI and total values for both groups according to reproductive performance (pregnant or non-pregnant) were also analyzed. On day of TAI the animals with PF and a lack of corpus luteum (CL) in both groups were more that those with PF and CL (39.3% and 30% vs. 60.7 % and 70%), with significant (P < 0.05) difference in PRID-5-day group. The pregnancy rate tended to be higher in PRID-5 day than Ovsynch treatment (65% vs. 35.7%). A higher percentage (100% and 67.9%) of the pregnant animals in both treatments had not CL on day of TAI, and the size of the PF (1.58 ± 0.12 cm and 1.64 ± 0.13 cm) was increased (P < 0.05). Similar effects of the ovarian status on reproductive performance were obtained after a comparison of the total values between pregnant and non-pregnant animals. The percentage of heifers with observed PF without CL on day of TAI was significantly greater (P < 0.05) in pregnant compared to non-pregnant group (91.3% vs. 40%). The opposite dependence was determined for the parameter presence of follicles and corpus luteum (8.7% vs. 60%; P < 0.05). Furthermore, the size of the PF measured immediately before TAI was increased in animals became pregnant (1.60 ± 0.12 cm vs. 1.34 ± 0.17 cm; P < 0.05). Discussion: The analysis of the obtained results showed that the ovarian status on day of TAI affects the reproductive performance in dairy heifers subjected to estrus synchronization and timed artificial insemination with sexed semen. Hormonal pre-treatment with onset of PRID-5-day protocol 6 days later and TAI with sex-sorted semen ensure acceptable pregnancy rate. The greater preovulatory follicle and a lack of corpus luteum before insemination provide significantly (P < 0.05) more pregnant animals, compared to the cases when CL is presented. Ultrasound determination of the ovarian function before insemination can be used in selection of heifers for TAI with sex-sorted semen. Keywords: heifers; estrus synchronization; sexed semen, pregnancy.

Simple Summary Shortening the inter-calving interval is the most important problem in buffalo breeding, especially on organic farms, where the use of hormones is prohibited. The demand for herbal preparations that stimulate the activity of ovaries, as well as the choice of an appropriate time for their application, remains essential today. This study provides the results of the positive effect of the herbal product, which identified a wide range of bioactive substances—carotenoids, flavonoids, and fatty acids, including esters of trienoic fatty acids, on the resumption of the cyclic ovarian activity in early postpartum buffaloes. Overcoming postpartum anestrus in buffaloes is highly cost-effective due to cost savings for keeping dry, unproductive animals. Abstract 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. Seven experimental buffaloes were treated individually per os with AyuFertin according to producer instruction. All animals were subjected to regular ultrasound examination of ovaries. GC-MS analysis of fatty acids composition and HPLC-DAD analysis of carotenoid and tocopherol content in AyuFertin were conducted. The determination of estrus occurrence and natural mating were done by a fertile bull. The development of the large follicles (12.5–14.3 mm) in 85.7% of treated animals was observed on day 24 postpartum compared to 0% in controls. Clinical signs of estrus were recorded in 71.4% of the animals, followed by an 80% pregnancy rate versus 16% in controls within 70 days after calving. In conclusion, the supplementation of the bioactive herbal product AyuFertin from day 21 postpartum can stimulate the follicular growth in the buffalo’s ovary, which leads to the development of follicles with ovulatory capacity, followed by successful ovulation. The above-mentioned treatment resulted in a better pregnancy rate in the treated multiparous compared to the control buffaloes bred by natural service.

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 during a 7 days interval, between 21-63 day of pregnancy, and during a 14 days interval until the 133rd day of pregnancy. Ultrasound examinations were performed on 82 goats with a multi-frequency linear transducer (5.0-12.0 MHz). All animals were studied once during an interval of 7 days transrectally (21-28 day, 29-35 day, 36-42 day) and transabdominally (43-49 day, 50-56 day, 57-63 day), respectively. The accuracy of determining the number of singleton and multiple pregnancies by hormonal analysis were 51%, 58%, 69% and 47%, 52%, 62%, respectively. The accuracy of ultrasonography to determine the number of fetuses is highest in singletons 76.18%, followed by twins 72.56% and the lowest in triplets and more fetuses 21.43%. Highest accuracy, sensitivity and positive predictive diagnosis were established in the period 43-49 day of pregnancy (P

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 oxytetracycline (20 mg/kg) and samples of plasma, milk and uterine secretions were collected for determination of the antibiotic concentrations by HPLC-PDA analysis. Pharmacokinetics of the antibiotic and in silico prediction of its penetration into the uterus were described. Trueperella pyogenes with MIC values of 16&ndash, 64 &micro, g mL&minus, 1 was isolated (n of cows = 4) from uterine secretions. Oxytetracycline showed fast absorption and penetration in the uterine secretions and milk. No change of withdrawal time for milk was necessitated in cows with clinical metritis. Maximum levels in uterine secretions and predicted concentrations of oxytetracycline in the uterus were lower than MIC values. Systemic administration of long-acting oxytetracycline did not guarantee clinical cure and was not a suitable choice for treatment of clinical metritis associated with Trueperella pyogenes. The appropriate approach to antibiotic treatment of uterine infections of cows requires knowledge on penetration of the antibiotics at the site of infection and sensitivity of pathogens.

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 transducer for teat and 5.0 MHz transducer for udder parenchyma. Colour Doppler ultrasonography permitted the visualization of blood vessels in the udder parenchyma, the teat wall skin and the Furstenberg’s venous ring at the boundary between gland cistern and teat cistern. After differentiation of blood vessels, it was possible to determine the direction and velocity of blood flow. The three-dimensional (3D) ultrasonography of caprine mammary gland was capable of visualization of detailed description of the following morphological structures: papillary orifice, rosette of Furstenberg, teat wall, teat and gland cisterns, the parenchyma and the lactiferous ducts. The papillary orifice was seen as a small structure at the tip of the teat, and immediately above it, the teat canal was seen as a thin white band. The 3D image of the rosette of Furstenberg represented a clearly observable thickening at the boundary between the teat canal and the teat cistern. The 3D image of the teat wall allowed for differentiation of its three layers. In the region of the gland cistern, the lactiferous ducts and the parenchyma were distinguished, as well as the boundary between teat and gland cisterns. The analysis of results indicated that colour Doppler ultrasound permits the visualization of mammary blood vessels and their differentiation from anechoic lactiferous ducts and milk in teat and gland cisterns. The three-dimensional (3D) ultrasound check provides an opportunity for detailed observation of all morphological mammary gland structures of goats, which could serve as a background for detection of occurring pathological changes. The main advantage of 3D ultrasonography is the possibility for in-depth observation of the different udder parts, which allows for a more precise diagnostics.

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. Ultrasound investigations were performed during the 56 - 133 day of pregnancy, at a 2- week interval, via transabdominal approach and an 8.0 MHz linear transducer. Initially, the fetal and uterine structures were visualized in two-dimensional mode (B-mode), and then reconstructed into three-dimensional images using 3D software of the ultrasound machine (SonoScape S2 Vet). The results of this study have shown that 3D ultrasonography is a comparatively easy method to visualize individual parts of the fetus and its internal organs during the second and third pregnancy trimester. At the beginning of the second pregnancy trimester, it was possible visualization and differentiation of 3D ultrasound images of the fetal head and body. At the end of this period (90th day of pregnancy) is visualized clear outline of the skull of the fetus, as well as fetal orbit. During the last pregnancy trimester, internal fetal organs such as the forestomaches, kidneys, heart, ribs, etc. were visualized by 3D ultrasound examination. Throughout the study period, clearly 3D images of placentomes were visualized. The analysis of the obtained results shows that three-dimensional (3D) ultrasound examination of the fetal structures in the second and third pregnancy trimester in goats provides an opportunity for detailed observation of individual parts of the body and its internal organs. The resulting clear 3D images of fetal morphological structures can be used as a reference for early detection of embryo-fetal abnormalities, {"references":["Bega G., Lev-Toaff A., Kuhlman K., Kurtz A., Goldberg B., Wapner R. (2001). Three-dimensional ultrasonographic imaging in obstetrics: present and future applications. Journal of Ultrasound in Medicine, Vol. 20(4): 391–408.","Chandolia R. K., George J. (2011). Application of 3D/4D ultrasonography in canine gynaecology and obstetrics. Indian Journal of Canine Practice, Vol. 3(2): 99–102.","Dimitrova V., Markov D., Dimitrov R. (2007). 3D and 4D ultrasonography in obstetrics. Akusherstvo i Ginecologiia, Vol. 46(2): 31–40, (BG)","England G. C. W., Allen W. E., Porter D. J. (1990). Studies on canine pregnancy using B-mode ultrasound: development of the conceptus and determination of gestational age. Journal of Small Animal Practice, Vol. 31: 324–329.","Hildebrandt T. B., Drews B., Kurz J., Hermes R., Yang S., Göritz F. (2009). Pregnancy monitoring in dogs and cats using 3D and 4D ultrasonography. Reproduction in Domestic Animals, Vol. 44(Suppl. 2): 125–128.","Karadaev M., Fasulkov I., Vasilev N., Dimitrov N. (2014). Ultrasound measurements for monitoring of the second and third trimester of gestation in Bulgarian local goats. Bulgarian Journal of Veterinary Medicine, Vol. 17(Suppl. 1): 43–44.","Karadaev, M., Fasulkov I., Vasilev N., Petrova Y., Tumbev A., Petelov Y. (2016). Ultrasound monitoring of the first trimester of pregnancy in local goats through visualisation and measurements of some biometric parameters. Bulgarian Journal of Veterinary Medicine, Vol. 19(3): 209–217.","Kotoyori Y., Yokoo N., Ito K., Murase H., Sato F., Korosue K., Nambo Y. (2012). Three-dimensional ultrasound imaging of the equine fetus. Theriogenology, Vol. 77(7): 1480–1486.","Kumar K., Chandolia R. K., Kumar S., Pal M., Sandeep K. (2015). Two-dimensional and threedimensional ultrasonography for pregnancy diagnosis and antenatal fetal development in Beetal goats. Veterinary World, Vol. 8(7): 835–840.","Markov D., Dimitrova V. (2006). Prenatal diagnosis of structural anomalies of the fetus by 3D/4D ultrasound. Akusherstvo i Ginecologiia, Vol. 45(Suppl. 3): 32–36, (BG)","Markov D., Pavlova E., Atanasova D., Markov P., Ivanov S. (2010). Prenatal diagnosis of structural abnormalities of the fetus by three-dimensional ultrasound in the first trimester - possibilities and limitations. Akusherstvo i Ginecologiia, Vol. 49(7): 4–10, (BG).","Merz E., Welter C. (2005). 2D and 3D ultrasound in the evaluation of normal and abnormal fetal anatomy in the second and third trimester in a level III center. Ultraschall in der Medizin, Vol. 26: 9–16.","Michailidis G., Economides D., Schild R. (2001). The role of three-dimensional ultrasound in obstetrics. Current Opinion in Obstetrics and Gynecology, Vol. 13: 207–214.","Pavlova Е. (2016). Clinical application of three-dimensional ultrasound in obstetrics. PhD thesis, Sofia, p. 152, (BG)."]}

The aim of the current study was to determine the gestational age in goats through the measurement of some foetal and uterine structures. Twenty-four pregnant Bulgarian local goats were submitted to ultrasound foetometry by transrectal and transabdominal approaches. Ultrasound measurement of studied parameters was done at 7-day intervals during the first trimester of gestation (days 21-49) and at 14-day intervals between gestation days 49 and 133. Associations of foetometry data with foetal age were investigated by linear (y = a + bx), quadratic (y = ax2 + bx + c) and exponential (y = axn ) equations. According to the results, some biometric parameters (uterine lumen diameter, crown-rump length, trunk diameter, biparietal diameter, foetal aortic diameter) exhibited a stronger correlation to gestational age (R2 ≥ 0.90) and lower standard error of the estimate (SEE ≤ 8) as compared to foetal eye orbit diameter, and outer and inner placentome diameters (R2 ≤ 0.90; SEE ≥ 8). Each of these biometric parameters could be measured in different periods of gestation, thus allowing for monitoring and determination of foetal age at almost all stages of pregnancy.

The purpose of the present study was monitoring of the first trimester of pregnancy in local goats through ultrasound visualisation and measurements of some biometric parameters. Eighteen local Bulgarian goats, 2 to 4 years of age, weighing 48–56 kg, reared in the Biobase of the Faculty of Vete­rinary Medicine – Stara Zagora were included in the experiments. All animals underwent ultrasound checks on gestation days 21, 28, 35, 42 and 49. Ultrasound measurements included the following biometric parameters: uterine lumen diameter, crown-rump length, trunk diameter, biparietal diameter, inner and outer diameter of placentomes, long and short heart axis, foetal heart rate, foetal orbit diameter. The analysis of results indicated that ultrasound check during the first trimester of pregnancy of local goats could start at 21st day of pregnancy when two biometric parameters were visuali­sed – uterine lumen diameter (10.3±2.7 mm), filled with anechoic amniotic fluid and foetal crown-rump length (5.2±0.9 mm), which was hyperechoic. From the 28th day of gestation, ultrasound measu­rement of trunk diameter was possible. The inner and outer placentome diameters, biparietal diameter and foetal heart rate could be used for monitoring of pregnancy by the end of the first trimester (days 42 and 49).

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 subclinical mastitis with high milk SCC and with-out microbiological findings; the IIIrd group: 13 cows with untreated subclinical mastitis with high milk SCC and with microbiological findings. The IVth group consisted of 17 cows with subclinical mastitis, high milk SCC, microbiological findings, treated with tetracycline HCL 200 mg, neomycin 250 mg, bacitracin 2000 IU, prednisolone 10 mg (Mastijet fort®, MSD Animal Health), and the Vth group – 28 cows with clinical mastitis treated with Mastijet fort®, MSD Animal Health. Our results showed that the mean plasma haptoglobin concentrations in the I (control) group was 0.054±0.003 g/L. In the IInd group (0.288±0.04 g/L) Hp was 5.2 times higher that the mean values of controls (P

A clinical case of an 11-year-old bitch with unilateral ovarian dysgerminoma and pyometra is described. The owner reported purulent discharge from external genitalia, fastidious appetite and depression. Transabdominal ultrasonography of the reproductive organs showed a hypoechoic mass in the region of the left ovary (7.18 × 6.65 cm) and a strongly enlarged uterine lumen full of anechoic fluid. Vaginal cytology demonstrated about 50% superficial cornfield epithelial cells and multiple neutrophils. Complete blood counts and blood biochemistry analysis indicated a significant leukocytosis and a mild anemia. Blood progesterone (3.96 ng/ml) and estradiol (86 pg/ml) were assayed. Median laparotomy revealed an enlarged uterus, substantially altered left ovary, of the size of a grapefruit. The right ovary was of normal size and structure. Tumor metastases in other organs were not seen. Histologically, diffusely located cancer cells resembling primitive germ cells, specific for dysgerminomas, were established. One year after the surgery, according to the owner the dog is vital, with normal appetite and without general condition abnormalities.

a b s t r a c t The aim of the present study was to establish ultrasonographic findings for some patholog- ical changes of the mammary gland in goats. A total of 80 goats of a Bulgarian local breed were included in the study. Ultrasonography was performed using a 5 MHz linear trans- ducer for evaluation of the mammary parenchyma (transcutaneous ultrasonography) and the teat (indirect technique by using a water bath). From all animals examined, 18 (22.5%) had acute mastitis, 9 (11.25%) teat stenosis, 3 (3.75%) abscessation-localized in the mam- mary parenchyma (n = 2) or in the teat wall (n = 1) and 2 (2.5%) indurative chronic mastitis. Acute mastitis was characterized ultrasonographically by a non-homogeneous and hypo- to hyperechoic structure of the mammary parenchyma, with an accompanying lack of clear visualization of the lactiferous ducts and the blood vessels. A thickened and hyperechoic teat wall, as well as numerous hyperechoic structures in the teat cistern, corresponding to milk coagula, were identified. In goats with teat stenosis ultrasound revealed proliferations in the area of the teat canal, the rosette of Furstenberg, the teat wall and at the boundary between teat and gland cisterns exhibiting a high echogenicity. In case of abscessation, a hypoechoic structure with small hyperechoic particles, representing pus collections, sur- rounded by a capsule was found. The loss of the parenchyma's normal granular pattern, a lack of anechoic milk canals, and the presence of hyperechoic structures, representing the increase of connective tissue characterized chronic indurative mastitis.

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 6 years of age, weighing 46-57 kg. The experimental infection was done with a stationary phase culture of a field Staphylococcus aureus strain isolated from a cow with clinical mastitis. Blood haptoglobin in goats was considerably higher (P < 0.05) as early as 8 h after the pathogen's inoculation. The most significant differences from baseline values occurred 24 and 48 h (P < 0.01) after infection. Plasma fibrinogen increased significantly (P < 0.05) 8 h after infection and reached the highest mean concentration (9.12 g/L) by 72 h. Leukocytosis was established as early as 4 h after the experimental infection when leukocyte counts were significantly higher than baseline (P < 0.001). The analysis of results indicates that in experimentally induced Staphylococcus aureus mastitis, significantly higher (P < 0.05) levels of the leukocyte, fibrinogen, and haptoglobin are established as early as 8 h after the infection.

Slow-release GnRH agonist implants are considered an effective, reversible alternative to surgical castration in male tom cats. Individual differences exist regarding the onset of efficacy and might be delayed in some animals. Single measurements of testosterone (T) might result in basal concentrations also in intact male cats. Consequently, GnRH stimulation tests are performed to measure T increase in intact animals and to differentiate castrated from intact male cats. In this study, five tom cats were treated with a 4.7-mg deslorelin implant and GnRH stimulation tests using buserelin were performed before treatment and at 4-week intervals afterward until Week 20. After the last test in Week 20 all animals were castrated. Four of five animals had basal T after 4 weeks and-in contrast to pretreatment-application of buserelin did not result in any further T increase. In one animal, T was low after implant insertion, but not basal; however, a GnRH stimulation test induced a slight increase of T in Week 8 and 16 only and no response in Weeks 4, 12, and 20. Testicular volume was significantly decreased and penile spines disappeared in all cats. Testicular histology showed mixed atrophy, but also fully elongated spermatids in three of five male cats making infertility questionable. Because of the loss of the stimulatory effect of short-term GnRH application (buserelin), it can be assumed that long-term GnRH agonists also act by some mechanisms of downregulation of pituitary GnRH receptors in the tom cat.

The effect of ejaculation frequency on spermatozoa survival in diluted Pleven Blackhead ram semen was investigated. Thirty-two ejaculates were examined. From each ram 4 ejaculates were collected at 10-min intervals in the morning and in the afternoon. Semen parameters, namely, color, density, transparency, volume, concentration, motility, and abnormal sperm, for each ejaculate were determined. The sperm motility was assessed from the moment of dilution up to 60 min at 10-min intervals, then again at 90 min and 120 min. The semen characteristics were determined by means of "Motic Image Plus" equipment and the data were processed statistically. Sperm volume and concentration in semen samples decreased gradually with increase in ejaculation frequency. The values were significantly lower for the 4th ejaculate compared to preceding ones (P < 0.05). The highest survival rate (P < 0.05) of sperm was found in the 2nd ejaculate, and this trend was preserved up to the second hour. Up to 50 min after dilution, the sperm motility did not change considerably, after which it was found to be reduced (P < 0.05). The frequency of ejaculation and the period of semen collection had an impact on sperm motility in extended and short-time stored semen from Pleven Blackhead rams. The spermatozoa in a 2nd ejaculate showed higher survival rates and could be recommended for additional processing.

Intramammary infections have received a lot of attention because of their major economic impact on the dairy farm. Management strategies, including greater awareness for efficient milking and hygienic measures, have resulted in a significant decrease of clinical mastitis worldwide. Subclinical mastitis, however, continue to be a serious problem.

The purpose of the study was to investigate the uterine involution in goats from a local Bulgarian breed through ultrasonography. Six goats from a local breed, 3 to 7 years of age, weighing 42-60 kg, housed in the Production Animal Farm of the Faculty of Veterinary Medicine, Trakia University, Stara Zagora, were included in the experiment. Ultrasonography was performed with Aloka SSD 500 Micrus (Tokyo, Japan) ultrasound and a 5 MHz linear transducer. Goats were examined in standing position for the transabdominal approach, and when the visualisation of studied structures was impossible, the transrectal approach was used. Uterine involution in goats was evaluated by serial ultrasound examinations at days 1, 3, 6, 9, 12, 15, 20 and 30 postpartum. The outer and inner diameters of the caruncles, uterine body lumen, and uterine wall thickness were measured. The visualisation of outer and inner caruncular diameters was possible until the 9th day postpartum. The ultrasound measurement of uterine lumen diameter, outer and inner caruncular diameters revealed a statistically significant reduction in their size (P