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Biomedical subjects

L Kostov

Publications and source records attributed to L Kostov.

At least 19 recordsLinked to original sources
PubMed1986

[Methods for synchronizing estrus and selecting recipient heifers in embryo transplantation].

Threefold thorough gynecological investigations were carried out with a total of 108 heifers with normal cycle, which remained uninseminated--in their choice, treatment with hormonal preparations, and transplantation of embryos, reducing their number up to 76. With the first test group of 35 heifers estrus was synchronized with implants, containing 3 mg norgestomet each. On the 9th day these were removed, and the heifers were injected with 500 IU PMSG (Intervet) each. The animals of the second test group (73 in number) were injected with 7.5 mg prostaglandin F2-alfa at 11-day intervals. The conception rate was 31 per cent higher with heifer-recipients treated with norgestomet implants and serum gonadotropins. Death was established with 47 transplanted embryos (61.8 per cent). With 19 embryos (25 per cent) death set in on the 21st day, and with 28 ones (26.8 per cent)--within the period of the 60th days of pregnancy up to calving. In 17.10 per cent of the transplanted embryos migration was seen toward the opposite horn, on the side of which the ovary contained no yellow body.

Animals↗
PubMed1986

[Superovulation induction in donor cows using the embryo transfer method].

A total of 108 cows were gynecologically investigated. Twenty-four of them were found to be suitable as donors. These were within the range of the 40th to the 60th day following calving, were not inseminated, and had no complications at calving and over the puerperal period. Estrus was synchronized via implants (3 mg norgestomet Synchromate B, Intervet in s/c application); 8 days later the donors were injected with 3000 IU PMSG each in order to induce superovulation. On the 10th day the implants were removed, and each animal was injected with 22 mg prostaglandin F3 alpha. At the 24th hour following the onset of estrus half of the donors were injected with anti-PMSG (i/v). It was found that the capacity of cows to respond with superovulation after hormonal treatment was quite individual. The application of antigonadotropic sera on the first day of estrus limited superovulation and raised the number of fertilized ova, resp., of embryos able to be transplanted. It was demonstrated also that to shorten the period from washing the uterus up to the impregnation of the donor animals it is necessary to apply hormonal therapy and preventive measures in dependence on the functional and morphologic state of the ovaries and the sexual apparatus.

Animals↗
PubMed1986

[Regulation of the reproductive functions of cows by hormonal preparations].

Studied was the effect of some hormonal preparations--progesteron, GnRH, and HCG with progesteron--injected immediately prior to artificial insemination on the reproductional functions of cows raised under industrial conditions. It was found that the conception rate of cows at first insemination was highest upon treatment with GnRH--67.86 percent, i.e., by 14.29 percent higher than that of the control group. The same trend remained with the total conception rate. Lowest was the use of pellets per cow--1.33--with animals treated with GnRH prior to insemination. The application of GnRH (Berlin Chemie, GDR) was sufficiently effective at single i/m injection before artificial insemination. It could be employed to raise conception rate as well as to lower the use of pellets for impregnation of cows.

Animals↗
PubMed1985

[Outlook for the programmed insemination of sheep in the anestrual season].

Studied were certain methods for programming the estrus and fixing the optimal term for the insemination of sheep. A record was kept of the changes taking place in the genital apparatus in various periods of time following the use of hormonal preparations during the anestral period. The fertility of sheep was also taken into consideration both after the first treatment with serum gonadotropin and after the two-fold programmed insemination at a 16-day interval with regard to the total fertility. It was shown that the optimal time for programmed insemination of sheep was between the 36th and the 56th hour after the three-fold injection with Prolosan at 12-hour intervals so far as periods other than the breeding season were concerned. Fertility at two-fold injection rated at 121 per cent, and conception--at 78.2 per cent.

Anestrus↗
PubMed1984

[Comparative studies of hormonal methods for affecting the reproductive functions of cows being raised by different technics].

Studied was the effect of two raising technologies in the industrial rearing of cows (tied and loose housing) along with the effect of the use of hormonal-and-stimulating therapy on their reproductive functions. It was found that the duration of the service period with the two technologies without using hormones was considerably long (respectively 124.3 +/- 7.8 up to 133.0 +/- 5.1 days, and 138.5 +/- 8.1 up to 144.0 +/- 3.3 days). The rate of conception at first insemination with tie-up housing varied from 20.23 to 56.67 per cent, and the total conception--from 74.41 to 86.67, whereas the fertilization of a cow required 2.35 to 2.77 doses of semen. At loose box housing the conception rate varied from 25.13 to 47.69 per cent and 75.15 to 84.61 per cent, and the used doses of semen were 2.40 to 2.69. Treatment with gravohormon between the 40th to 60th day following calving raised the total conception and the conception at first insemination--54.70 and 94.70 per cent at loose box housing, and 62.65 and 95.18 per cent at tie-up housing. Combined hormonal treatment with gravohormon and oroestron within the interval of the 100th-160th day following calving with the two technologies led to the very high clinical manifestation of the estrus, however, it did not raise the conception rate. Treatment with estrumate between the 100th and the 160th day after calving produced a higher effect with regard to conception as against the combined treatment with gravohormon and oroestron. The stimulating hormonal therapy had a higher effect on the conception at first insemination with the technology of tie-up housing.

Animal Husbandry↗
PubMed1982

[Results and problems of a new breeding method in pig husbandry].

The results and problems are referred to of the mass and model implementation in this country in the past 5 years of biotechnical methods of reproduction in industrial pig farming, namely: 1. Methods employed on a mass scale in the field of artificial insemination, synchronization of estrus with replacement pigs, diagnosis of early pregnancy along with hormonal methods for the stimulation of conception and prolificacy of sows. 2. Methods of model implementation -- programmed farrowing with the use of prostaglandin F2 alpha, hormonal protection of embryogenesis along with apparatus methods determining the most appropriate time of insemination. 3. Methods in the phase of scientific development -- insemination with deep-frozen semen, implantation of fertilized zygotes, programming of ovulation, and others. Established were organizational and administrative advantages and the veterinary and zootechnical of these methods.

Animal Husbandry↗
PubMed1982

[Morphological studies of follicular atresia in the estrogen syndrome of swine].

Studied were 86 ovaries of sows with clinically manifested estrogenic syndrome and of ten controls. Strongly expressed atresia was found of the follicles in the ovaries of sows exhibiting estrogenic syndrome. On the basis of the most frequently manifested changes as many as five types of follicular atresia were differentiated. The luteinization of newly ovulated tertiary follicles observed in that case represented a particular phenomenon. The changes observed in most cases were characterized by fatty degeneration. It is believed that the persistence of the estrogenic syndrome could lead to complete and irreversible sterility of sows.

Animals↗
PubMed1982

[Attempt to stimulate labor in cows and heifers].

Attempts were made to induce delivery in 79 cows and 20 heifers, using the preparations dexametasone, cloprostenol, and dinolytic. The level of progesterone and estradiol was determined in four cows. A group of 20 heifers were injected with the preparation fortecortin at the rate of 30 mg. Four cows with induced parturition were used to evaluate the changes setting in with the blood level of estradiol 17 beta and progesterone. The following conclusions were made: 1. Best effects with regard to the indices duration of calving parturition and post-partal complications, and independence and service period are produced with the combined application of 50 mg sodium selenite and 680 UI vitamin E with 30 mg dexametasone. 2. The decrease in liveweight of the newborn calves from heifers at an average of 6 kg leads to the prevention of dystocia and the shortening of the post-partal period.

Adrenal Cortex Hormones↗
PubMed1979

[Induction of synchronized labor on commercial swine farm complexes with the synthetic prostaglandin F2 alpha analog, cloprostenol].

Experiments were carried out under conditions existing in industrial swine complexes with two groups of experimental sows: I group -- consisting of 17 sows injected on the 108th and 109th day of pregnancy with 175 g cloprostenol, and II group -- consisting of 145 sows injected on the 110th, 111th, 112nd and 113th day of pregnancy. On 125 sows of 110--111 day of pregnancy a reduced single dose application of 150 g cloprostenol was tested. Studies were performed on the period to farrowing following cloprostenol injection, the duration of farrowing, the changes in physiological behaviour, the number of viable and unviable new born piglets, the results following weaning of offspring at the age of 28 days and on the economic evaluation of the technology of forced synchronized and programmated farrowing in industrial swine complexes. It was established that the synthetic analogue of prostaglandine F2L (cloprostenol) applied once by intramuscular injection at a rate of 175 g per sow on the 110--113th day of pregnancy has a luteinizing effect and leads to forced synchronized farrowing of 75--80% of the sows, 27 +/- 5 h post treatment. Similar results were obtained by a reduced rate of 150 g cloprostenol. Synchronized farrowing provides an opportunity for simultaneous weaning of equated piglet groups and contributes for better labour organization and veterinary service. Shortening the pregnancy period below the 110th day is not feasible physiologically and economically.

Animals↗
PubMed1978

[Use of gravohormone to increase conception and fertility in cows].

Tested was the gravohormone preparation (produced in USSR and Bulgaria) to shorten the period from calving to impregnation and raise the conception rate and the fertility in cows. The experiments were carried out with a total of 84 cows (34 of the Bulgarian Red breed and 51 of the Bulgarian Brown breed) under productional conditions. The animals of the first group were injected on the 25th-28th day following calving, singly, i/m, using the Soviet made gravohormone at the rate of 10 IU per kg body weight. The cows of the second group were additionally injected with 1500 IU of the preparation (produced in 0ulgaria) on the 3rd and 6th day following insemination. It was found that the single application of 4000 IU of gravohormone between the 25th and the 28th day after calving shortened the time from calving up to the first insemination by 7.29 days, on an average, and the time from calving to impregnation--by 13.57 days, raising the conception rate at first insemination by 13.50%. The additional twofold injection with 1500 IU each time raised the rate of fertility in cows by 23.58% as against the controls.

Animals↗
PubMed1976

[Hormonal methods of increasing fertility in swine].

Experiments were carried out to raise the conception rate in sows during the summer season under industrial conditions of breeding. Eight test groups of 365 animals were formed as well as four control ones with 137 pigs. The sucking period lasted 28 to 33 days. When in estrus the sows were mated with boars twice at a 24-hour interval. In five groups that were dried up from July to September was recorded the effect of several kinds of gonadotropic hormones administered alone or in combination with vitamin E and steroid hormones -- Gravohormone Tolligon, an oil emulsion of PMS (500 IU), with 250 Chorulon and 2 mg estradiol benzoicum; an oil solution of PMS (500 IU) with 2 mg estradiol, 25 mg testosterone and 30 mg vitamin E. During the same period three other groups of test sows were formed to use steroid hormones such as Gravignost, an oil solution of 2 mg estradiol benzoicum, and 40 mg testosterone propionate as well as the same preparation in combination with 30 mg vitamin E. The deterioration of the temperature and humidity regime in the summer at the industrial pig-breeding complexes was shown to inhibit the manifestation of estrus and lower the conception rate in sows. Either alone or in combination with vitamin E and estradiol the gonadotropic hormones largely raised the per cent of animals manifesting estrus for ten days in summer after weaning their piglets (89 to 100 per cent) as well as the number of lively born offsprings per sow (9.8 to 11.3). The optimal doses used were as follows: Gravohormone, 13--14 IU/kg liveweight; Folligon or PMS, 6--7 IU per kg; and choriogonadotropin at the rate of 500 IU per sow. One the other hand, the steroid hormonal preparations bring about estrus of a lower quality leading to a low conception rate and fertility at first insemination, disturb the sexual cyclicity. They should not be administered alone as cycle starters in pig-breeding.

Animals↗
PubMed1976

[Clinical and endocrinological studies of the puerperium in cows].

A total of 85 cows were used to study the clinical course of the involution processes in the genital tract following calving. According to the season of calving the animals were divided into two groups: 1st group consisting of 29 cows whose calving and puerperium had taken place during the spring/summer period; IInd group of 56 cows with which these processes were observed in the autumn/winter period. Seven cows of each group were subjected to endocrinologic studies for the evaluation of the pituitary gonadotropic hormones (FSH, and LH) in the blood plasma, applying Brown's method and Parlow's method, respectively. The following conclusions were drawn: 1. The intensity of the involution processes in the sexual apparatus of cows depends on the season. In the spring/summer period they usually last 34.3 days, and in the autumn and winter -- 37.5 days. 2. Fast involution of the uterus has been observed during the first two weeks after calving. This process is considerably delayed during the third week. 3. The yellow body regresses in the course of 14 days following calving. Up to the 35th day this has been established only im 3.5 per cent of the cows. Clinically, follicles in the ovaries are established as early as the 15th day after calving. 4. The FSH and LH level in the blood plasma during the first days after calving has been low -- 73.7 mg/% for FSH, and 7.04 mg/% for LH, both showing a rising trend. The peak values have been established between the 15th and 40th, and the 22nd and 28th day, respectively.

Animals↗
PubMed1975

[Study of the influence of some factors on conception and fertility rates in sheep in the anestrus period].

Experiments were carried out with a total of 520 sheep, two-breed crosses, during the anestrus period (January-May) in 1972 and 1973. Estrus was induced by means of hormonal preparations, such as implants (Silestrus), vaginal swabs (Veramix), pregnant mare sera (Rigaoux) as well as estradiol-valerianat. Both the test and the control groups of animals were divided into four lots to study: a. the effect of the interval following lambing and the season on the results of hormonal treatment; b. the conception and fertility rates in lactating ewes with weaned lambs in the anestrus period; c. the effect of hormonal treatment in young and adult ewes nursing single lambs or twins and d. the influence of the functional status on the results of hormonal treatment.

Age Factors↗