Relation between biochemical components in the blood of cows of various strains and the daily milk yield

During the evaluation of the biochemical components of the arterial and venous blood of cows before and after milking, an insignificantly higher content of ash was found in the blood of the cows of Black-Pied Lowland breed, as compared with the Slovak Pied breed. The difference in the activity of alkaline phosphatase was found to be significant: the higher alkaline phosphatase activity was recorded in the blood of the cows of Slovak Pied breed than in the cows of Black-Pied Lowland cattle of the same age and in the same stage of lactation. A positive relationship was found between the milk yield and albumin level in the blood of the dairy cows of Black-Pied Lowland cattle; in the same breed a negative relationship was found between venous blood before milking and the level of gamma-globulins.     

Levels of cAMP, cGMP, 17 beta-estradiol and progesterone in the follicular fluid of the largest follicle during the follicular phase of the estrus cycle and after induced superovulation with gonadotropins in cows]

The objective of this study was to compare the concentrations of 17 beta-estradiol, progesterone, cAMP and cGMP in the follicular fluid of the largest cow follicle from the follicular phase of physiological sexual cycle and of follicles after synchronization of fut by cloprostenol (PGF2 alpha) and superovulation treatment with serum gonadotrophin (PMSG), in dependence on steroidal dominance of follicles. 2 x 25 cows, Slovak Pied x Lowland Black-Pied crossbreds with active corpus luteum, were subjected to superovulation treatment on the basis of rectal examination. Rut synchronization was achieved by cloprostenol of Czechoslovak provenience (Oestrophan Spofa), administered at the amount of 500 micrograms per dose. Serum gonadotrophin (Bioveta Concern, Ivanovice na Hané) at the amount of 2500 I. U. was administered forty-eight hours before the second dose of closprostenol. The animals were killed in slaughterhouses 48 hours later, or 72 hours later, since administration of the second dose of cloprostenol. The phase of the sexual cycle of control animals was determined by the method after Ireland et al. (1980) on the basis of morphological appearance of corpus luteum, presence of large preovulation follicle and by means of average concentrations of progesterone in blood serum. Aspirated follicular fluid was centrifuged using a cooling centrifuge at 3000 G. After separation, the supernatant was stored in a freezer at -18 degrees C until further treatment. 17 beta-estradiol and progesterone in the follicular fluid were determined by means of kits under the brand-names RIA-test-ESTRA (SI-125-9), or RIA-test-Prog (SI-125-6). Concentrations of cyclic nucleotides were determined by the RIA kits from the Institute vor Radioisotope Research, Production and Use (Prague), cAMP by 125J RIA kit (RIO12) and cGMP by 125J RIA (RIO42).(ABSTRACT TRUNCATED AT 250 WORDS)     

Changes in surface follicles and ovarian weight in testing for responsiveness in dairy cows after induction of superovulation using PMSG and cloprostenol

We evaluated the ovaries of 34 cows cross-bred of the Slovak Pied and Lowland Black-pied breeds which were culled and intended for slaughter during the winter type of feed rations. For superovulation treatment we used PMSG in the preparation Serum Gonadotropin (Bioveta, Nat. Ent., Ivanovice na Hané) and cloprostenol in the preparation Oestrophan inj. Spofa. We weighed the excised ovaries, fixed them in formalin 10% and made a quantitative evaluation of the surface follicles and differentiated them into recruited and selected or dominant follicles. We determined the concentration of 17 beta-estradiol and testosterone with the aid of the 3H RIA set from the firm Sorin after extraction by diethylether with separation of free and bound hormone with active charcoal. 72 hours after the giving of cloprostenol 43% reacted positively to superovulation treatment and after seven days a 50% positive response was recorded. After a dose of 2000 i. u. of PMSG (n = 6) embryo was obtained, whereas after 3000 i. u. of PMSG (n = 8) we flushed out eight embryos, of which four zygotes were suitable for transfer. After a higher dosage of PMSG there was an increase in the average weight of the ovaries, in right-hand ovaries significantly with P less than 0.05. After super-ovulation treatment the concentration of 17 beta-estradiol (E2) in the follicular fluid from follicles seven days after insemination was found to be so low as to be below the limit of detection, with the exception of four samples (mean = 8.60 nmol.l-1). The greatest concentration of E2 was from animals (n = 5) 72 hours after the giving of cloprostenol--1099.61 nmol.l-1) of follicular fluid. The concentration of testosterone was lower in the follicles of untreated cows in the follicular phase (mean = 5.92 nmol.l-1) compared with the follicles of super-ovulated animals the seventh day after insemination (mean = 14.12 nmol.l-1). The number of recruited and especially selected surface antral follicles 72 hours (n = 7) after the giving of cloprostenol and seven days (n = 8) after insemination was significantly higher in the group of brood cows reacting positively to superovulation in comparison with the animals which did not respond. It appears that the simultaneous monitoring of hormonal and morphological changes in the follicular system will help in objectivising the evaluation of the functional activity of stimulated follicles.     

Analysis of factors affecting the electric conductivity of cow's milk--breed, locale, season

The problem was studied in a set of 678 mammary glands of 212 cows - crossbreds between the Holstein-Friesian breed with the Slovak Spotted cattle, crossbreds of the Black-Pied Lowland and Bohemian Spotted breed, and three-way crossbreds of the Black-Pied Lowland, Swedish White and Bohemian Spotted cattle. The confrontation of the confidence intervals of milk conductivity (MC) in healthy mammary glands at alpha = 0.05 showed that in the crossbreds of the Black-Pied Lowland cattle the MC was statistically significantly higher than in the breed types of the Holstein-Friesian cattle. The MC values decrease when there is a larger proportion of the blood of beef-and-dairy cattle (Slovak Spotted and Bohemian Spotted breeds). The locality where the stock was kept was found to act as an important factor underlying MC only in cases when both the geographical conditions and breed proportions were different. In a set homogenized with respect to the breeds, statistically significant differences in MC were demonstrated between the spring and summer season, spring and autumn, summer and autumn, and autumn and winter season.     

Estradiol, progesterone and cyclic nucleotides in the fluid of persistent follicles and luteal phase follicles in the estrus cycle in cows]

The objective of the present study was to compare the concentrations of 17 beta-estradiol, progesterone, cyclic adenosine monophosphate and cyclic quinosine monophosphate in the largest follicles of cows that persist for seven days after insemination following the preceding synchronization of oestrus and superovulation and in follicles of the luteal phase of cycle (5th-10th days). Animals included in the experiment were selected on the basis of rectal examination. Synchronization of oestrus was achieved in 24 crossbreds of Slovak Pied x Lowland Black Pied breeds (SS x Nc) using two doses of cloprostenol of Czechoslovak provenience Oestrophan Spofa, 500 micrograms in each, within 11 days. Serum gonadotrophin at the amount of 2500 I. U. was administered forty-eight hours before administration of the second dose PGF2 alpha. Experimental animals were inseminated after 72 hours. On the 7th day after mating the cows were killed at a slaughterhouse. Evaluated were only the ovaries of the 14 cows in which the persistent large follicles occurred. Ovaries of the 13 control cows in the luteal phase between the 5th-10th days were obtained at the slaughterhouse by the method after Ireland et al. (1980). Correct determination of the phase of sexual cycle was substantiated by determination of progesterone concentrations in blood serum. Follicular fluid was obtained from the largest follicles by aspiration and centrifuged in a cooled centrifuge at 3000 G. The concentrations of 17 beta-estradiol and progesterone in follicular fluid were determined using kits from URVJT at Kosice, designated RIA-test-ESTRA (SI-125-9) or RIA-test-Prog (SI-125-6).2+ persistent follicles (9.15 +/- 5.47 nmol.l-1).(ABSTRACT TRUNCATED AT 250 WORDS)     

The effect of hormonal stimulation on the follicle population in the ovaries of ewes during estrus and anestrus

In the oestral and anoestral periods, 129 ewes of the Slovak Merino breed were treated with different doses of the stimulants PMSG, PGF2 alpha, HCG, SG and FSH after synchronization by means of Ageline tampons. In the anoestral period, PMSG doses of 750 and 1000 i. u. were found to increase the number of tertiary follicles from 12.3 to 17.2 and 18.6, whereas the dose of 1500 i. u. was found to reduce this number from 18.6 to 13.5. PGF2 alpha increases the average number of tertiary follicles from 12.3 to 22.2 and when it is combined with 750 i. u. PMSG, the increase is to 29.3 tertiary follicles. At higher PMSG doses the ratio of atretic (A) to non-atretic (N) tertiary follicles rose and the number of ovulations increased from 2.5 to 4.0. After synchronization with Ageline and administration of PMSG at the doses of 750 and 1000 i. u., the number of tertiary follicles increased from 16.0 to 18.4 and the number of ovulations from 3.1 to 5.7; the number of atretic tertiary follicles showed no change. In the oestral period, the dose of 1000 i. u. PMSG administered after PGF2 alpha reduced the number of tertiary follicles from 18.9 to 14.5 and increased the number of ovulation from 1.6 to 2.6; an increase was also recorded in the number of atretic tertiary follicles.(ABSTRACT TRUNCATED AT 250 WORDS)     

Incidence of mastitis in cows of various breeds and their crosses-- estimation of the heredity of this disease

In a large set of cows (24,165 head), consisting prevailingly of Bohemian Pied breed, Black Pied Lowland and Holstein breeds, and of their crosses, significant differences in the incidence of mastitis were proved. Mastitis was demonstrated by the bacteriological findings in milk. The lowest mean incidence was recorded in the cows of the acclimatized Bohemian Pied breed (8.0%). As observed in the examined population, the increasing genetic proportion of solely dairy breeds results in higher demands on the environment, and the susceptibility of animals to mastitis usually increases. In three-breed crosses of this set, mastitis was found in 699 animals, i. e. in 25.4%. With respect to mastitis prevalence, a heritability estimate was performed on the basis of the first and second lactation using the method of alternative characters. In the Bohemian Pied breed, the heritability estimate was ?2 = 0.17 +/- +/- 0.08, in the Black Pied Lowland breed ?2 = 0.28 +/- 0.14.     

Superovulation induction in sheep using PMSG

The effects of application of differentiated PMSG rates (Antex Leo, Denmark) were investigated in 30 ewes of the Slovak Merino breed in the period of May--June in experimental conditions on the induction of superovulation and on the speed of egg transport through the sexual organs. After administration of PMSG at rates of 750, 1000 and 1500 i. u. per head/day, increases were recorded in the average weight of ovaries, number of large follicles and ovulations. Flushing the eggs from different parts of the sexual organs indicated that the higher the PMSG rate, the faster was the egg transport.     

Changes in the biometry of the sex organs of sheep after estrus synchronization and superovulation in the breeding period

In twenty ewes of the Slovak Merino breed coming from a demonstration farm at Zemplínska Teplica, to the age of two-three years biometrical variations of the sex organs and overall follicular response to PMSG and PGF2 alpha administration were investigated in the autumn period (October-November). In the ewes of all groups the heat was synchronized by i. m. administration of PGF2 alpha (Oestrophan Spofa) at a dose of 125 micrograms in the interval of 11 days. On the ninth day the ewes of the second and fourth group were given 1000 i. u. of PMSG (Antex Leo, Denmark), the ewes of the third group 750 i. u. of PMSG. The ewes of the third and fourth group were administered at the same time 50,000 i. u. vitamin A (Axerophtol Spofa) (each group). The weight and dimensions of the sex organs were investigated. The results demonstrate that the administration of PMSG in the mating period increases significantly the weight of oviducts and horns of uterus in the ewes while there are no variations of the weight of the other sex organs and of their length, or it is lower than in the ewes of the control group. The overall follicular response was not influenced by the higher weight of ovaries.     

The follicular system of bovine ovaries after estrus synchronization using the luteolytic action of cloprostenol

Oestrus synchronization was studied in samples from six cows of the Black-Pied Lowland breed. Three cows four to five days from oestrus were used as the control; three animals with marked periodic corpora lutea were given an i. m. injection of 0.5 mg cloprostenol. The eighth day from the administration of the preparation, the ovaries of the cows were excised and, after histological processing in a simultaneous series in a 4mm interval, the preparations were subjected to qualitative and quantitative microscopic evaluation. The structure of non-atretic and atretic follicles was described in different stages of the atretic process. The lymphoid cells of atretic follicles were observed to penetrate into the granulosa membrane. A multiplication of non-atretic tertiary follicles was observed after the administration of cloprostenol. This multiplication was more pronounced on the right ovary where the preceding ovulation had taken place (P less than 0.01). The treated animals, compared with the controls, showed a significant multiplication of tertiary follicles at early atresia and at total collapse atresia (P less than 0.001), whereas the number of follicles with contractive atresia showed a significant decrease (P less than 0.001). The results suggest that cloprostenol can influence follicle population mostly through the stimulation of the growth and ripening of tertiary follicles; its modulation effect seems manifest itself in cooperating relation with gonadotrophic hormones, mainly with the follicular secondary hormone (FSH), in the theory of the complex effect of proteohormones .     

Changes in neurosecretory activity in the hypothalamus of sheep after administration of PMSG

By means of histological methods of histochemical nature we examined the qualitative alterations in neurosecretory cells of anterior (nucl. paraventricularis - NPV. nucl. preopticus medialis - NPM), medial (nucl. arcuatus s. infundibularis - NARC), and posterior (nucl. tuberomamillaris - NTM) hypothalamus of sheep with a simultaneous caryometric analysis of neurons of the same nuclei after administration of various PMSG doses. The examination was performed on the brain samples of 23 two- to three-year-old sheep, of the Slovak Merino breed, at the live weight of 30 to 40 kg. in the period of physiological anoestrus (June-July). The animals were divided into three experimental groups and were instilled agellin sponges (20 mg). On the 13th day the sponges were removed and the first group was applied 1000 i. u. PMSG, the second group 750 i. u. PMSG. The sheep were killed within 30 to 36 hours after the oestrus determination with a teaser ram. After bleeding of animals the brains were perfused with 2% buffered paraformaldehyde and after taking out the brains from the crania their fixation was finished in buffered picroformol. Paraffin slices were stained with haematoxylin-eosine and crotonaldehyde-fuchsin to neurosecretions. Caryometric analysis was carried out with a 1000 fold magnifying and with a measuring of 200 cells from one sample. We recorded the neurosecretion increase in all hypothalamic nuclei under study. The caryometric analysis has shown a moderate shift to the right, it means the volume increase of nuclei of neurosecretory cells, which demonstrates a stimulation of the function of hypothalamic structures.     

PMSG profiles in superovulated and anti-PMSG antiserum treated mice and heifers with enzymeimmunoassay

A sandwich enzymeimmunoassay (EIA) for pregnant mare serum gonadotropin (PMSG) using a microtiter plate was developed. Sensitivity of the assay to PMSG was 15.6 mIU/ml (0.2 ng/well). The PMSG levels in serum were measured with the EIA in superovulated and anti-PMSG rabbit antiserum treated mice and heifers. In mice, the PMSG blood level was measurable in the serum 4-6 days after intraperitoneal injection of 5-30 IU of PMSG. The administration of anti-PMSG antiserum at the same dose level as PMSG caused a rapid decrease in the PMSG blood level, declining to undetectable levels within 17 hours. In heifers, the PMSG level was measurable at 10-11 days after the injection of 2500 or 3000 IU of PMSG. When antiserum was injected 48 hours after the PMSG injection, the clearance rate of PMSG was affected by the route of the administration. The administration of 3000 units of anti-PMSG antiserum intravenously caused a rapid decline and the disappearance of circulating PMSG within 17 hours. When 3000 units of anti-PMSG antiserum was injected intra-muscularly, the PMSG blood level also decreased and became unmeasurable 24 hours after administration; however, it was still detectable for up to 17 hours. These results indicate that the administration of anti-PMSG antiserum at the proper timing and dosage could lead to successful superovulation through the improvement of hormonal conditions.     

Mineral levels of the arterial and venous blood in cows

The values of calcium, phosphorus, magnesium, potassium and sodium in the arterial and venous blood of cows before and after milking two to three months from calving were found to be within the standard range. The differences are not significant. In venous blood the values are lower than in arterial blood, which proves that minerals are utilized by the organisms for milk production. The values of minerals in the blood of the Slovak Spotted cows are higher than in the blood of the Black--Pied Lowland cows; they are also higher in the blood of lower-performance cows than in the blood of cows giving high milk yields. This means in practice that Black-Pied Lowland cows and high-performance cows need a higher supply of minerals to their blood stream.     

The Use of a Monoclonal PMSG Antibody in Cows Superovulated with PMSG

Contents A monoclonal PMSG antibody has been injected on the first day of standing heat in 15 superovulated cows (3 000 I.U. PMSG on day 10, 37.5 mg PGF₂α on day 12). The treatment gave comparable results as when a PMSG antiserum raised in sheep was used i.e. a decreased number of unruptured follicles, a shorter external heat with less inseminations to be performed and a sharp decline of circulating oestrogens to basic levels shortly after administration of the antiserum.     

Quantitative micromorphological study of the ovaries in sheep after estrus synchronization and superovulation in the autumn mating season

The quantitative micromorphological changes of tertiary follicles and corpora lutea (CL) were studied in ewes in the autumn mating season after oestrus synchronization, induced by administration of PGF2 alpha (Oestrophan Spofa) at a rate of 125 micrograms, and after superovulation, induced by administration of PMSG (Antex Leo, Denmark) at a rate of 1000 I. U., or PMSG at rates of 750 and 1000 I. U. together with 50,000 I. U. vitamin A (Axerophthol Spofa). The highest number of ovulations was obtained in ewes treated with 1000 I. U. together with vitamin A (3.4 +/- 3.0) and after administration of 1000 I. U. PMSG alone (2.6 +/- 2.74). The highest number of tertiary follicles was recorded in ewes after administration of PGF2 alpha. The proportion of tertiary atretic follicles was the highest in ewes after administration of PMSG (64.6%). The occurrence of the luteinizing form of atresia was recorded only in ewes treated with PMSG (4% of the total number of atretic follicles). Using the caryometric analysis of the luteal cells of corpora lutea, the ewes of the experimental groups had two-peak variation curves; this corresponds to the theory of the presence of two luteal types in the tissue of the corpus luteum in ewes. As determined morphometrically, the smallest proportion of connective tissue out of the total volume of ewes' ovaries was found after administration of 1000 I. U. PMSG together with vitamin A. Administration of vitamin A together with PMSG had a favourable influence on the over-all follicular response, on the average number of ovulations, and on the proportion of non-atretic follicles.     

Relation of lactose levels in milk and indicators of mammary gland health in the first third of lactation]

A total of 662 bucket milk samples from cows of two breed groups were examined: red and white breed = Bohemian Pied cattle with different genetic proportions of Ayrshire and Red Holstein improvement breeds; black and white breed = Black and White Lowland breed and different degree of absorptive crossing with a genetic proportion of the Holstein breed. Samples of daily milk yields were taken in the first three months of lactation once a month within a year. A possibility of using lactose content as an auxiliary indicator for detection of the mammary gland secretion disorders in the initial lactation stage was evaluated. The average values of the different indicators and their variability are summarized in Tab. I showing also the significance in a statistical model of included effects. Lactose content (L) was 4.88 +/- 0.20%, chloride content (Cl-) 113.7 +/- 22.4 mg/100 ml, somatic cell (SC) count 474 +/- 805 thousand/ml, SC count log corresponds to the geometrical mean of 234 thousand/ml, titratable acidity (SH) 7.34 +/- 0.83 x 2.5 mmol/l, chloride-lactose ratio (ClL) 2.27 +/- 0.51, conductivity (gamma) 442.4 +/- 34.5 mS/m and mastitis test (MT-NK) 0.72 +/- 1.18. The efficiency of the used statistical model was highest for Cl- content (Tab. I, R2 = 0.41), and it was lowest for SC counts (R2 = 0.07), while it increased to the twofold value (R2 = 0.15) after logarithmic transformation of SC counts. The breed group exerted a significant effect on Cl-, SC, log SC, SH, ClL, gamma and MT-NK (Tab. I). The breed group of red and white cows (Tab. II) had higher component contents and better indicators of the udder health state (Cl-, SC, log SC, ClL, gamma and MT-NK). The month of lactation influenced significantly SC, log SC, SH and gamma (Tab. I). A decrease in SC counts with the accruing month of lactation was observed (Tab. II), the trend of gamma and SH was opposite. The effect of lactation number was found to be significant for L, SC, log SC, SH, ClL, gamma and MT-NK (Tab. I). A tendency of a gradual decrease with the lactation number was observed in these indicators: L, SH, proteins and solids-non-fat (Fig. 1), while Cl-, gamma and ClL showed an opposite tendency. The year season influenced significantly L, log SC, SH, ClL, gamma and MT-NK (Tab. I, Fig. 2).(ABSTRACT TRUNCATED AT 400 WORDS)     

Changes in antiproteolytic activity in blood and ovarian follicular fluid in 3 breeds of sheep after stimulation of superovulation]

Serine proteases help to regulate the ovarian cycle at different levels and they are subjected to the control of gonadotropic hormones and protease inhibitors. Superovulation stimulations influence the activities of trypsin inhibitors (model serine protease) in blood plasma (BP) and in follicular fluid (FF), and also in dependence on the breed. Trypsin inhibiting activities were determined from the reduced rate of trypsin hydrolysis of a chromogenic substrate (TAPA) and they were determined in percent. A change in absorbancy at 405 nm = 1.0 after 10-minute incubation at 25 degrees C and pH = 8.05 was taken as 100%. The incubation mixture as a sample contained 100 microliters blood plasma or 10 microliters follicular fluid, diluted with gammaglobulin at 1:10. The differences in the trypsin inhibiting activities (TIA) of BP in ewes of the Merino, Tsigai and Wallachian breeds were insignificant, but Agelin synchronization (20 mg chlorsuperlutin per vaginal swab) induced statistically significant differences. The lowest TIA BP was recorded in the Tsigai breed (T), P less than 0.001 in comparison with the Wallachian (W) and Merino (M) breeds. Following the administration of 1,500 IU PMSG, the TIA BP within 120 hours decreased in W (P less than 0.001), it increased in T (P less than 0.1) and in M the changes in the TIA BP were insignificant. The average numbers of ovulations increased from 2.25 +/- 2.5 to 3.0 +/- 1.2 in W; from 0.25 +/- 0.43 to 2.5 +/- 1.6 in T and from 0.00 +/- 0.0 to 2.5 +/- 2.3 in M. Following the single administration of 2,000 IU PMSG after Agelin synchronization, the changes in M ewes were also insignificant, and there were no different responses in pregnant (1st to 2nd month) and nonpregnant ewes. In pregnant T ewes the TIA BP increased after Agelin synchronization and stimulation (P less than 0.01), in nonpregnant ewes these changes were not significant. In W lambing ewes the TIA BP increased (P less than 0.001), the effects of Agelin were greater than those of PMSG. The TIA of follicular fluid (FF) of antral follicles were on average tenfold if compared with BP. After hormonal treatment of ovaries, the TIA FF mostly increased at different levels of statistical significance. The TIA FF of follicles less than 10 mm were lower than in follicles greater than 10 mm (P less than 0.001 for M and W, P less than 0.1 for T).(ABSTRACT TRUNCATED AT 400 WORDS)     

Changes in the follicle system and the population of tertiary follicles in sheep after the administration of PMSG in anestrus

The total quantitative changes of ovaries, proportion of atretic and non atretic follicles and changes of tertiary follicles in sheep after administration of increasing doses of PMSG during the anoestrous period were observed. In experimental groups the statistically significant increase of average weight, volume and dimensions of ovaries in comparison with control group were determined biometrically. The average number of tertiary follicles was greater in experimental groups but at the same time we observed a higher proportion of atretic follicles (64% of the total number in the control group; 71-77% in the experimental groups). In the group of sheep administered a dose of 1500 m.u. PMSG we determined a high proportion of luteinized follicles (as much as 21% of the total number of atretic follicles). The total number of small follicles in the so called transient phase in the comparison of experimental and control groups was not changed significantly. In the experimental group an increased incidence of preovulatory follicles and a reduction of tertiary follicle dimensions in the period of follicle cavity formation was determined.     

Comparison of microsatellite and blood group diversity among different genotypes of cattle

Genetic variability and relationships among five cattle breeds (Holstein, Pinzgau, Limousin, Slovak Spotted and Charolais) bred in the Slovak Republic were investigated separately using 11 microsatellite markers and 61 blood group systems. Allele frequency, heterozygosity (Ho, HE) and PIC values were investigated. F-statistics were computed separately. For microsatellite markers FIS, FIT, FST and for blood groups HS, HT, GST parameters were calculated. Microsatellite and blood group comparison showed similar results by F-statistics but some differences were marked using the other methods. Both methods were able to detect close relation between Slovak Pinzgau and Slovak Spotted cattle breeds. Their relation was confirmed by genetic distance, principal component analysis (PCA) and coefficient of admixture (mY). Important divergences between different markers used in the study were observed by the characterisation of Limousin and Charolais breeds.     

Morphologic and biochemical changes in the hypothalamus in hormonally stimulated sheep

The effect of exogenous hormonal preparations (PMSG, SG, PMSG + PGF2 alpha and FSH) was studied as exerted on neurosecretion and on changes in the nuclear volume of nucleus paraventricularis, nucleus ventromedialis, nucleus infundibularis and nucleus tuberomamillaris, and on histological changes in the third cerebral ventricle. Changes in catecholamine concentrations were determined in the rostral, medial, and caudal hypothalamus of the ewes. The study was performed with 28 ewes of the Slovak Merino breed during the oestrus period. The oestrus was synchronized by the Agelín vaginal tampons (Spofa). The ewes of four experimental groups were stimulated by the administration of 1000 I.U. PMSG (Antex-Leo), 1000 I. U. Serum Gonadotropin (Bioveta Ivanovice na Hané), 1000 I. U. PMSG with 250 micrograms Oestrophan inj. (Léciva Praha), and 450 I. U. Folistiman (VEB Arzneimittelwerk Dresden, GDR). The brain samples were processed by common histological methods. A caryometric analysis was performed at 3000-fold magnification and by measurement of 200 cells of one sample. The data were subjected to mathematical processing after Fischer and Inke (1956). The amount of neurosecretory material was evaluated by light microscopy (Nakahara, 1963). The multiplication of neurosecretion in the hypothalamic nuclei testifies to the fact that the administration of hormonal preparations stimulates the function of hypothalamic structures, which corresponds with the results of the caryometric analysis. It also ensues from the results that the administration of serum gonadotropins (PMSG and SG) at the dose of 1000 I. U. results in a statistically significant decline (P less than 0.001) of the concentrations of norepinephrine in the rostral, medial and caudal hypothalami of the ewes, although the PMSG preparation has a more pronounced effect when compared with SG. The hormonal stimulation with PGF2 alpha and with FSH causes no significant changes in the concentration of norepinephrine in the hypothalamus of the ewes. As norepinephrine is considered as a neurosecretion inhibitor, the multiplication of neurosecretion in the hypothalamus nuclei after stimulation with serum gonadotropins correlates with the decline of hypothalamic norepinephrine concentrations.