[The effect of experimental metabolic stress on ovulation and blood progesterone levels in cows]. / Vliv experimentálne vyvolaných metabolických zátezí na prubeh ovulace a hladiny progesteronu u krav.

The effect of a long run subclinic metabolic stress of acidotic and alkalotic nature was examined with respect to the course of cloprostenol induced estrus, ovulation and progesterone levels in blood and milk. The stress of acidotic nature was induced by widening the ratio of digestible crude protein to total dietary energy to the value 1:8.1 in 11 cows, while the alkalotic stress was due to narrowing the nutrient ratio to 1:2.81 in eight cows. Control group with the nutrient ratio 1:4.5-5 comprised 11 cows. The stress of acidotic nature was accompanied by ovulation disorders in 4 out of 11 cows (36.4%), in the group with the stress of alkalotic type it was in 2 out of 8 animals (25%). No ovulation disorders were observed in control group. Within 7 days after estrus, the average progesterone levels were 1.26 +/- 0.84 ng/ml in the blood of cows with stress of acidotic type, 3.48 +/- 2.99 in cows with stress of alkalotic type and 3.12 +/- 1.98 ng/ml in control cows. The differences between acidotic stress and control were statistically significant (P < 0.05). During the whole pregnancy (18 to 276 days), average progesterone levels were lowest in the group subjected to stress of acidotic nature. They ranged from 1.9 to 3.8 ng/ml with the average value 2.65 +/- 1.40 ng/ml. In the group with stress of alkalotic type they ranged from 2.55 to 5.43 ng/ml with the average value 3.67 +2- 2.29 ng/ml. In this control group, they ranged from 4.00 to 8.68 ng/ml with the average value 5.62 +2- 2.24 ng/ml. Variations in cortisol concentrations indicated a certain stressing effect of feeding rations on the internal environment of dairy cow organisms and activation of compensatory mechanisms.

[Testosterone levels in testicular and epididymal tissue during histopathologic changes in the testes in bulls]. / Obsah testosteronu ve tkáních varlat a nadvarlat pri histopatologických zmenách ve varlatech býku.

A total of 42 sexual organs of bulls were used to study the relationship between the level of testosterone and the effect of histopathological changes. Genital organs were obtained immediately after slaughter at the Brno abbatoir. Bulls were 14 to 20 months of age and weighed 450 to 650 kg, they were of the Czech Pied, Black and White breeds and their crossbreds. After an assessment of testosterone contents in testicular and epididymal tissues and microscopic examination of organs the concentration of testosterone determined according to the histopathological findings were (Tab. I) as follows. The mean content of testosterone in testicular homogenates was 38.96 +/- 47.0 ng/g. The values for the head, corpus and cauda regions of the epididymal tissue were 5.7 +/- 4.7, 5.3 +/- 5.1 and 3.2 +/- 3.5 ng/g tissue, respectively. The mean level of testosterone in testicular homogenates in the group without histopathological changes of the spermatogenic epithelium was 9.2 +/- 6.77; 5.26 +/- 4.2. In this group the concentration of 5.3 +/- 4.2 from the head 5.4 +/- 5.3 from the corpus and 3.23 +/- 3.26 ng/g tissue were revealed in the cauda of the epididymis. In the group with oedematous infiltration of the interstitium the mean level of testosterone in testicular tissue was determined 16.2 +/- 24.6, in the head of the epididymis it was 6.2 +/- 3.59, in the corpus 4.6 +/- 3.3 and 2.07 +/- 1.2 ng/g of testosterone was obtained from the cauda of the epididymis.(ABSTRACT TRUNCATED AT 250 WORDS)

[The ovarian response and conception rate in cows during experimental nitrate loading]. / Ovariální odpoved a koncepcní schopnost krav pri experimentální zátezi dusicnany.

The effects of potassium nitrate were investigated on ovarian activity, especially on ovarian activity, especially on follicle ripening and ovulation, conception rate and progesterone levels in the milk of cows with cloprostenol-induced oestrus (Oestrophan Spofa) at a rate of 500 micrograms i.m. Potassium nitrate was administered at an amount of 150 g per head/day, and this amount increased by 50 g every other fortnight to the total rate of 300 g per head/day. In a group of 11 cows exposed to potassium nitrate load, clinical examination of ovaries on day 8 after oestrus revealed the presence of CL in seven cows (63.6%), persisting follicles in two cows, and two cows did not have any CL or follicles (Tab. I). After the first insemination three cows got in calf (27.3%), and after all inseminations it was 10 cows in total (90.9%) on average in 24.4 days after cloprostenol administration, with SP 96.7 days and insemination index 1.7. No ovulation disorders were found in the control group. All five cows got in calf after the first insemination in three days after cloprostenol administration with SP 61.5 days and insemination index 1.0 (Tab. II). The progesterone levels in milk were 22.3 and 21.1 ng/ml before the second administration of cloprostenol, 2.7 and 2.1 ng/ml in oestrus and at the time of A.I., and 16.6 in eight days after insemination in cows exposed to nitrate load, and finally 21.7 ng/ml in the control group (Tab. III). Ovulation disorders were easily detectable by a clinical check of ovaries on day 8 after oestrus.(ABSTRACT TRUNCATED AT 250 WORDS)

[The ovarian response and fertility in cows with acidosis induced by acetic acid]. / Ovariální odpoved a koncepcní schopnost krav pri acidóze vyvolané kyselinou octovou.

The effects of acetic acid administered at an amount of 300 to 600 g (5 to 10 mol) to the rumen of breeding cows, were investigated on ovulation, conception and progesterone levels in the blood and milk of cows with cloprostenol-induced (Oestrophan Spofa) oestrus at a dose of 500 micrograms i.m. In the group of 15 cows exposed to the acetic acid load five cows got in calf after the first insemination (33.3%), and 12 cows (80.0%) after all inseminations in 37.6 days after cloprostenol administration, with the insemination index 1.67 (Tab. I). In the control group (five cows) four cows (80.0%) got in calf after the first insemination, in total all five breeding cows got in calf in 20.6 days after cloprostenol administration, with the insemination index 1.2. In the experimental group of 15 cows a clinical examination of ovaries on day 7 after insemination revealed ovulation disorders in eight cows, that means in 53.3% of the animals (Tab. II). No ovulation disorders were observed in the control group of five cows. Progesterone levels in the blood showed high variability (Tab. III). In the group of cows administered acetic acid they were by more than a half lower (1.49; 0.67; 1.53 per ml) on days 7, 14 and 21 after insemination in comparison with the control group (3.35; 2.5; 3.38 ng per ml). The average progesterone levels in milk (Tab. IV) were 1.27 and 1.53 on day 7, 6.74 and 7.27 on day 14 and 3.52 and 11.85 ng per ml on day 21, respectively, the higher values apply to the control. It was not possible to evaluate reliably from the progesterone levels in the blood and milk if ovulation took place and if the corpus luteum was developing (Tab. V and VI). The clinical control of ovaries on days 7 and 8 after oestrus and insemination was more reliable to determine the ovulation disorders than the progesterone determination in the blood and milk of cows.

[Levels of testosterone and 17-beta estradiol in the seminal plasma of bulls and boars]. / Hladina testosteronu a 17-beta-estradiolu v semenné plazme býku a kancu.

The levels of testosterone (T) and 17-beta-estradiol (E2) in seminal plasma were determined by the direct RIA method with tritium-labelled testosterone and 17-beta-estradiol. Testosterone was determined in 47 ejaculates and E2 in 132 ejaculates of seven bulls whose age ranged from 10 to 26 months, and in 60 ejaculates of two breeding boars old 20 months. The seminal plasma of bulls was found to contain 2.09 +/- 1.67 nmol/l testosterone and 2.75 +/- 1.94 nmol/l E2. Without respect to the age of the sires, the marginal values of the studied steroids showed a comparatively high fluctuation so that the average values are not very different between individual animals. No relation was found between the level of steroids and the concentration of fructose; this applies to the fertile bulls as well as to the bull suffering from epididymitis with the formation of epididymal cysts. Breeding boars had 0.338 nmol/ E2 (+/- 0.3) and 6.40 +/- 4.01 nmol/l testosterone in their seminal plasma. When the obtained values are recalculated to an average ejaculate volume, 5 ml of the seminal plasma of bulls will contain about 0.013 nmol E2 and 0.010 nmol T and 300 ml of the seminal plasma of boars will contain about 0.101 nmol E2 and 1.920 nmol T.