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Biomedical subjects

M Lebeda

Publications and source records attributed to M Lebeda.

13 recordsLinked to original sources
PubMed1989

[The development of beta-carotenemia in dairy cows 1975-1987].

On investigation of beta-carotene levels in the blood plasma of 9193 cows in the first and second phases of lactation, and in the eight, ninth months, and to the tenth mid-month of their pregnancy showed the same dynamics in beta-carotinaemia development in all groups, with a wave-like tendency to decrease. The lowest beta-carotene values were recorded during the 1985-1986 winter season and in the following 1986 summer season. Beta-carotene levels also remained low during the subsequent winter and summer feeding season. Different beta-carotene concentrations in the blood plasma were repeatedly found in the phases of lactation reproduction cycle. Increases in the milk production and deteriorated reproduction indicators were recorded in the cows at the time of a steep decrease in beta-carotene concentrations in the blood plasma. The causes of decreasing beta-carotene concentrations in the cow blood plasma are discussed.

Animals↗
PubMed1987

[Interdependence of the level of total proteins, magnesium and beta-carotene in the plasma of dairy cows].

The degree of dependence of the concentration of total protein, magnesium and beta-carotene in the blood plasma of over 3,400 dairy cows in the first and second phases of lactation and in months 8 and 9-9.5 of pregnancy was attested statistically. It was shown that in late pregnancy the concentration of all three indices drops both with winter and summer feed rations and that the connection between all three pairs of indices is positive. The highest values of the linear correlation coefficient were ascertained between the total protein and magnesium of blood plasma (+0.87 in the winter period, +0.63 in the summer period and +0.75 in both periods), the correlation was somewhat lower between magnesium and beta-carotene (+0.56, +0.75 and +0.36) and it was lowest between total protein and beta-carotene (+0.45, +0.41 and +0.42). The discussion deals with the causes of the stochastic correlation of these components of blood plasma.

Animal Feed↗
PubMed1986

[Magnesium in the blood and urine of cows during various stages of the reproductive interval being fed summer and winter feed rations].

Magnesium concentration was investigated in the blood plasma and urine of 3460 cows in the course of four green-feeding seasons and four winter feeding seasons in 1980 to 1984. A decrease in the magnesium content in blood plasma was found to intensify in the last six weeks of gravidity. In the first stage of lactation the magnesium concentrations of plasma begin to grow to reach a relative maximum in the cows in the second stage of lactation. These regularities apply to both the summer and winter feeding seasons. The magnesium content in urine has a similar pattern. The summer values of the magnesiemia of whole cow populations are significantly higher than the winter values. Tendencies to lower magnesium concentrations generally prevail in both blood plasma and urine; these tendencies are most conspicuous in the cows in the last six weeks to parturition. As a rule, the concentrations of magnesium in urine were lower in summer than in the season of winter feed rations. As for the contents of the blood plasma magnesium of the cow populations as well as individual cows, there are considerable differences between various stages but the trends are the same in all groups. In the green feeding season the range of fluctuation of the magnesiemia values is larger than in the winter feeding season. The same tendency of changes in individual groups was also recorded in the magnesium concentrations in the urine of cows in different stages. However, the direction of the changes did not always correspond to the direction of the changes in the blood plasma. A practical requirement has been derived from the results of the study that magnesium contents should be increased in the feed rations given to high-pregnant cows and cows in the first lactation.

Animal Feed↗
PubMed1986

[A decrease in blood beta-carotene in dairy cows during late pregnancy period].

In four successive seasons of green and winter feeding in the years 1980-1984, beta-carotene concentrations were determined in the plasma of venous blood of 3441 cows in the first phase of lactation, in the other phase of lactation, in the eighth month of pregnancy and in the 9th-9.5th months of pregnancy. The cows in the other phase of lactation had the significantly highest beta-carotene concentrations in the two feeding seasons. In the eighth month of pregnancy there occurs a significant drop that continues also in the 9th-9.5th months of pregnancy. In the first phase of lactation beta-carotene concentrations remained at the level of the values from the 9th-9.5th months of pregnancy. In the period of winter feeding, the mean concentrations of beta-carotene in all groups of cows were deep below the limit value of 7.44 mumol . l-1, which indicated that it was necessary to fortify feeds with vitamin A; in the cows in the 9th-9.5th months of pregnancy and in the cows in the first phase of lactation they were lower than the critical value of 5.58 mumol.l-1, which signaled the disorders of reproduction processes. In the course of the years of investigation beta-carotene concentrations varied in the same manner in all groups of cows in keeping with the vegetation period of the feed, feed kind and quality.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Feed↗
PubMed1985

[Seasonal changes in the concentration of total blood proteins in cows during various phase intervals].

In four one-year stages (A, B, C, D) in the summer (L) and winter (Z) feeding seasons, the total protein (CB) of blood plasma was determined in 3207 cows included in three groups: I - the first stage of lactation, II - the second stage of lactation, and III - the 8th to 9.5th month of pregnancy. 1948 cows were examined when given the winter feed rations and 1259 cows on the summer rations. At the same time, the supply of required digestible crude protein (SNL) and energy (starch units) was calculated for the feed rations of different groups of cows. High-pregnant cows (III) had the lower total protein in all the four years and feeding seasons, as compared with the groups of lactating cows. The difference was significant in nine out of ten cases in relation to group I and in eight cases in relation to group II. This is a regular phenomenon, independent of the summer or winter feed ration type and of the seasonal climatic effects of each year. The trend of decreasing crude protein levels with the length of lactation is less conclusive (significant in four out of ten cases); nevertheless, it is still apparent, since none of the three reverse cases was significant. The differences in total protein concentration between cows of different groups are absolute and their causes must be endogenous: they cannot be attributed to differences in the supply of required nutrients. A rise of total protein content was recorded in both feeding seasons at stages C and D in all groups of cows. The higher occurrence of hyperproteinaemia is ascribed to increased proteosynthesis at better utilization of the supplied crude protein. Relative (concentration) hyperproteinaemia was excluded. The effect of the summer or winter type of feed rations on total protein concentration was insignificant when considered for the whole four-year period; at individual stages significantly higher total protein values in the summer feeding season than in the winter feeding season were recorded three times and the reverse case was recorded only once.

Animal Nutritional Physiological Phenomena↗
PubMed1984

[Concentration of ammonia in the urine of dairy cows given green feed rations and winter feed rations].

The concentration of ammonia in urine at a known level of energy yielding nutrients offered in feed rations was determined in 987 dairy cows in four summer feeding seasons and 1420 cows in three winter feeding seasons. The long-term average ammonia levels in urine showed no significant variation with the two types of feed rations. Different feed rations in the feeding seasons had no significant influence on ammonia concentration in the urine of lactating cows. On a long term-average as well as in the overwhelming majority of the winter and summer feeding seasons, high-pregnant cows had significantly higher ammonia contents in urine than the cows in the first and second lactation stage. At feeding rations complying with Czechoslovak Standard CSN 46 7070 the content of ammonia in the urine of lactating cows was lower than the recorded long-time averages and averages for individual stages; on the other hand, in high-pregnant cows the ammonia level was higher in both types of feed rations and the difference from lactating cows increased 3.25 times. This suggests that neither do the feed rations currently used in practice nor those strictly adhering to the Czechoslovak Standard meet the biological demand of high-pregnant cows and often lead to the injury of hepatal parenchyma. Ammonia concentration of 11.7 to 58.7 mmol per litre of urine is considered as a tolerable limit.

Ammonia↗
PubMed1983

[Blood sugar in dairy cows].

Glycemia was found in 1270 cows and high-pregnant heifers fed summer feed rations and in 1981 cows fed winter feed rations, with the known levels of energy-yielding nutrients in feed rations for cows in the first (I) and in the second (II) lactation phases and cows and heifers in the eighth to ninth and a half month of pregnancy (III). The levels of glycemia were significantly lower after the summer feed rations than after the winter feed rations, both in the whole population and in all groups. The basic type of feed rations has a stronger influence on the level of glycemia than the phase of the reproduction cycle. In all groups, hypoglycemic deviations prevail over hyperglycemic ones. Hypoglycemia is most expressive in group I, least expressive in group III. The coefficient of glycemia variability is high (26.5 to 34.6); it is higher after the winter feed rations. Covering of the nutrient need is significantly higher in the summer period than in the winter period, the narrow calorie-protein ratio prevails over the increased ratio and is most obvious in groups II and III. Gaussian character of the glycemia distribution curves suggests a large number of independently acting factors, none of them prevailing over the others; the effects of these factors are mostly additive. This phenomenon limits strongly the employment of glycemic values as indicators of the energy balance in the organism. Glycemia is to be judged within the framework of the metabolic profile and nutritive indicators. Further study of glycemia should be performed by means of multivariate statistical methods.

Animal Feed↗
PubMed1982

[Ketonuria in dairy cows].

In 3337 dairy cows, urine was examined for ketone bodies by help of Bililabstix during the first and second phase of lactation and in the eighth to the ninth and a half month of pregnancy; at the same time needed supply of energetic nutrients in 175 summer and 308 winter feed rations was calculated. Intensity and frequency of ketonuria in lactating cows fed winter rations is significantly higher than in those fed green feeds; it decreases significantly with a phase of lactation and with milk production. On the contrary, cows in late pregnancy have higher intensity and frequency of ketonuria (32.9%) when fed green feeds than when fed winter rations (30.7%). In winter feed rations energy input was significantly lower, percentage of deficient feed rations at a relatively broader caloric-protein ratio was higher than in summer season. The highest deficits of energy and digestible nitrogen compounds were observed in cows in the first phase of lactation. Discussion concerns the causes and mechanisms of different ketonuria in groups of dairy cows in relation to deficit of energetic nutrients, caloric-protein ratio, to the level of glycaemia, non-esterified fatty acids in plasma, triglycerides of plasma and to the state of liver function.

Animals↗
PubMed1977

[Metabolic reactions of calves to the feeding with Laktosan or unpasteurized whole milk].

The acid-base and other metabolic reactions to nutrition with Laktosan produced by two feed plants and with unpasteurized whole milk after transport to a dairy plant were studied in calves up to the ninth week of age. Laktosan feeding reduces the metabolic component of the acid-base balance; the use of a lower-quality Laktosan mixture, containing drum-dried milk, gives a picture of metabolic acidosis lasting about 11 days. The changes are cuased by an increased intensity of dissimilation, by the release of metabolic H+, and, in part, by the loss of bases during diarrhoea. With the use of low-quality Laktosan, the utilization of the nutrients of the feed ration is much lower than the utilization of the nutrients of unpasteurized milk or high-quality Laktosan. The use of high-quality Laktosan causes much lower acid-base changes, far from reaching pathological values. At the same time, the utilization of nutrients is higher than with the use of unpasteurized milk. This milk which cannot be considered microbially or chemically undamaged offers no advantages from the health-condition and economic point of view. The facts, revealed by the study, emphasize the high health and economic importance of the production of calf feed mixtures. At the same time the results show that enither milk nor Laktosan feeding provides enough magnesium for the calves to grow. Other metabolic aspects of different calf nutrition are discussed.

Acid-Base Equilibrium↗
PubMed1977

[Effect of potassium-hydrogen interaction in the excretory mechanism of the kidneys on the acid-base and other biochemical values of the blood and urine in calves].

The effect of the competitive relationship between potassium and hydrogen in the excretory mechanism of the kidneys on metabolism was studied in calves. The intraruminal exposure of calves to 5.6 meq potassium chloride (KCl) per kg per day has, in itself, only a slight acidotic effect ascribable to a slight reduction of the excretion of acid by the kidney. The same dose of ammonium chloride (NH4Cl) has a strong acidotic effect combined with a negative influence on weight gain. Both basic types of exposure increase the concentration of inorganic phosphorus and reduce the concentration of chlorine in the blood serum. The addition of 2.8 meq of potassium chloride per kg per day to the basic dose of ammonium chloride increases metabolic acidosis, worsens the health condition (being, at times, hazardeous to life) and leads to weight losses. The same amount of ammonium chloride added to the basic dose of ammonium chloride has a relatively small acidotic action on the blood, evoking only a slight and temporary potassium retention in the serum. The negative action on the weight gains and clinical symptoms are generally weaker than in the other group. The results indicate that the acidotic environment creates in ruminants a very dangerous situation if the organism is excessively exposed to the effect of potassium at the same time.

Acid-Base Equilibrium↗