[Levels of metabolites in the blood of cows during a 24-hour period]. / Hladina niektorých metabolitov v krvi kráv pocas 24 hodín.

Blood samples were taken from the vena subcutanea abdominis sinistra of four Black-Pied Lowland cows in one-hour intervals within a 24-hour period. No significant circadian changes were recorded in the studied blood components (protein, glucose, ash and dry matter contents). The amount of protein remained unchanged during the 24-hour period. Some changes were observed in the level of glucose, with a decrease from 12.00 to 14.00 o'clock, followed by an increase continuing until late at night (1.00 a.m. to 3.00 a.m.); another decline came in the other half of the night and during the forenoon. More pronounced changes were recorded in the content of dry matter in the blood of the cows, with lower values from 3.00 to 12.00 o'clock. Ash content grew from 12.00 to 20.00 o'clock and then it declined.

[Relation between biochemical components in the blood of cows of various strains and the daily milk yield]. / Vztahy medzi niektorými biochemickými zlozkami krvi kráv rozdielnych plemien k dennému výdoju.

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.

[Relation between the biochemical composition of the blood of cows and variations in milk production]. / Vztah medzi biochemickými zlozkami krvi kráv s rozdielnou produkciou mlieka.

A significantly lower alkaline phosphatase activity was recorded in the arterial blood of cows with higher milk efficiency. They also had higher sugar contents in their blood: highly significantly in arterial blood and significantly in venous blood after milking. As to the other blood components, the differences are low and insignificant. A significant positive relationship between the daily milk yield and the content of ash in blood (mainly in venous blood before milking), highly significant positive relationship between protein content in arterial blood and daily milk yield, and significant to highly significant negative relationship between the activity of alkaline phosphatase in arterial and venous blood before milking and the level of gamma-globulins in arterial blood were recorded in the group of cows with higher milk output. In the group of cows with lower milk production, significant to highly significant negative relationships were obtained between protein content in blood and the daily milk yield (in arterial and venous blood before milking).

[Relation between biochemical parameters in the blood of cows and milk production]. / Vztah medzi niektorými biochemickými zlozkami v krvi kráv a produkciou mlieka.

No differences in blood samples were found out when the biochemical parameters in arterial and venous blood of dairy cows were compared before and after milking. Negative correlation coefficient (r = -0.3460) approaching the significance level was determined by comparing the values for milk yield on the day of sampling (in ascending phase of lactation) and protein content in venous blood after milking, and significant negative correlation coefficient (r = -0.3813) for daily milk yield and gamma-globulin concentration in venous blood before milking. The relationship between butterfat content on the day of milking and the values of alkaline phosphatase can be characterized by significant up to highly significant negative correlation coefficients in all three blood samples (r = -0.3232 to -0.3908).

[Relation between the mineral content of cow's milk, the quantity of milk and the fat content of the milk]. / Vztahy medzi obsahom minerálnych látok v mlieku kráv, mnozstvom mlieka a obsahom tuku v mlieku.

The reverse evaluation of the effect of the content of minerals in milk on the milk yield per day and on the milk fat content indicated that the milk of less productive cows had a significantly higher content of sodium and a highly significantly higher content of magnesium, as compared with the higher-yielding cows. The milk with a higher content of fat showed a highly significant difference in the content of calcium and a significant difference in the content of potassium in favour of the less productive cows. The content of phosphorus in milk and the daily milk yield bear a significant relation. The group of cows with higher milk yields showed a highly significant positive relation between the content of calcium, potassium and sodium in milk on the one hand and the fat content in milk on the other. The lower-yielding cows were found to have a significant negative relation between sodium and fat content in milk. The results suggest that minerals are involved in the metabolism in cows' organisms, thus influencing the production of milk and the content of fat in milk.

[Relation of the levels of mineral substances in the blood of cows, the quantity of milk and the fat content of the milk]. / Vztahy medzi obsahom minerálnych látok v krvi kráv, mnozstvom mlieka a obsahom tuku v mlieku.

No explicit relations to the milk yield on the day of sampling were found when studying the content of calcium, phosphorus, magnesium, potassium and sodium in the arterial and venous blood of cows before and after milking in the peak lactation period. However, there is a tendency of higher milk yields at higher phosphorus levels in the milk of the Black-Pied and higher-yielding cows. Some relations to milk fat content were found to be significant: a positive effect of phosphorus content in the blood of Slovak Spotted cows, a positive effect of calcium and magnesium content in the blood of more productive cows and a negative effect of magnesium content in the blood of less productive cows.

[The effect of free amino acid levels in the blood and milk of cows on protein levels in milk]. / Vplyv hladiny vol'ných aminokyselín v krvi a v mlieku kráv na obsah bielkovín v mlieku.

In the cows of the whole group under study, a significant negative relation (r = = -0.4797) was found between the histidine level in arterial blood and protein content in milk; further, there was a significant positive relation (r = 0.4624) between alanine level in milk and protein content in milk, and a significant negative relation (r = -0.5028) for the level of threonine. The group of cows with a higher milk output showed a significant negative relation between methionine level in milk and protein content in milk (r = -0.7482) and a highly significant negative relation between threonine level and protein content in milk (r = -0.8410). The negative relations of some amino acids to the content of protein in milk suggest that there is a poor supply of these amino acids for the production of protein in milk.

[Level of free amino acids in the milk of cows in relation to values in arterial and venous blood]. / Hladina vol'ných aminokyselín v mlieku kráv vo vztahu k ich hodnotám v arteriálnej a vo venóznej krvi.

The levels of free amino acids in cow's milk vary greatly. The highest value of 164.484 mumol/l was recorded in glutamic acid, followed by glycine, alanine, lysine, and the lowest values were found in cystine, methionine, phenylalanine, tyrosine and isoleucine (5--10 mumol/l). The levels of free amino acids in milk and their order differ from the values and the order in blood. For a large proportion of free amino acids, significant to highly significant relations exist between the levels in arterial blood and venous blood before and after milking. On the other hand, significant positive correlations were found only between the level of cystine in arterial blood and in venous blood after milking, between threonine level in arterial blood and in venous blood before milking, and a highly significant negative correlation was recorded between the leucine level in venous blood before milking and the respective value in milk.

[Relation between the level of free amino acids in milk and milk production]. / Závislost medzi obsahom vol'ných aminokyselín v mlieku a produkciou mlieka.

A negative relationship of glutamic acid content and milk yield over the first 100 days of lactation was found in a set of 20 cows. In some free amino acids, large differences exist between the cows with the higher milk yield and those with the lower milk yield, the largest difference being recorded in the content of glutamic acid (in favour of the cows with the lower milk output). The group of cows with the higher milk output per day or per first 100 days of lactation showed no dependence on any of the free amino acids in milk. The group of cows with the lower milk yield showed a significant negative relation of glutamic acid content to milk yield over the first 100 days of lactation and a significant to highly significant positive relation between serine, threonine and alanine contents on the one hand and daily milk yield on the other.

[Mineral levels of the arterial and venous blood in cows]. / Hladiny niektorých minerálnych látok v arteriálnej a vo venóznej krvi kráv.

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.

[Free amino acids in the arterial and venous blood of milk cows with different milk production levels]. / Vol'né aminokyseliny v arteriálnej a vo venóznej krvi dojníc s rozdielnou produkciou mlieka.

The cows with a higher production of milk had a lower content of free amino acids in their arterial blood (the difference was significant for lysine and phenyl alanine), as compared with the cows with a lower milk production level. Similarly, the high-performance cows had a higher content of free amino acids in their venous blood before milking (difference significant to highly significant for lysine, phenyl alanine, leucine, isoleucine, valine, cystine and alanine) and after milking (difference significant for lysine). Aspartic acid was the only amino acid contained at a higher amount in the blood of low-performance cows, the difference being partly significant after milking. The protein percentage was somewhat higher in the blood of less productive cows, particularly in venous blood before milking (insignificantly).

[The content of free amino acids in arterial and venous blood of cows]. / Obsah vol'ných aminokyselín v arteriálnej a vo venóznej krvi kráv.

Before and after milking the order of free amino acids was very much alike but differences were observed in amino acid content levels. After milking the venous blood of cows had less free amino acids than before milking; this testifies to their utilization for proteosynthesis in the udder, except for some glucoplastic amino acids whose content increased after milking. The changes in the content of free amino acids in the blood of cows before and after milking draw attention to the fact that blood-borne precursors are transformed in the udder.

[Relationship between the chemical components in the meat of bulls]. / Vztahy medzi chemickými zlozkami mäsa býckov.

During the chemical analysis of the meat of bullocks of different breeds (sample from Musc. long. dorsi), a negative relationship was found between free and bound water on the one hand and dry matter, nitrogen compounds, protein, and fat on the other, between nitrogen compounds and fat, and between protein and fat, and a positive relationship between the content of dry matter, nitrogen compounds, protein, and fat, between free and bound water, and nitrogen compounds and protein. The dependences were mostly significant to highly significant. No relationship was found between the content of ash and the studied chemical components of meat.