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Mineral Metabolism in Young Beef-Cattle During Transfer from Winter Feed Ration to Grazing

ZITNAN R, SOMMER A, GALLO M, GALLO J, BOMBA A, VENGLOVSKY J, BULECA J, BINDAS L
Veterinarni Medicina 40, 1995, 65-69

Concentrations of calcium, inorganic phosphorus, magnesium, sodium and potassium were observed in the blood serum of beef bullocks after their transfer from winter feed ration to grazing and in the successive grazing cycles within two years. Blood samples were taken by puncture from the vena jugularis from the identical six bullocks. In the first year of observation, blood collection took place a week before transfer to grazing while in the second year of observation twice in weekly intervals before grazing. In the period of grazing, the biological material was sampled in weekly intervals from week 1 to week 5 (May - Ist cycle, June - IInd cycle), then in week 10 (July - IIIrd cycle) and in week 14 (August - IVth cycle of grazing). Calcium concentrations in the blood serum of beef bullocks (Pig. 1) decreased after transfer from stable feeding to grazing while this drop was significant in the second year of observation (P < 0.05). That period was followed by an increase in serum calcium concentrations in both target groups. The concentrations of inorganic phosphorus in the serum of beef bullocks (Fig. 2) dropped after transfer to grazing but a gradual increase in the values was recorded in week 4 in the first year of observation and in week 5 of grazing in the 2nd year of observation. These changes were not statistically significant. The concentrations of serum magnesium in beef bullocks (Pig. 3) statistically significantly dropped (P < 0.05) after transfer from stable feeding to grazing in week 3 in the first year of observation and in week 4 of grazing in the second year of observation. In the successive period of grazing, a slight increase in magnesium concentrations was determined in both years of observation followed by a decrease at the end of the period of observation. The sodium values in the serum of beef bullocks (Pig. 4) significantly dropped after transfer from stable feeding to grazing in both years of observation (P < 0.05). A highly significant drop of serum sodium (P < 0.01) was observed in week 3 after transfer to grazing in both years of observation. In the successive period, serum sodium concentrations became stabilized and in the second half of the grazing period the sodium concentrations were gradually going up. Potassium concentrations in the blood serum of beef bulls after transfer from stable feeding to grazing (Fig. 5) showed an increase in both years of observation that was statistically significant in week 2 (P < 0.05). In the successive period the concentrations of serum potassium were going up to reach the highest values in week 10 of the first year of observation and in week 5 in the 2nd year of observation, which was also statistically significant (P < 0.01). The average daily weight gain of beef bullocks during the grazing season was 0.530 kg in the first year of observation and 0.470 kg in the second year of observation


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