THE EFFECTS OF VARIOUS DIETS IN CALVES ON SOME CHARACTERISTICS OF MINERAL METABOLISM

The objective of the present paper was to investigate the effect of fe eding milk and milk replacer (Lactavit) to calves on the changes in th e studied characteristics in calves with equal conditions of housing. Two groups each comprised five heifers on the Black-Pied breed at the age of 1 to 17 weeks. The first group received Lactavit since the thir d week of age, the other group received milk at an amount of 5 to 8 li ters per head and day. Alfalfa hay and TKS concentrate mix were availa ble ad libitum. The calves were weaned at nine weeks of age. The avera ge concentrations of sodium, potassium and calcium were within the ref erence range, iron concentrations were slightly below the standard and copper levels slightly above the standard. Na concentrations were inc reasing until the age of six weeks, then they were maintained at a mor e or less balanced level, after weaning they were decreasing. Even tho ugh there was not a statistically significant difference in Na content , its slightly higher concentrations were observed in the calves on La ctavit diet. On the contrary, the calves on whole milk diet had the hi gher potassium concentrations. The highest differences were determined in the calves after weaning at the age of 10 to 12 weeks. The differe nces in calcium levels between the groups were not clearly explicit. C alcium concentrations were decreasing until the age of four weeks, whi le they were increasing from five to eight weeks of age. Iron concentr ations were mostly higher in the calves on Lactavit diet, particularly at the age of four to five weeks. Fe concentrations were more or less balanced. Copper concentrations also had a steady level, except in th e fourth week, when their decrease was larger in both groups. The calv es on whole milk diet had the higher live weight from the fifth week t o the end of the trial if compared with the other group. The same find ing applies to their weight gains; the group on whole milk diet had th e live weight gains higher by 0.2 kg than the group on Lactavit. Bioch emical analyses of blood serum in both groups document sufficiently hi gh supplies of these elements to the calves. Them were no large differ ences in the investigated characteristics between the two groups. The calves on whole milk diet had the higher live weight as well as the hi gher weight gains.