[Immunoglobulin dynamics in calves in a commercial rearing system].

The levels of immunoglobulins were studied in the colostrum of dairy cows and in the blood serum of calves after birth. The study also included tests concerning the effect of colostrum intake, age and season on immunoglobulin levels. In the colostrum of cows, the highest levels were as follows: IgG 69.4 +/- 27.5 g per litre; IgM 7.83 +/- 1.92 g per litre. In the first milking (12 hours from parturition) their content decreased to half the starting values. Threshold values of immunoglobulins were found in the blood serum of calves before the administration of colostrum. After optimum colostral nutrition the levels of immunoglobulins increased rapidly, the highest values being obtained 24 hours from birth (total immunoglobulin 23,3 +/- 4.1 U ZST: IgG 17.6 +/- 3.1 g per 1; IgM 1.8 +/- 0.5 g per 1). The immunoglobulin levels are significantly influenced by the age of the calves. From the starting values, the levels decrease to the minimum in the fourth to fifth week, followed by a marked rise. In the calves with low immunoglobulin levels the increase was already observed after the first week, and in the calves with high initial values only after the fifth week of age. A marked seasonal dynamics of immunoglobulins in the blood serum of calves was demonstrated. The lowest levels were recorded in February to April, the highest in May to October.