Studies on parturient paresis in dairy cows. V. On the composition and calcium binding capacity of two bovine serum protein fractions, with special regard to parturient paresis

In healthy cows unaffected by imminent or recent calving the protein in serum can directly bind the overwhelming proportion of the bound calcium. In recent calvers this capacity is considerably less. When adding ammonium sulphate to blood serum to 62 % of total saturation a protein fraction precipitates which is mainly albumin. This fraction has a far greater calcium binding capacity than the soluble fraction, which contains most of the serum globulin, and the lowering of this capacity after calving is entirely referable to the former fraction. No difference has been found in these respects between normal cows after calving and cows with parturient paresis.An analysis of 10 amino acids in the two protein fractions described above showed that the amino acid composition of both exhibits differences between recent calvers and cows outside the calving period, and likewise that each of the two fractions differs in composition between healthy cows after calving and cows with parturient paresis.