Serum protein reference values in foals during the first year of life: comparison of chemical and electrophoretic methods

Normal reference values for serum proteins of foals from birth to 1 year of age have been established. Chemical and electrophoretic/refractometric methods for total protein, albumin, total globulin and Albumin/Globulin (A/G ratio) have also been compared. The biuret total protein method and Bromcresol Green (BCG) method on the Technicon SMA 12/60 autoanalyzer were used and compared with total protein determined via refractometry and albumin determined by Cellulose Acetate (CA) electrophoresis/densitometry. Globulin and A/G ratios were calculated from the chemical method data and compared with that obtained electrophoretically. Total protein, albumin, total globulins and A/G ratios all were in agreement at all sample times studied. Data on the subfractionation of serum globulins via CA electrophoresis is also presented. Wide variations in alpha and beta globulin levels were noted among the foal sera early in life. As a result, two distinct populations of foals with respect to both globulin content and A/G ratio were identified. One of these populations (Group A) appeared to have obtained passive immunity more slowly than the other (Group B) animals. Comparison of these data with clinical cases of foals in which failure of passive transfer was a part suggests that the A/G ratio may be useful in assessing adequate colostral antibody levels in the newborn foal.