Serum concentration and properties of alpha-fetoprotein and serum level of albumin in sucking piglets.

Porcine alpha-fetoprotein (AFP) was purified from the sera of four-day-old piglets using an immunoadsorbent column. The molecular weight of the AFP was 80,000 when determined by gel filtration on Sephadex G-200 and 75,000 when determined by sodium dodecylsulphate polyacrylamide gel electrophoresis. The isoelectric point of the AFP was pH 4.85 at 0 degree C. The maximum concentration of serum AFP was reached on the fourth day after birth (mean value 1.1 mg ml-1), and it then decreased to 10 micrograms ml-1 when the piglets were 35 days old. The concentration of serum albumin increased rapidly between birth and seven days old, reaching 16 to 17 mg ml-1 at seven days old. Between birth and seven days old, the serum concentrations of AFP and albumin were approximately inversely proportional.