[Lipoprotein profile of the lactating cow]

The profile of serum lipoproteins in the dairy cow in the 8th week of lactation was studied with different techniques: sequential ultracentrifugation, selective precipitation, gel filtration. The dairy cow has characteristically low levels of triglycerides and VLDL (d less than 1.006 g/ml). Most of the circulating lipids are related to HDL (d = 1.063-1.21 g/ml). The fraction that corresponds to LDL (d = 1.006-1.063 g/ml) has some features of alpha and beta lipoproteins. An electrophoretic study of fractions isolated by agarose gel filtration shows a progressive alpha and beta mobility transition between LDL and HDL. This study demonstrates that the density interval 1.006-1.063 g/ml contains LDL and "light" HDL.