Evidence for conservation of dietary lipid in the rat during lactation and the immediate period after removal of the litter. Decreased oxidation of oral [1-¹⁴C]triolein

Production of 14CO2 from an oral load of [1-14C]triolein was greatly decreased (70%) in lactating rats or immediately after (24-48 h) removal of the litter, compared with virgin rats. This decreased oxidation of dietary lipid was accompanied by accumulation of 14C-labelled lipid in lactating mammary gland or adipose tissue (after litter removal). No difference in 14CO2 production between lactating and virgin rats was observed when [1-14C]octanoate was administered. It is concluded that a major factor in this conservation of dietary triacylglycerol is the relative activity of lipoprotein lipase in the tissues.