Analysis of apolipoprotein A-IV expression and the levels of blood plasmamain lipid fractions of calves during the first week of life before and after theadministration of milk replacer supplemented with lactose

The current study presents an analysis of main lipid fractions and expression of apolipoprotein A-IV (apoA-IV) of the blood plasma of calves during the first week of life, before and after administration of a milk replacer with additional quantity of lactose. The experiment was performed on 7 male Polish-Friesian calves, var. Black-and-White. Blood samples were collected before the morning feeding from the 6th to 8th day of life. In the evening on the 6th day of the experiment and in the morning on the 7th day of the experiment, monohydrate lactose in an amount of 2 g per 1 kg of body weight was added to the milk replacer. In all tested calves, after the administration of the additional quantity of lactose, there was a significant increase observed in expression of apoA-IV in the blood plasma. At the same time, no significant differences in the concentrations of triglycerides, total cholesterol, and low-density lipoprotein cholesterol were recorded, both before and after the administration of an additional dose of lactose. A gradual low increase observed in the plasma high-density lipoprotein cholesterol of calves allows us to conclude that the increase of this lipid fraction after the supply of an additional lactose is associated with elevated expression of plasma apoA-IV.