The effect of N-arachidonoylethanolamide administration on energy and fat metabolism of early lactating dairy cows : [Preprint]

The endocannabinoid system (ECS) is involved in the regulation of fat and energy metabolism, but knowledge about its influence in early lactation of cows is scarce. The aim of the study was to investigate the effect of N-arachidonoylethanolamide (AEA), an endocannabinoid with orexigenic characteristics, on plasma endocannabinoid concentrations, feed intake, energy balance, lipomobilisation, and hepatic lipid metabolism of early-lactating dairy cows. The experiment involved 10 pairs of Holstein half-sibling cows (end of 2nd -3rd pregnancy). Half-sibs of each pair were randomly assigned to either AEA (n = 10) or control (CON) group (n = 10). The AEA group received repeated intraperitoneal injections of 3 µg/kg body weight AEA and the CON group 0.9% NaCl. In week 1 to 3 postpartum, AEA administration had no effect on dry matter intake, body weight, or lipomobilisation, but affected plasma triglyceride concentration and mRNA abundances of genes related to hepatic triglyceride synthesis. In week 4 postpartum, the AEA group showed reduced feed intake and whole-body carbohydrate oxidation, but increased whole-body fat oxidation and hepatic lipid accumulation, likely as a result of a counter-regulatory leptin increase. In conclusion, the present study shows a tissue-specific AEA insensitivity and may point to a leptin-controlled regulation of the ECS in early-lactation.