Abstract
Among the endocannabinoids, N-arachidonylethanolamide (AEA; anandamide) plays a key role in regulating energy homeostasis and energy intake. Recent studies suggest the existence of a peripheral mechanism by which AEA increases feed intake in the short term and modulates whole-body energy metabolism in dairy cows. Here, we aimed to test the hypothesis that AEA has a long-lasting central effect in increasing feed intake that leads to an increase in milk yield of dairy cows. In the present pilot study, 3 nonpregnant Holstein dairy cows were equipped with an intracerebroventricular (i.c.v.) catheter. Cows were deprived from feed for 2 h and received either no injection or an i.c.v. injection of either 12 μg of AEA or DMSO (control), followed by measurement of feed intake for 10 h and milk yield. Administration of AEA increased 10-h dry matter intake (DMI) by between 1.13 and 2.06 kg, whereas 22-h DMI was only marginally altered. However, compared with the control treatment, AEA reduced daily milk yield by 0.3 to 1.4 L/d in all 3 cows. The results demonstrate that i.c.v. administration of 12 µg of AEA increased 10-h DMI but decreased daily milk yield by a central mechanism.