Effects of endocannabinoids on feed intake, stress response and whole-body energy metabolism in dairy cows

Abstract

Endocannabinoids, particularly anandamide (AEA) and 2-arachidonoylglycerol (2-AG), are instrumental in regulating energy homeostasis and stress response. However, little is known about the endocannabinoid system (ECS) in ruminants, although EC could improve dairy health and productivity, at least by increasing feed intake. In this study, we report if intraperitoneal (i.p.) AEA and 2-AG administration affects feed intake, whole-body macronutrient metabolism, isolation and restraint stress, and whether diet composition modulates circulating endocannabinoid concentrations in cows. Twenty Simmental cows in late lactation were fed a grass silage and a corn silage based diet. On each diet, cows received daily i.p. injections with either AEA (5 µg/kg; n = 7), 2-AG (2.5 µg/kg; n = 6) or saline (n = 7) for 8 days. Endocannabinoid administration for 5 days under free-ranging (non-stressed) conditions had no effect on feed intake or energy balance, but attenuated the stress-induced suppression of feed intake when housing changed to individual tie-stalls without social or tactile interaction. Endocannabinoids increased whole-body carbohydrate oxidation, reduced fat oxidation, and affected plasma non-esterified fatty acid concentrations and fatty acid contents of total lipids. There was no effect of endocannabinoids on plasma triglyceride concentrations or hepatic lipogenesis. Plasma AEA concentrations were not affected by diet, however, plasma 2-AG concentrations tended to be lower on the corn silage based diet. In conclusion, endocannabinoids attenuate stress-induced hypophagia, increase short-term feed intake and whole-body carbohydrate oxidation and decrease whole-body fat oxidation in cows.

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

“…Our results are in contrast to a previous study in late-lactating cows, in which AEA administration increased short-term feed intake, metabolic heat production, and COX, while decreasing FOX 15 . These contrasting ndings suggests that the effect of AEA administration clearly depends on the energy balance differing between stages of lactation.…”

“…Nevertheless, endocannabinoid concentrations were found to directly correlate with an increase 27 or decrease 73 in feed intake during early-lactation, suggesting their involvement in the regulation of feed intake when not disturbed by leptin. When cows in late lactation are treated with AEA, they respond with a reduction in plasma NEFA concentration and thus lower lipomobilisation 15 . In contrast, AEA administration did not reduce lipomobilisation in early-lactation.…”

“…The best-characterized endocannabinoid AEA is known to exert orexigenic effects. Peripheral and central administration of AEA increases short-term feed intake of mid-and latelactating cows [14][15][16] . Furthermore, AEA is involved in the regulation of fat metabolism.…”

Endocannabinoid administration affects taste preference and the expression of cannabinoid and opioid receptors in the amygdala of early lactating cows

“…The AEA dose was calculated based on the BW determined at the day of calving, and the application dose remained constant over the course of the trial. A low dosage in the µg/kg range was based on Ackern et al 13 and was chosen to avoid unwanted side effects which can occur in the mg/kg range in mice 86 . The CON group received 50 ml of 0.9% NaCl i.p.…”

“…It has also been shown that intraperitoneal (i.p.) administration of AEA reduces stress-induced hypophagia and increases the short-term feed intake of dairy cows 13,14 . AEA acts as a partial agonist of the cannabinoid receptor type 1 (CNR1) 15,16 , type 2 (CNR2) 15,17,18 and G protein-coupled receptor 55 (GPR55) 19,20 .…”