Recent studies have shown that endogenous serotonin is not required for colonic peristalsis in vitro. nor gastrointestinal (GI) transit in vivo. However. antagonists of 5-Hydroxytryptamine (5-HT) receptors can inhibit peristalsis and GI-transit in mammals. https://www.bekindtopets.com/save-now-Rx-Chorulon-HCG-for-Cattle-save-extra/