A close-up photo of a cow grazing on a field of grass, showcasing the intricate process of herbivorous digestion. The image should capture the cow's teeth grinding the grass, the saliva breaking down the cellulose, and the cud being regurgitated for further chewing. The cow's rumen, reticulum, omasum, and abomasum should be visible, representing the four chambers of its complex digestive system. Consider using a macro lens to capture the details of the cow's mouth and the grass blades.
