Why do artiodactyls generally have larger stomachs and longer intestines than carnivores?

Artiodactyls generally have larger stomachs and longer intestines than carnivores because plant matter is significantly more difficult to digest than meat.1

Plant cell walls are primarily composed of cellulose, a complex carbohydrate that mammalian digestive enzymes cannot break down on their own. To extract nutrients from this material, artiodactyls rely on specialized digestive adaptations:23

• Microbial Fermentation: Many artiodactyls utilize a multi-chambered stomach or enlarged digestive structures to house microorganisms, such as bacteria and protozoans, that ferment cellulose into absorbable fatty acids.23
• Extended Processing: The process often involves rumination, where food is regurgitated and re-chewed to increase surface area for microbial action. This complex, time-consuming process requires a larger capacity to hold food for the necessary duration of fermentation.234
• Nutrient Extraction: Because plant-based diets are less energy-dense and harder to process than animal protein, a longer digestive tract is required to maximize the absorption of available nutrients and water.13

In contrast, carnivores consume high-protein, easily digestible meat, which does not require the extensive fermentation chambers or the prolonged transit times characteristic of herbivorous artiodactyls.1