Capybaras are strict herbivores that primarily eat aquatic plants, grasses, tree bark, and fruit. A mature capybara consumes 6 to 8 pounds (2.7 to 3.6 kg) of vegetation daily, focusing on a select few plant species to maximize nutrient intake. Because they are autocoprophagous, they also eat their own cecal feces to re-ingest undigested nutrients and maintain necessary gut microbes.
From what I’ve observed working directly with capybaras in managed environments, their grazing is highly strategic rather than random. They will systematically clear a patch of specific succulent grasses down to the root before moving on, utilizing their hypsodont teeth-which grow continuously-to grind down tough, fibrous plant walls. One thing I've noticed is that they are incredibly picky; a capybara will routinely bypass lush-looking grass if it lacks the specific moisture content they desire.
The Mechanics of Capybara Digestion and Diet
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Grass Selectivity: During the wet season, their diet consists of up to 80% of just five specific grass species, heavily favoring Hymenachne amplexicaulis (marsh grass). In the dry season, when these grasses dry out, they switch to eating reeds and more abrasive dry-land vegetation.
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Cecotrophy Dependency: Capybaras produce two types of waste: oval feces and a soft, nutrient-rich green pellet (cecotrope). They consume the green pellets directly from the anus, which provides vital proteins and vitamins synthesized by bacteria in their large cecum.
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Ascorbic Acid Requirement: Unlike many rodents, capybaras cannot synthesize Vitamin C on their own. In captivity, a lack of dietary Vitamin C quickly leads to scurvy, presenting as joint swelling and gum bleeding within 3 to 4 weeks.
Overlooked Nutritional Realities and Complications
A common mistake in managing capybara diets is providing unrestricted access to commercial fruits and sugary vegetables. Because their digestive systems are optimized for low-calorie, high-fiber forage, excess sugar disrupts their cecal fermentation balance, causing rapid, life-threatening bloat (tympanites) or severe enterotoxemia.
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In winter or dry conditions where aquatic plants are unavailable, they require high-quality orchard grass or Timothy hay, supplemented with specific rodent pellets containing a minimum of 15% crude fiber and ascorbic acid stabilization. They will also chew on thick tree bark (such as willow or birch) not just for nutrition, but as a mechanical necessity to wear down their incisors, which can grow over 4 inches per year if not naturally filed.
Source: sandiegozoowildlifealliance.org


