Guinea Pig Nutrition 2026: Complete Diet, Feeding & Health Guide

Adult guinea pigs need 10-30 mg of vitamin C daily. Young, pregnant, nursing, or ill guinea pigs need 30-50 mg daily. The most reliable sources are fresh vegetables like bell peppers (1 slice provides 10-15 mg), kale, parsley, and broccoli. Vitamin C in pellets degrades rapidly, so never rely solely on pellets. According to the Merck Veterinary Manual, vitamin C deficiency can develop within 2 weeks if not properly supplemented.

Fruits should be limited treats due to high sugar content. Offer no more than 1-2 teaspoon-sized pieces weekly. Suitable fruits include apple (no seeds), blueberries, strawberries (with tops), and melon. Always introduce new fruits slowly and monitor for digestive upset. The high sugar content can disrupt gut flora and contribute to obesity if fed regularly.

Timothy hay is the best choice for most adult guinea pigs due to its ideal calcium-to-phosphorus ratio and high fiber content. Orchard grass hay is a good alternative with similar nutritional value. Alfalfa hay is too high in calcium and protein for healthy adults and should only be fed to babies under 6 months, pregnant/nursing sows, or underweight guinea pigs under veterinary guidance. Always choose green, fragrant hay without dust or mold.

Signs of proper nutrition include: consistent weight, firm and well-formed feces, bright eyes, glossy coat, good energy levels, and normal eating/drinking habits. Warning signs of nutritional issues include: weight loss or gain, soft or misshapen feces, dull coat, lethargy, changes in water consumption, or dental problems. Regular weight checks (weekly) are the best way to monitor nutritional status.

Most commercial treats are unnecessary and often unhealthy, containing high sugar, artificial colors, and inappropriate ingredients. Instead of commercial treats, use small pieces of fresh vegetables as rewards. If you do use treats, choose simple, single-ingredient options like plain dried herbs or flowers. The healthiest "treat" is actually variety in their regular diet rotating different vegetables provides novelty and nutritional diversity.

Yes, fresh grass is excellent for guinea pigs if harvested safely. Ensure the grass has not been treated with pesticides, herbicides, or fertilizers. Avoid areas where dogs or other animals may have contaminated the grass. Introduce grass gradually to prevent digestive upset. Never feed lawn clippings that have begun to ferment. Always wash grass thoroughly before feeding. Wild grasses provide excellent nutritional variety when sourced safely.

Store hay in a breathable container in a cool, dry place (not plastic bags that trap moisture). Pellets should be kept in an airtight container in a cool, dark place to preserve vitamin C use within 90 days of opening. Vegetables should be refrigerated and used within 3-5 days. Always check expiration dates and discard any food that smells musty, moldy, or rancid. Buying smaller quantities more frequently ensures freshness.

The best vitamin C sources for guinea pigs are: red bell pepper (128 mg/100g), green bell pepper (80 mg/100g), kale (93 mg/100g), broccoli (89 mg/100g), Brussels sprouts (85 mg/100g), parsley (133 mg/100g), and mustard greens (70 mg/100g). Rotate these vegetables to ensure consistent vitamin C intake. Remember that cooking destroys vitamin C, so always feed vegetables raw and fresh.

Baby guinea pigs (under 6 months) need unlimited alfalfa hay and alfalfa-based pellets for growth, plus small amounts of vegetables introduced gradually. Adults (6+ months) need unlimited Timothy hay, limited Timothy-based pellets (⅛ cup daily), and 1 cup of varied vegetables daily. Pregnant/nursing sows need unlimited alfalfa hay and pellets plus extra vegetables. Always transition diets gradually when switching from baby to adult formulas around 6 months.

While consistency is important for digestion, variety prevents nutritional deficiencies and food boredom. Rotate at least 5-6 different vegetables weekly. Hay can remain consistent (Timothy as staple), but offering different grass hays occasionally adds variety. Pellets should remain consistent to avoid digestive upset. The key is consistent hay and pellets with varied vegetables for micronutrient diversity.