What Do Guinea Pigs Eat? Daily Portions, Foods & Schedule

Guinea pigs are herbivores built for grazing. Their natural diet is fibrous grasses, and that fact shapes everything about how you feed them. The foundation is simple: unlimited grass hay, fresh water always available, a measured portion of plain pellets, and a daily serving of varied vegetables. Get those proportions right from day one and you’ll avoid the most common nutrition problems — scurvy, dental overgrowth, bladder stones, and life-threatening gut stasis.

What guinea pigs should eat every day: the simple bowl plan

Daily amounts: hay, pellets, vegetables, and water

Hay, pellets, and vegetables: what each contributes

• Hay is the non-negotiable base. Offer timothy or orchard grass free-choice; alfalfa hay is reserved for juveniles, pregnant, or nursing pigs because its high calcium and protein can promote bladder stones in adults.
• Pellets should be a plain, timothy-based formula. Muesli mixes encourage selective feeding, obesity, and dental issues.
• Vegetables round out the diet. Rotate romaine, green leaf, bell pepper, cilantro, zucchini, and other safe greens so no single item dominates.

How to portion hay, pellets, and vegetables by weight

A practical pellet measuring rule

Pellet recommendations look contradictory because sources use different measures. The three most common rules, converted to grams:

*Grams vary by pellet size and density — weigh your actual brand once, write the number on a sticky note inside the pellet bin, and scoop with the same cup every day.

Worked examples

• 700 g juvenile (under ~6 months): Growth takes priority. Offer age-appropriate (often alfalfa-based) pellets more liberally — roughly 2 tablespoons (≈15–20 g) or per the product label — alongside alfalfa hay, and let appetite guide you with a vet’s sign-off.
• 1 kg adult: Start at ⅛ cup. If that weighs 18 g on your scale, that’s your number (~1.8 % of body weight — right in range). If weekly weigh-ins show a steady gain with pellets left over, step down to ~15 g.
• 1.2 kg senior: Weight alone doesn’t justify cutting pellets. Keep ~15–20 g unless the scale shows climbing weight, then trim in ~5 g steps. A senior losing weight may actually need pellets topped up — pair any change with a vet check, since weight loss at this age often means dental trouble.

Guardrail: never restrict hay to compensate — hay stays unlimited at every weight.

How to weigh your guinea pig and assess trends

1. Use a digital kitchen scale (0.1 g resolution).
2. Place a small container on the scale, tare it, then gently set the pig inside.
3. Record the weight in grams before the morning vegetable serving.
4. Weigh weekly on the same day; a slide or spike over 2–3 weeks matters more than a single 10–30 g wobble.

A safe-food chart for daily vegetables, occasional treats, and foods to avoid

How to read the safe, caution, and never-feed chart

The table below consolidates every common food into three tiers. "Daily rotation" means the item can be part of the ~1 cup of varied vegetables offered each day — rotate 3–4 different vegetables rather than serving the same one every day. "Limited" items are treat-sized portions a few times a week — that tier also answers questions like whether guinea pigs can have grapes (one halved grape, at most weekly). "Never" items are toxic, pose a mechanical hazard, or cause severe metabolic upset.

Why some foods need limits or should never be offered

• Oxalates (spinach, kale, parsley) bind calcium and raise bladder-stone risk.
• Calcium-to-phosphorus ratio: excess calcium from alfalfa or high-calcium greens can precipitate stones in adults.
• Gas production (cruciferous vegetables) can trigger bloat, a life-threatening condition.
• Sugar and acidity (fruit, citrus) cause digestive upset and mouth sores when fed daily — which is why sugary fruits such as bananas for guinea pigs are capped at a thin coin a week.
• Toxicity (chocolate, avocado, alliums, rhubarb) is well documented in small mammals.
• Lawnmower clippings ferment within hours, producing gas that can cause fatal bloat.

Vitamin C: daily needs, reliable sources, and early scurvy signs

Food sources and supplement cautions

Guinea pigs cannot synthesize vitamin C and must obtain it daily from food. The most reliable dietary sources are:

• Bell pepper (any color) — one of the highest vegetable concentrations.
• Fortified timothy-based pellets — but vitamin C degrades with light, heat, and time.
• Leafy greens such as parsley, kale, and mustard greens (fed in limited amounts due to calcium/oxalates).

Adding vitamin C to the water bottle is unreliable: it oxidizes within hours and may change the taste, causing reduced water intake. Routine supplements (drops, tablets) should only be used under veterinary direction, especially when the diet already includes fortified pellets and vitamin-C-rich vegetables.

Signs that need a veterinarian

Early scurvy can appear within 2–3 weeks of deficiency. Watch for:

1. Reluctance to move or hop; stiff gait.
2. Painful, swollen joints (especially hocks and knees).
3. Poor appetite and weight loss.
4. Rough, unkempt coat.
5. Bleeding or sore gums, sometimes with loose teeth.

If you see any of these, contact an exotic-animal veterinarian the same day — do not attempt to self-treat with high-dose supplements.

A complete daily feeding schedule from morning hay refill to evening checks

Sample morning-to-evening routine

The following time-stamped plan turns the diet proportions into a repeatable cage-side routine. Adjust the clock times to your schedule; consistency matters more than the exact hour.

Changing foods without upsetting digestion

Transition new pellets or vegetables gradually over 14–28 days (2–4 weeks) to avoid digestive disruption. Mix a small amount of the new food with the current one, increasing the proportion every few days while monitoring appetite and droppings.

1. Day 1–3

   75 % current food, 25 % new food



2. Day 4–7

   50 % current, 50 % new



3. Day 8–14

   25 % current, 75 % new



4. Day 15+

   100 % new food

At a glance

How feeding changes for babies, adults, seniors, and pregnant guinea pigs

Life-stage feeding comparison

When a veterinarian should tailor the plan

Any deviation from the baseline — persistent weight change, dental disease, pregnancy, illness, or medication — warrants a vet-approved adjustment. Don’t guess pellet amounts for a pregnant sow or a pig on antibiotics; the wrong calcium or vitamin C level can cause stones or scurvy.

Track weight and droppings to spot digestive trouble early

Weekly weight and daily appetite checks

• Weigh each guinea pig weekly on a kitchen scale, in grams, before the morning veggies — record the number.
• Note appetite: normal / reduced / refusing food.
• Note droppings: normal number and shape / fewer / smaller / misshapen / none seen.
• Note anything odd: hunched posture, less movement, wet chin (drooling can mean teeth trouble).

Trend matters more than any single weigh-in — small wobbles of 10–30 g are common; a slide or spike over 2–3 weeks is not.

Bloat, gut stasis, and droppings changes

Do not do these while waiting: no force-feeding, no home remedies, no withholding food "to rest the gut" — a blocked or bloated gut is an emergency, not a diet problem.

Use this first-week checklist to put the feeding plan into practice

• ☐ Set up unlimited fresh grass hay (timothy or orchard), a clean working water bottle, and a measured adult pellet portion appropriate to the pig’s life stage.
• ☐ Choose a small rotation of washed vegetables (e.g., romaine, bell pepper, cilantro, zucchini); introduce unfamiliar foods gradually using the 2-week transition.
• ☐ Use the safe-food chart before offering any treat; keep fruit and high-calcium greens to the limited tier — that includes checking details like whether guinea pigs can eat apples before sharing a slice.
• ☐ Record weekly weight on the same day; log appetite and droppings daily.
• ☐ Store hay in a cool, dry, ventilated place; discard damp, dusty, or musty hay. Never feed lawnmower clippings.
• ☐ Contact an exotic-animal veterinarian promptly for any warning signs: not eating, very few/no droppings, swollen belly, weight drop ≥50 g in a week, hunched posture, labored breathing.

With this chart, schedule, and monitoring habit, you’ll have a complete, evidence-backed feeding system that works at the cage — not just on the screen.

FAQ

Can guinea pigs eat grass from the yard?

They can eat clean, pesticide-free grass introduced gradually, but avoid areas contaminated by chemicals, animal waste, or traffic. Never feed lawnmower clippings, which can heat and ferment quickly and may cause digestive problems.

How should I store hay and tell whether it is fresh?

Store hay somewhere dry, cool, and ventilated, away from damp floors and direct moisture. Good hay smells fresh and grassy; discard hay that is damp, dusty, discolored, or musty.

Do I need to give a vitamin C supplement if the pellets are fortified?

Not necessarily: fresh vitamin-C-rich vegetables and properly stored fortified pellets may provide a reliable dietary source. Ask an exotic-animal veterinarian before supplementing, and do not rely on adding vitamin C to drinking water.

Is citrus safe for guinea pigs?

A small piece of citrus can be an occasional treat for many guinea pigs, but its acidity and sugar make it unsuitable as a daily food. Introduce it sparingly and stop if it causes mouth irritation or digestive upset.

Do guinea pigs eat their own droppings?

Yes, and it’s essential: guinea pigs produce soft droppings called caecotrophs and re-ingest them to absorb B vitamins, protein, and other nutrients. You rarely see it happen, but a pig that suddenly can’t or won’t should be checked by a vet.