Guinea pigs are one of the few pets that can't make their own vitamin C, so it has to come from what they eat every single day rather than occasionally — which is why Supreme's Science Selective range adds it directly into the nugget rather than leaving it to fresh veg alone.

This is the Junior version, aimed at growing guinea pigs up to 20 weeks old, with extra protein for growth and added vitamin C built into a single-component extruded nugget — the "single component" part matters because it stops a guinea pig sorting the bowl for its favourite bits and leaving the rest, which is how selective feeders end up with gaps in their diet. The base is alfalfa meal, wheat, wheat feed, soya bean hulls and flaked peas, with dried fennel and dandelion added.

• Protein 18%, crude fibre 15%, fat 4%, ash 6%
• Calcium 0.6%, phosphorus 0.5%
• Vitamin C added at 1000mg/kg
• Single-component nugget — no mixed pieces to pick out
• Also suitable for pregnant and lactating guinea pigs
• 1.5kg bag

What feeding "freely" doesn't tell you. Supreme's own guidance is to feed freely with regular monitoring of weight, rather than a fixed daily gram amount by bodyweight, so there's no number here to work from if you want a precise starting ration — you'll be watching your own guinea pig's weight instead of following a chart. Hay and fresh vegetables still need to sit alongside it; this isn't meant to be the only thing in the bowl.

Who it's for: owners of a growing guinea pig under 20 weeks, or anyone currently feeding a mixed seed bowl and wanting to move to a nugget that can't be picked through.