Grain-Free vs Grain-Inclusive Cat Food: Which Suits Your Cat?

By PDSA Pet Store | Published: 2026-10-17

Category: Comparaisons

Grain-free or grain-inclusive? Compare Calibra and Royal Canin options for sterilised cats, plus a kitten digestive formula, to match your cat's needs.

Quick answer

Grain-free food like Calibra Verve Sterilised Herring suits cats that do well on high fresh-fish protein and need a recipe designed for spayed or neutered adults. Grain-inclusive options such as ROYAL CANIN® Feline Adult Neutered Maintenance Slices in Gravy fit cats that prefer a wet, slice-and-gravy texture and a long-established veterinary nutrition approach. Neither is automatically better; the right pick depends on your cat's digestion, weight, and texture preference.

What actually changes between grain-free and grain-inclusive recipes

Grain-free doesn't automatically mean low-carb or higher protein. It means the recipe avoids grains and uses other carbohydrate sources. Calibra Verve Sterilised Herring, for example, is grain-free and built around fresh fish, with fresh mackerel and salmon making up 29% of the overall content and animal-source proteins accounting for 75.4% of total protein. Grain-inclusive foods may use rice, wheat, or corn, and their protein can come from a wider mix of animal and plant sources. The practical difference for your cat is often how the food sits in the stomach, how firm the stool stays, and whether your cat actually finishes the bowl.

How to test a switch without guesswork

Transition over seven to ten days, mixing a small amount of the new food into the old one and increasing the ratio every two to three days. Keep a simple log for two weeks: stool consistency, appetite, scratching or head-shaking, and how quickly your cat leaves the bowl. If you're moving from a grain-inclusive to a grain-free recipe, watch for looser stool in the first few days; if it persists past a week, slow the transition or step back. For sterilised cats, weigh your cat at the start and again after a month, because neutered cats often need portion control more than a specific grain status.

Where kittens and sensitive stomachs fit in

Kittens aren't small adults, and their digestive systems are still developing. ROYAL CANIN® Gastrointestinal Kitten Dry Cat Food is formulated to support digestive health in kittens and comes in 400 g or 2 kg bags, so you can start small before committing to a larger bag. If your kitten has persistent vomiting, diarrhoea, or blood in the stool, that's a veterinary issue, not a food-label choice. Grain-free versus grain-inclusive matters less than getting a formula designed for the kitten's life stage and confirming with your vet that nothing else is going on.

Trade-offs at a glance

Grain-free, fish-forward (Calibra Verve Sterilised Herring): Grain-free with 29% fresh mackerel and salmon and 75.4% animal-source protein, aimed at sterilised adults. The trade-off is that grain-free isn't automatically better for every cat, and some cats need a slower transition to avoid loose stool. Choose this if your sterilised cat does well on fish-based, higher animal-protein recipes and you want a grain-free option.
Grain-inclusive wet food (ROYAL CANIN® Feline Adult Neutered Maintenance Slices in Gravy): A wet slices-in-gravy formula for neutered adults, backed by a veterinary nutrition heritage dating to 1968. The trade-off is that it's a different texture and moisture profile than dry grain-free kibble, and it may not suit cats that do best on dry food. Choose this if your neutered cat prefers wet food or you want to increase moisture intake.
Kitten digestive support (ROYAL CANIN® Gastrointestinal Kitten Dry Cat Food): Formulated for kittens with developing digestive systems, available in 400 g or 2 kg bags. The trade-off is that it's a kitten-specific formula, so it isn't the right comparison for an adult cat choosing between grain-free and grain-inclusive. Choose this if you have a kitten with digestive sensitivities, not an adult cat.

Products compared in this guide

Calibra Verve Grain Free | Adult | Sterilised Herring: Calibra Verve Grain Free Sterilised Herring is a complete grain-free food with a high content of fresh fish, designed for spayed and neutered cats. Fresh mackerel and salmon make up 29% of the overall content, and animal-source proteins make up 75.4% of the recipe's total protein. A good fit if you want a grain-free, fish-forward recipe specifically positioned for sterilised adults and you care about animal-protein proportion.
ROYAL CANIN® Feline Adult Neutered Maintenance Slices in Gravy 48x 85g: ROYAL CANIN® Feline Adult Neutered Maintenance Slices in Gravy is a wet food for neutered adult cats, built on Royal Canin's veterinary nutrition approach since 1968. A practical pick for neutered cats that prefer a wet, slice-and-gravy texture or need more moisture in their diet.
ROYAL CANIN® Gastrointestinal Kitten Dry Cat Food: ROYAL CANIN® Gastrointestinal Kitten Dry Cat Food is designed to support a kitten's digestive health and is available in 400 g or 2 kg bags. Useful when the cat in question is a kitten with digestive sensitivities rather than an adult choosing between grain-free and grain-inclusive.

Which food fits your cat?

Best for

Sterilised adult cats that do well on grain-free, fish-based recipes with high animal-protein content
Neutered adult cats that prefer wet food or need more moisture in their diet
Kittens with digestive sensitivities that need a life-stage-specific formula