Cat grass is simply a marketable name given to several different types of grass that have been packaged up and sold for cats to eat or chew on. There’s no such thing as a species called “cat grass”. Instead these products will use well known grasses like oat, rye, wheat and barley.
So if you’re wondering whether a cat grass product can be given to your guinea pigs, you first need to pinpoint what sort of grass (there can be more than one) is going to grow from a cat grass product.
Let’s look at the common types of cat grass products individually to consider their suitability and safety for guinea pigs:
Barley Cat Grass
Barley grass and/or hay is a recommended staple food in the diet of guinea pigs.
Alfalfa Cat Grass
Some cat grasses will consist of alfalfa. Guinea pigs should not be eating alfalfa (also called lucerne) due to it containing excess calcium and protein.