The nutritional value of all types of grasses is very very low and is actually completely indigestible to cats - which is why your cat is certainly likely at some stage to vomit the grass back up as they lack the enzymes in their gut which would be necessary to break it down and properly digest it in their gut. One highly plausible explanation as to why they do this is that when a cat eats a mouse or a bird it is impossible for the cat to separate fur and bones from the meat. Therefore the cat gulps down the entire mouse usually in one piece. Once the meat has been digested the undigestible parts such as the hair and bones remain in the cat's stomach. Eating grass makes the cat vomit, and this brings the grass back up, now neatly wrapped around undigested mouse parts. Now, this is just a theory but is widely thought to be plausible. How convenient! Of course, anyone who owns a cat is sure to know that this is the part that ends up on your carpet, that you, unfortunately, tread on first thing in the morning!
When should you worry? If your cat repeatedly likes eating grass or leaves, take obvious precautions and ensure that you do not apply weedkillers to the lawn which may be inadvertently ingested. If they do not have access to grass they may chew other plants instead so ensure that your houseplants are not toxic to cats lists are available online of what plants are poisonous to cats. Every now and then a cat will get a blade of grass stuck at the back of their throat. That's where a veterinary specialist comes in. Many of these grass blades can be removed under anesthetic with a dental mirror and a surgical instrument is known as a spey hook, by your vet. If the blade is lodged far in the nose, a camera known as a rhinoscope is required to see the blade so it can be removed - a painless procedure for the patient but a technically tricky one for the endoscopist.
To conclude our review of cats and grass, probably the funniest reason cats eat grass comes from a well-known pet website. Cats may nibble on grass blades for the same reason as country yokels do it. It is quite palatable, and they may enjoy the taste.