Right, so I've got two 3yr old cats, and a 5 month old kitten.

As much as I try and stop it happening, the kitten keeps eating the left over adult food.

The packets of kitten food say I should use kitten food until he is 12 months old, but if I was to switch him to regular adult food now (I'll use up all the kitten food I have here which will be about another month I should think) am I going to do him any real harm?

He doesn't get an upset tummy from eating it, and seems to prefer it if anything.

At 5 months old, he will soon be ready to make more kittens!

He will be fine on adult food but avoid the senior range which is designed for less active cats.

The manufacturers are only trying to maximise sales of more expensive food.

He's been done already so would be firing blanks.

The vets even commented that he had the smallest testicles they had seen for a while, so I think he may not have had much success in that department even if he had kept them.

This 'kitten food' nonsense is just a marketing ploy to entrap the gullible. There was no such thing as kitten food a few years ago.

Shame

I have to say there is a difference in the dry food. The pieces in the kitten dry food are smaller than for older cats.

my mum's kitten who she rescued when it was just over two months old refused to eat kitten food after a few weeks as he preferred what the other cats ate , it has not done him any harm and he has regular check ups with a vet due to an injured tail he had when found the vet is happy with his diet , when he is old enough ( the cat not the vet ) he is going to have half his tail amputated due to his injury .

No such thing as cat or kitten food BC but cats and kittens somehow never died out.

My girl is just over a year now and for the first few months ate kitten biscuits nearly all of the time. We always made wet food available but she didn't really take to it until she was about 4 months old and then only a small amount but gradually it increased and now she has about 90% wet food. TBH we were so intent on getting her to eat wet food it didn't even occur to us to buy kitten food. She still loves her kitten biscuits though!

Cats will eat what they want to eat. My two had kitten food for the first couple of weeks, and then I thought sod it, and fed them normal cat food and they were fine on it. At 5 months he might just be eating anything going because he's growing fast.

My two went through a phase of pinching off plates, but it stopped once they were more or less fully grown. Now we can leave a cooked chicken on the side and they don't even bother. Marshmallows, strawberry yoghurt and empty blister packs for tablets (I honestly don't know why one of them licks the inside of them) are different matters though.