I know people say that I should not change my cat's cat food because:
However I always change his food and he likes trying new things. As long as he likes it and does not vomit can I still feed him different brands of food?
You can, of course, change his food without ill effect and he may quite enjoy having variety. However, in my experience, most cats seem to prefer that you don't mess with their diet and routine, especially as they get older. If your cat is young, they may be more tolerant of the switch, but don't assume that their eating as a result of hunger is actually enjoyment of the variation.
I've also heard of the issue of not changing cat's food, infact it is stated here that the first rule of cat food is to never change its food. But thanks to petmd.com we are given some steps to take when changing cat's food.
Find a Similar Cat Food Formula : Always try to pick a new cat food that is similar to the previous one.
Offer Small Meals Gradually : Don't rush your cat on the new food. Offer it gradually
Go Easily Digestible : Get a food that is easily digestible.
Consult Your Veterinarian : If you cant still find a food suitable for your cat, then consult your veterinarian.
Also see : Steps to Switch Cat Foods
Changing a cat's food randomly (or based on whatever's on sale) is not a good tactic, but having a regular food rotation of 3-5 foods can prevent your cat from becoming so attached to a particular food that he will not eat anything else (which can become a problem if the manufacturer changes the formula to something unpalatable suddenly).
In addition, a food rotation also can protect against accidental nutritional deficiencies due to manufacturing error. An article found on Pawnation reviewed a study that found:
"Since 2009 [article published September 2013], there have been 5 major voluntary pet food recalls involving thiamine-deficient pet foods in the United States that ultimately involved 9 brands of cat foods and at least 23 clinically affected cats. Most of these recalls were instituted in response to a report from a consumer or veterinarian after treating a cat that had clinical signs consistent with thiamine deficiency."
(the study is not available on the web, but it is: Thiamine deficiency in dogs and cats. Markovich JE, Heinze CR, Freeman LM. J Am Vet Med Assoc. 2013 Sep 1;243(5):649-56. )
Many cats are suspicious of changes they can't control, including menu changes.
I generally tended to keep the same kibble for long periods unless there was a medical need for a change, offering a variety by mixing up the treats. With the most recent pair, wet food was mostly considered a treat, since they liked gravy but were only slightly more interested in the meat pieces that in their kibble.
As far as I could tell, they found the stable diet comforting rather than boring.
The easiest way to introduce a new food is to present it alongside the previous food, wait until you see the cat eating it (ideally, preferring it), and then phase out the prior food if you want to do so. That isn't always possible if you are moving them to a food that is better for them but that they don't like as much; in that case you may need to start progressively offering less of "the good stuff" to get the cat hungry enough to eat the new diet.
Regarding cats vomiting when they try new food: they may have an allergy... or they made just coincidentally hack up a hairball after trying the new food. I wouldn't rush to associate the two unless it happens every time the cat tries the new diet.
My vet: "Any vomiting?" Me: "Not more than usual for a cat."
