Found this in a website. Might be useful :
HOW TO READ THE INGREDIENT LIST:
When looking at the ingredient list on the back of a can or bag of cat food, pay particular attention to the first 5 ingredients in the list. These ingredients comprise the majority of what the food is made of as the order of the ingredient list is based on weight.
INGREDIENTS TO AVOID:
In both dry and wet food, there are certain ingredients to watch out for and avoid like the plague. The reason these ingredients are even used is because they are cheap and increase a pet food company’s profit margin. Ingredients to avoid include:
CORN – Cats are obligate carnivores and can’t process carbohydrates the way we do. Grains, in particular, corn, are terrible for their health. Corn and other grains are the leading cause of overweight, obese, and diabetic cats (corn is naturally high in sugar). In addition, since corn is not a sufficient source of protein, your cat will eat even more of the food because it feels malnourished. This can lead to unwanted eating habits such as gorging and vomiting. If corn or anything corn based (i.e. corn gluten meal) is listed as one of the first 5 ingredients of the cat food, that cat food is garbage for your cat’s health. Consumers are catching onto this, and pet food companies have responded by listing corn as “maize.” [1]
ANY TYPE OF GRAIN – This may include brown rice, cracked barley, and oatmeal, which are higher quality grains than corn, but still not great since cats shouldn’t be eating grain at all.
BREWERS RICE/ BREWERS YEAST – Another useless additive. As the name implies, these ingredients are used to process beer which are later dried and sold to pet food companies as a cheap source of carbohydrates.
MEAT BY- PRODUCTS / MEAT BY-PRODUCT MEAL - Parts of slaughtered animals not including meat. This includes organs such as kidneys, intestines, brains, bones, etc. Under this definition, meat by-products are not necessarily bad for your cat, but the problem is you don’t know what the source of the meat by-product is. It is in fact legal for meat by-products to contain, quote: “4D animals (dead, dying, diseased, down), road kill, euthanized cats and dogs, including their collars. These source products are rendered, the fat is siphoned off to be used as “animal fat,” and the remaining material is extruded to form “meat by-product meal.” [2]
If the meat by-product is described as a meal, this means that the by-products were ground and rendered (cooked under high heat and reconstituted).
POULTRY BY-PRODUCTS / POULTRY BY-PRODUCT MEAL – Same definition as meat by-products, except using poultry. It may include the use of feathers, beaks, and feet.
ANIMAL DIGEST - Similar to meat by-products, except that it may include refuse from restaurants and supermarkets.[2] It’s a poor source of protein.
GOOD INGREDIENTS TO LOOK FOR:
CHICKEN or CHICKEN DEBONED- Chicken meat from muscle meat.
TURKEY or TURKEY DEBONED - Turkey meat from muscle meat.
DUCK or DUCK DEBONED - Duck meat from muscle meat.
RABBIT or RABBIT DEBONED - Rabbit meat from muscle meat.
CHICKEN MEAL - Ground and rendered chicken meat; not as nutritious as chicken deboned, but still quite good.
TURKEY MEAL - Ground and rendered turkey meat.
SALMON OIL and/or FLAXSEED OIL - Good for your cats fur (shiny and soft coat) and eyes (bright and clear).
CRANBERRIES, ACAI BERRIES, or BLUEBERRIES – Good source of antioxidants; good for maintaining your cat’s urinary tract system. Should be listed after the top 5 ingredients.
TAURINE - May be listed as a supplement. This is critical to your cats overall health. If the ingredient list is full of good proteins, it may not be listed as the taurine comes from the protein.
PERCENTAGES:
According to veterinarian and cat foster mother, Dr. Lisa A. Pierson, DVM, a cat’s diet should be composed of:
Protein calories = 50 – 70%
Fat calories = 10 – 30%
Carbohydrate calories = <5%
CAT FOOD BRANDS TO AVOID:
Unfortunately, a lot of the most popular pet food brands on the market are also the brands with the worst ingredients lists. My list is by no means thorough, but I am cherry-picking the ones that claim to be a superior food and/or what most consumers go for.
A particular brand I am actually disgusted with is…
HILL’S SCIENCE DIET [3]
What I hate about Science Diet is that it touts itself as being a “scientific diet recommended by veterinarians” when the ingredient list says otherwise. Here are the first five ingredients of Hill’s Science Diet Mature Adult Indoor cat food:
Chicken By-Product Meal, Corn Gluten Meal, Brewers Rice, Ground Whole Grain Corn, Animal Fat (preserved mixed tocopherols and citric acid).
By-product meal. Okay… at least it’s not animal digest. Wait… Corn gluten meal is the SECOND ingredient? Ground whole grain corn is the THIRD? Brewer’s rice?! Awful, awful food! It’s one thing if this is a grocery brand food, but Hill’s Science Diet isn’t cheap and is frequently recommended by actual vets. Why? Well, it turns out Hill’s Science Diet (which was purchased by Colgate in the 1970s) has given bucket-loads of money to veterinary schools and hospitals in exchange for having their brand featured in textbooks and presentations, and recommended by licensed vets. Sometimes they even have vet offices give away bags for free as a promotion. The company has certainly done a lot to effectively market their brand, and we the consumer have been none the wiser that we’ve been had. I hate this brand. Well-meaning people think they’re paying for the best, when in fact they might as well be buying Meow Mix. At least Meow Mix doesn’t pretend to be a superior food.
EUKANUBA (IAMS) / PURINA ONE / ROYAL CANIN [3]
Like Science Diet, these claim to be a superior food. Sadly, these brands actually are “superior” to Science Diet because they actually list chicken as the first ingredient. Chicken by-product meal is also listed, but at least it isn’t listed first.
FRISKIES / MEOW MIX / PURINA KIT N’ KABOODLE / WHISKAS [3]
First ingredient is corn. Second ingredient is corn meal. Nothing to see here.
DRY & WET FOOD BRANDS I RECOMMEND:
WELLNESS CORE
I currently feed this to my cat as part of her dry diet. The first 5 ingredients include:
Deboned Turkey, Deboned Chicken, Chicken Meal, Whitefish Meal, Potatoes
Interestingly, Wellness CORE offers more protein by percentage than Wellness canned cat food [1] (more on this later). Note that further along the ingredient list, there are phosphorous and magnesium. In high quantities, these can cause struvite crystals [4], so it’s important to make sure your cat gets plenty of water and a portion of wet food. It’s not cheap, so I buy the smaller bag for $10.00 and mix it with…
MERRICK BEFORE GRAIN (chicken)
The first 5 ingredients include:
Chicken deboned, Chicken Meal, Potato Dehydrated, Turkey Meal, Chicken Fat (preserved with mixed tocopherols – a source of Natural Vitamin E)
Unlike Wellness CORE, this doesn’t have phosphorous, which is good since I’m blending the two brands. There is a carb listed as a main ingredient (potato), but at least it’s not a grain. Being a dry food, having some kind of carbohydrate is inevitable.
ORIJEN
A very good food from Canada. It’s actually pricier than Wellness CORE and is imported from Canada. The first 5 ingredients include:
Deboned chicken, chicken meal, turkey meal, russet potato, lake whitefish
INNOVA EVO
Good, but rather pricey. The first 5 ingredients include:
Turkey, chicken meal, chicken, herring meal, chicken fat
NATURE’S VARIETY: INSTINCT [5]
What I like about this brand is that it offers cat food in three forms: raw, dry, and canned. I also like that they offer rabbit as a main protein, which is nice for variety and something a cat could feasibly hunt in the wild. The first 5 ingredients include:
Rabbit Meal, Chicken Meal, Salmon Meal, Herring Meal, Tapioca
ON WET FOOD:
Here’s the problem with grain free, by-product free wet food: inevitably, the company needs to cut a corner to make money. Since grain and by-products are out of the picture, the pet food company will instead load their wet food with fat. Wellness, a reputable brand, is guilty of this.[6] For a thorough breakdown of protein to fat to carb percentages based on brand name and formula, please visit:
Fortunately, cats metabolize fat better than they do carbohydrates. My concern, however, is that over time my cat may develop heart problems. Since she’s still technically a kitten, the high fat content is actually good for her for now. As a precaution, I mix Wellness canned chicken or turkey with Merrick Before Grain canned chicken, chicken and quail, or turkey, OR Merrick “Grammy’s Pot Pie” or “Cowboy Cookout.” The Before Grain canned food is more bland (Cici always eats the Wellness portion first), and the gourmet Merrick canned food is comparatively lower in fat and carbs. In fact, “Grammy’s Pot Pie” and “Cowboy Cookout” are two formulas that closely match a cat’s ideal protein to fat to carb ratio. I hope mixing the brands will cut the fat in Wellness by a little bit. It’s probably a lost cause, but it’s a small comfort to know I’m trying.
As for wet food with no grains, but with meat by-products, it’s honestly a toss up. When we first adopted Cici, she was initially on a diet of Before Grain Chicken Dry and Fancy Feast wet food (which uses by-products). While she loved the taste of Fancy Feast, she would suffer diarrhea and/or very foul stool that would stink-up the whole apartment. Once I weaned her off Fancy Feast and got her on Wellness, the diarrhea stopped and her stool (though still stinky) didn’t stuff up the whole apartment. If your cat reacts well to Fancy Feast, I think it’s a reasonable compromise as it’s low in price, low in fat, and zero in grain (check the ingredient list) though high in by-products.
its abit long but it's quite useful seriously...