This is a common argument: instead of feeding kibble, why not feed a home-cooked diet? Advocates of this have you believe that you avoid all the 'dangers' associated with raw-feeding like bones and bacteria. But is a home-cooked diet a viable option?
Complex recipes aside, there are several aspects of cooked diets that pose problems. Tom Lonsdale deals with this in depth in Chapter 4 of his book Raw Meaty Bones, but I will cover these briefly here.
First, the act of cooking alters the proteins, vitamins, fats, and minerals in a food. This alteration can make some nutrients more readily available and others less available. Cooking can alter fats to the point of being toxic and carcinogenic (The American Society for Nutritional Sciences. April 2004. Meat Consumption Patterns and Preparation, Genetic Variants of Metabolic Enzymes, and Their Association with Rectal Cancer in Men and Women. Journal of Nutrition. 134:776-784.), and cooked proteins can be altered to the point where they cause allergic reactions whereas raw proteins do not (Clark, W.R. 1995. Hypersensitivity and Allergy, in At War Within: The double edged sword of immunity, Oxford University Press, New York. pg 88.). If an animal has an "allergy" to chicken or beef, it may very often be cooked chicken or beef and not the raw form.
Second, cooked food lacks all the benefits of raw food. Cooked food is deficient in vitamins, minerals, and enzymes, because the very act of cooking destroys or alters much of them (exceptions to this are things like lightly steamed broccoli or tomatoes, but these are not appropriate foods for carnivores!). This decreases the bioavailability of these valuable chemicals and makes them less available to the animal. This is why these things have to be added back into pet foods and why a variety of supplements need to be added to home-cooked pet food—and why a variety of species inappropriate items are utilized as ingredients in these meals!
Vitamins and minerals can be added back into cooked food, but finding the appropriate balance is incredibly difficult. Synthetic vitamins and minerals do not always exhibit the same chirality (three dimensional structure) that the natural forms had, which means their efficiency and use to the body are substantially decreased. This is compensated by oversupplementation, which then results in the inhibited uptake of other necessary vitamins and minerals. For example, excess inorganic calcium reduces the availability of iron, copper, iodine, and zinc (Lonsdale, T. 2001. Raw Meaty Bones. pg 88). If you are feeding a cooked, home-made diet, can you be sure that your pet's needs are being sufficiently met if the very act of cooking destroys much of what is beneficial to your pet? Essentially, once you cook your pet's food you are now guessing which vitamins or minerals have been destroyed, how much of these might have been destroyed (which means you would have to know how much was present in the food in the first place), and how much supplementation your pet needs. Then you run into another problem: no one really knows what our pets REALLY need and use in terms of vitamins and minerals. We only know what amounts are too much and what amounts are too little OVER A SIX-MONTH PERIOD, not over a period of years. Additionally, how can we be sure that researchers have discovered all the nutrients necessary for our pets? This still is an on-going process (such as Eukanuba adding DHA to their foods; DHA is found in raw prey, so any dog or canid eating raw prey has been receiving appropriate levels of DHA), and since cooking food destroys minerals and vitamins and enzymes, researchers may be missing some very important nutrients. Feeding cooked food also causes pets to miss out on these 'unknown' nutrients, whereas raw food contains them in appropriate amounts.
People compensate for vitamin and mineral deficiencies without resorting to supplements: they simply add vegetables, grains, and dairy products to their carnivores' diets. Complex recipes are developed that create a wide range of foods for the dog (or cat) that must be cooked, steamed, blended, etc. in order for the dog to receive proper nutrition. Our carnivores once again have an omnivorous diet forced upon them in order to help them obtain all the appropriate nutrition that could simply be had by feeding a variety of raw meaty bones and organ meats. Simplicity and perfection are traded for complexity and imperfection.Raw food, however, has the perfect balance of vitamins and minerals if fed as a part of a prey-model diet (i.e. a whole rabbit) (Lonsdale, T. 2001. Raw Meaty Bones. Chapter 4.). Raw food also has unaltered proteins and nutrients, and the bioavailability of these nutrients is very high. And raw food—particularly whole carcasses and raw meaty bones—provide the NECESSARY teeth-cleaning effects that are lacking in any cooked diet. Periodontal disease-causing bacteria are scraped away at each feeding, whereas a cooked food-fed dog has that bacteria remaining, which are then coated over by a sticky plaque resulting from the cooked grains, vegetables, and meat proteins. Some feed raw beef bones to help clean teeth and continue feeding a home-cooked diet. Is this better than kibble? Of course! But is it the best? Those promoting a raw diet say 'No.'
For more information on cooked food versus raw food, please check out the famous Pottenger cat study: