Cats are the only real carnivorous domestic animals. Its digestion system "is programmed" for 28 hours cycle that is why cat can eat seldom (once in 28 hours) but contacts with people caused the fact that if cats have always something to eat then they may eat more often. Cats are conservators in their choice of food. When they choose it they take into account such facts as smell, consistence (solid, friable, liquid) taste. At the same time such facts as noise, light, dish, presence or absence of people. Such caprices have physiological origin. It is connected with the fact that cats are more subjected to poisoning than people or dogs. Cat may come to a hungry death if you give it food which it doesn't want to eat! That means that food self-limitation is stronger than instinct of self-preservation! Neither man nor dog can do this. Remember this fact then you try to make you cat get used to the new food.
LEVEL OF HEIGHT
A few words about it. The largest quantity of using food by cats is at the age of 150-160 days (5 months), the period of the quickest growing finishes to 200-220 days (7 months).
The role of calories in the food takes the important place because protein (albumen) may be adopted only with the necessary quantity of energy. To say in other words if you give much meat to your cat then it needs much fat for the adaptation of meat. For adult cats is 70 kcal on 1 kg of weight recommended.
Water is one of the most important conditions of good health of your cat and also it is one of the necessary things for cat that is often forgotten by the owners. The necessary quantity of water will help the cat to avoid illnesses of urinary bladder, to wash out the toxins from the organism, to control appetite and to clean the organism at all. Cat needs 60-80 ml of water on the kilogram of weight. It gets water together with food or as liquid. Besides, water is secondary product of substances exchange, especially of fats exchange. Cat which gets wet food can live without drinking. For example, if the cat gets canned food Whiskas(r) or kitekat(r), then it gets 80-90 % of liquid needed but if it gets dry food then just 10%. Cats with dry or half dry ration must obligatory get water. The quantity of water is individual for every animal and is also connected with many facts, such as the temperature of environment and of body, of mobility of cat, of its health, etc. You must care that cat usually has clear water (milk can't change water if it doesn't cues diarrhea). If your cat likes milk you may offer it special milk drinks with less contain of lactose in spite of cow milk, such as Whiskas Milk Plus for example, because adult cats lose their ability to adopt lactose. Try to change water at least three times a day.
Cat need more albumen than other animals. Healthy animals need for 2 g of high quality protein per day on each kilogram of weight. It is about 100 g of good beef. The quality of ration is usually set by the quantity of energy in it. The best ration for cat is that has energy (calories) of protein for adult cats no less than 21% of general calories. After some inventions it was known that cats must get amino acid taurine (with the aim of prevention the eyes illness) which is contained in protein. Companies which produce cat's food are recommended to include in it not less than 0.1% of taurine (0.1 g on 100 g of albumen). It is connected with specialties of substances exchange of cats.
Apart from providing of activity fats are important for adaptation of some other substances. About 60% of the whole energy of ration must be got in with fats. The normal diet is with 14-60% of fats (in dry substance). But we should know that cats like people may suffer from getting stout it they are motionless the main part of their life. Such advice has some danger because if the diet has much fats but is not provided with vitamin E then it may cause steatite ("soap stones" in the intestines). Fats of ration must also contain not less than 1% of linolic acid and 0.1% of arachydonic acid. Most illnesses are accompanied by weakness or absence of appetite and that is why cat gets little necessary substances and energy. In such cases it there are no direct complications it's better to add some more fat to the food. Because in such cases you must less the dose of protein and compensate energetic loses with fats and carbohydrates.
Carbohydrates (noodles, bread, sugar, starch, cellulose) are not obligatory in the cat's ration. But because of their relatively low cost they can be taken as cheaper source of energy than protein or fat. The products which contain starch (potato) must be prepared (boiled). In other case they are bad adopted and may cause different damages of intestines.
About needs for vitamins of cats much written a lot. Here are the points which differ cats from another animals (mostly from dogs as the most popular competitors in friendly relations with people).
Vitamin A is necessary in diet because cats unlike other mammals can not turn carotene (predecessor of vitamin A) into the active vitamin A. The sources are fish, fish oil, liver, synthetic medicines.
Vitamin D. Classical sign of rickets which is caused by the lack of vitamin D are seldom for cats. It happens with kittens whose mothers were usually in dark rooms and were poor of calcium, phosphorus and vitamin D in their rations. It is necessary to avoid big portions of vitamin D (hypervitaminosis is more dangerous than the lack of vitamins).
Vitamin E. As it was said before the lack of this vitamin causes steatite especially if the diet contains much fats (the case is in fat acids). Especially it concerns the fat of sea fish. The recommended daily portion of vitamin E for prevention is 30 mg. The sources are grass seeds and oils; synthetic medicines.
Vitamin B1 (thiamine). Cats need it five times more than dogs! It is better not to feed cats with fresh fish because it contain ferment thiaminase which destroys this important vitamin. Danger of this situation is that the clinical picture of lack of thiamine is much alike to that of poisoning and may deceive even the specialist. If the quantity of fresh fish is more than 10% of day ration of cat then it is necessary to give this vitamin to the cat.
Vitamin B2 (riboflavin). The lack of it causes fat reborn of liver, damage of sexual function, bolding around the ears.
Vitamin PP (nicotine acid). The lack of it also causes hard for diagnostic condition. It should be marked that the signs of lack of vitamin PP, B2 and B1 sometimes grows because of rations with too high level of energy because in such cases the animal gets less the general using of food and, with it, of vitamins.
Vitamin B6 (pyridoxine). The lack of it causes lose of weight, anemia (it is not cured with medicines of iron and cuprum) and damage of kidneys.
Vitamin H (biotin). The lack of it causes different dermatitis and anomalies of fur growing, blood diarrheas.
There are also some differences in this group from the other mammals.
Ca:P (calcium: phosphorus). These trace-elements are described together purposely because their actions biologically connected with each other. The lack of calcium or plenty of phosphorus (which decreases getting of calcium) may cause food secondary hyperthyroidism (damage of vertebra apparatus with the following temporary or constant paralysis, "washing out" the calcium from the bones of vertebra and pelvis). In other words: on 1 g of calcium must be 0.8 g phosphorus. If there is more phosphorus then the plenty of it will disturb getting of calcium. It means that you must not only give to your cat necessary portion of calcium but also give to eat restricted portion of phosphorus.
J (iodine). The lack of it caused by the plenty of meat in the ration, but it practically can't be found in sea fish or commercial seeds.
Fe, Cu (iron and cuprum) are contained in meat. They are adopted by cats very well. The lack of these elements cause complications seldom.
Zn (zinc). Adaptation of it is connected with iron and cuprum. The lack of zinc causes damages of eyesight, discolor of fur, weakness.
Mn (manganese). The lack of it is not described. The plenty of manganese causes falling of the level of prolific.
Remember! Canned goods for people are not useful for cats because they contain roots and substances which are harmful for the cats.
I recommend to feed your cat with canned goods. They are the most expensive but also the most useful kinds of food. besides, I let my cat eat dry food during 24 hours (remember about water!). It doesn't matter how many times you feed your cat if it is not inclined to overeating.