Essential fatty acids (like omega 3 and omega 6 fatty acids) and fat soluble vitamins (Vitamin A, Vitamin E, Vitamin, D, Vitamin K). The plain fat is a nutrient too.
Kittens, generally, can begin to use a litter box at about four weeks of age, and a kitten being raised without its mother or adult cat will take slightly longer to litter train; so, keep this in mind when you begin the task of litter training your kitten. - Place the kitten in the box 1/2 hour after play or meals.
Stress is the most common behavioral trigger for house soiling. Many cats will urinate outside of the litter box in response to the box not being kept adequately clean. Cats may refuse to use a litter box in which they do not feel safe. Cats may refuse to use a litter box that lacks privacy. Cats in the house may urinate in any area that has previously been soiled, due to the odor of urine in that location. Elderly cats may suffer from cognitive dysfunction (senility), leading to a lapse in litter box habits. Urinating outside of the litter box occurs as normal marking behavior in some cats.