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.
When they were kittens the cats would use the same Litter Robot but they are now big cats and one prefered using a 'regular' litter box. But we weren't too happy about that! When we saw this new model, we crossed our fingers and decided to give it a try, hoping our cat would like it. And he did!!!