Additional beneficial fats and water soluble vitamins and minerals can be found in an equal mix of kelp & alfalfa. Most pets will get all the calcium they need from bones but if they don't eat bones then you should add a commercial calcium supplement.
Essential fatty acid oils help development of your pets hair, heart, joints, skin and much more. For dogs, you can use a combination of plant and fish based oils but for cats use only animal and fish based oils.
As with everything else, use common sense with supplements and remember too much can be as bad as not enough. If you are unsure ask your animal health care practitioner or nutritional consultant for advice.