Piper with Beef Liver and Potatoes This pet food has a high content of products of animal origin, including beef liver, a good source of easily digestible protein, fat-soluble vitamins, as well as zinc, magnesium, and selenium. The profile of fatty acids has been enriched with the addition of flaxseed oil. The saturated fatty acids contained in the food help maintain anti-inflammatory processes. The addition of potato improves the digestibility of the food and helps regulate the course of digestive processes.