Raw lamb kidney may have palatability and nutritional advantages as a cat food ingredient over other co-products. Researchers at Massey University observed distinct differences among cats’ preference for various raw organ meats and co-products from cows and lambs. Likewise, raw ingredients from lamb and beef had different palatability. Overall, cats preferred liver and kidney from both species of livestock. Comparing equivalent raw ingredients from either animal, the cats tended to prefer lamb over beef.

The journal Animals published the study, which examined palatability of raw lung, heart, kidney, tripe, liver and mechanically deboned meat (MDM) from lamb and beef. Eight domestic short-haired cats ate each of the six lamb and six beef components. The researchers used two-bowl acceptance and preference tests to develop palatability ranking of ingredients within and among species.

While liver was the most palatable raw ingredient in the test, the scientists pointed out limitations in the ingredients use. Since liver contains high amounts of vitamin A, pet food formulators need to avoid upper limits for the vitamin’s inclusion in pet food. The researchers wrote that lamb kidney is a viable, highly palatable and safer alternative to liver for high value pet food.

Cats preferred lamb over beef ingredients, except for heart and liver, which were equal between species. The researchers suggested that the age of the animals at slaughter may have influenced this. In New Zealand, lambs are butchered at typically 4 to 9 months old, while farmers cull cows at 5 to 8 years generally. Off-flavors may develop as the animals age, or the ingredients may become tougher with connective tissue.