Fat Content in ZIWI Recipes
At first glance, it might look like ZIWI Peak recipes contain a high level of fat. This is especially so if people are used to feeding kibble.
The high level of crude fat percentage in ZIWI Peak recipes is due to the lack of carbohydrates in the recipes. As per AAFCO and NRC guidelines (*see below for explanation), carbohydrates are not considered an essential dietary nutrient for dogs and cats. Dogs and cats source glucose and energy from fat and protein.
The fat in ZIWI Peak recipes is the fat which naturally occurs in the meat of the source animal species. On examining the nutritional analysis, the fat percentage may look high because of the low moisture in air-dried ZIWI Peak - the air-dried recipes contain less than 14% moisture. The fat in ZIWI Peak recipes is similar to what you would find in raw or cooked meat, it just has the moisture removed.
(* The National Research Council (NRC) and AAFCO publish nutrient profiles for dogs and cats for various life stages. They aim to list minimum nutrient requirements and maximum nutrient requirements for nutrients with potential toxicity. To read more about AAFCO, click here.)
Is a diet high in crude fat % healthy for dogs and cats?
Dogs and cats are classified as “high density lipoprotein mammals” and express atherogenic resistance (NRC, 2006). High-density lipoprotein, or “good” cholesterol, absorbs cholesterol and carries it back to the liver. Thus, dogs and cats can tolerate high dietary fat (lipid) concentrations. Even if obese, dogs do not develop fasting hyperglycaemia, atherogenic hyperlipidaemia, or type 2 diabetes (see Verkest, 2014). For dogs and cats, dietary fats are an essential nutrient. Indeed, essential fatty acids must be contained in the diet as these are unable to be synthesised by the body.
Lipids provide a carrier for fat-soluble vitamins; they are essential for the absorption of the vitamins A, D, E, and K. When there is insufficient fat in the diet, these vitamins cannot be absorbed efficiently, and deficiencies can arise as a result. Dietary fats generally improve the palatability of food and add an acceptable texture to foods. Palatability tests generally show that dogs and cats find ZIWI Peak to an extremely palatable food.
The digestibility of fat is higher than that of carbohydrates and proteins, and fat contains approximately three times the energy. Fat accounts for approximately 2.25 times the metabolisable energy (ME) of either protein or carbohydrates (NRC, 2006). Even though fat may be only a small percentage of the diet, it can provide most of the kilocalories.
The main use of fat in the body is energy storage. Animals have an unlimited capacity to store excess energy as fat, whereas they have a limited capacity to store carbohydrates as glycogen. Glycogen is made up of many connected glucose molecules and is the stored form of glucose (NRC, 2006). Glucose is the main metabolite of carbohydrate digestion in humans. In dogs and cats, where there is an absence of dietary glucose, through the process of gluconeogenesis glucose will be synthesised from amino acids and glycerol (NRC, 2006).
The dog is capable of meeting its metabolic requirement for glucose from gluconeogenic pathways throughout growth and adult maintenance, provided that sufficient fat and protein are included in the diet.
Cats are in a constant state of gluconeogenesis, and do not appear to utilise carbohydrates as rapidly as do dogs. Cats have lower rates of glucose utilisation; they have lower levels of glucokinase activity, a hepatic enzyme that in other species adjusts to diet and blood glucose levels (NRC, 2006). Additionally, cats have comparatively longer blood glucose elimination times. Even though cats can readily absorb dietary carbohydrates, the utilisation for the resulting glucose is not efficient (NRC, 2006).
When consuming a higher fat diet, dietary protein is required as dispensable amino acids to provide nitrogen and carbon for the synthesis of energy through gluconeogenesis. For either dogs or cats that consume primarily animal tissue, amino acids provide carbon chains for gluconeogenesis to supply glucose to tissues that require it to maintain normal tissue metabolism (NRC, 2006).
The risk with a high fat diet occurs when the diet is low protein and high fat. When the diet is rich in bioavailable, high quality protein, this risk is negated for an average dog or cat. Studies have reported tolerance for 40 percent fat (Ivy, 1936; Axelrod et. al., 1951). However, when dogs were fed a low protein, high fat diet containing 7g of lean meat and 10g of lard per kilogram of body weight, along with 50g sucrose plus vitamin and mineral supplements, pancreatitis was induced (Lindsay et. al., 1948). ZIWI Peak has a digestibility rating of over 95%, and is rich in quality, highly bioavailable meat protein sources.
Currently, the NRC states that the safe upper limit for total dietary fat is approximately 70 percent metabolizable energy (NRC, 2006). All the ZIWI Peak recipes are inside this safe upper limit.
Why Fat is the Preferred Energy Source for Carnivores
(rather than carbs)
What about pancreatitis?
Most cases of pancreatitis in pets are idiopathic. Many veterinarians are concerned about fat consumption as a cause of pancreatitis in dogs, but fat does not actually cause pancreatitis.
In a 2009 study, using 10 healthy adult dogs, it was found that dietary fat content had no effect on serum cTLI, cPLI, or gastrin concentrations (James et al., 2009). In this study, dogs were fed one of four diets. Diets A and B contained 16% and 5% crude fat, respectively; diet C was composed of diet A with pancreatic enzymes; diet D was composed of diet B with pancreatic enzymes and MCTs.
It was found that serum cTLI, cPLI, or gastrin concentrations in the dogs did not differ among the different diets fed, among dogs, or over time. When multiple comparisons were analysed, diet D caused the least amount of measurable pancreatic response, although this difference was not significant.
A relevant factor for pancreatitis is certainly dietary indiscretion (i.e., consuming things that aren’t proper food, like garbage). A study in 2008 identified that ingesting unusual food items, table scraps and getting into the trash increased the odds of pancreatitis (Lem et al, 2008).
This is likely to be a relevant factor because QUALITY of fat is also as relevant as quantity of fat consumed.