Focus On Nutrients Part:2 Zinc (Zn)
By paying careful attention to detail and using lean meats, one can make homemade and prey model ruminant (beef, bison, lamb) diets with zinc contents that meet ancestral diet amounts, and scientific standards for adult dogs and all life stages for cats. Pregnant dogs and puppies require more zinc.
- No fatty beef diet I’ve ever seen or modeled meets zinc minimum standards unless supplemented.
- Chicken and turkey diets usually need the addition of either whole zinc-rich foods or supplements.
Zinc is an essential trace (meaning measured in parts per million, ppm or mg/kg) element for all mammals. Zinc has many essential functions, including being involved in cell replication, protein metabolism, skin function, wound healing, and plays a crucial role in the structure of biological membranes.
Lack of zinc in the diet has been linked to atrial fibrillation; GI problems including diarrhea, nausea, and decreased appetite; decreased sexual function; low sperm counts; poor wound healing; mental depression; skin and coat problems; and vision problems.
Even short term zinc deficiencies can have negative consequences. New research carried out at the Technical University of Munich has found that even minimal zinc deficiency impairs digestion, albeit without any typical symptoms such as skin problems or fatigue. Hence, short-term zinc deficiency in the diet should be avoided[i].
Obviously we need to make sure our dogs and cats consume sufficient amounts of zinc. In the ancestral diet of our dogs and cats – primarily wild prey animals – most of the zinc in large prey animals was in the muscles, liver and kidneys. In smaller prey animals, such as mice and rats, most of the zinc was in the bones, teeth, and hair, coat and skin, parts that are now difficult to feed. The table below shows the zinc content of typical prey animal parts.
AAFCO minimums for puppies is 25 mg/1000 kcal, for adults 20 mg/1000 kcal, kittens and adult cats 18.8 mg/1000 kcal. The typical ancestral diet contained 24 mg / 1000 kcal.
Table 1: Where the Zinc Is Found In Prey Animals
Most beef 80/10/10 or prey model diets using lean meats (90% and leaner) meet or are close to meeting AAFCO 2016, FEDIAF 2013, and ancestral standards. Using fattier meats than 90% or fatty sources of bone (see Ca and P blog) make it difficult to reach ancestral or scientific standards for growth without adding specific zinc-dense foods or supplements.
Table 3: Calories (kcal) Added For Every 1 mg Zn
Many bone-in chicken recipes that I’ve analyzed, even the lean ones, lack zinc, unless a lot of chicken hearts are used. For most homemade recipes using lean (skin and fat removed) bone-in meats, add 3 mg (about ½ oz. oysters) for every 1,000 kcal for adult, and 8 mg for growth. For moderately lean (1/2 the skin and fat removed), add 10 – 15 mg of zinc or add supplements.
What is 1,000 kcal (Calories)?
The amount of Calories a typical 40-pound dog consumes in one day
Ground beef, 1000 kcal
- 1 pound, 8.5 oz. (703 grams) 93% lean, raw
- 1 pound, 5 oz. (600g) 90% lean, raw
1 pound, 1 oz. (482g) 85% lean, raw
2/3rd pound (300g) 70% lean, raw
Our completed adult recipes (with 13% vegetables)
1.5 pounds chicken
1.6 pounds beef
Breeders and puppy families please note:
If you’re planning a litter, have a litter, or have a young puppy, whether you’re feeding dry, canned or raw foods, I highly recommend adding zinc-dense foods (those near the top Table 2) several times a week, starting before conception.
Boosting the Zinc Content of Dog and Cat Foods
Try to add foods with the most zinc per calorie. As I stated in the manganese, vitamin D and other blogs, there are at least seven essential nutrients that we worry about when making meat-based diets, and since we want to provide these nutrients with whole foods if possible, we need to solve each nutrient with foods providing the most of that nutrient per calorie. This is especially important for fat dogs and cats.
The best source of zinc, the most zinc per calorie, is oysters. When I bred dogs, I added oysters to the dogs’ diets starting one month before conception through weaning. I lived not far from the coast of Oregon (and before that Maine) so I was able to get oysters. But outside of coastal fishing towns, oysters are often hard to find and too expensive to feed often. That’s why supplements are often needed.
Types of zinc supplements used in commercial foods include zinc oxide, zinc sulfate, and chelated forms of zinc, including proteinates, amino acid chelates and polysaccharide complexes. Zinc oxide and zinc sulfate are not as bioavailable as are the chelated forms; in addition, these less expensive forms of zinc can interact with the fats in the diet, potentially causing rancid fats. (Darwin’s uses zinc proteinates and amino acid chelates.) IMO, one should avoid zinc sulfates and oxides in frozen chicken diets; the large amounts of polyunsaturated fats in chicken diets are more susceptible to oxidation than are the saturated fats in beef and bison foods.
Table 2: Zinc Content of Selected Foods
In mg/1000 kcal, number of grams of food needed for 1 mg of zinc, and calories added when adding 1 mg of zinc.
[i] Technical University of Munich (TUM). “Diet lacking in zinc is detrimental to human, animal health: Even moderate zinc deficiency is bad for digestion.” ScienceDaily. ScienceDaily, 9 June 2016.
Steve Brown is a dog food formulator, researcher, and author on canine nutrition. In the 1990s he developed one of the leading low-calorie training treats, Charlee Bear® Dog Treats, as well as the first AAFCO-compliant raw dog food. Since 2003 he has focused on research and education. He is the author of two books on canine nutrition (See Spot Live Longer, now in its 8th printing, and Unlocking the Canine Ancestral Diet (Dogwise Publishing, 2010); and a 40-page booklet, See Spot Live Longer the ABC Way.