In this article, we will look at the benefits of feeding chicken eggs, raw or cooked, in a canine or feline's diet.
The egg is comprised of four main parts:
Yolk
Egg White or Albumen
Egg Shell Membranes
Egg Shell
In general, the shell contributes 9–11%, the yolk 25–33% and egg white 56–64%. The total edible portion of the egg is 89–91%. The egg yolk is a homogeneously emulsified fluid and is the first part of the egg to develop. Egg yolk is comprised of 51–52% water, 16–17% protein, 31–33% fat including cholesterol, fat soluble vitamins and pigments, 0.2–1.0% carbohydrates and some minerals (1%). Egg white is composed of mainly water (80%), and proteins (11%), with the remaining made up of carbohydrates (0.4%) and water soluble vitamins and pigments. Other inorganic components include phosphorus, magnesium and trace amounts of iron and sulfur comprises less than 0.05%.
The nutrient content of a large egg is shown in the table below. As can be seen from the table, protein and fat constitute the major macronutrients in the egg. (Cherian, 2009)
Egg Protein in Diets for Dogs with Kidney Failure
The following study from the Journal of Veterinary Internal Medicine takes a look at how egg protein can improve the health of dogs with renal/kidney failure, who must be kept on a low-protein diet. Previous studies have shown that reduced protein diets help improve morbidity and mortality of dogs with renal failure, however, the source of protein is another important factor.
Abstract: “The effects of two reduced-protein diets and a canine maintenance diet on renal function, nutrition, serum and urine acid-base and electrolyte values, and divalent ion metabolism were compared in Beagle dogs with induced chronic renal failure. Two reduced-protein (18%) diets differed in their protein sources. One 18% protein diet was formulated using egg protein as the only protein source. The other 18% protein diet was formulated using a mixture of animal and vegetable proteins. The 42% protein diet contained a mixture of animal and vegetable protein sources. Results of this study indicate that the egg-based and mixed protein-based diets had similar effects on most clinical and laboratory evaluations in dogs with chronic renal failure. However, the egg protein diet appeared to promote hyperchloremic metabolic acidosis. Both reduced-protein diets were beneficial in reducing azotemia, polyuria, hypermagnesemia, and fractional excretion of phosphorus compared with the 42% protein diet.” (Journal of Veterinary Internal Medicine 1988; p15-21)
The discussion section further reveals that “however, in three of seven dogs fed the mixed protein diet, but none of the dogs fed the egg protein diet, dry skin and increased shedding were observed. This finding may suggest a nutritional benefit associated with feeding the egg protein diet. The calculated indices of protein quality indicated only minimal superiority of the egg protein diet over the mixed protein diet. None of the other tests used to evaluate nutrition (serum albumin concentration, body weight, and packed cell volumes) indicated a benefit of the egg-based protein; however, these tests may be relatively insensitive indicators of overall nutritional status.”
Effect of Egg Whites on Protein-Deficient Dogs
Another study from the Journal of Nutrition explains that “continued feeding of egg white results in a decrease in the excretion of nitrogen on a protein-free diet (NEo). The data can be interpreted to mean that egg white spares body nitrogen. Regeneration of plasma protein increases in magnitude as the nitrogen balance increases on the positive side. Thus regeneration of tissue proteins in hypoproteinemic dogs as reflected in the increase of plasma proteins is a function of the nitrogen balance produced and therefore of K or K′.” (The Journal of Nutrition 1946, p237–247).
Egg Yolk on Bone Formation in Neutered Dogs
Looking at a third potential benefit of using egg in a dog’s diet, egg yolk has been shown to aid in bone metabolism/formation in young dogs shortly after orchiectomy, where bone density loss can occur due to changes in rates of bone resorption versus bone formation.
A 2015 study from Japan states that “we examined the effects of chicken egg hydrolysate (also known as “bone peptide” or BP) on bone metabolism in 5- to 8-month old orchidectomized dogs. The bone formation marker serum bone alkaline phosphatase (BAP) and the bone resorption marker urine deoxypyridinoline (DPD) were used as indicators to measure changes in bone metabolism. The following results were observed that serum BAP was higher in dogs fed BP-enriched food throughout the clinical investigation. Serum BAP was statistically significantly higher in dogs fed BP-enriched food than dogs fed non-BP-enriched food at 2 months after orchiectomy. This suggests that BP promoted bone formation immediately after orchiectomy.” (Kobayashi 2015)
Continued Discussion
As we can see from the studies referenced, eggs and their components (yolk and whites) have several health benefits that are evidenced by experimental results.
To recap, egg protein was shown to be beneficial for dogs with kidney failure, egg whites were shown to help re-establish serum protein balance in hypoproteinemic dogs, and lastly egg yolk was shown to promote bone formation in recently neutered dogs.
What we can take away from these findings is that chicken eggs are a great source of protein and other nutrients in a dog's diet, and can even help treat several health conditions in dogs. As seen from Table 16.1 at the top of the article, eggs provide a variety of important nutrients including vitamins A, D, E, and B.
Also of note is these vitamins are almost entirely found in the yolk of the egg, therefore if a dog or cat is only fed egg whites and no other appropriate vitamin source, you could run into a biotin (vitamin B7) deficiency among other possible deficiencies.
Egg shells are also a great source of calcium. If the home prepared diet for your dogs or cats needs a boost of calcium, you may consider adding homemade ground egg shell powder to meals. Shells from farm fresh eggs are typically safe to feed to pets as is. When it comes to store-bought eggs (from grocery stores in the United States), to reduce the risk of salmonella infection, eggs are washed and sprayed with a chemical sanitiser before they are sold to the public, so I typically suggest not feeding shells from eggs that have been sprayed.
Another source of protein and additional nutrients in an egg that must not be overlooked is the shell membrane!
Egg shell membrane can be a great diet supplement and promote joint health as a great source of hyaluronic acid, glucosamine, chondroitin, collagen, elastin, and plenty of essential amino acids.
In a 2016 study, eggshell membrane supplementation once daily was found to “significantly reduce joint pain and improve joint function rapidly and demonstrated a lasting improvement in joint pain leading to an improved quality of life. Moreover, a profound chondroprotective effect was demonstrated following 6 weeks of supplementation with eggshell membrane.” (Ruff 2016).
From its yolk to the membrane that lines its shell, the egg has several nutritional and health benefits for dogs and cats that make it a great addition in their diet!
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Want to compare the nutritional data between chicken eggs, duck eggs, goose eggs, quail eggs, and turkey eggs?
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Please consult physicians/veterinarians, and/or other trustworthy science-based sources for advice on human and animal dietary questions.
As always, I hope this post was helpful!
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xoxo
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