Why do dogs need protein?

Protein is required to supply dogs with essential and non-essential amino acids. Essential amino acids are those the dog does not produce in sufficient quantities and therefore needs to consume them in their diet.

Essential amino acids are threonine, valine, methionine, isoleucine, phenylalanine, histidine, tryptophan, and lysine.

The dog needs amino acids to maintain body protein such as skin, hair, skeletal muscle, digestive enzymes, hormones and serum transport proteins. (Case et al 2011, Billinghurst 1993)

How much protein does my dog need?

Factors that affect how much protein a dog needs include:

• The quality of the protein source – as the quality of the protein source increase, the amount your dog needs decreases.

• The number of amino acids provided.

• The digestibility and availability of amino acids in the protein source.

• Energy density of the protein source.

• Your dog’s activity level.

• Your dog’s physical state – are they lean and healthy or obese and inactive?

• Dog’s stage of life – dogs need more protein when they are growing, during pregnancy or when lactating.

(Case et al 2011, Nap et al 1991, Billinghurst 1993)

How can you measure the quality of protein?

The quality of protein can be measured in three ways.

1. The composition of essential amino acids it provides. Essential amino acids are those that the dog needs to eat because their bodies cannot produce it in sufficient quantities, if at all.

2. Digestibility of the protein can be measured as the difference between the amount of protein consumed and excreted.

3. Bioavailability of amino acids is the amount of amino acid that is available to have an active effect in the dog’s body. Bioavailability of amino acids are based on a number of factors including exposure to heat, oxygen and combination with other food sources. Look out for a future blog about factors that affect bioavailability,

(Gilani et al 2005, Williams et al 2001)

What are the best sources of protein for dogs?

Based on the composition of amino acids and digestibility, the best sources of protein in order of quality are:

1. Animal sources such as muscle and organ meat.

Meat contains all the essential amino acids with beef containing the highest amount of protein followed by lamb, chicken and pork. Unlike other protein sources, meat is highly digestible. In a study of rats, animal sources of protein were found to be 93 – 100 % digestible. (Gilani et al 2005, Billinghurst 1993, Williams 2007, Barroeta 2007)

2. Chick peas, overheated skim milk, rolled oats, whole wheat cereal, pea protein concentrate.

In the rat study, these protein sources were found to have 86 – 92% protein digestibility. Additionally, grain does not contain all the essential amino acids. It lacks lysine. Similarly, legumes are not a complete protein source as it lacks the amino acid methionine. (Gilani et al 2005, Billinghurst 1993)

3. Beans, lentils, grain, legumes and pulses

Lentils and grain are an incomplete source of amino acids: they are deficient in lysine and methionine. Further, these protein sources were found to have 73 – 84% protein digestibility. Rice is a popular inclusion in home cooked diets however it is low in protein and contains no lysine. Likewise, wheat is the principle protein source in many commercial pet foods. While it contains nearly twice the amount of protein as rice, compared to animal sources, it is a poor quality protein. (Gilani et al 2005, Billinghurst 1993)

Full Stride works with clients to formulate nutritionally complete diets that suits dogs and owner’s lifestyles. For more information please email me at jlconlon@fullstride.com.au.

Subscribe to my blog for notification of future blogs about how to prepare grains so they are nutritious for your dog and the factors that affect the bioavailability of amino acids.

Until next time, enjoy your dogs.

Sources:

Barroeta, A, 2007, “Nutritive value of poultry meat: relationship between vitamin E and PUFA”, World’s Poultry Science Journal, Vol 63, 277 – 284

Billinghurst, I (1993), Give your dog a bone:the practical common sense way to feed dogs for a long and healthy life, Warrigal Publishing, Bathurst NSW.

Case, L.P, Daristotle, L, Hayek, M & Raasch, M.F, (2011), Canine and feline nutrition (3rd ed), Mosby Elsevier, Missouri.

Gilani, G. S, Cockell, K.A. & Sepehr, E (2005). “Effects of antinutritional factors on protein digestibility and amino acid availability in foods.” Journal of AOAC International 88.3: 967-987.

Nap, R.C, Hazewinkel, H.A.W, Voorhout, G, Van Den Brom, W.E, Goedegebuure, S.A, Klooster, A.T.V.T, 1991 “Growth and skeletal development in Great Dane pups fed different levels of protein intake”, The Journal of Nutrition (121), S107-S113

Williams, C.C, Cummins, K.A, Hayek, M.G, Davenport, G.M 2001, “Effects of dietary protein on whole-body protein turnover and endocrine function in young-adult and aging dogs”, Journal of Animal Science (79) 3128 – 3136

Williams, P.G. 2007 “Nutritional composition of red meat” Nutrition & Dietetics, 64 (Suppl 4) S113 – S119