Vince the Vet - Better Nutrition Better Health Series - 3. Why Protein Quality Is Key

Vince the Vet - Better Nutrition Better Health Series - 3. Why Protein Quality Is Key

20-08-17

We saw in article 1 of this series that carnivores need a diet rich in animal protein to supply the building blocks (amino acids) for healthy organs, tissues and cells.

It is also needed for the production of digestive enzymes, antibodies, hormones and many other 'functional' molecules in the body, without which a wide range of diseases affecting digestion, nerve function, musculoskeletal health, the immune system, skin, endocrine glands and many other parts of the body will occur.

Cats have an even higher requirement for protein than dogs, because unlike their canine counterparts who can obtain a significant amount of energy from carbohydrates (although this is not recommended for reasons which will be covered later on) they need protein for energy too. As such they are called obligate carnivores, which means that an almost entirely meat diet is necessary to provide the nutrients necessary for cats to be as healthy as they can be.

Given the importance of dietary protein for the health of our dogs and cats, it is good to know where it comes from and which sources are best. 

 

Quantity

Different parts of an animal contain different amounts of protein.

This is how the 3 commonest sources of protein used in raw food compare:

 

SOURCE % PROTEIN (approximate)
Muscle meat eg sirloin 25
Heart (cows) 17
Tripe (cows) 12

 

It can be seen from this that muscle meat is the richest source of protein of the three.

Heart is next, with tripe supplying the least.

These figures also show that if muscle meat is replaced by heart (which contains 8% less protein) 50% more would need to be fed to make up for the fall in protein caused by the switch.

And so if a pet needs 100g of muscle meat in their diet each day for optimum health and this is replaced by heart, 150g of this would need to be fed to supply the same amount of protein as before.

And if muscle meat is replaced by tripe (which contains 50% less protein) double the amount would need to be fed to make up for the fall in protein caused by the substitution.

And so if a pet needs 100g of muscle meat in their diet each day for optimum health and this is replaced by tripe, 200g of this would need to be fed to supply the same amount of protein as before.

Given that heart and tripe are far cheaper than muscle meat, it's tempting to use these as sources of protein instead, but there are drawbacks to this as we shall see.

 

Quality

When judging how beneficial a food is as a source of protein, it is important to consider not only the amount it containsbut it's quality, which determines how much of it can be used by the body.

HIGH QUALITY PROTEIN is easy for the body to digest, absorb and utilise to support health.

POOR QUALITY PROTEIN is harder to break down, uses up more energy in the process and provides less nourishment to the body.

The distinction between the two is important.

Eggs, beef and fish for example are not only high in protein, but the quality is high too, making them valuable sources of this nutrient.

Feathers and hair on the other hand, although high in protein, the quality is poor making them virtually indigestible (despite this however, they are used as ingredients in some processed dog and cat foods).

So how do muscle meat, heart and tripe compare in this respect?

Muscle meat supplies high quality protein, which is easiest for pets to digest and is readily utilised by the body.

Heart supplies good quality protein, which is harder to digest (due to a higher elastin content).

Tripe supplies the poorest quality protein, which is hardest to digest because it contains a higher percentage of elastin and connective tissue (which allow the stomach to stretch to accommodate the intake of large amounts of food). 

 

Summary

From the above this is how the three commonest sources of protein in raw food compare:

SOURCE % PROTEIN (approximate) PROTEIN QUALITY DIGESTIBILITY ADDITIONAL AMOUNT NEEDED* COST
Muscle meat eg sirloin 25 Highest Easy  0 Expensive
Heart (cows) 17 Medium Harder 50% Cheaper
Tripe (cows) 12 Poorest Hardest Double Cheapest

*How much more would need to be fed to supply the same amount of protein to a pet as the right amount of muscle meat.

 

Heart and Tripe

If heart is a good source of protein and is much cheaper than muscle meat, why not feed large amounts of this in the diet instead?

Heart is interesting. It is an organ and can therefore be classed as offal. It is also a pump however, and so is composed largely of muscle. For this reason, it is rich in salts which if fed in too large a quantity can cause gastrointestinal irritation and diarrhoea, and possibly other health disturbances too. For this reason the amount fed to many dogs and cats - particularly those with sensitive bowels - is best limited to around 10%

Tripe is a very cheap source of protein. At half the level of muscle meat however, twice as much needs to be fed to provide an equivalent amount. In addition to this, the body has to expend significantly more energy breaking tripe down, which leaves pets nutritionally less better off as a result. And if a dog or cat has any kind of a health problem, wasting energy in this way is best avoided, so that the body's energy reserves can be conserved and directed towards healing and maintaining quality of life. 

 

Offal and Protein 

Liver and kidney were mentioned alongside heart in article 1 as the three most nutritious organs (offal).

These too supply good quality protein. Like heart however, they are also rich in nutrients which can cause bowel disturbances and so are best fed to most petsin small amounts only.

 

Assessing Protein In Raw Food

So lets look at some raw beef recipes and score them for protein quantity and quality.

High = high protein content, high quality and easy to digest source.

Medium = moderate protein content, lower quality and harder to digest.

Low = low protein content, poorer quality and hardest to digest.

 

Vince the Vet Superfood Raw Beef with Beef Offal

Protein sources = minced beef meat 70%, beef offal 20% (heart, liver and kidney)

Percentage muscle meat = 70%
Percentage heart   = ?
Percentage tripe = 0
Quality score (high, medium, low) = high

Recipe Raw Beef A

Protein sources = beef heart, green tripe and liver(45%), chicken

Percentage muscle meat = ?
Percentage heart   = ?
Percentage tripe = ?
Quality score (high, medium, low) = medium / low (depending on percentages of chicken, heart and tripe which can't be determined from the label) 

 

Recipe Raw Beef B

Protein sources = 85% fresh meat and offal - beef heart, green tripe, kidney, liver

Percentage muscle meat = 0
Percentage heart   = ?
Percentage tripe = ?
Quality score (high, medium, low) = medium / low (no muscle meat present and proportions of heart, tripe and other offal not specified)

 

Recipe Raw Beef C

Protein sources = 80% meat, bone and offal - 1% egg, beef with bone, liver, kidney, heart

Percentage muscle meat = ?
Percentage heart   = ?
Percentage tripe = 0
Quality score (high, medium, low) = medium / low (only 80% meat, bone and offal, and of this no percentage of muscle meat, heart or offal specified)

 

Using these as examples, how would you score the following recipe when considering feeding it to your pet?

Recipe Raw Beef D

Protein sources = 80% raw meat and bone - beef, heart, liver,

Percentage muscle meat = 
Percentage heart   = 
Percentage tripe = 
Quality score (high, medium, low) = 

 

In the next article in this series, we'll take a look at the importance of offal and bone...

 

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