27 December 2010

Commercially produced dog food ~ making sense of the label

Commercially produced dog food - kibbles, cans and pouches - is big business, and with such a wide and differing range of brands and varieties, all claiming to be the best food that you could possibly give to your dog, picking the right one (or even a good one) is confusing to say the least. Even a high price is no guarantee of nutritional quality - maybe of quality of ingredients, but whether those ingredients are biologically appropriate and digestible requires a bit of study.

There's a TV advert for a particular brand of dry kibble that annoys the pants off me, in which a 'clever collie' claims that gram for gram, his kibble contains more high quality nutrition than canned food, so much so that for every 3kg bag of this kibble you'd have to feed up to 37 cans. The real deal is that this kibble uses cereals and grains as bulking agents, whereas any canned food uses water. Water is not considered to be a nutrient and so therefore has no nutritional value, and so it's simply a case of mathematics that gram for gram, any dry kibble will contain more high quality nutrition than any wet canned food because a dry kibble will contain around 10% moisture (i.e. water) and a wet canned food around 80%. That's 90% dry ingredients compared to 20%.

However, based on the average can size of 400g, 37 cans (14.8kgs) amounts to 2.96kgs (20% of 14.8kgs) of dry ingredients compared to 2.4kgs of dry ingredients (80% of 3kgs) for the kibble in the advert. So gram for gram of dry ingredients - and bearing in mind that many canned foods contain little or no cereal/grain as an added ingredient to the meat content (i.e. high quality nutrition) and so on average, say around 80% of the dry ingredients will be meat (2.37kgs) - the kibble in the advert actually contains considerably less high quality nutrition at around only 25% meat content, which equates to just 600g high quality nutrition for every 2.4kgs of dry ingredients for the kibble in comparison to 1.92kgs for every 2.4kgs of dry ingredients of canned food (1.92 arrived at by dividing 2.37 by 2.96 and then multiplying by 2.4).  So by my reckoning, gram for gram of dry ingredients - i.e. the ingredients that are considered to be nutrients so not including water - the average canned food actually contains over 3 times as much high quality nutrition as the kibble in the pants-off-annoying advert. But then as the dog in the advert freely admits, he's no good at counting.

There's a formula to convert foods to 'dry matter basis' that I have included further on, but there's more to understanding dog food labeling than subtracting the moisture content, so please keep reading ...

CRUDE SOURCE ~ The protein and fat levels are listed as crude sources, not as digestible sources. The digestibility of protein and fat varies widely depending on the source. The ingredients should be examined closely to determine how digestible the crude sources actually are. As a rough guide, crude protein and fat from animal sources such as meat, poultry, fish and eggs are highly digestible protein sources for dogs. Crude protein and fat from cereals and pulses offer low digestibility.

GUARANTEED ANALYSIS ~ The guaranteed analysis information panel lists the minimum levels of crude protein and fat, and the maximum levels of fibre and water. This information is a legal requirement for pet food labelling in many countries including the US, Canada, UK, Europe, New Zealand and Australia.

ORDER OF INGREDIENTS ~ The legislation covering the listing of ingredients in UK manufactured pet foods is vague to say the least. Currently, the FSA (Food Standards Agency) requires that the ingredients in livestock food be declared and listed in descending order of weight, but pet food manufacturers have the option to declare them by category, e.g. ‘meat and animal derivatives’, ‘oils and fats’, ‘cereals’, ‘vegetable protein extracts’. Declaration by categories allows for fluctuations in the supply of the raw materials used and provides flexibility for labeling ingredients without incurring costs.

A vast number of often-perceived ‘British’ brands, including Royal Canin, James Wellbeloved, Winalot, Pedigree, Cesar and Chappie, are actually owned by UK subsidiaries of large American corporations. For pet foods produced in the US, ingredients must be listed in order of weight. This presents the best way to determine the quality of the food, and with a little knowledge of the ingredients, a food that is highly digestible and free from unnecessary ingredients can be chosen.

Be careful not to fall for the tactics of some manufacturers – ingredients are often split into several, smaller ingredients, for instance, although the first (and therefore heaviest) ingredient may be brown rice say at 63%, what follows might include chicken meal say at 20%, rice flour, rice gluten, oats, sunflower oil, chicken fat, mixed tocopherols, vitamins, minerals. In a dry food, the last three ingredients will be present in tiny amounts and therefore weigh virtually nothing, so if 21% of the total weight is from chicken sources (20% meal + 1% fat) at least 73% of the weight is from cereals (not 63% as the first ingredient would suggest) with the remaining 6% being mostly moisture.

Going back to crude sources of protein and fat, these are likely to be 18% and 7% according to the particular dry food example outlined above, however, with brown rice, rice flour, rice gluten and oats making up at much as three quarters of the food’s weight, a substantial part of the crude protein content is coming from low digestibility cereal/grain sources. The same goes for the crude fat at 7% - sunflower oil is listed before chicken fat, so this could constitute a 6:1 ratio of low digestibility sunflower oil to highly digestible chicken fat.

NUTRITIONALLY COMPLETE? ~ To be labelled as ‘complete’, a food needs to provide levels of protein, fat, etc, according to the recommendations and standards of AAFCO (the Association of American Feed Control Officials). AAFCO has two standards – lower and higher. To qualify for AAFCO’s higher standard, a food has to have been tested on a population of animals for six months and shown to provide adequate nutrition. Such a label might read ‘provides complete and balanced nutrition’. Testing a food for six months is not long enough to determine if deficiencies or other long-term effects may occur once the product has been fed for a year or more. Also, the manufacturer can use this statement on other products in the same ‘family’, without those products having to undergo independent testing.

On pet food labels that meet AAFCO’s lower standard, a statement such as ‘formulated to meet your dog’s nutrient requirements’ might be present. The right combination of leather, motor oil and coal would meet this requirement, so even though a food may measure up to the lower AAFCO standard, it can be of extremely poor quality with regards to its digestibility and ultimately its nutritional value.

There are currently no ‘nutritionally complete’ standards or recommendations from the FSA for UK manufactured pet foods, although most manufacturers choose to produce their foods according to AAFCO standards. Foods labelled as ‘complimentary’ are not considered by AAFCO standards to provide adequate nutrition.

INGREDIENTS ESSENTIAL TO GOOD AND LONG-TERM HEALTH ~ Most commercially prepared dog foods are, in my opinion, not nutritionally complete, despite the claims on the labels. Biologically inappropriate low-meat-content/high-cereal-grain-content aside, there is no legal or formal requirement for pet food manufacturers to include essential fatty acids (EFA’s) in their products. EFA’s are more commonly known as the ‘omega’ oils, 3, 6 & 9. The clue as to why these fatty acids should be included in the diet is in the name really – they are ESSENTIAL. The body cannot make EFA’s from fat, and so needs to be provided with them in raw form. Some pet foods will say ‘includes EPA and DHA’ – these are the abbreviated names for the two main types of omega 3, however, as with protein and fat, these can be of high or low quality depending on the source (from fish = high, from sunflower oil = low) and depending how they are processed, they can end up having very little usable, nutritional value. GLA is the chemical abbreviation for omega 6 (linoleic acid), and omega 9 is often referred to as oleic acid. Oleic acid is only of nutritional benefit if it has not been heated – the manufacturing processes of both dry and tinned foods involves heat, and so any oleic acid contained in the food will be rendered ineffective by the process. Vitamins such C and K are absent in many ‘complete’ foods, and levels of B vitamins may be inadequate too.

CONVERTING FOODS TO ‘DRY MATTER BASIS’ ~ All pet foods have a moisture content. Canned foods can contain as much as 80% moisture, whereas some dry kibbles can have as little as 6%. Converting foods to their ‘dry matter basis’ is necessary when comparing crude protein and fat levels between different brands. The listings on the label are for the food as it is, including moisture, so without converting each brand to a dry matter basis, an accurate comparison cannot be drawn. The conversion is not complicated and is calculated as follows:

If a dry kibble food has 10% moisture, we know that its dry matter content is 90%.
So if the protein level on the label reads 20%, we need to divide the 20% protein by the 90% dry matter to get 22%. 22% is the crude protein content of the food on a dry matter basis.

If a canned food has 80% moisture, we know that its dry matter content is 20%.
If the label shows 5% protein, we need to divide this by the 20% dry matter to get 25%.
25% is the crude protein content of the food on a dry matter basis.

The same formula is used to calculate the dry matter basis for fat, fibre, etc.  It may seem that with tinned food, such a high moisture content makes the food more expensive when compared with dry kibble because you are paying for 80% water and only 20% food, however, the crude protein source of most canned foods comes from meat. Much of the crude protein source in the vast majority of dry kibble comes from grains/cereals, and so on a dry matter basis, the 25% protein content of a canned food not only exceeds the 22% protein of the dry kibble in amount, it is of a far higher quality too. In addition, because water is used as the bulking agent in wet food, canned foods rarely contain inappropriate levels of cheap, low digestibility cereal/grain sources and are therefore more in line with a biologically appropriate diet.

So what is a 'biologically appropriate diet' anyway?  Biologically, the dog is a carnivore, therefore a biologically appropriate diet for a dog means a diet that is suited to the digestive tract of a carnivore.  Ideally, this would consist of the whole, raw carcasses of animals of an appropriate size for a dog to catch and kill on its own, however, in reality, although the dog is technically a carnivore and to varying degrees has the instinct to hunt live prey, it is also an opportunist and a scavenger  – and domesticated.  The normal diet of a  free-roaming 'village dump dog' consists of any old scraps of raw and cooked food that have been thrown away by humans and a smorgasbord of faeces (including human) – and occasionally, anything living and small enough that the dog is able to catch and kill (mice, rats, etc).  So perhaps, although not biologically appropriate, this is a more natural diet for the self-domesticated dog?  I can't see pet food manufacturers basing their recipes on it though.  My point is that whilst a diet based on whole raw carcasses is the most biologically appropriate way to feed a dog, the dog's digestive tract is pretty adaptable, however, biologically, it is simply not geared up for the effective digestion and assimilation of complex carbohydrates (grains and cereals) and over time, this can lead to gut problems and nutrient deficiencies.

My advice to clients is, if you want to feed kibble, choose a high quality, meat-based, no-grain/cereal kibble such as Acana, Origen or Applaws.  If you want to feed canned, choose from those that contain high-quality and/or organic ingredients such as Terra Canis, Hermanns Organic, Bozita or Lukullus.  And if you want to feed raw, there are a number of commercially prepared options available ...  http://liziangel.blogspot.com/2011/05/raw-convenience.html      


Don't just be a dog owner - be an informed dog owner.   

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