HOW TO COMPARE DOG FOODS
Every dog reeder and owner has experienced, what it feels like to face the wide choice of dog foods. Picking the right diet has become a misleading process. What´s the best for my dog and how would I know that? The labels on pet food packets give limited information about the nutritional value of the food. The following should help pet owners to evaluate different commercial pet foods.
The information on labels differ in countries, but in the EU they should be quite similar. The labels usually include the following:
- the name of the product (name, animal species, feeding goal, full food or dietary supplement)
- content of raw proteiin, raw fat, raw ash, raw fibre and humidity)
- content of A-, D3- and E-vitamins that are guaranteed to preserve until the end of expiry date)
- listing of single ingredients or their groups
- feeding guide
- neto weight
- „best before“ date
- adress of the manufacturer or the importer
This is what´s regulated by law, but this won´t give enough information t omake a right choice between foods with different content of proteins, fat or humidity. The same law won´t allow to give information about energy content, digestability or the fission of necessary fatty acids. Mentioning the carbs on the label is optional and therefore practically never done, but these things can easily be calculated.
The chemical analysis shows the percentual content of several nutrients. Percents are proportional to grams per 100 grams of food. 30 % of proteins means that 100 grams of food includes 30 grams of proteins. Chemical analysis shows the amount of proteins in food, but won´t tell anything about the quality or digestability. Fur and skind are also proteins, but undigestable. That´s why chemical analysis must be used with the list of ingredients, in which the sources of proteins are mentioned.
Studying and comparing the analysis of pet foods, humidity definitely must be considered. Pet foods differ hugely in their content of water. Cat´s and dog´s dry foods usually include 6-14% of water, but some wet foods even up to 70-80 %. To get a valid comparison of nutrients it is necesary to convert the contents of nutrients on a dry food basis.
Comparison of foods on a label basis (= a it is eaten)
Food A (dry) Food B(dry) Food C (wet)
Proteins 30 % 20 % 6 %
Fat 20 % 10 % 5 %
Humidity 8 % 8 % 80 %
Comparison of foods on a dry basis
Food A (kuiv) Food B (kuiv) Food C (konserv)
Proteins 32.6 % 21.7 % 30 %
Fat 21.7 % 10.9 % 25 %
Humidity 0 % 0 % 0 %
Formula: nutrients (f.e. proteins) % divided by dry substances of a diet
Content of dry substances = 100 % – humidity %
Food A: (30 : 92) x 100 = 32.6 % of proteins in dry substance
Food C: ( 6 : 20) x 100 = 30 % of proteins in dry substance
List of ingredients
List of ingredients is a conclusion of important nutrients used. It´s up to manufacturer whether to declare ingredients individually or to group them by categories. Quality seires pick the first method. It will give the most detailed information to the consumer. When they declare ingredients separately, for ex.: chicken, polutry, etc. , then the consumer can decide about the quality of proteins used. With the ohter method „meat and animal products“ can be found on the label and this won´t refer to which part of an animal was used, of which quality are the proteins used and even which animal´s meat was used.
Ingredients are listed by ranking – on the first place are those, which are included the most in a food, following by the ohter in decreasing order. The consumer will also see, whether the cereal proteins are used as a source of protein. Generally, the cereal proteins are of lower quality compared to animal proteins. It is important that the proteins used in dog foods would almost exclusively be of animal origin. List of ingredients will also show, whether the oils used are of vegetable or animal origin. Not all series write sources of fats on the label, some of them only write „oils and fats“. What´s more – some series won´t give any information about the way the product was made. Cooking technology, quality and sanitary standards during the manufacturing process are different for different manufacturers. The only indicator is manufacturer´s reputation and sometimes even not this.
Energy or calories is the pet´s primary need. Calories are the fuel of the body. The goal of feeding is to balance your pet´s energy need and the amount of calories offered with food. Animals eat to satisfy their calorie need, they don´t eat „percents“. The animal needs the exact same amount of calories, no matter if he´s eating diet A, B or C. A dog must eat more food that contains less energy per 100 grams, than the food that contaisn more energy per 100 grams. That´s why a packet that is Richter in energy lasts longer and therefore it will cost less to sum it up. Unfortunately the law won´t allow to show energy content on the label (kcal / kg of metabolic energy). This information can be found on the brochures given out by manufacturers or can also be calculated basing on the information on the label. Comparing the food eaten on the energy basis is the best option to compare different foods, especially when comparing dry and wet food.
The energy content can be calculated with the information on the label or determine with feeding test. The last option is the most thorough and trustable method. This information reflects the real amount of energy, that animal uses. The consumer should be aware of the fact, that when the manufacturer uses the „calculation method“, no further feeding tests are necessary. We can´t know whether the food has passed feeding tests or not, unless there´s a AAFCO (Association of American Feed Control Officials) or NRC (National Researche Council) mark on the packet.
In case of high quality ingredients the measured values of metabolizable energy are higher, than the ones acquired in calculation method. The calculation method has one shortage – the average values are used for digestability and quality.
We can give you a simple way to calculate the content of metabolic energy in the food as a guideline using the information on the label:
100 % -(protein % + fat % + ash % + fibre % + humidity %) = carbs %
1 g of proteins = 3.5 kcal of ME
1 g of fat = 8.5 kcal of ME
1 g of carbs = 3.5 kcal of ME
For example , food A:
30 % of proteins (= 30 g proteins in 100 g of food) x 3.5 = 105 kcal / 100 g
20 % of fat (=20 g of fat in 100 g of food) x 8.5 = 170 kcal / 100 g
31 % of carbs (=31 g of carbs in 100 g of food) x 3.5 = 108.5 kcal / 100 g
Sum: 383.5 kcal per 100 g (or 3835 kcal per kg)
To calculate, how much does a dog need a specific food per day, you must first calculate the daily energy need, depending on the weight and activity of the dog.
Formula: Metabolic energy need = K x BM 0,67
K = constant (according to activity level, not active: K = 132; active: K = 145; very active: K = 200; sledge dogs: K = 300)
BM = body mass
For example a 4-year-old, 15 kg dog needs about 889 kcal a day. The food calculated above (3835 kcal/ kg) he needs about 232 grams a day. That food which contains 3335 kcal / kg, he needs 267 g per day.
Labels must include the recommended amounts of food, which is expressed as a daily amount of food for a dog or a cat. Clear and detailed feeding guides help the consumer prevent misleading calculations, which can result in wrong amounts of food. Puppy and kitten foods must offer different dietaries depending on age and weight, because while growing the need of nutrients is crucial. But bear in mind: feeding guides are just general recommendations. Sometimes less or more food is required for maintaining the right condition, depending on the activity or changes in the environment.
Unfortunately the quality of foods cannot be compared just by reading the packet´s label. That needs time or knowledge of a reeder and even then the label gives incomplete information. If you can´t reach a decision, please don´t hesitate to ask for our advice!