Research Diets, Inc. has developed over 19,000 original OpenSource diet formulas, too many to list on this web site. Stock diets are a very small portion of our formula database. If you do not see the diet number you are looking for contact us for assistance. It is recommended that you contact one of our scientists to assist you before choosing a diet. New formulas are created daily as our scientists work with researchers, in complete confidence, to define their experimental protocol. One reason for such proliferation is that open formulas are easy to report, repeat and revise.
It is important that when modifications are made, the remainder of the diet should be identical to the unmodified control diet. This makes comparisons across experimental groups easy to make, since only one diet component is changing at a time. This concept is quite simple to understand when it comes to removing or adding components that do not have caloric content – vitamins and minerals for example. So when vitamin B6 is removed from a diet, no calories are removed – just the vitamin. Hence the experimental and control diet are different only in presence or absence of this vitamin.
Protein, carbohydrate and fat? At this point, it is necessary to introduce a concept called the nutrient-to-calorie ratio . Not to be confused with the caloric density (the number of calories per gram of diet), this ratio compares the level of a particular nutrient (or nutrient group) per calorie of diet.
When planning a study, the composition of the diet deserves attention. All too often in the literature, one will find that diets used in the experiments are not well matched, thereby introducing confounding factors. For example, in many cases a chow (cereal based diet) is used as a low-fat “control” diet for a purified high-fat diet. Chows diets contain plant-derived ingredients which are subject to changes in the growing season and will vary in composition at the time of harvest. Thus, diet formulas may change based on the nutritional composition. Purified ingredients, on the other hand, are highly refined and contain just a single nutrient (ie. sucrose = carbohydrate). These ingredients have little variability and therefore provide consistency between batches. There are numerous differences between chows and purified diets, creating countless variables, thus making it difficult to interpret the results when these diets are used together in a study.
The answer lies in the fact that animals will for the most part, eat for calories, not weight of food, in an effort to consume the same amount of calories over the long term. This means that if an animal is used to eating a low-fat diet and they are switched to a higher-fat diet which (because fat is such an energy-dense nutrient) contains more kcal per gram of food, they will (after a period of adjustment) spontaneously eat fewer grams of food. They do this in order to continue eating the same number of calories (not grams) of food as they were when eating the low-fat diet. The reverse is true if switched from a high- to a low-fat diet. Similarly, rodents will eat more grams of food when the levels of dietary fiber (which has no caloric content) are increased, thereby lowering the caloric density of the diet. (In reality the ability to eat for calories does not always hold true – some species/strains will not regulate feeding and will overeat when exposed to a very high-fat diet for example).
Knowing that the animals will generally eat for calories explains why diets of different caloric densities (high- and low-fat diets for example) should be formulated to have similar nutrient to calorie ratios. This ensures that per calorie of food consumed (but not per gram), animals consuming diets of different caloric densities will receive the same absolute amount of nutrients (except those changed by design).
OpenSource Diets Common Formulas:
These formulas represent some of the most common formulas we produce. For all other formula numbers please