Protein Modifications to Purified Diets
We can alter the protein concentration of any purified diet; diets with high and low protein concentrations are possible. Protein levels are usually adjusted by making adjustments to either the carbohydrate level or fat level of the diet. These formulas can be "calorie-balanced" or "quantity-balanced." (For more information see About Diet Formulas.)
Traditionally and most commonly, milk casein is the source of protein in purified diets, often supplemented by one (or more) amino acid. Vitamin-free casein contains approximately 90-91% protein.
A number of purified diet manufacturers use in their diets less-expensive milk casein that is not vitamin-free; consequently, unknown and random amounts of various vitamins are introduced into each batch of diet without being recognized or reported. The protein content of this less expensive casein can also fluctuate significantly. This cost-cutting practice defeats the fundamental purposes of a purified diet – full knowledge of all ingredients, complete open formulas, and repeatable consistency, resulting in accurate, reliable data.
Consistent with the value of your research, at TestDiet® we use only the more expensive, more precise vitamin-free milk casein in our purified diets; and, we routinely assay our casein to confirm that the protein content is within tight tolerances.
Occasionally, soy protein is used as a protein source where the research protocol requires, e.g. when a diet from purely vegetarian or non-animal ingredients is desired. The researcher must be aware of the presence of phytoestrogens in all soy protein products and the estrogenic activity that may result in test animals.
The following diets were formulated for mice and rats by varying the protein levels in TestDiet® 5755 Basal Diet. The protein source was increased or decreased at the expense of carbohydrate. Young rats placed on TestDiet® 5767 5% Protein will just maintain their body weight. Our testing showed an average gain of two grams for a 28-day experimental period where barrier-sustained Sprague-Dawley rats were the experimental animals. Likewise, the use of TestDiet® 5779 40% Protein and 5787 High Protein 60% resulted in sub-optimal growth performance due to the high protein concentration and its effect on metabolism of the animal. Where desired, different protein sources may be used in lieu of the vitamin-free casein for specific research needs. Diets can be custom formulated to any protein level. Modifications of individual amino acids are also possible.
Just call and tell us what your needs are and let us make a diet to your specifications.
Examples of Protein Modifications to TestDiet® 5755 Basal Diet –
|
|
TestDiet® # |
|
0% Protein |
5765 |
|
5% Protein |
5767 |
|
8.5% Protein |
5769 |
|
12.5% Protein |
5771 |
|
16.5% Protein |
5773 |
|
19.0% Protein |
|
|
20.5% Protein |
5775 |
|
23.5% Protein |
5776 |
|
40% Protein |
5779 |
|
High Protein 60% |
5787 |
Protein-Modified Basal Diets Study
To study the effect of dietary protein level on the performance of male Sprague-Dawley rats, diets were obtained by modification of Basal Diet 5755. The animals used were barrier-sustained, weanling Sprague-Dawley male rats, ten replications (one animal/replication). The study took place over a 28-day period.
Data Summary
|
TestDiet® # |
5767 |
5769 |
5771 |
5773 |
5775 |
5779 |
5787 |
|
Protein Content, % Assayed |
5.0 |
8.8 |
12.5 |
16.6 |
20.6 |
39.1 |
58.8 |
|
Number of animals started |
10 |
10 |
10 |
10 |
10 |
10 |
10 |
|
Average Weight (grams) |
|
|
|
|
|
|
|
|
Initial |
48 |
49 |
49 |
49 |
50 |
50 |
50 |
|
Final (28 days) |
50 |
94 |
157 |
202 |
211 |
191 |
180 |
|
Average Gain (grams) |
|
|
|
|
|
|
|
|
0-28 days |
2 |
45 |
126 |
152 |
161 |
141 |
130 |
|
Grams Diet Consumed per rat |
|
|
|
|
|
|
|
|
0-28 days |
358 |
412 |
445 |
424 |
438 |
404 |
421 |
|
Grams Diet/Grams gained |
|
|
|
|
|
|
|
|
0-28 days |
193 |
11.4 |
3.6 |
2.8 |
2.7 |
2.9 |
3.3 |
7/10/00