Product labels: What are they saying?
When buying feed it is often difficult to understand the information on the label attached to the product. The information on a label is generally a combination of what has to be there legally and what the manufacturer wants to tell you about that product.
The example label below is similar to many labels on protein supplements.
|Equivalent crude protein||23%|
Common ingredients listed on labels
Crude protein: The total amount of protein in the feed. Crude protein includes true protein (from protein meals, grain, etc.) as well as protein derived from urea and Gran-Am®. Crude protein may also be listed as protein and total protein. (Protein contains nitrogen).
Protein from urea and Gran-Am: The rumen microbes use the nitrogen from these products to form protein. This protein is referred to as microbial protein. The nitrogen from these products is referred to as non protein nitrogen (NPN) indicating that it has been derived from a source that is not a protein. The microbes also use the nitrogen from the true protein in grass, protein meals and grains to form microbial protein.
Equivalent crude protein: The proportion of crude protein that is derived from sources of NPN.
Urea: The total percentage of urea included in the ration.
Sulphur: Used in conjunct with nitrogen, by the rumen microbes to form some amino acids. Sulphur and nitrogen are required in the ratio of 1S to 10N.
Calcium: Included in most commercial licks but rarely, if ever, deficient in grazing cattle.
Phosphorus: An important ingredient in phosphorus deficient areas.
Salt: Generally included to control intake of the supplement. The higher the salt content the less palatable the supplement.
Other minerals: Included to maintain a mineral balance. Minerals are generally divided into two broad categories.
- Macro minerals – needed by animals in grams per day:
- Micro (trace) minerals – needed by animals in milligrams per day:
Calculating protein in a feed
The protein in any feed is calculated by determining the amount of nitrogen in that feed and multiplying it by 6.25. This formula can also be used to calculate the protein equivalent of urea and other sources of NPN.
- Urea with 46% N x 6.25 = 287% protein
- Gran-Am with 20% N x 6.25 = 126% protein
In our example label, if you multiply the urea, 8%, by 287% it comes to 23% (rounded), which is the amount of equivalent crude protein shown on the label.
This demonstrates that of the total 30% crude protein, 23% is due to urea and the 7% comes from true protein such as protein meals or in some cases grain that have been included in the feed.
This can be done by calculating how much of the nutrient you are looking for is supplied in an arbitrary weight of the product. For example, 100g of this lick will supply 30g of crude protein (mostly from urea) and 4g of phosphorus. This means that you would have to feed 500g per head per day to supply the recommended 150g of protein but only 125g to supply the recommended 5g of phosphorus.
Russ Tyler, formerly Queensland Government.