More on a Feed Tag
The following information appears on a feed tag of a protein supplement. Because the feed is a protein supplement, the name on the tag usually indicates the percentage protein that the supplement contains. As an example, let's evaluate the feed tag of a medicated protein supplement called Protein Gem Fortifier 32-10 B70. The 32-10 indicates that this supplement is a 32% protein supplement and that 10% comes from a non-protein nitrogen source; therefore 22% coming from an all natural protein source (see the example below). The guaranteed analysis will indicate that this feed has a Min. (minimum) of 32% crude protein.
An example from a feed tag.
- Crude Protein (not less than) 32%
- Protein Equivalent from NPN (not more than) -10%
- Amount of Natural Protein 22%
You can determine the proportion of the protein in a supplement that is supplied by the NPN source(s) by dividing the percentage of protein equivalent from non-protein nitrogen by 2.81 if the NPN source is urea. Urea is 281% crude protein equivalents, so the decimal of 281% is 2.81 (move the decimal two places to the left to convert a percentage to a decimal). The above feed tag is 10% NPN and, again, let's assume that the NPN source is urea, so 10%/2.81 = 3.55%; therefore is supplement is 3.6% urea.
To determine the amount of urea that is being supplied, simply multiply the percentage by the pounds fed. In this case, if the supplement is being fed at 1 lb/hd/da x 0.036 = 0.036 lb/hd/day urea. When supplementing cows protein in range conditions when it is warranted, the supplement should contain only small amounts of urea.
The most common NPN source in cattle feeds is urea. Urea is not protein, but provides a nitrogen source so that the rumen microbes can make their own protein. There are enzymes in the rumen that allows the nitrogen source to be cleaved away from the urea and the microbes incorporate the nitrogen with a carbohydrate chain to make bacterial protein. A component of all protein is nitrogen. A question may be, do cattle use the bacteria as a protein source? The answer is yes. The bacteria flow from the rumen to the small intestine where they are broken down by digestive enzymes into amino acids and the amino acids are absorbed across the wall of the small intestine. In the research world, this is called bacterial crude protein.
In many articles, we have discussed the concepts of degraded intake protein (DIP) and undegraded intake protein (UIP). DIP is the proportion of the total crude protein in a feedstuff that is degraded in the rumen. This fraction is used by rumen microbes to build their own protein and is later digested by the animal in the small intestine. This is the primary source of protein for most ruminants. UIP in a feedstuff that is not degraded in the rumen, but remains intact to be digested by the animal in the small intestine. UIP is commonly referred to as by-pass protein. If a protein source is 30% crude protein and 80% DIP, by subtraction, the UIP is 20% (100% - 80% = 20%; %DIP + %UIP = 100%). Urea is 100% DIP.
The DIP and UIP content of a protein supplement will not be on a feed tag. As a general rule, most of the protein supplement will contain a greater amount of DIP as compared to UIP. However, distillers grains is an excellent source of UIP and is used as an ingredient in protein supplements because it is 30% crude protein. So the DIP in protein supplements that contain distillers grains will contain less DIP. But that is ok as these by-product based cubes work well as a supplement. A cube or pellet will not be 100% distillers. Distillers grains are high in fat and fat is difficult to cube or pellet. In most cases, a distillers based cube will not be greater than 2/3 of the ingredients in a protein cube.
Continuing on with the protein concept, a producer is considering a 32% protein supplement, this producer has cows grazing dormant range and has determine that there is plenty of forage, and cows are deficient in protein. If the cows are in mid-gestation, how much of a 32% protein supplement does the producer need to feed? Usually a dormant forage is less than 7 percent crude protein (dormant pasture and crop residue will often be 3-6 percent crude protein), the rumen bacteria are being starved for nitrogen, and will not break down the forage as efficiently as possible. By supplementing with protein source, the bacteria will do a more effective job of breaking down the consumed forage and the animal will get more out of the forage. In addition, as digestion of the forage improves, cows will consume more forage and, in this scenario, the supplemented cows will also get more energy from the diet. As an example, 1200 pound cow grazing unsupplemented dormant sandhill range in NE will consume about 1.8% of her body weight on a dry matter basis or about 22 lb of range daily. If the forage is 5.5% crude protein and her protein requirement is 7% CP in the diet, she is deficient. She needs to consume 1.54 lb of protein daily and she is getting 1.21 lb daily; therefore deficient 0.33 lb daily. The pounds of supplement needed per head per day of the 32% protein cube is 1.03 lb/hd/da (.33 lb/.32 = 1.03 lb). Supplements are about 90% dry matter, so the producer would deliver 1.2 lb/hd/da on an as-fed basis (1.03 lb/.90 = 1.146 lb).
The B on the feed tag mentioned at the beginning of this discussion denotes that the feed contains the ionophore Bovatec (Lasalocid) and that the concentration of the ionophore is 70 grams per ton of feed. The inclusion of the Lasalocid is the reason for the supplement be tagged medicated.
There is also information in regard to fat, fiber, and mineral and vitamin components of a feed tag.
For additional information, please see these two articles in our series.
Dr. Rick Rasby, Professor of Animal Science
Animal Science, University of Nebraska - Lincoln, Lincoln, NE