Part 1 in a series
Over the years we have discussed mineral programs and the various facets on many occasions. Of all the nutrients or nutrient groups producers find the need to supplement, minerals (and vitamins) tend to be the most complex and the most misunderstood. While a good mineral program and product are not a cure-all for problems on the ranch, many producers still do not understand how integral a sound program is to basic production and performance. This is true in terms of reproduction (the most important performance parameter on a breeding operation), health and growth or gains. As has been said before, a great mineral is not a silver bullet and will not replace proper supplementation of protein and energy when needed. There is something that producers need to understand – while there are times of the year when supplemental protein or energy may not be necessary above and beyond what the forage base can provide, it is extremely doubtful that you will EVER encounter a time of the year or a point in your production calendar when mineral supplementation is not required at some level. In other words, a mineral program is required 365 days per year.
On to the real purpose of this article. One of the most common questions I get when talking to producers on the farm or at meetings where I speak is “do I need chelated minerals in the product I am feeding?” Equally common is “what are chelated minerals?” Hopefully the following will answer these questions and shed some light on a confusing topic. One point I will make however, before we get into a discussion differentiating mineral sources we need to consider some background information. To be sure this makes sense, this will take a bit and another part in this series.
Absorption is the Key
With every nutrient the animal consumes there is a process that must be undergone before that nutrient can be used by the animal. This is true whether we are talking about protein, energy (from any number of sources), fat, minerals or vitamins. In each case, raw feed or forage material is taken in via the mouth and from that point the breakdown process begins, reducing the material to smaller and smaller particles until ultimately a given component can be absorbed. This is a complicated process and one requiring time, energy and many steps and processes, regardless of which component we are considering.
The intake, digestion and absorption process is the most basic concept in the discussion of nutrition. If the nutrient cannot be absorbed by the animal it cannot be utilized and ends up on the ground in manure. This then becomes a whole different topic for discussion as we grow more concerned about nutrient residues (especially Nitrogen and Phosphorus) on the ground but we'll talk about that later in another article).
Since this is a mineral article we'll obviously focus on this process for the mineral component of what is required in the diet. We have to look at a series of factors when we consider how well a given nutrient is absorbed.
1) What is the source of that nutrient? In many cases the sources may be multiple including forages, feed or feed supplements, mineral supplements and water (yes, even water can be a mineral source). In general, mineral availability is greatest from plant sources since they are complexed or integrated into the plant material (fiber, carbohydrate and other components). Remember that plants have mineral requirements too and will take in minerals as available in the soils on which they are growing. Subsequently these minerals become integrated into plant cells and tissues for the normal growth and health of the plant. There will be some variability in the availability of minerals in the various plant tissues depending on how digestible the specific plant material is. Certain parts of the plant are not digested as well as others and so minerals integrated into these tissues are likewise not as available. Plant material that has become older and more mature subsequently have higher percentages of this less digestible material making all nutrients, including the mineral portion, less digestible and thus less absorbable. This being the case we can then come to the conclusion that the minerals available from plant material when the plants are young, lush and immature is greater than when the plant is older, more rank and mature.
Secondly, we have to consider what the basic mineral levels in the plant are as related to the levels in the soil. Producers commonly test their soils for nitrogen, phosphorus and potassium (NPK) since research has shown us that these are the mineral components needed in greatest volume as related to efficient plant growth. In many cases, cattlemen do not consider the other nutrients (i.e. minerals) required not only by the plant but subsequently by the animal consuming these plants when they evaluate soil fertility and what their fertilization program should be. Research has shown that plant growth can benefit greatly from fertilization with added nutrients such as magnesium, zinc and copper. This is especially true if we consider the long term use of the soil and we find that pastures and hay fields are located on old cropland that may have been in production for decades and which may have had much of the mineral content “mined” from it through the production of various crops. Also, the producer has to consider what the management of these lands has been over the years. In many cases a lot of cropland was put into production that should have never been because of the slope or grade and soil types, all of which led to extensive erosion of nutrient rich top soils. This being said, forages produced on these types of land will not be as mineral rich, especially if not fertilized to replenish lost mineral components. Thus, the mineral content of that forage material will not have as high of a mineral content as other forages produces from more mineral-rich soils. Once again, this shows us the importance of forage testing so that we can evaluate the nutrient content of forages and hays and can make other supplementation decisions accordingly.
2) What is your supplementation program? We generally assume in grazing cattle operations that forages (grass, hay, silage) make up the largest portion of the nutrients consumed by the animal and that supplements are required to make up deficiencies in specific nutrients based on the forage, production schedule or type (time of year, cows nursing calves, stocker cattle gaining X number of lbs/hd/d, etc.) producer goals and so on. In some cases if forages are of very poor quality or in short supply, higher levels of supplementation is needed. Secondly, how the supplementation program is composed is of concern. Is the producer feeding a commodity such as whole cottonseed, corn gluten feed or soy hulls, a complete or near complete supplement such as cubes, liquid feeds, blocks/tubs, etc. Finally, is a mineral program currently in place and what is it? A quality free choice loose mineral fed in an appropriate feeder to protect it from the elements or is it a white salt block and a red trace mineralized salt block simply thrown out on the ground? In each of these cases some mineral will be provided although it may be very difficult to determine how much and in what form. Commodity feeds (basic raw ingredients) such as whole cottonseed, corn gluten feed, etc. will be much like forages and will vary in terms of mineral content due to many of the same reasons that forages vary. Processed commodities such as corn gluten feed that are by-products from a production process of some type will also vary related to the production process (chemicals used, heat, pressure applied).
Manufactured supplements (cubes, liquids, blocks) will be more consistent since they are formulated to be more consistent and also to carry specific levels of the various nutrients (i.e. a range cube may be formulated to contain 1 percent calcium, .5 percent phosphorus, etc.). Additionally, certain feed supplements may or may not include a complete profile of minerals (including trace minerals) and will vary in terms of what the sources are. This will be true regardless of what the supplement is.
Regardless of your supplementation program, some mineral will be delivered to the animal. It is just very difficult to precisely identify what those amounts are. When you consider the protein and energy supplements as discussed you will need to consider the book values for the commodities (or if you actually have them tested), and the tag or other nutrient information you can obtain on the supplements you buy. In many cases tags do not include all the nutrient data of concern and additional information is needed which can be obtained from the manufacturer. Once you have evaluated the forage and supplement levels then you can go on to considering the mineral supplement part of the program.
Another important factor to consider is that depending on your forage quality and other supplementation, this will have a direct effect on mineral supplement intake. Generally, mineral intake will be lower under conditions where forage quality is good and/or larger amounts of other supplements are used. It is important to recognize that this DOES NOT mean that mineral supplementation is not needed. We can't figure out our diets and we expect a cow to be able to figure our hers?? In some cases, in order to meet the animal's needs, a mineral supplement may have to be “force fed” to the animal by including it with other supplements fed.
Manufactured mineral supplements also vary greatly in terms of what they contain and whether or not they “fit” your application. Don't take for granted that the one the local feed store carries is correct for your operation either (we've looked at the variables). In many cases the product carried may have been formulated a 1000 miles away by a company that has no idea what your situation is. Not a slight toward any specific company it's just impossible to be all things to all people. Also, and this is true of all supplement programs, if you are serious about your performance, DO NOT base a buying decision solely on price of the supplement. In many cases I have seen the cheapest supplement may be the most expensive one you could purchase because it does not do what you need for it to do. A more expensive product may have better met your needs and been more efficient thus improving your overall profitability. The producer needs to be cost conscious but you also need to be efficiency and profit conscious as well (we don't want to be “penny wise and pound foolish” as the saying goes).
Also, and I know I'll step on toes with this one, a white, red or yellow salt block ARE NOT a mineral program. Years ago, when all we knew was that cattle craved, and in some cases, needed salt, keeping a block or two was not a bad thing. Today we know volumes more about mineral nutrition and what is and is not needed and this simply does not fit the bill. Additionally, trace mineralized blocks normally do not allow for sufficient intake to meet the animal's needs. Aside from meeting some of their salt craving, the main thing cattle will get from licking blocks like these are a sore tongue! I simply cannot emphasize how important the use of a high quality, LOOSE mineral supplement is. While I am on my soap box a mineral does not have to be RED in color. The red color (or in some cases other colors as used by certain mineral companies) comes from the inclusion of red iron oxide, an ingredient that has essentially no value (nutritionally) whatsoever except to contribute the color. As mentioned other colors have been applied as well as part of an overall program to help identify a given product as a specific step in a program but in general this is marketing and the color contributes no real value.
Mineral Absorption and Contributing Factors
Manufactured minerals also vary greatly in the ingredients they use to produce the information you see on the tag. Subsequently the ingredients will vary greatly in terms of digestion and absorption or “bioavailability” the word we use in mineral nutrition to describe how well or how poorly a given mineral is absorbed by the animal. This is where our discussion actually starts on the titled topic (I told you it would take a while). In the past we have discussed the different sources of minerals primarily separating them in terms of inorganic (whether the form is ultimately an oxide, sulfate, carbonate, for example – Zinc Oxide, Copper Sulfate, Cobalt Carbonate) or organic (the many differences which will ultimately be discussed in this series). Consider the following:
We find variation in the availability of the various minerals from one source to another. Depending on which specific source a given manufacturer uses there can be quite a bit of difference. Consider several Zinc sources. In livestock minerals we typically find zinc oxide and zinc sulfate (both inorganic sources) as well as zinc methionine (organic source). Research has shown that the bioavailability of these zinc sources falls into the following ranges: Zinc Oxide -- 0 to 35 percent; Zinc Sulfate -- 30 to 60 percent; Zinc Methionine -- 75 to 95 percent.
In other words, of the amount actually fed, only the amounts shown will actually be absorbed. The absorption range for each of the three shown is affected by even other factors such as actual manufacturing process, potential antagonistic substances and so on. As you can see there is a substantial range in the availability in these three sources. While zinc oxide is inexpensive it is also not absorbed well at all. You can assume that the better a complex is absorbed (higher bioavailability) the more expensive it will be. This goes back to what was discussed earlier that the cost may be a bit higher but the improved efficiency and subsequent improved performance can prove more profitable
As with the example shown with zinc, same situation exists for other minerals as well – copper, manganese, cobalt, etc. We typically find an improvement in absorption as we follow a path such as: