Cattle Today

Cattle Today

cattle today (10630 bytes)

by: Stephen B. Blezinger

The last decades have proven quite prolific in the area of beef cattle nutritional and management research. Both corporate America and academia alike have generated tremendous amounts of data which have been highly useful in improving performance, efficiency and profitability in the beef industry. Particular interest has been shown to the host of feed additives which are now commonly available to the cattleman. Feed additives fall into many different forms and can be helpful in improving feed efficiency, rate of gain, heat suppression and bloat control to name a very few. When properly used in a well managed environment, many of these additives can improve performance and profitability substantially. They cannot, however, take the place of good management. Unfortunately, under many circumstances, many additives will be used as a “band-aid” to attempt to cover poor management practices. In situations such as these, the cost of the additive is exactly that, a cost to the program and not an investment as many are designed to be, producing a positive return. In many situations, cattlemen have become frustrated with the apparent lack of response after they have spent added dollars on one or more additives. They often come away from the situation with a bad taste in their mouth and a poor perception of a given product. This perception is often not deserved because circumstances were not appropriate for the product to work as it was designed.

This section will discuss some of the more common additives available on the market, some basic background on the product and what they are designed to do. This article is not designed to be an exhaustive summary of all products available but a guide to some of the more common. Keep in mind that the products outlined here are those which have been repeatedly proven by research and practice. Many products exist in the market place which are aggressively marketed and are in use on many operations although little, if any, scientific data is available to support the effectiveness of these products.


The name ionophore is the technical name for a class of additives commonly fed to cattle to improve feed efficiency and rate of gain. Trade names for the most common products in this class include Rumensin™, Bovatec™ and Cattlyst™. Ionophores are added to feeds or supplements and are designed to effect the microbial population found in the rumen. In their most basic form, ionophores can be classified as antibiotics, having a detrimental effect on certain types of bacterial in the rumen. Although research has shown that some of this compound may, in fact, be absorbed by the animal, none is actually incorporated into the muscle or fat tissues of the animal. The predominant effect of ionophores are, as mentioned, on rumen bacteria. An ionophore such as Rumensin, when fed to a ruminant will select against certain types of bacteria. These microbes tend to be those that reduce the efficiency by which a beef animal utilizes energy. These types of bacteria will take nutrients from feed, utilize certain components and release other non-usable or detrimental by-products. Some of these by-products can include methane gas, carbon dioxide, lactic acid and heat. These are all basically wastes of energy found in feeds. When we feed an ionophore, they act as an antibiotic or anti-bacterial agent on many of these types of bacteria. This results in a shift in the bacterial population to a higher concentration of “beneficial” bacterial or those which consume nutrients and produce helpful by-products in the rumen. These helpful by products include bacterial protein and organic acids which can be used to make energy sources in the cows body. When this process takes place, the remaining bacterial population becomes more efficient, thus requiring less feed to provide the same or more energy to the animal. Often, this will actually result in a decrease in intake. This occurs since energy intake effects actual dry matter intake. When more energy becomes available, overall intake will tend to drop. Other theories regarding this intake reduction are that ionophores tend to be unpalatable but since they are fed in such a small amount this may be questionable.

Ionophores are fed extensively in the feedyard industry. Virtually every feedlot animal will receive one of the above mentioned ionophores during the finishing phase although it is also common in the grazing phases as well. Use of Ionophores is becoming more common in breeding cattle as well. This is true not only in growing and developing bulls and heifers but also in mature cows to improve energy efficiency. In situations such as these it is important to note that an ionophore should only be used in situation where good quality forages are available. If fed with a poor forage where nutrient intake is already a problem, feeding an ionophore which may depress intake will only compound this problem.

Interestingly, like most additives, ionophores are typically fed in very small amounts, ranging from 100 to 360 milligrams per head per day. In a finished feed where cattle consume all they can eat, this will equal about 25 to 30 grams per ton. The level of ionophore added must be correlated with actual feed intake in order to optimize the dose of product delivered into the animal. Specific guidelines have been established by the Food and Drug Administration (FDA) for the use of this additive and many others and the combinations in which it can be fed with other additives.

Tylan (Tylosin)

Tylan™ is an antibacterial product which is commonly fed to finishing cattle in combination with an ionophore. Clearances by the FDA exist to feed Tylan in combination with Rumensin and Bovatec as well as with other additives to help in the prevention of liver abscesses in feedlot cattle. Often, when a steer or heifer are fed a high concentrate feed for long periods of time, abscesses will develop in the liver. The abscesses are believed to be caused by the entrance of detrimental bacteria into the bloodstream either through damage to the ruminal wall or in the intestine. Once there, these bacteria travel in the blood stream until they reach the liver where they take up residence causing an abscess to form. The presence of abscesses in the livers of feedlot cattle cause two basic problems. One, by damaging the liver the performance of the animal is reduced since the liver is essentially the central organ for much activity such as energy metabolism. Second, a heavily abscessed liver will be condemned by the packer thereby reducing the value of the carcass.

MGA (Melegesterol Acetate)

Cleared for use in heifers, MGA™ is a widely used heat or estrus suppressant. Fed to heifers at an exceptionally low dosage (.25 to .5 milligrams per head per day), MGA works to reduce or eliminate cycling activity during the time it is fed. This, in feedlot heifers, has proven to improve gains and feed efficiency. This effect is due primarily to the reduction of riding activity and other estrus expression which consumes energy.

The use of MGA in heat synchronization in combination with the prostaglandin Lutalyse™ has been shown to be effective. Typically, .5 milligrams of MGA is fed per head per day for 14 days. On the 15th day it is removed from the ration. On day 16 to 17, heifers receive an injection of Lutalyse to induce estrus. This has shown to be an effective method of synchronization and somewhat less labor intensive than other methods. Quite a bit of research exists on this methodology.

Anti-Bloating Agents

A common occurrence, especially in pasture cattle grazing lush, rapidly growing grasses and legumes or in high concentrate rations is bloat. Bloat is the accumulation of gasses in the rumen and which, for any number of reasons is not released. Bloating can cause symptoms ranging from severe discomfort to death. A couple of products have been shown to be very helpful in reducing or eliminating bloating. One of these is a compound known as Poloxolene. Poloxolene is a compound which aids in reducing the surface tension of the liquid in the rumen and therefore greatly reduces any trapped gasses in the rumen liquid. This product can commonly be found in manufactured feeds or in blocks.

A second product that has shown some benefit against bloating are the ionophores, especially Rumensin and Bovatec. Because of their action in the rumen, reducing the population of certain gas forming bacteria, these compounds are helpful in reducing bloat. As an aside, they have also been found to reduce acidosis in the rumen as well in some situations. It should be noted that the methods by which poloxolene and the ionophores work is very different.


Coccidiosis is a common disease commonly faced in young cattle and calves in the spring and fall of the year. A disease caused by a microorganism, coccidiosis seems to occur regionally and is especially prominent in newly received stocker cattle. It does, however, occur in calves still in the cow as well. Coccidiosis can cause severe scouring and a host of other symptoms leading to death. A number of products have been found to be helpful in offsetting coccidiosis. One of the more commonly used products is Decox™ (decoquinate) which is a product designed specifically for the prevention of coccidiosis in these types of cattle. As with most of the other feed additives, it is fed at a low level but is very helpful in reducing this disease. Another compound which has been helpful in combating this problem is Chlorotetracycline (CTC). This is a wider ranging antibiotic which is cleared for other therapeutic purposes in addition to treatment for coccidiosis. It is commonly fed to help combat the effects of shipping fever and other stress related diseases

Microbial Products

Microbials have become exceptionally popular over the last few years. These products are very diverse and have been purported as being helpful in reducing the effects of stress, improving intake and a host of other benefits. A fair amount of research has been done on these products although it is not as conclusive as would be desirable. It has been found that many of these products are effective in helping reduce stress effects as mentioned previously. However, it appears that many of these seem to work with in a “window” of opportunity. In other words, if cattle have only been stressed a small amount, little or no positive effect will be noticed from feeding microbials. If the cattle are overstressed, little positive effect will be observed. Therefore, it appears that microbials are effective within a given range of stress in the animal and unfortunately no one really knows what this range is. It has become common to feed a microbial product to newly received cattle at least for the first few weeks as insurance.

Microbials fall into many different classes and forms, far too numerous to mention here. We'll briefly cover a few to familiarize you with some of the terms. One of the most common are the yeast products. Yeasts have been widely fed to ruminants, especially dairy cattle to reduce stress and improve intake. Yeasts are believed to improve the fermentation activity in the rumen and aid in the ruminal microbial activity Yeasts themselves will fall into several forms including products which are predominantly the substrate on which the yeasts live and the metabolites or by-products produced by the yeast cells. Other yeast products actually contain the yeast cells themselves in either a live or dormant form. Although research can be found from the different manufacturers illustrating the benefits of the different types, not truly conclusive evidence as to which form is best has been published. Other microbials commonly used are known as probiotics. These are products containing bacterial cultures or bacterial substrates sometimes known as fermentation extracts. The theory behind the use of probiotics is partially like the yeast products in that they may be helpful in improving fermentation activity in the rumen. They are also believed to be helpful in the lower intestine, helping to reduce the population of non-beneficial or “bad” bacterial in the intestinal areas or taking up space on the intestinal wall where these detrimental microbes might otherwise take up residence. We could spend an entire article on these products alone due to the diversity of the various cultures available. The more common products include cultures of lactobacillus and aspergillus bacteria or once again, the substrates on which they grow and exist.


As mentioned this list and descriptions of products is far from all inclusive. It does however give you some feel for some of the additives available which can be quite helpful in your feeding and management program. Remember that each of these is a tool and has a specific purpose. It is important to carefully monitor the use and effects of these additives to insure you are getting a return on your investment. While they can greatly improve your profitability they can also be very expensive if used incorrectly or if used as a cure-all for poor management. Another factor is to be careful of products which are available but are non-proven. When you are being shown a product be sure to insist on seeing the research that is available. This data needs to come from more than one source and needs to come from someone besides just the manufacturer. Be sure to do your homework and these additives can become an important part of your program.

Dr. Steve Blezinger is a nutritional and management consultant with an office in Sulphur Springs, TX. He can be reached at 667 CR 4711 Sulphur Springs, TX 75482, by phone at (903) 885-7992 or by e-mail at


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