Lauren Bills
Reading Feed Labels
I chose my topic on the importance of feed labeling for animals and how the wrong product beening delivered,sold to or fed to horses can cause serious problems. Chapter 13.of the Wyoming statue I found legisweb.state.wy.us/statutes/statutes.aspx?.../T11ch13.htm. What if the local coop or sales you the wrong feed or accidently loads the wrong feed or delivers it you, who would be respsonsible,liable for damages if the mistake isn’t caught ? I hope you find the research on the product to be helpful in the importance of labeling for feed products and for education purposes of the people who sale the product and the ones who load it.
Rumensin kills horses by interfering with the normal function of a horse’s heart, nervous system, and other body systems. Rumensin was developed for use in finishing cattle before they are sent to market for slaughter, it is also used in poultry in order to control coccidiosis. Rumensin is the generic name for monensin, which is the way it will be listed on the feed labels found on bags of feed that contain it. Typically, most horses that are exposed to rumensin or monensin share a common feed source with cattle.
I. Monensin Development
The IUPAC name for monensin is 2-5-Ethyltetrahydro-3-methyl-5-[tertahyrdo-6-hyrdoxy-6-(hyrdoxymethyl)-3, 5-dimethyl-2H-pyran-2-yl]-2-furly-9-hydroxy-beta-methoxy-alpha, gamma, 2,8-tertamethyl-1,6-dioxasprio[4.5] decane-7-butyric acid; monensic acid (OSHA). Monensin is produced by a strain of Streptomyces cinnamonensis, a form of mold. The precursors involved in this process are methylmalonyl-coenzyme A (CoA) and ethlmolonyl-CoA (monensin A). The common
form for monensin in nature is in a crystal form. See appendix A for a diagram of monensin.
When used in feeds it is referred to as an ionophore, which modifies the movement of monovalent (sodium and potassium) and divalent (calcium) ions across membranes. The outer surface is composed of many nonpolar hydrocarbons that are highly soluble in the lipid components of membranes. The membrane itself determines how the ionophore will be expressed. It may improve the use of nitrogen in the body and increase the dry matter digestibility of ruminants.
II. Differences in the Digestive systems of cattle and horses
Every animal on the farm has different requirements for nutrition, and over the years, many different types of feeds have been developed in order for each animal to reach the optimal growth potential. Monensin was originally developed for use in cattle in order to increase their rate of gain per pound per head per day. It has also been shown to improve the growth rate of grazing cattle. The stomachs of cattle are designed to hold large amounts of food and for the animal to be able to ferment that food. The stomach of a cow is divided into four different compartments that each have there own function the reticulum, the rumen, the omasum and the abomasums. In the rumen of the cow is where fermentation of foodstuffs is achieved due to microbial activity.
The horse on the other hand has a simpler stomach and digestive tract. Given the average size of an adult horse, the stomach is small for that animal. In comparison to cattle the horses stomach will only hold about three to three and a half gallons, where as a cows stomach will hold forty to fifty gallons (Jackson, Greer, and Baker 137). There is limited digestion that occurs in the horse’s stomach the majority is done in the small intestines. Because of the limited digestion that actually takes place in the horses stomach is one of the key factors for the effect that monensin has on horses.
When used in cattle feed monensin is designed to interact with the microflora in order to achieve the benefits previously mentioned it also, increases propionic acid, and decrease acetic and butyric acids. When a horse consumes feed that has monensin in it, they will develop monensin poisoning with one common affect being vacuolization
(Mollenhauer, Morre, and Rowe abstract). This is where the mitochondria will start to swell in the spleen, lungs, liver, and the kidneys.
III. Symptoms and Signs to Diagnosing Monensin Poisoning
Animals that have been exposed to monensin will exhibit a wide range of symptoms depending on the amount ingested. One of the key signs to be watchful for in healthy horses is the refusal to eat mixed grain feeds. Some animals will exhibit signs of colic and go off their feed because they have ingested monensin that is mixed into a ration at thirty grams to a ton of feed. As the amount of monensin is increased in the feed per ton, more horses will show signs of going off their feed and in some cases, one will die. Monensin poisoning should be considered when there is a change in the feed that is fed daily that leads to a refusal to eat or reluctance on the part of the animals to eat and when sudden death occurs within eight to twenty four hours of consuming the feed.
Symptoms in some animals include mild diarrhea, colic, weakness, and incoordination in the rear leg, stiffness, wide stance, and occasionally reluctance to move (Lewis 361). Some animals will also press their heads against a solid object, show signs of profuse sweating and form blindness. As the symptoms, progress the horse may shows signs of urinating often, then a decrease in urination with blood. The majority of the mucous membranes in the horse’s body become severely congested with fluid leading to an increase in the heart rate and an irregular heart beat. The heart itself will change color to a light link from dark red. In those that show signs similar to colic there is the lack of gastrointestinal sounds, also some horses will begin to hyperventilate. Some animals will attempt to lie down and will keep getting up until they are finally able to lie down. Once
the animal is, down they tend thrash their legs and are quite alert and aware of the surroundings. Shortly before death, the animal will begin to have trouble in breathing.
Other symptoms to watch for are horses that develop a form a form of anorexia, cardiac failure with signs of tachycardia, as well as myoglobinuria. For animals that have died from rumensin, poisoning the necropsy showed the heart to have the look of meat that had been slowed cooked and then shredded. The heart itself will change color to a light link from dark red. Also seen during the necropsy was sign of pulmonary congestion.
In the animals that less severely affected there is the possibility for a partial recovery to begin within three to four days of the ingesting the monensin.. For most animals, death comes with the first twelve to twenty four hours. For those that do survive there is still the possibility of death in the next few months due to complications from the poisoning, due to a weakened heart and respiratory system. For animals that are repeatedly exposed to small doses, there is the potential for the animal to become listless, lose conditioning and for the hair coat to become rough. Some animals become very nervous when they are handled and may start to drag their hind legs.
Older horses are less likely to suffer from the effects of rumensin poisoning because they will tend to avoid feed that has it in it. Older horses have a more developed sense of taste; they are more able to determine bitterness than a young horse. Younger animals tend to eat almost anything they can get into their mouths and chew. If available older horses will eat pasture or hay until the only thing left is the feed that contains the rumensin additive, they will eat it as a last resource in order to keep from starving.
IV. Treatment and Recovery
If there is no permanent damage done to the horses liver and heart there is the potential for a full recovery for that animal. Unlike many of the diseases that affect horses there is no treatment for monensin poisoning, it can only be treated symptomatically. If there is damage to the heart or any other major organ of the body than the damage is permanent and cannot be healed, and is the damage is severe enough than the horses usefulness will be affected (Blake 36). Young animals that have ingested monensin can have their growth stunted and become listless as they grow older. Typically, death from monensin poisoning rarely affects just one animal, it tends to affect the entire herd of horses that have access to the feed.
V. Feed Label Requirements
The United States Department of Agriculture requires all companies that manufacture feeds to print on there label what is in the feed. Also, they must list the percentages of the additives that are placed in the feed. Refer to Appendix B to see an example of the MFA feed label for rumensin. Each label must also contain any warnings that may effect what animals maybe fed that mix. It is important for all producers that may have both cattle and horses eating in the same area, that they read the label closely in order to prevent ionophore poisoning.
Any company that mixes feed that maybe harmful to different types of livestock must take great measures to be sure that cross contamination of the feeds do not occur. Since the late nineteen seventies when monensin was first approved for use in livestock feeds there have been documented cases of where a feed manufacture has had cross
contamination of the feeds that they are producing. It has either occurred from human error, and not checking to see all one product has been run threw before the next is started. In most cases of this happening the mill started by running feed intended for use with beef cattle and failing to get the machine completely cleaned before starting a ration for horses. During the first few occurrences people often mistook it for colic or similar gastrointestinal diseases. Most mills tend to use whole a “cleaner” for their machines during the transition of one feed to the next. In some of the plants located here in Missouri the owners will run feed with rumensin in it, and then turn around and start to run sweet feed or something that has whole or crimped corn ran into it. Because of the size of the corn and the roughness of the seed coat it helps to gather what feeds have gotten caught in the crevices of the machine and flush it on into the system. The ideal situation for plants that make horse feed would be to have a separate system in order to blend, grind and form pellets of the feed. But, do to the cost of the equipment most small mill operators are unable to do this. In those cases they must be more careful to watch what feeds are mixed after each other.
People who face the greatest risk of exposing their animals to rumensin are those that buy their feeds from plants that do mill both cattle and horse feeds. If a person is not familiar with rumensin poisoning or their veterinary is unfamiliar with the signs they have to look for things that have been changed in the horse’s diet in order to determine what is making the animal sick. Veterinarians in the western portion of the United States where the first to start to recognize that the horses aliments where related to the feed that they where sharing with the herds of cattle. One of the keys to rumensin is that it is not a
drug that will accumulate in the body of animals, which is why it has become so popular with cattle producers. The producer does not have to worry about having to withdraw the animals from it for a period of time before selling the animal for slaughter. Unfortunately for horses that are fed with cattle, it is the repeated expose that causes the long term damage or death of the animal. A continual dosage of rumensin in horses causes greater internal damage to the horse’s systems.
To summarize the key points of this rumensin is just the generic name for monensin and the two names are often interchanged with each other. For people who own both horses and cattle and prefer to buy a feed that can be fed to both animals, the must remember to read the feed label and be sure that it is approved for all the animals that will be receiving it as a food source. Animals that have been exposed to rumensin will never be the same as they were before the exposure.
Works Cited
Jackson, N., Greer, W., and Baker, J. (2000). Animal Health. Danville, IL: Interstate Publishers, Inc.
Lewis, L. (1995). Feeding and Care of the Horse (5th edition). Media, Pa: Williams & Wilkins.
Perry, T., Cullison, A., and Lowery, R. Feeds & Feeding (5th edition). Prentice Hall.
Pilliner, S. (1992). Horse Nutrition and Feeding. Blackwell scientific Publications.
Allen, D., Anderson, D., Jeffcoat, L., Quesenberry, K., Radostits, O., Reeves, P., and Wolf, A. Merck Veterinary Manual (9th edition). Merck & Co., Inc.
Blake, L. Rumensin: Death in a Feed Bag (1981). Horseman 25, 33-40.
Zhang, W., and Reynolds, K. MeaA, a Putative Coenzyme (2001). Journal of Bacteriology, 2071-2080.
Rumensin Dairy Pak. MFA Incorporated.
