Prussic Acid Poisoning

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1 September 2010 Prussic Acid Poisoning...a concern after a light frost Bob LeValley It was discovered in the early 1900s that under certain conditions sorghums are capable of releasing hydrocyanic acid or commonly called prussic acid. Prussic acid when ingested by cattle, is quickly absorbed into the blood stream, and blocks the animal's cells from utilizing oxygen. Thus the animal dies from asphyxiation at the cellular level. Animals affected by prussic acid poisoning exhibit a characteristic bright red blood just prior to and during death. Lush young regrowth of sorghum plants are prone to accumulate prussic acid especially when the plants are stressed such as drought or freeze damage. Light frosts, that stress the plant but do not kill it, are often associated with prussic acid poisonings. Producers should avoid grazing fields with sorghum type plants following a light frost. The risk of prussic acid poisoning will be reduced, if grazing is delayed until at least one week after a "killing freeze". As the plants die and the cell walls rupture, the hydrocyanic acid is released as a gas, and the amount is greatly reduced in the plants. One can never be absolutely certain that a field of sorghum is 100% safe to graze. Cattle that must be grazed on sorghum pastures during this time of year should be fed another type of hay before turning in on the field, and should be watched closely for the first few hours after turn in. If signs of labored breathing, such as would be found in asphyxiation, are noted, cattle should be removed immediately. Call your local veterinarian for immediate help for those animals that are affected. Be certain to read OSU Fact Sheet F-2904 before turning cattle to potentially dangerous fields. Oklahoma State University, U.S. Department of Agriculture, State and Local governments cooperating. In compliance with Title VI and VII of the Civil Rights Act of Executive Order as amended. Title IX of the Education Amendments of 1972, Americans with Disabilities Act of 1990, and other federal and state laws and regulations, does not discriminate on the basis of race, color, national origin, sex, age, religion, disability, or status as a veteran in any of its policies, practices or procedures.

2 Use of Corn and Sorghum Silages for Beef Cattle Bob LeValley Silage can work very well in growing programs for stocker cattle, can be used to stabilize or increase stocking rates on wheat pasture, and can even be used in the winter feeding program for cows. Corn silage will have a higher energy content than sorghum or small grain silages, but is more expensive to produce due to higher input costs as well as water requirements. Feeding Value: The feeding value of silage can be quite variable. Drought-type growing conditions will typically reduce the energy value of corn silage while increasing the protein content. About 50% of the dry matter weight of well-eared corn silage is grain and the remaining 50% is stalk, ears, and forage Generally when corn silage is grown under dry land (non-irrigated) conditions, it does not produce this much grain. Therefore, the energy content may be a little lower than most book values. The medium energy, high fiber content of sorghum and corn silage makes them a valuable component of a growing program for stocker calves. Sorghum silage is usually at least 15% lower in energy than corn silage. The protein concentration is moderate and frequently below the protein requirement of growing cattle, resulting in the need for protein supplementation in most cases. The following chart provides typical feed values for corn and sorghum silage as well as a couple of more common feeds for comparison purposes. D.M. %C.P. % TDN NEm NEg % Ca %P Corn Silage Sorghum Silage Alfalfa Hay Corn Nitrates can be a concern in silage. During the fermentation process, some nitrate is reduced to nitrous oxide and dissipated as a gas. High levels can be reduced, but ensiling may not necessarily be a cure for the problem. Just another reason to have a lab analysis on silage! Silage for Growing Programs: Silage works well in stocker growing programs. One of the advantages is the reduction of dust in the diet. To accurately predict performance, on a particular ration, intake must be estimated, which can be difficult. A rule of thumb is estimate intake at about 5-7% of body weight on an as is basis. This assumes the silage is about 32-35% dry matter. Several of the by-product feeds can work nicely to compliment the nutrient content of silage. Corn Gluten Feed, Distillers Grains, and Wheat Midds are examples. Corn is traditionally used to add energy, but will also need a high protein feed such as cottonseed meal to meet the animal s requirement.

3 Following are a few ration ingredient combinations for a 400 pound steer, with an estimated 2 lb. gain per day. Sample rations with Corn Silage Using Different Grain or By-Products (400 lb medium frame steer, approx. 2 lb adg) As Fed Basis Corn or Wheat or Corn Gluten Feed or Dried Distillers Grains Corn Silage 92% 91% 85% 87% Corn Wheat 3% Corn Gluten Feed 11.5% Dried Distillers Grains 11.5% Wheat Midds Cottonseed Meal 7% 6% 3% 1% Limestone 1% 0.5% 0.5% 0.5% Sample rations with Sorghum Silage Using Different Grain or By-Products (400 lb medium frame steer, approx. 2 lb adg) As Fed Basis Corn or Wheat or Corn Gluten Feed or Dried Distillers Grains Sorghum Silage 84% 84% 83% 84.5% Corn 10% Wheat 11% Corn Gluten Feed 15% Dried Distillers Grains 15% Wheat Midds Cottonseed Meal 5.5% 4.5% 1.5% Limestone 0.5% 0.5% 0.5% 0.5% The above rations would need to be adjusted to consider an individual s available feeds, ingredient prices and target daily gain. They were constructed to compare ingredients necessary for approximately the same rate of gain. Use of Silage to Supplement Wheat Pasture Cattle Silage can be used effectively to stabilize or help maintain stocking rates on wheat pasture when forage is marginal. It can be a great benefit to increase a producer s flexibility when considering marketing dates, etc. Intake will be extremely variable, but in OSU research trials, has ranged from about 0.3% to 0.8% of body weight on a dry matter basis. For a 600 pound calf, this would be a range of about 5.5 to 15 pounds of silage per day on an as fed basis.

4 Silage for Cows Silage could certainly be used in a winter feeding program for cows. To what if a feeding program using silage and make comparisons to other feeding scenarios, use the OSU Cowculator computer software. Weed Control in Seedling Alfalfa Mark S. Gregory As you probably realize, when alfalfa is established in the fall of the year, our recommendation for weed control is usually to wait for grassy or broadleaf weeds to emerge, and then to treat what problems appear, before it gets too cold in winter. The question may be, why do we even treat the seedling stands to get rid of weeds? In some work done just as I came to the SW District, in , Jim Stritzke gained some insight into the detriment of having a weed problem, especially a grassy weed problem, in a seedling alfalfa stand. In this particular study, weeds were primarily rescuegrass and downy brome. An over-thetop grass product was used in early December and air temperature was 55 o F. The following table indicates that, with an untreated grassy weed problem, not only will less alfalfa be produced in the first cutting, the competition of the weeds prohibits the alfalfa from establishing as it should, and a thin life-long stand may be the result. Cool-season Grass Yield lbs/a Alfalfa Stem Counts stems/sq.ft Alfalfa Yield lbs/a Poast Plus No herbicide From: 1995 Forage Weed Control Report, PA95-1 (PTGCA4C1.SM1) Rescuegrass Downy Brome

5 Coccidiosis Prevention Pays Gene Parker Jr. DVM Coccidiosis control programs should start before weaning Coccidiosis stalks young beef calves from birth through adolescence. The first big threat hits at weaning time when stress from location changes, different feed, and intermingling threatens to challenge the calf s immune system. As an organism of opportunity, coccidiosiss infections thrive in wet conditions provided by weather or confinement production systems. Not only is coccidiosis a threat to the calves health but it opens the door to other diseases, including respiratory (pneumonia) pathogens. While the clinical signs of acute coccidiosis bright red bloody diarrhea, dehydration and depression are easily recognized, subclinical coccidiosis remains the unseen threat responsible for loss of gain. Subclinical coccidiosis can be a huge problem in beef calves. If we see signs of acute coccidiosis in a pen of calves, we estimate that half of the pen has subclinical coccidiosis, which is not apparent; but, still causing production loss and lack of weight gain. Back to basics Coccidiosis ranks as one of the top five most economically important diseases in the cattle industry, according to the Oklahoma Extension Service. Little data has been generated in recent years to weigh its economic impact, but a 2002 article in Veterinary Parasitology cited a 1994 U.S. report estimating that cattle ranchers lose an estimated $400 million dollars a year. That s well over $560 million a year in 2005 dollars. Bovine coccidiosis is caused primarily by two highly prolific strains of microscopic protozoa parasites, Elimeria bovis and Eimeria zuernii. For every single oocyst(egg) ingested by a calf, these two parasites are capable of producing 15 to 28 million oocysts (eggs) during a single 3 to 4 week life cycle. Coccidiosis-causing oocysts are found everywhere cattle are found. Most all healthy cattle will have a few coccidia oocysts in their intestinal tract. Shed in feces, oocysts are able to survive in moist, shaded areas for a long time. Animals become infected by ingesting fecal material in soil, feed, water, or by licking themselves or other animals in the herd. Unfortunately, a significant portion of the intestinal damage contributed to coccidiosis occurs before clinical signs present themselves. And once clinical signs are present, the disease is more than half way through its life cycle. If the calf s gut lining is damaged by coccidiosis it may never recapture its full absorptive potential. Setting up for success Management strategies target prevention of coccidiosis by reducing calf stress. The organism is always present in the environment and in normal healthy carrier animals just

6 waiting for the right conditions to strike. Cow/calf producers may experience coccidiosis outbreaks when the animals are confined during the weaning process. Wet, warm weather during late spring and early summer are ideal conditions for coccidia survival in the pasture environment; and, this is when highest numbers of young spring born calves are exposed to the coccidian organism. Improving backgrounder performance There is plenty or research showing that it s much more cost effective to prevent coccidiosis than to try and treat an outbreak. Yet, many calves aren t fed an anticoccidial until after weaning when they reach the backgrounder. Today, progressive beef producers start calves on a feeding program that includes an ionophore mineral supplement or a pelleted anticoccidial before weaning. These producers recognize the value in preventing not only coccidiosis but reducing the respiratory diseases that strike a calf with a weakened immune system. The physiological stress of weaning, transportation, intermingling, new diets and often cold, wet weather, sets up calves for an outbreak of coccidiosis when they reach the backgrounding yards. Backgrounders recognize the value of feeding a coccidiostate in the receiving rations. These animals need the anticoccidial to enhance feed conversion during the acclimation process when they re under stress and fighting off respiratory infections. Dr. Denny Hausmann, a technical service veterinarian at Alpharma Inc. Animal Health, who works closely with the disease, agrees that prevention is the best strategy. Weather, shipping and new diets are stressors that beef producers have little control over, notes Hausmann, but using an anticcodials in these situations helps prevent outbreaks making cattle less susceptible to other diseases. Management Strategies to Reduce Coccidiosis Outbreaks Mother Nature deals her own set of cards to cow/calf producers in the weather department, but progressive beef producers can counter with these ace-in-the-hole management strategies. Avoid mud and manure contamination of drinking water. Fencing cattle out of small shallow ponds and provide water to calves in an above ground tank. Place gravel around stock tanks to reduce wet areas around tanks where cattle congregate. Move feeding sites to clean areas frequently when feeding on the ground. Don t feed round bales in the same spot in the pasture Keep feed bunks and water tanks clean and free of manure. Start calves on an anticoccial before weaning. Either in the free choice mineral supplement or creep feed

7 Reduce physiological stress due to castration, weaning an intermingling Always use an anticoccidial or an anticoccidial-antibiotic combination in the receiving ration. A new FDA approval permits using the anticoccial Bovatec (lascalocid sodium) and the antibiotic Aureomycin (chlortetracycline) in the same cattle feed to optimize weight gain and feed efficiency while controlling coccidiosis and the leading causes of bacterial enteritis (diarrhea) and pneumonia. Other anticoccidial medications commonly added to receiving rations are Decocox (decoquinate), Rumensin, and Amprolium.