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Previous issues of the BEEF Cattle letter
Issue # 693
June 30, 2010
Vomitoxin Concerns? Feeding Heavily Discounted Wheat and/or Bedding With the Straw - Stan Smith, OSU Extension, Fairfield County PA
It's now apparent that much of Ohio's wheat crop is testing positive for vomitoxin. Results of "quick tests" completed at grain elevators I've contacted have ranged from only 1 ppm to over 10 ppm.
In some cases the elevator is accepting the wheat after discounting the price anywhere from a nickel per bushel up to more than a dollar per bushel. In fact, in some cases the wheat has even been rejected for acceptance at any price by the elevator. While the negative economic impact on the wheat grower quickly becomes obvious, by contrast, this may be an opportunity for cattle feeders.
When wheat receives up to a $1 per bushel discount, its value becomes equal to or less than the current value of corn per pound. Add to that the fact that protein content is greater in wheat than corn and you discover that wheat, which may have once been intended for human consumption, potentially becomes a cost effective component of a beef cattle ration.
Below, OSU Extension beef and sheep veterinarian Dr. Bill Shulaw responds to some of the questions we've been receiving in regard to the use of wheat and straw for beef cattle. In the subsequent article, OSU Extension beef specialist Dr. Steve Boyles goes over the basics of including wheat, and especially wheat with known amounts of vomitoxin, into beef cattle rations.
Q: Do all vomitoxin tests yield equally reliable information? In other words, can I take the results of the "quick test" for vomitoxin which was done at the grain elevator and use that information to formulate a safe wheat inclusion rate for my beef cattle?
A: Elevators have to use rapid and relatively inexpensive "screening" tests when faced with the large numbers of loads submitted to them during wheat harvest. Some of these tests are semi-quantitative which means that they give an approximate level of vomitoxin in the grain. They are not meant to be definitive for the quantity of vomitoxin in the grain, and other more accurate tests are used for that purpose if needed. The USDA provides guidelines for this testing, and specific information can be found at: http://www.gipsa.usda.gov/GIPSA/documents/GIPSA_Documents/don.pdf. Some variability among results should be expected from these screening tests and can be largely attributed to the sample itself, sample preparation, the analytical method, and of course, the technical expertise of the laboratory in preparing the sample and using and handling the test kits.
If farmers decide to feed wheat to cattle or other livestock that they suspect may be contaminated with vomitoxin, they should consider sending representative samples from that source to a laboratory such as the Ohio Department of Agriculture's Division of Plant Industry - Grain, Feed, & Seed Section (614/728-6383) for testing to verify the level of vomitoxin present.
Q: Is vomitoxin the only mycotoxin I have to worry about if I want to feed this wheat?
A: Vomitoxin (DON or deoxynivalenol) is probably the most common mycotoxin found in small grains like wheat and barley, and it is produced by some fungus species of the genus Fusarium. However, these species may also produce other mycotoxins and you may remember the concerns about DON and zearalenone in last fall's corn crop. The presence of a mycotoxin, like vomitoxin, in a grain sample indicates that suitable conditions for fungus growth and mycotoxin formation have occurred. Although swine are the most susceptible to the effects of vomitoxin (vomiting and feed refusal) and cattle more resistant, some of the other mycotoxins produced by Fusarium species, such as T-2 toxin or fumonisin, can cause clinical and subclinical disease. Many laboratories such as the ODA laboratory mentioned above offer testing panels that check for the other important mycotoxins besides vomitoxin, and if farmers plan to feed wheat or other grain they suspect has mycotoxin contamination, testing a representative sample would be wise.
Q: Is there risk of vomitoxin levels changing while the wheat is in storage causing the need to retest it occasionally throughout the feeding period?
A: Fusarium growth and vomitoxin formation occur in the field. Cleaning and removing the dockage may remove a substantial portion of the vomitoxin. Storing the cleaned wheat at low moisture content should prevent further fungal growth and mycotoxin formation (some references suggest a minimum of 19-25% moisture is needed for Fusarium growth). If there is any question about storage conditions, then retesting to be certain of what you are feeding may be advisable.
Q: Is there risk to cattle or calves when using the straw from vomitoxin-contaminated wheat fields for bedding?
A: This is a difficult question as there appears to be little or no information from research to answer it directly. Vomitoxin, and potentially some other mycotoxins, can be found in the straw and other parts of the plant. In some cases the concentration of vomitoxin may approach that of the grain. If animals are intentionally fed contaminated straw as a regular part of their diet, such as might occur if wheat is used for balage or silage, then a potential disease risk might be present. However, the new FDA Guidance for Industry advisory levels document (published online June 29, 2010) indicates that wheat containing up to 10 ppm of vomitoxin can be fed to adult beef cattle with the stipulation that the total ration should not exceed 10 ppm for beef cattle and should not exceed 5 ppm for adult dairy cattle. For calves and other animals except swine, wheat containing vomitoxin at up to 5 ppm can be fed if it composes no more than 40% of the diet. Wheat containing 5 ppm vomitoxin can be fed to swine if it composes no more than 20% of the diet. You may review the new FDA Guidance for Industry document in its entirety here: http://www.fda.gov/Food/GuidanceComplianceRegulatoryInformation/GuidanceDocuments/NaturalToxins/ucm120184.htm
It seems unlikely that cattle, or other livestock, would voluntarily consume a sufficient amount of dry straw bedding containing these levels of vomitoxin if other nutritious feed were available.
Data on risks from airborne particles containing vomitoxin (and other mycotoxins) or risks from skin exposure for animals are equally scarce. Some research addressing these risks for humans is available but is not directly applicable for animals in their environment. It is clear that the greatest hazard for vomitoxin is when it is in the diet. In light of the current state of our knowledge on acceptable dietary levels of vomitoxin in human and animal diets, it is difficult to see how wheat straw bedding from this year's crop might pose a risk to livestock.
For more information on the health and safety aspects of handling wheat which tests positive for vomitoxin, as well as legal and other aspects of managing wheat this year and perhaps in the future, please review 4 timely and related articles in the June 29 issue of the OSU Agronomic Crop Team CORN newsletter.
Feeding Wheat to Beef Cattle - Steve Boyles, OSU Extension Beef Specialist
Wheat can be used to replace a part of the grain ration when protein prices are high and wheat is relatively cheap compared to other grains. As a general rule, limit mold-free wheat to 50% of the grain portion in finishing diets. However, some experienced feeders have used larger amounts of wheat. I tend to recommend lower levels to people not familiar with feeding wheat though (fast fermentation). Lower quality wheat: Limit wheat to 40% of dry matter or 50% of corn, whichever is highest. Take a longer time to build up to full feed than you would with corn. I would not recommend using wheat in high grain diets on self feeders or in creep rations. Salt (7-12%) might be used as an intake inhibitor for cattle on grass using a self-feeder. However, producers need to monitor consumption.
Wheat can range form 9-17% protein. Full value can be given to the protein in wheat. Since cattle can use nonprotein nitrogen to meet protein needs, beef feeder probably should not pay much premium for high protein wheats.
Processing Wheat: Although the kernel must be cracked or broken, over processing will result in the production of many fines that are undesirable since the rate of wheat starch digestion in the rumen is very rapid. Therefore, an excessive amount of fine particles will cause generally low and erratic intakes, digestive upsets and poor performance. If wheat is dry-rolled, it should be rolled or ground as coarsely as possible while still breaking all the kernels. Rolling rather than grinding generally results in fewer fines. Steam flaking wheat can improve animal performance. Mixing grains should occur after grain processing rather than before. Mix wheat with silage, haylage or corn grain to reduce the risk of animals eating too much at one time.
Problems of Feeding Wheat: Once on full feed, feed should be kept before the cattle at all times. It is not advisable to change back and forth from wheat to other feed grains when feeding high concentrate rations. Wheat is a fast fermenting grain in the rumen. Problems of depressed feed intake, acidosis and abscessed livers have been reported. They are the basis for recommendations on limiting the amount of wheat in the ration, mixing it with other grains, and for feeding at least 15% roughage. In general keep fiber levels above 6%. Wheat rations that have 6-10% fiber can work well. The addition of ionophores has made it possible to reduce some of these digestive problems and feed the higher levels of wheat.
Buffers: Buffering agents have been added to overcome the problems of reduced feed intake when high-wheat rations are feed to cattle. Adding 3.5 ounces of sodium bicarbonate (baking soda) per head daily gives a slight improvement in performance of steers on wheat rations. A finely ground feed-grade limestone can also serve as a buffer. Adding an additional 1.0 to 1.3% (dry matter basis) finely ground feed grade limestone to wheat rations may give a slight improvement to performance of cattle. However, avoid increasing the calcium levels of the ration above 0.9 (dry matter basis).
Sprouting: Wheat showing more than 2% percent sprouted kernels is classified as sprouted wheat. The nutritional value of grain protein does not appear to be depressed, providing the sprout is not lost. The value of sprouted wheat for ruminant feed is apparently only slightly affected, if at all by moderate sprouting. One aspect of the feeding of field sprouted grains that must be mentioned is the fact that mold and fungal infestations are more likely with sprouted grain. Care must be taken to avoid feeding moldy wheat to livestock to prevent mycotoxin poisoning. If you suspect toxins, have it tested.
Scab: The occurrence of scab in wheat does not automatically mean vomotoxin but high levels of scabby kernels in harvested grain should be suspect. If you suspect mold/toxins have it tested. Here is a link from the OSU Beef Team Library on what to do if aflotoxins are present. http://beef.osu.edu/library/mycotoxins.html
DON (vomotoxin): New FDA limits for "beef" cattle are indicated in Dr. Shulaw's response in the previous article. Research conducted in North Dakota and Minnesota has suggested growing and finishing cattle can tolerate higher levels (up to 18 ppm) based on research at the Carrington Research Extension Center). Assume all other classes of livestock (including horses) have much lower levels of tolerance. Molds/mycotoxins can be higher in screenings than the grain.
Forage Focus: Summer Pasture Management - Rory Lewandowski, Extension Educator, Athens County, Buckeye Hills EERA
The goal of managing a rotational grazing system is to keep the pasture forage plants healthy and growing so that grazing livestock can meet their nutritional needs by eating those plants. This goal is accomplished by adhering to some general grazing principles within a context of understanding an animal's nutrient needs. The summer months of July and August typically are months of hot temperatures and limited rainfall. Let's examine some specific management decisions required by summer conditions.
There are two general grazing principles to keep in mind; residual leaf cover, the take half, leave half rule, and second, provide a rest period until the plant is ready to be grazed again. Specifically, in the summer, do not graze pasture grasses below 4 inches in height. Keeping some leaf cover will result in quicker plant recovery after a grazing pass. The leaves will provide some shading of the soil, helping to keep the soil cooler and more conducive to cool season grass growth. Shading the soil from the sun will also conserve moisture, and provide better regrowth conditions. In the summer the rotation through pasture paddocks must slow down. Cool season grasses grow slower under summer temperatures. More time is needed for the grass to re-grow to grazing height after a grazing pass. Specifically, allow the pasture sward to regrow to an 8 to 10 inch height before entering a pasture paddock for another grazing pass.
The application of these grazing principles requires an adequate number of pasture divisions or paddocks. What is an adequate number? In our beginning level grazing school we teach that the number of paddocks needed is determined by this formula: # of paddocks = Rest period/Grazing days + 1. The rest period during a typical summer can vary from 30 days in early summer or if temperatures do not exceed the mid 80's and some timely rains continue, to 45 or 50 days when temperatures are in the 90's and rains are few and far between. In the case of a drought, the required rest period can be 60 days plus. The amount of grazing days spent in the paddock depends upon several factors, including stocking density and grass regrowth.
If stocking density is light, more days can be spent in a paddock, but there is a high amount of selective grazing and at some point desirable plants that are beginning to regrow can get grazed again. From a plant health and productivity standpoint, plants should not be grazed again as they begin growth following a grazing pass. So, grazing management will dictate that the time it takes a plant to begin active regrowth after being grazed determines the grazing days part of this formula. In the summer, it is generally accepted that plants do not begin active regrowth until about 4-5 days after a grazing pass.
Alright, back to determining an adequate paddock number. We will use as bookends, a favorable grass growing scenario and a drought condition. Under favorable summer conditions assume a rest period of 30 days with a 4 day grazing period per paddock and under drought conditions assume a rest period of 60 days with a 5 day grazing period per paddock. Plugging these values into our formula says that we will need between (30/4) + 1 and (60/5) + 1 or 8 to 13 paddocks to manage our summer conditions. In other words, 8 to 13 paddocks are needed to allow the grazier to make management decisions that prevent pasture plants from being overgrazed, and to allow pasture plants a long enough rest period to regrow to proper grazing height.
Pasture paddocks do not have to be made with permanent fencing. Paddocks can be made with a single strand of high tensile wire that is electrified for cattle, and electro-netting can be used to make temporary pasture divisions for sheep and goats. The important concept is that more pasture divisions allow the grazier to put into practice management principles and utilize management skills. I have yet to hear a serious grazier say that they regret using or putting in more pasture divisions.
Weekly Roberts Agricultural Commodity Market Report - Mike Roberts, Commodity Marketing Agent, Virginia Tech
LIVE CATTLE futures on the Chicago Mercantile Exchange (CME) closed up on Monday with exception of June and August 2011 contracts. JUNE'10LC futures were up $0.25/cwt at $91.200/cwt bu and $1.08/cwt over last report. The AUG'10LC contract closed at $89.675/cwt; up $0.300/cwt and $0.380/cwt higher than last week at this time. The June contract expires on Wednesday. Stable beef prices, higher feeder futures, and good news that Russia will let in poultry were supportive. Cash cattle continued to sell around $91.00/cwt as packers spurned bids for $93.00/cwt. Next week will be a short processing week due to the holiday. USDA put the 5-area price at $90.99/cwt; $0.03/cwt lower than last report. USDA on Monday put choice boxed beef at $154.47/cwt; up $0.18/cwt from Friday and $0.53/cwt over last report. According to HedgersEdge.com, the average packer margin was raised $20.90/hd from last report to a positive $36.85/hd based on the average buy of $91.04/cwt vs. the average breakeven of $93.95/cwt.
FEEDER CATTLE at the CME closed up on Monday. AUG'10FC futures closed at $113.975/cwt; up $0.775cwt and $2.28/cwt over last report. The OCT'10FC contract finished up $0.65/cwt at $113.850/cwt and $2.30/cwt over last week at this time. Lower corn futures and higher fat cattle prices were supportive. The latest CME feeder cattle index was put at 111.34; up 0.38 from Friday and 2.99 over last report. Late Monday the Oklahoma City National Stockyards estimated receipts for 7900 head vs. 6048 head last week and 11,617 head this time last year. Next week the auction market will be closed for the July 4th holiday. Feeders were steady to $2.00/cwt higher amid moderate demand for feeders and good demand for calves.
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