Originally posted on the BEEF Newsletter– Mark Sulc, OSU Extension Forage Specialist
As cold weather approaches this week, livestock owners need to keep in mind the few forage species that can be extremely toxic soon after a frost. Several species contain compounds called cyanogenic glucosides that are converted quickly to prussic acid (i.e. hydrogen cyanide) in freeze-damaged plant tissues. A few legumes species have an increased risk of causing bloat when grazed after a frost. Each of these risks is discussed in this article along with precautions to avoid them.
Species with prussic acid poisoning potential
Forage species that can contain prussic acid are listed below in decreasing order of risk of toxicity after a frost event:
- Grain sorghum = high to very high toxic potential
- Indiangrass = high toxic potential
- Sorghum-sudangrass hybrids and forage sorghums = intermediate to high potential
- Sudangrass hybrids = intermediate potential
- Sudangrass varieties = low to intermediate in cyanide poisoning potential
- Piper sudangrass = low prussic acid poisoning potential
- Pearl millet and foxtail millet = rarely cause toxicity
Species not usually planted for agronomic use can also develop toxic levels of prussic acid, including the following:
- Black cherry
It is always a good idea to check areas where wild cherry trees grow after a storm and pick up and discard any fallen limbs to prevent animals from grazing on the leaves and twigs.
Fertility can affect poisoning risk. Plants growing under high nitrogen levels or in soils deficient in phosphorus or potassium will be more likely to have high prussic acid poisoning potential.
Fresh forage is more risky. After frost damage, cyanide levels will likely be higher in fresh forage as compared with silage or hay. This is because cyanide is a gas and dissipates as the forage is wilted and dried for making silage or dry hay.
Plant age affects toxicity. Young, rapidly growing plants of species that contain cyanogenic glucosides will have the highest levels of prussic acid. After a frost, cyanide is more concentrated in young leaves and tillers than in older leaves or stems. New growth of sorghum species following a non-killing frost is dangerously high in cyanide. Pure stands of indiangrass can have lethal levels of cyanide if they are grazed when the plants are less than 8 inches tall.
Animals can die within minutes if they consume forage with high concentrations of prussic acid. Prussic acid interferes with oxygen transfer in the blood stream of the animal, causing it to die of asphyxiation. Before death, symptoms include excess salivation, difficult breathing, staggering, convulsions, and collapse.
Ruminants are more susceptible to prussic acid poisoning than horses or swine because cud chewing and rumen bacteria help release the cyanide from plant tissue.
The following guidelines will help you avoid danger to your livestock this fall when feeding species with prussic acid poisoning potential:
- Do not graze on nights when frost is likely. High levels of toxic compounds are produced within hours after a frost, even if it was a light frost.
- Do not graze after a killing frost until plants are dry, which usually takes 5 to 7 days.
- After a non-killing frost, do not allow animals to graze for two weeks because the plants usually contain high concentrations of toxic compounds.
- New growth may appear at the base of the plant after a non-killing frost. If this occurs, wait for a killing freeze, then wait another 10 to 14 days before grazing the new growth.
- Don’t allow hungry or stressed animals to graze young growth of species with prussic acid potential. To reduce the risk, feed ground cereal grains to animals before turning them out to graze.
- Use heavy stocking rates (4-6 head of cattle/acre) and rotational grazing to reduce the risk of animals selectively grazing leaves that can contain high levels of prussic acid.
- Never graze immature growth or short regrowth following a harvest or grazing (at any time of the year). Graze or greenchop sudangrass only after it is 15 to 18 inches tall. Sorghum-sudangrass should be 24 to 30 inches tall before grazing.
- Do not graze wilted plants or plants with young tillers.
Green-chopping frost-damaged plants will lower the risk compared with grazing directly, because animals are less likely to selectively graze damaged tissue. Stems in the forage dilute the high prussic acid content that can occur in leaves. However, the forage can still be toxic, so feed greenchop with great caution after a frost. Always feed greenchopped forage of species containing cyanogenic glucosides within a few hours, and don’t leave greenchopped forage in wagons or feedbunks overnight.
Hay and silage are safer
Prussic acid content in the plant decreases dramatically during the hay drying process and the forage should be safe once baled as dry hay. The forage can be mowed anytime after a frost if you are making hay. It is rare for dry hay to contain toxic levels of prussic acid. However, if the hay was not properly cured and dried before baling, it should be tested for prussic acid content before feeding to livestock.
Forage with prussic acid potential that is stored as silage is generally safe to feed. To be extra cautious, wait 5 to 7 days after a frost before chopping for silage. If the plants appear to be drying down quickly after a killing frost, it is safe to ensile sooner.
Delay feeding silage for 8 weeks after ensiling. If the forage likely contained high levels of cyanide at the time of chopping, hazardous levels of cyanide might remain and the silage should be analyzed before feeding.
Nitrate accumulation in frost forages
Freezing damage also slows down metabolism in all plants that might result in nitrate accumulation in plants that are still growing, especially grasses like oats and other small grains, millet, and sudangrass. This build-up usually isn’t hazardous to grazing animals, but green chop or hay cut right after a freeze can be more dangerous. When in doubt, send a forage sample to a forage testing lab for nitrate testing before grazing or feeding it.
Species That Can Cause Bloat
Forage legumes such as alfalfa and clovers have an increased risk of bloat when grazed one or two days after a hard frost. The bloat risk is highest when grazing pure legume stands and least when grazing stands having mostly grass.
The safest management is to wait a few days after a killing frost before grazing pure legume stands – wait until the forage begins to dry from the frost damage. It is also a good idea to make sure animals have some dry hay before being introduced to lush fall pastures that contain significant amounts of legumes. You can also swath your legume-rich pasture ahead of grazing and let animals graze dry hay in the swath. Bloat protectants like poloxalene can be fed as blocks or mixed with grain. While this an expensive supplement, it does work well when animals eat a uniform amount each day.
Frost and Equine Problems (source: Bruce Anderson, University of Nebraska)
Minnesota specialists report that fall pasture, especially frost damaged pasture, can have high concentrations of nonstructural carbohydrates, like sugars. This can lead to various health problems for horses, such as founder and colic. They recommend pulling horses off of pasture for about one week following the first killing frost.
High concentrations of nonstructural carbohydrates are most likely in leafy regrowth of cool-season grasses such as brome, timothy, and bluegrass but native warm-season grasses also may occasionally have similar risks.
Another unexpected risk can come from dead maple leaves that fall or are blown into horse pastures. Red blood cells can be damaged in horses that eat 1.5 to 3 pounds of dried maple leaves per one thousand pounds of bodyweight. This problem apparently does not occur with fresh green leaves or with any other animal type. Fortunately, the toxicity does not appear to remain in the leaves the following spring.
By Christine Gelley, Noble County Extension
Beef and dairy farmers who sell cattle through United Producers, Inc. have been formally advised to complete Beef Quality Assurance Training before January 2019. Muskingum Livestock in Zanesville has shared the same advice.
Throughout 2018, many agricultural organizations and businesses have been sharing the message that some of America’s largest meat distributers will only buy beef that is backed by BQA after the turn of the New Year.
This certification is not mandated by law. However, it is being required by some of the links that make up the beef supply chain, including auction barns, feed lots, packers, retailers, and consumers. Essentially, marketing beef without BQA certification will become increasingly difficult and those who do so successfully may find their compensation inadequate.
There are many opportunities for beef and dairy producers to get certified. You can take the training class at anytime, online, for free, through the National Cattlemen’s Beef Association at www.bqa.org. Local training courses have been and will continue to be offered.
Upcoming Beef Quality Assurance Trainings
- October 15 at 6 PM at the Morgan Co. High School Ag Room, 800 Raider Dr. McConnelsville, OH.
- October 18 at 6 PM at the Perry County Extension Office, 104 S Columbus St, Somerset, OH.
- October 22 at 7 PM at the Frontier Power Community Room, 770 South 2nd St. Coshocton, OH.
- October 30 at 6:30 PM at the Marietta High School Auditorium, 208 Davis Ave. Marietta, OH.
- November 13 at 7 PM at the Muskingum Livestock Auction Barn, 944 Malinda St, Zanesville, OH.
- November 29, 2018 at 7pm at the Knox County OSU Extension Office, 160 Columbus Rd, Mount Vernon, OH.
- December 13 at 6PM at the OSU Extension Regional Office, 16714 Wolf Run Road Caldwell, OH.
- December 18 at 7 PM at the Muskingum Livestock Auction Barn, 944 Malinda St, Zanesville, OH.
Learn more about Beef Quality Assurance at:http://u.osu.edu/beefteam/bqa/.
Take the online training at www.bqa.org.
Family: Pigweed, Amaranthaceae.
Habitat: Crop fields, pastures, and roadsides.
Life cycle: Summer annual.
Growth habit: Erect up to 6 ft. high.
Leaves: Prominent white veins on the undersurface unlike redroot pigweed, not pubescent, alternate, without hairs (glabrous), and lance or egg-shaped. Leaves are 2 to 8 inches long and 1/2 to 2 1/2 inches wide with prominent white veins on the undersurface. Leaves occur on relatively long petioles.
Flower: Small, green, inconspicuous flowers are produced in dense, compact, terminal panicles that are from 1/2 to 1 1/2 feet long. Smaller lateral flowers also occur between the stem and the leaf petioles (leaf axils). Male and female flowers occur on separate plants. Each terminal panicle contains many densely packed branched spikes that have bracts that are 3 to 6 mm long; can produce 500 thousand to 1 million seeds per plant.
Roots: Taproot that is often, but not always, reddish in color
Stem: One central stem occurs from which several lateral branches arise.
Similar Plants: Loosely resembles many other pigweed species. Palmer’s petioles are as long or longer than the actual leaf. This plant is hairless and has elongated seed heads. Leaves are typically more diamond shaped than other pigweed species, and occasionally has one hair at the tip of the leaf.
The Problem is……..Palmer amaranth is one of the most difficult weeds to control in agricultural crops. It developed a major glyphosate resistance problem in the southern US from 2006-2010, and has been spreading in the midwestern US since, causing crop loss and increases in weed management costs. Characteristics that make it a successful annual weed include: rapid growth rate; wide window of emergence (early May through late summer); prolific seed production (upwards of 500,000 seeds/plant); tendency to develop herbicide resistance; and tolerance to many post-emergence herbicides when more than 3 inches tall.
Family: Composite, Asteraceae.
Habitat: Thin turf, agronomic crops, pastures, orchards, fallow fields, waste areas, and roadsides.
Life cycle: Summer or winter annual.
Growth habit: Seedlings develop a basal rosette and mature plants erect are reaching 6 1/2 ft in height.
Leaves: The mature plant has leaves that are entirely without petioles (sessile). Leaves are 4 inches long, 10 mm wide, alternate, linear, entire or more often toothed, crowded along the stem, and hairy. Leaves become progressively smaller up the stem.
Stem: Erect, solid, hairy, reaching 6 1/2 ft in height.
Originally posted in the BEEF Newsletter, June 27,2018
– Josh Maples, Assistant Professor, Department of Agricultural Economics, Mississippi State University
Corn prices have been on a sharp downtrend since late May due primarily to a combination of trade uncertainty and a strong start to the growing season. Both nearby and new crop corn futures prices have tumbled by over 40 cents or approximately ten percent. The December 2018 corn futures contract price hit $4.26 on May 23rd – its highest level since July 2017. Just 18 trading days later, it closed Monday at a contract low of $3.77.
Reggie Voyles, undergraduate research intern, Department of Animal Science, Iowa State University
Mark Honeyman, professor, Department of Animal Science, Iowa State University
Iowa State University, Northwest Research Farms and Allee Demonstration Farm ISRF05-29, 31
(previously published on Talking Sheep – Sheep Education and Information: March 28, 2018)
As the demand for niche-marketed meats increases, so does need for research in this area. One niche market that is being examined is pork raised in deep-bedded systems. There is also a call for alternative bedding materials. Farm produced bedding sources such as cornstalks and various types of straws are commonly used. However, this study looked at other possible materials. Products were tested to see if they could be equal substitutes based on their absorbency. A ground lumber product and a ground lumber with drywall product with a ratio of 8:1 lumber-to-drywall were tested. These products were produced from demolished buildings. They had different performance qualities than wood shavings and were compared to cornstalks, recycled paper, oat straw, and triticale straw.