Avoid Forage Toxicities After Frosts

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:

  • Johnsongrass
  • Shattercane
  • Chokecherry
  • Black cherry
  • Elderberry

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.

Toxicity Symptoms

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.

Grazing Precautions

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.

Greenchop

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.

PEM or “Polio” in Small Ruminants

Richard Ehrhardt, Small Ruminant Extension Specialist, Michigan State University
(Previously published on the Michigan State University Sheep and Goat Extension Page)

 

Understanding how to prevent and treat Polioencephalomalacia (PEM) in sheep and goats.

Polioencephalomalacia (PEM) is also known as cerebrocortical necrosis (CCN) and is a relatively common nutritional disorder in sheep and goats. A common name for this disease in sheep and goats is “polio”; however, it has absolutely no relationship with the infectious viral disease found in humans (poliomyelitis). Cases of PEM can be successfully treated if detected early in the disease course, making recognition of early symptoms a critical issue for sheep and goat producers.

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Pneumonia in Sheep and Goats

Dave Van Metre, DVM, DACVIM Professor / Extension Veterinarian, Colorado State University, Originally posted in the Sheep Newsletter, August 14, 2018

Pneumonia is an infection of the lungtissue with multiple causes. It is an important medical problem of sheep and goats of all ages. In younger animals, various bacteria, viruses, and parasites of the upper and lower respiratory tract are often involved in the development of pneumonia. In adults, these same diseases – causing agents can create pneumonia.

 

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Ohio Noxious Weed Identification – Week 21 Palmer Amaranth

Palmer Amaranth

FamilyPigweed, 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.

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Ohio Noxious Weed Identification – Week 20 Marestail

Marestail

FamilyComposite, 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.

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Absorbency of Alternative Livestock Bedding Sources

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)

Introduction:
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.

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Mud Control is Grazing Management

By: Rory Lewandowski, OSU Extension Educator, Wayne County (originally published in Farm and Dairy)

An unseasonably warm February led to mud management issues for many pasture-based livestock operations. Spring typically leads to our April showers and the “traditional” time of managing around mud. We just arrived in mud season a little earlier.

All this mud is an undesirable condition, from an animal performance, resource management and environmental perspective.

Graziers need to have a mud control plan as part of a comprehensive grazing management system.

Within a grazing system, mud does not just happen. Wet soils combined with livestock create mud.

How quickly mud is created depends upon the number of livestock in a given area, the weight of those livestock, the saturation level of the soil, the time of year, and the strength of the surface to support those livestock.

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Control Winter Weeds for Better Pastures

Lauren Peterson, Hay and Forage Grower summer editorial intern
(Previously featured in Hay & Forage Grower: February 13, 2018)

Gone are the days when warm-season weeds seemingly had a corner on the warm-season pasture market. Producers who typically focus their control efforts on warm-season broadleaf and grass weeds, such as ragweed, broomweed, sandbur, or johnsongrass, may want to broaden their efforts.

Soils and crops consultant of the Noble Research Institute, Eddie Funderburg, explains that cool-season weeds, or those that emerge in the fall and grow throughout the winter and spring, are finding their way into warm-season pastures. Funderburg explains this growing problem and highlighted some of the main culprits in a recent Noble Research Institute News and Viewsnewsletter.

Annual ryegrass
“Ryegrass can be a valuable forage or a difficult weed, depending on your situation,” Funderburg began.

Commonly seen as a weed in summer forages, ryegrass hinders producers in two ways. The first is hay quality for horses. Funderburg noted that hay producers can struggle selling their first and second cuttings containing ryegrass as high-quality horse hay.

In pastures, where cattle consumption does not keep up with ryegrass growth, the species becomes extremely competitive with warm-season grasses in late spring. When it dies, ryegrass forms a mat that shades the ground, further inhibiting the growth of summer grasses such as bermudagrass. “I’ve seen quite a few stands of bermudagrass lost to excessive ryegrass competition,” Funderburg said.

For effective control of annual ryegrass, Funderburg recommended spraying a nonselective herbicide in the dormant season. He warned that this treatment is not ideal if plants like cool-season legumes are actively growing at that time.

Glyphosate, the active ingredient in Roundup, is frequently used when desirable plants are inactive because it will kill only green plants upon application. Funderburg added that in some regions, ryegrass has become resistant to glyphosate. Where this is the case, paraquat can be used as a substitute.

“Take extreme caution when handling paraquat since it can be lethal to the applicator if ingested,” Funderburg warned. “It is a good idea to rotate glyphosate and paraquat to prevent resistance from developing, even if resistance is not confirmed in your fields.”

Thistles
Thistles are a persistent problem in pasture management. This invasive species is best fought during the winter or early spring in order to see effective control results. Both treatments discussed above are effective in the rosette stage (lying flat on the ground), Funderburg noted.

Once thistles begin to bolt and shoot a seedhead, they are much harder to control. Before thistles bolt, broadleaf herbicides are more effective. Funderburg listed 2,4-D alone, 2,4-D with picloram, dicamba or aminopyralid, metsulfuron methyl, or a combination of metsulfuron methyl, 2,4-D, and dicamba as potential chemical control options.

Henbit
“Henbit is a plant that was not generally considered a pasture weed in the Southern Great Plains until the past few years, but now it can be a major competitor with bermudagrass in the early spring,” Funderburg said.

Although 2,4-D alone may not eradicate henbit, it can easily be taken care of with other herbicides when sprayed early. Funderburg recommended glyphosate in the dormant season, a mixture of 2,4-D and glyphosate, or mixtures of 2,4-D, dicamba, picloram, aminopyralid, and metsulfuron. For best results, spray when the henbit is still small.

Winter weeds aren’t always a bad thing. Warm-season pastures and hayfields simply need to be scouted to determine if control is necessary. Funderburg said that in most cases control of winter weeds requires an additional application in order to also control summer weeds. An exception to this is aminopyralid (sold as Milestone or formulated with 2,4-D and sold as GrazonNext HL). Research shows that if applied in February, aminopyralid gives season-long protection against western ragweed, Funderburg added.

“Always read the label before handling, mixing, or applying pesticides,” cautioned Funderburg. “Pay particular attention to safety information and follow all recommended safety practices. Remember, the label is the law.”

Protect Sheep and Goats with CDT Vaccine

Peggy Coffeen, Dairy/Livestock Editor

This week we have another achieved article resurfacing from just few years ago. In this article, Dr. Eric Gordon, a member of the OSU Sheep Team,outlines the importance of a proper vaccination program. Be sure to check out this quick piece to learn more about the benefits of vaccinating your herd or flock with CDT.

Failing to arm sheep and goats disease protection is a bit like heading into a tackle football game with no helmets or pads. Less protection means greater risk. Vaccines are an important component in suiting up small ruminants to hit the field – or pasture. At minimum, sheep and goats of all ages and stages should be protected from clostridial diseases.

Dr. Eric Gordon, DVM, The Ohio State University, believes that clostridial diseases are the only group that all sheep and goats should be vaccinated against. He recommends using a three-way vaccine generically referred to as CDT, which protects against Clostridium perfringens type C and D and Clostridium tetani (tetanus). Eight-way vaccines are also on the market, but the three-way CDT is the core vaccine for sheep and goats.

Protect Against these Three: CDT
The CDT vaccine is both inexpensive and very effective at preventing the quick and fatal consequences that can result from a clostridial infection. “The key here is vaccination and prevention rather than treatment because usually we are too late to treat it,” Gordon says.Types C and D are the culprits of enterotoxemia.

Type C:
Type C is found around the farm in manure and soil. A young animal may ingest this strain while nursing a doe or ewe with a dirty or contaminated udder. Once inside the body, the bacteria grow rapidly and produce a toxin that results in rapid death.

Type D:
Type D is the clostridial strain tied to overeating disease. While certain levels exist in the stomach, bacteria can proliferate in the small intestine when fast-growing lambs or kids ingest large amounts of feed, grain specifically. These toxins then enter the bloodstream, and the animal responds with body convulsions, jerky movements, salivation and coma. Death can occur in as little as 30-90 minutes.

Tetanus: 
When it comes to tetanus, wounds and lacerations are a conduit for the deadly bacteria to infect the body with deadly toxins. While puncture wounds incurred from in and around facilities are one way tetanus can infect the animal, surgical procedures like castration, docking and dehorning can also present a risk.

Based on his observations, Gordon believes that the method of castration matters when it comes to tetanus. He has seen a higher incidence of tetanus among animals that have been banded compared to those that were surgically cut. This is because the bacteria thrive in an anaerobic environment, which is created by the dead tissue that forms below the band. However, the infection risk from banding is reduced when animals are protected by a vaccine.

Vaccine Recommendations:
From babies to mommas and bucks, protecting against these swift and deadly clostridial infections is a wise choice. At a cost of roughly $0.30 per dose, it is a “pretty cheap and pretty effective” way in assure the health of your animals, Gordon notes. Following the vaccine protocol for kids and lambs and providing an annual booster through adulthood will provide optimal protection.

When ewes and does are vaccinated properly, they are able to pass on temporary protection to their vulnerable babies through colostrum. Gordon recommends that ewes and does be vaccinated in the last month of pregnancy. For first-time moms, he suggests giving two shots – one 6 weeks prior to lambing or kidding, followed by another 3 weeks prior to lambing or kidding. This puts the maximum amount of antibody in colostrum for the lamb or kid.

When the immunization status of the mother is unknown or uncertain, the best bet for disease prevention is to vaccinate the baby at 1-3 weeks of age, followed by two booster shots, each given at 4 week intervals.

For properly vaccinated babies, he recommends administering the CDT vaccine at about 8-12 weeks of age. If the ewe or doe was properly vaccinated, her colostrum will provide good protection up to that point. The timing should also be 1-2 weeks prior to castrating or docking.

And don’t forget about the boys. Gordon suggests hitting rams and bucks with a CDT vaccine about a month before going into the breeding pens. “That’s when most likely to get injured, and injury can lead to clostridial infection,” he notes.

Vaccines are Not Band-Aids:
“Vaccines shouldn’t be a Band-Aid for poor management,” adds Gordon. There are other ways to improve immune function other than vaccinations, and they are just as important. Reducing animal stress and providing good nutrition, clean bedding and housing, ventilation, and an ample water source are basic things that do wonders for animal health. Practicing good hygiene by keeping animals clean and dry will also help prevent the spread of clostridial diseases.

“If we do [these things], it’s amazing what the animal can fight off on its own,” he states. “Coupled along with the vaccination program, that is the answer.”

Livestock Water is Essential, Even in Winter

Ted Wiseman, OSU Extension Educator ANR, Perry County

(Image Source: Catskill Merino Sheep)

Water is essential for all livestock regardless of the time of year. So far this year we have certainly had our share of chopping ice, thawing water lines and troughs. With recent temperatures many of us often focus on keeping livestock well fed and with adequate shelter. However, often times we forget about the most important nutrient which is water. Water consumed by livestock is required for a variety of physiological functions. Some of these include proper digestion, nutrient transportation, enzymatic and chemical reactions, and regulation of body temperature.

Although water is the cheapest nutrient we may purchase or provide, it is the one we provide the most of on a per pound basis. For example, every pound of dry matter consumed, cattle will need to drink about seven pounds of water. Consumption of water varies depending upon temperature, size of the animal, feed intake, mineral intake and stage of production. Lack of water consumption will affect animal performance. With colder temperatures feed intake is increased to generate body heat. Decreased water availability reduces feed intake which results in decreased body condition. This is especially important if your newborns arrive in the spring, following reduced water and feed intake which leads to poor fetal growth rates and lactation levels.

To ensure adequate water intake, reports have indicated that water temperature should be 37 to 65 degrees. The rumen operates at 101-102 degrees; ingesting extremely cold water can decrease digestion until the water warms to body temperature. Be sure to monitor waterers regularly, for temperature and cleanliness. Stray voltage is another issue that should be monitored for new installations as well as established watering devises. An electrical AC current above three to four volts is enough to decrease water intake. Tank heaters can be an option, but keeping electrical cords away from any contact with livestock can be an issue.

For many grazing operations ponds, streams and developed springs are the primary sources of water. These may limit the areas to be grazed and where winter feeding is done depending upon how far livestock need to travel to the water source. Producers over the years have utilized technologies by installing pipelines, storage tanks and more recently the use of solar power to move water to various locations. There are numerous styles of watering designs, each have advantages and disadvantages, especially during the winter.

Which style to choose depends upon many factors and you need to spend some time looking at various types and speaking with producers in your area for advice. Just a few things to consider, first what type(s) of livestock do you have or plan to add and how many animals can the waterer handle? Where do you need to place it and how is water going to be delivered? Are you going to need external heat source during the winter? How much maintenance is required and how easy is it to clean? Will your livestock need to be trained to use the system? What is the life expectancy of the waterer? And lastly of course price, but this should not be the deciding factor. A cheaper waterer that doesn’t last as long and requires more of your time to maintain will be much more expensive in the long run.

If given a choice of water sources cattle do prefer to drink from a tank instead of streams or ponds. In a few studies that looked at this, cattle where given access to both with no restriction to stream or pond access. In both studies cattle preferred to drink from tanks 75 to 90 percent of the time. When cattle drink from a pond or stream the second cow normally travels farther into the water source for a cleaner drink.

Good quality water is essential for livestock, regardless of the source you have. Rarely do many of us test our water on a regular basis, but it should be considered. Especially if you notice reduced water intake or refusal. Water analyses for livestock typically include total dissolved solids or salinity, pH (acid or alkaline value), nitrates, sulfates, and hardness. Bacteria can be a health concern, especially during summer months and during drought conditions. If you plan to test your water, consult your water testing lab for proper water sample collecting procedures.

Until spring arrives, keep those water sources opened up and clean.