When to Start Grazing: Don’t Rush It!

– Chris Penrose, Extension Educator, Ag and Natural Resources, Morgan County

Originally posted on the BEEF Newsletter

 

One goal I have had with livestock grazing over the years is to start as soon as I can. I put spring calving cows on stockpiled grass in early March to calve with the hope of not having to feed any more hay. Many years this works but not this year, grass is just starting to grow. The stockpile is about gone and I have started feeding them some more hay but hope to move the group with the fall calving cows this weekend. I then plan on starting a fast rotation around many of the paddocks and hay fields which is actually later than many years.

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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.

Autumn Grazing Tips for Extending the Growing Season

Originally Posted in the Sheep Newsletter- Victor Shelton, NRCS State Agronomist/Grazing Specialist

The older I get, the more I tend to philosophize about things. I’ve been asked a few times why I am such an advocate for sound grazing practices. Best management grazing practices, just like conservation practices for reducing or preventing soil erosion on cropland, help preserve and or regenerate resources not only for present generation, but also for future generations.                         

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Good Management Practices for Fall Grazing

Ted Wiseman, OSU Extension Educator ANR, Perry County
(Previously published in Farm and Dairy: August 9, 2018)

 

Fall pasture management is a critical period for pastures. For many of us we have had adequate rainfall up until recently and pastures have done well to this point.

As we transition into late summer and early fall it is critical to pay close attention to your forages. Some pastures may be stockpiled, but those intended to be grazed this fall still need time to rest.

It’s very tempting to use those forages that green up late in the fall. Management decisions made this fall will greatly impact forage growth next year.

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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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Ohio Noxious Weed Identification – Week 18 Wild Mustard

Wild Mustard

FamilyMustard, Brassicaceae.

Habitat: Wasteland, roadsides, grain and other fields crops, primarily in northern Ohio.

Life cycle: Annual annual or summer annual.

Growth Habit: 1-2 feet high, branched and erect.

Leaves: Alternate, 2-7 inches long. Lower leaves have petioles and are irregularly lobed and toothed with bristly hairs; upper leaves are smaller and may not be lobed; petioles lacking or short.

Stem: Branched near top, bristly.

Flower: June – October. 1/2 inch, bright yellow, four-petal flowers borne in small terminal clusters.

Fruit: Slender, slightly curved, smooth seedpod about 1 inch long; borne on upper branches.

Similar plantsThe yellow rocket looks similar but has rounded lower leaves that are more heart shaped.

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Ohio Noxious Weed Identification – Week 17 Wild Carrot

Wild Carrot

Family: Parsley, Apiaceae.

HabitatDry fields, wastelands, pastures, and no-till field crops.

Life cycleBiennial, forming a rosette the first year and producing flowers and seed in the second.

First Year Growth Habit: A basal rosette.

Second Year Growth Habit1-3 feet tall, branched and erect.

Leaves: Alternate, pinnately compound, finely divided and hairy.

Flowering StemTall, hairy, stout, and branched.

Flower: June – October (second year). Small, lacy white 5-petaled flowers in flat-topped, umbrella shaped clusters with one dark reddish-brown flower in the center. Flower closes up and turns brown as it matures.

Root: Fleshy taproot.

Similar plants: Leaves have the appearance and odor of a garden carrot. Wild carrots taproot is not as large as the garden carrot. The plant also resembles poison hemlock (Conium maculatum). However, wild carrot has a hairy stem while poison hemlock has a smooth stem with purple blotches. The dark floret in the center of the inflorescence in second year and a distinctive carrot smell in the first year will also help distinguish this common weed.

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Ohio Noxious Weed Identification – Week 16 Poison Hemlock

Poison Hemlock

Family: Parsley, Apiaceae.

Habitat: Wet sites, gardens, roadsides, wastelands, pastures, and meadows.

Life cycleBiennial, forming a rosette the first year and producing flowers and seed in the second.

First Year Growth HabitBasal rosette of finely divided leaves with a pungent odor.

Second-Year Growth Habit: 2-7 feet tall, branched plant with flowers.

LeavesAlternate, pinnately compound, finely divided, toothed, and glossy green.

Stems: Branched, waxy with purple blotches; hollow between nodes and grooved.

FlowerJune – August (second year). Clusters of small white flowers with 5 petals in a loose, umbrella-like cluster, 2-7” across.

Root: Fleshy taproot.

Similar plants: During the first year, poison hemlock resembles wild carrot, but has a strong, pungent odor. Further, young leaves of wild carrot are more finely divided and its stem is hairy. At maturity, poison hemlock can be difficult to distinguish from water parsnip and water hemlock. Look for purple blotches on the stem to identify poison hemlock. Water hemlock (Cicuta maculata), which is also highly poisonous, has a magenta-streaked stem and lanceolate leaflets with sharply-toothed edges. Water parsnip (Sium suave) is not poisonous and has toothed lanceolate leaflets.

The problem is….This plant is highly poisonous to both humans and animals. Poison hemlock is a large and impressive plant which has been planted as an ornamental in some areas. It grows quickly in fertile soils.

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Ohio Noxious Weed Identification – Week 15 Johnsongrass

Johnsongrass

FamilyGrass, Poaceae.

Habitat: Rich soils, cultivated fields throughout Ohio.

Life cycle: Perennial, spreading by rhizomes and seed.

Growth Habit: 3-6 feet or more.

Leaves: 0.5 -1 inch wide, smooth blades with a prominent white midvein.

Flower: July – October. Can be up to 1 foot or more in length; panicles are loosely branched, purplish, and hairy. spikelets occur in pairs or threes.

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