Dangerous Pasture and Hay Crops, Poisionous Plants, Toxic Plants

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What you should know about what your pastured animals eat everyday!Things you should know about the grasses and plants in your pasture. Don't Miss our NEW page about Tansy Ragwort control!

Hunter's Pony Farm offers this information as a service to our readers, we are not veterinarians, and take no responsibility for errors or consequences of using this information. If you are concerned about your animal, you should consult a licensed veterinarian immediately.

Have you ever wanted to know the poisonous or toxic
plants that could be growing in your pasture? With the news of foals dying from the possible ingestion of cherry leaves it is fresh in our minds now to consider what our own horses may be exposed to in the pasture. Use the lists below to learn more about the plants that may be growing in your grass!

What about the things you hear about bugs in hay?

Well, this is the place to find out about those problems...
ones faced not just by horse owners, but farmers,
cattle and dairy farms, goat keepers, hay growers and others. Some of these plants are even poisonous to you and me! So read on, then check your pasture!

There are a few topics I want to cover here:
    *    Nitrate Poisoning
    *    Sudan Grass (sorghum)
    *    Blister Beetles
    *    Tall Fescue Toxicity
    *    Johnson Grass

Other issues include animals ingesting plants that are "borderline" in toxicity causing abortion, reduced milk flow, lower weight gains, vitamin A deficiency

Management Practice
* Feeding rations high in carbohydrates will reduce and some times prevent losses from nitrate poisoning* Control weeds that accumulate nitrates. Freshly sprayed plants may become more palatable, so defer grazing of sprayed areas.
* During periods of cool or cloudy weather. avoid grazing a suspect area if possible. During periods of sunlight allow’ animals to eat large quantities of dry forage and then graze the area.
* Test the nitrate content of forage when in doubt.
* Distinguish nitrate poisoning from prussic acid poisoning or grass tetany, so the appropriate treatment may be administered.

OAT HAY MOISTENED WITH WATER can convert nitrates to nitrites in a short time.

Guide B-807, Christopher D. Allison, Extension Range Management Specialist College of Agriculture and Home Economics, New Mexico State University
http://www.cahe.nmsu.edu/pubs/_b/b-807.html

Sudan Grass - (sorghum) including Improved Varieties

Members of the Sorghum family contain dhurrin, a glucoside that breaks down to release hydrocyanic acid also known as prussic acid. A sudden disruption of growth such as frost, drought or cutting, causes prussic acid to be released inside the plant at a more rapid rate. High prussic acid levels may be lethal to cattle and horses. Prussic acid will breakdown in one to two weeks, so material made into hay or silage is safe to use after curing.

Nutritional Concerns and Animal Health Hazards

Prussic acid poisoning is a concern in feeding Sorghum, Sudan grass, or Sorghum-Sudan grass hybrids. In the stomach, these compounds are converted into prussic acid, which is easily absorbed into the blood. High blood levels of prussic acid interfere with respiration and cattle can soon die from respiratory paralysis. Horses should not be allowed to graze these plants as they may develop cystitis syndrome. This condition looks like colic with accompanying bloody urine and can be fatal to horses. Affected animals may show a staggering gait and urine dribbling. Pregnant mares may abort. There is no treatment for this poisoning and poor prognosis of recovery.

Nitrate poisoning and formation of toxic silo gas can be a problem with Sorghum-Sudan grass. High nitrate levels are only a problem under abnormal growing conditions such as:

* High nitrogen fertilization caused by heavy fertilizer or manure applications or following legume plow down.
*   Prolonged drought followed by rain.
* Any condition which kills the leaves while the roots and stems remain active will initiate accumulation of nitrates (frost, hail, grazing and trampling, or sometimes drought and overcast weather).

If you suspect high nitrates in the forage, have it tested .

This Fact sheet was authored by:
Beth Wheeler, Dairy Nutrition Specialist, OMAFRA, Kemptville.
Joan McKinlay, Soil and Crop Specialist, OMAFRA, Markdale.
For more information...Joan McKinlay at jmckinla@omafra.gov.on.ca
http://www.gov.on.ca/OMAFRA/english/crops/facts/98-043.htm

Dangerous Pasture and Hay Crops

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An alphabetical listing of toxic plants:
    *   Alsike Clover
    *   Azalea
    *   Star of Bethlehem
    *   Black Locust
    *   Black Walnut
    *   Bouncing Bet
    *   Brackenfern
    *   Buckeye
    *   Bulbs
    *   Common Burdock
    *   Buttercup
    *   Castorbean
    *   Catnip
    *   Cherry
    *   Cocklebur
    *   Dumbcane (Aroids)
    *   Dutchman's Breeches
    *   Easter Lily
    *   English Ivy
    *   Ergot
    *   Fescue
    *   Foxtail Barley
    *   Green False Hellebore
    *   Poison Hemlock
    *   Water Hemlock
    *   Horsechestnut
    *   Horsetail
    *   English Ivy
    *   Jack-in-the-Pulpit
    *   Jimsonweed
    *   Johnsongrass
    *   St. Johnswort
    *   Larkspur
    *   Easter Lily
    *   Black Locust
    *   Lupine
    *   Red Maple
    *   Marijuana
    *   Milkweed
    *   Mustards
    * Stinging Nettle
    * Nightshades
    * Red Oak
    * Oats
    * Oleander
    * Pigweed
    * Christmas Plant (Poinsettia)
    * Poison Hemlock
    * Pokeweed
    * Jack-in-the-Pulpit
    * Senecio, Ragwort
    * Red Maple
    *, Rhododendron
    * Rhubarb
    * Rosary Pea
    * White Snakeroot
    * Spurges
    * St. Johnswort
    * Star of Bethlehem
    * White Sweetclover
    * Tansy
    * Tobacco
    * Black Walnut
    * Water Hemlock
    * White Snakeroot
    * Yellow Sweetclover
    * Yew

Plants to watch out for:
Field Crops
    * alfalfa
    * millet
    * soy bean
    * barley
    * oats
    * soy bean
    * corn
    * rape
    * sudan
    * fescue
    * rye
    * wheat

Vegetables
    * beets
    * lettuce
    * spinach
    * celery
    * mangles
    * squash
    * cucumbers
    * parsnips
    * swiss chard
    * kale
    * radishes
    * turnips

Weeds
    * bindweed
    * elderberry
    * Russian thistle
    * blue-green algae
    * fiddleneck
    * smartweed
    * bull thistle
    * goldenrod
    * stinging nettle
    * burdock
    * lambsquarter
    * sunflower
    * Canadian thistle
    * nightshades
    * velvetweed
    * carelessweed
    * ragweed
    * whitecockle

Other plants may have toxic levels under certain conditions.

TALL FESCUE
Festuca arundinacea (grass family)
TOXICITY RATING: Moderate to high, depending upon
individual circumstance.
ANIMALS AFFECTED: Horses, cattle, possibly other ruminants.
DANGEROUS PARTS OF THE PLANT: Seed head, stem and leaf
sheath.
CLASS OF SIGNS: Reproductive problems, "poor doers", lameness, dry gangrene, fever, death.
PLANT DESCRIPTION: This grass (fig. 15), often cultivated in wet pastures for forage or for turf, is a perennial, 3 to 4 foot tall clump grass with medium-wide leaves that are rough-ribbed on top. It has no rootstocks (rhizomes). The heads are open and many-branched. Escaped plants may be found along roadsides and in waste areas.
SIGNS: Toxicity is the result of an endophytic ("in side the plant") fungus, Acremonium coenophialum, which is believed to enable the grass to be more hardy and outcompete other grass species. The grass itself is not toxic. The fungus is passed in the seed, and is not transmitted directly from plant to plant. In horses, pregnant mares are most at risk when eating fescue, since the alkaloids produced by the fungus inhibit prolactin release. Mares will have an increased risk of prolonged gestation, abortion, stillbirth, dystocia (difficult birth), foal mortality, retained or thickened placenta, no milk, and mare death (in foaling, or from a retained placenta). Additional note: Fescue can accumulate nitrates under conditions of overfertilization (see the section on oats for more information on nitrate toxicosis).
FIRST AID: There is only supportive and symptomatic treatment once signs appear. A veterinarian can advise on treatment of more severely affected animals. Pregnant mares will be likely to need assistance when foaling and in the post-foaling period. Foals that survive will require supplemental colostrum. Management and prevention are the best means to minimize losses.
SAFETY IN PREPARED FEEDS: The toxin remains active in hay.
PREVENTION: Fungicides do not work, so animal and pasture management are the only viable alternatives. Pastures can be tested for the presence and degree of fungal contamination, and reseeding may be needed. If reseeding the pasture is not an option, keeping the pasture short will prevent seed formation. Feeding other forages, such as other warm season grasses or legumes, will be of benefit. Fescue pastures can also be diluted with legume planting (red or white clover). Heavy fertilization may make the problem worse, especially in cattle. If fescue has to be used for mares, at least avoid feeding fescue hay or pasture during the last 30 to 60 days of gestation to minimize problems. Endophyte-free strains of fescue exist, although they do not grow as well as tall fescue with endophyte.

JOHNSON GRASS
Sorghum halepense (grass family)

TOXICITY RATING: Moderate to high.
ANIMALS AFFECTED: All types, especially ruminants.
DANGEROUS PARTS OF PLANTS: Leaves and stems, especially young plants.
CLASS OF SIGNS: Breathing problems, staggering, severe anxiety, convulsions, coma, death (may be very sudden).
PLANT DESCRIPTION: Johnsongrass , a coarse perennial grass, produces large, scaly rootstocks and grows in dense stands up to 6 feet high. Seed heads are large and loose. This plant grows commonly in the fields, fencerows, and ditch banks of the southern part of the US and is rapidly spreading northward. Once grown for dike stabilization or for hay, it is now classified as a "noxious" weed.
SIGNS: The toxic signs resulting from ingestion of Johnsongrass are due to the presence of cyanide in the leaves and stems. This toxicity is identical to that resulting from the ingestion of wilted or damaged cherry leaves. In normal, healthy Johnsongrass plants, the levels of free cyanide are low, and the plant can be consumed safely. Other members of this grass genus have been bred as grain or forage plants (milo, Sudan grass, etc.) and also have the potential to produce cyanide, although not as much as Johnsongrass. The young shoots are the most dangerous, and when wilted, trampled, herbicide treated or frost damaged, a great deal of free cyanide is liberated in the leaves. Upon ingestion, the animals quickly develop signs related to cyanide poisoning. Mature plants have much lower toxicity, and well-cured hay is relatively safe for consumption.

This article may be reprinted on your web site if you include this entire paragraph when copying it to your site. Copyright 2004 - 2011, Pam Hunter, Hunter's Pony Farm http://www.huntersponyfarm.com

About: Pam Hunter
Pam Hunter has 50 years
experience with animals of
all kinds, especially horses,
cats, dogs, poultry, goats,
pigs, and other farm animals.
Some of her work has been
referenced in magazines like Horse Illustrated. She has also had a profile published in "the entrepreneurial parent". "I love animals, painting, writing. I have been published online for several years on sites like PetPlace, About, and others.

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