Beware Toxic Woes
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Contrary to popular belief, goats are quite selective in their dietary choices. Their browsing capabilities allow them to utilize a wide variety of forages found in virtually all types of climates. But, on the flip side, it also means they have a high risk of exposing themselves to all kinds of toxins from plants. A goat may not ingest much of a single toxin, but even small amounts can have negative impacts not immediately noticeable to the naked eye.
What Is Toxicity?
Essentially, a toxin is a type of poisonous substance produced by the cells of living organisms. Nature is abundant with these substances, but what is toxic to a specific species might not be to another. The level of toxicity can also fluctuate from case to case. For example, the amount of any toxic substance consumed plays a significant role in how much damage is done once consumed. Even the amount of toxin present in a plant at any given time can vary based on its age, point in its lifecycle, and general environment.
Many people believe “toxicity” means that an effect should be evident and life-threatening. However, neither of these is entirely accurate. Toxins can be cumulative and/or long-acting. Sometimes they will harm different bodily systems like the digestive, reproductive, or mammary — but the animal otherwise appears healthy.
How quickly a toxin acts depends on multiple things.
“If (toxins) are water-soluble, then they’re going to be absorbed quicker because of all the fluid within the digestive system,” explains Kevin Pelzer, DVM of Virginia Tech. “Essentially, those fluids migrate through the intestinal cells. If the compound is fat-soluble, it doesn’t get dispersed as quickly. Usually, there’s some act or process that needs to occur within the gut to absorb those fats or those fat-like toxins.”
Another way toxins can impact ruminants is during the fermentation process, where they are activated as the bacteria break them down. Pelzer adds that the GI tract can also absorb some toxins.
Getting Into Trouble
Most goats consume toxic plants by coming across them in the pasture. However, sometimes it happens due to an unsuspecting caretaker.
Accidentally feeding decaying or moldy hay products can cause botulism, a paralytic disease that is usually fatal. But sometimes, feeding seemingly “good” forages can have catastrophic results.
An example Pelzer gives is the very common ornamental bush Japanese Yew. Because it looks like a pine tree, which is perfectly safe for goats to enjoy, this may mislead people to feed it without a second thought. In reality, it is highly toxic due to its high taxine alkaloids.
Specific Toxin Types
Different alkaloid compounds exist across many weeds, including fescue, nightshade, hemlocks, and pokeweed.
Pelzer says that cattle, consuming large amounts of fescue, can suffer decreased conception or stunted growth. On the other hand, goats and sheep don’t tend to consume as much and don’t encounter such drastic side effects.
However, owners should survey the grazing area to see varieties and amounts of high-alkaloid-containing plants before turning goats out.
Cyanide, one of the fastest-acting poisons, can be found in various fruits and seeds. And because the rumen microbes directly interact with cyanide’s compounds, goats are even more vulnerable than animals with a simple stomach.
Those wanting to provide fresh fruits as a special treat to their goats need to be highly cautious never to feed the seeds. High levels of cyanide can occur in apple seeds, cherry and peach pits, and bitter almond.
Cyanide can also be found in various pasture plants, including Russian knapweed, certain hemlocks, cassava, and even wild carrots. When plants have young foliage, levels are highest, so do spring pasturing with great care.
Other toxins present in plants cause lesser-seen metabolic issues. Plants in the Brassica genus are a great example, and brassicas include Brussels sprouts, cabbages, radishes, turnips, and rhubarbs. While consuming some brassicas in small amounts may not be harmful, overconsumption of certain types can cause significant issues due to some varieties containing high oxalate levels, which can cause poisoning and kidney failure.
“Oxalates bind with calcium as well,” says Pelzer. “Some of these plant toxins inhibit or bind to a lot of minerals and prevent their absorption. As a result, the animal, despite eating so much of the mineral, may not actually end up absorbing it.”
Brassicas can also cause nitrate poisoning due to high nitrogen fertilization levels on these crops, which can, similar to calcium, inhibit magnesium and potassium availability. Certain brassicas found in pastures such as grazing rape or turnips have been known to cause bloating.
Pasture, weeds, and even the occasional atypical treat can all contribute to a healthful goat diet. But we should remember that toxins can lurk in all these places. Identifying questionable plants and monitoring how much they consume all contribute to long-term safety.
- Mudge, D. (n.d.). Toxic Plants Dangerous to Goats. Orlando; University of Florida. https://sfyl.ifas.ufl.edu/media/sfylifasufledu/orange/ag-nat-res/docs/pdf/toxic-plants_goats060210.pdf
- Extension Foundation. (2019, August 14). Which plants are poisonous to goats? Goats. Retrieved November 25, 2021, from https://goats.extension.org/which-plants-are-poisonous-to-goats/.
- Tegzes, J. H., Puschner, B., & Melton, L. A. (2003). Cyanide toxicosis in goats after ingestion of California Holly. Davis; California Animal Health and Food Safety Laboratory System. https://journals.sagepub.com/doi/pdf/10.1177/104063870301500515
- Barnes, A. (2021, November 29). Things that are toxic to goats. The Open Sanctuary Project. Retrieved December 10, 2021, from https://opensanctuary.org/article/things-that-are-toxic-to-goats/.
- Arnold, M. (n.d.). Forage of the month: Brassicas. Forage of the Month: Brassicas | Master Grazer. Retrieved November 25, 2021, from https://grazer.ca.uky.edu/content/forage-month-brassicas.
- Scheib, Michele. “Plants Causing Cyanide Poisoning in Pastures.” OSU Extension Service, Oregon State University Extension Service, 21 Dec. 2020, https://extension.oregonstate.edu/gallery/plants-causing-cyanide-poisoning-pastures.
- “Goat Pastures Poisonous Plants Alkaloids.” Goats, 14 Aug. 2019, https://goats.extension.org/goat-pastures-poisonous-plants-alkaloids/.
Originally published in March/April 2022 Goat Journal and vetted for accuracy.