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Yet another question


ejano
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I understand that wilted cherry leaves are quite toxic to sheep. I am assuming that this warning refers to the American Black cherry tree (Prunis serotina) (sued for lumber)

 

What about the bird cherry (Prunis padus-- is it Hackberry?)?

 

What about cultivated fruit cherry trees -- sweet and sour?

 

And while we're at it -- the Black Walnut? Butternut?

 

(Remnants of a fruit orchard surround my paddock and just caught my cousin planting a fruit cherry on his side of the stone wall....sigh...

 

Liz

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Here's a good website:

http://www.ansci.cornell.edu/plants/index.html

 

Since you're in PA I assume you will share many of the same plants with NY.

 

ETA: Funny, they don't list black walnut but it is my understanding that it is toxic to horses. Then, again, my sheep eat the saplings that grow under a big sprawling walnut tree that borders my pasture without problems.

 

Kim

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Here's a good website:

http://www.ansci.cornell.edu/plants/index.html

 

Since you're in PA I assume you will share many of the same plants with NY.

 

ETA: Funny, they don't list black walnut but it is my understanding that it is toxic to horses. Then, again, my sheep eat the saplings that grow under a big sprawling walnut tree that borders my pasture without problems.

 

Kim

 

This website is terrific - answers my question about cherry trees - and much more!

 

According to the site, Wild Cherries, Black Cherry, Bitter Cherry, Choke Cherry, Pin Cherry are all hazardous to the sheep's health (seeds and leaves)...this is going to be a big problem for me...may have to relocate the paddock...sigh...there's a big Black Cherry tree at the south end of the barn - so that one needs to come down immediately before it leafs out/drops seeds into the paddock. (Though I'll miss it, it is a very nice tree. I don't think it will get much bigger where it is so we won't lose board feet of lumber). I need to walk the south wall with someone who really knows their trees... glad to know that Walnut trees are relatively safe! There are several growing behind the barn.

 

Thanks,

Liz

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Put that chain saw away. Just make sure that if you have a high wind storm you don't let the sheep get at any of the leaves on any broken branches. Leaves the drop naturally are not a problem.

 

Here's what happens. In the sap of the genus Prunis (which also includes several other stone fruits) there's a very tiny amount of hydrocyanic acid, also known as prussic acid. This is so dilute that sheep can feed on fresh cherry leaves and eat the bark off cherry trees with not ill effect. In fact, they love cherry leaves.

 

The problem arises when a branch breaks off a tree. The leaves continue to draw sap up from the wood, and the water transpires out the leaves. Because this sap is not being replenished, gradually the non-water portions of the sap are concentrated in the leaves. The ones that concern us here are sugar and cyanide. After a time, the leaves start to run out of sap from the wood and will start to wilt. At this stage, they are still quite sweet, as the sugars have been concentrated. But they are also carrying a toxic load of cyanide.

 

When the leaves fall off the tree normally in the autumn, they wall themselves off from the sap supply, and there simply isn't enough in them to cause any harm.

 

Similarly the tiny amount of whole sap in the stones of the fruit won't cause harm, even if the sheep eat them which is unlikely.

 

Remember when looking at information about toxic plants, that "toxic" means something to a scientist that it might not mean to a shepherd.

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Remember when looking at information about toxic plants, that "toxic" means something to a scientist that it might not mean to a shepherd.

 

Can you please elaborate on this Bill? I assume you mean that shepherds need to balance what's practical/feasible with what's "ideal."

 

I'm fairly certain that some of the unexplained/sudden deaths in my flock are from (sensitive sheep) eating toxic plants. To a certain degree this is unavoidable. I graze and/or hay ~ 75 - 100 acres (and buy hay from various sources) so it would be difficult to avoid and/or eliminate all toxic plants. For example, my sheep love milkweed and my pastures are filled with it. If I had to graze in pasture without milkweed, I wouldn't have sheep. However, if I were planning where to lay out my pasture, I wouldn't put it under cherry trees. Would I cut down a nice cherry? - I'd probably try to prune it back or to divert the sheep away from the tree. I'm also careful not to buy wood shavings (from a local sawmill) that contain cherry. I also don't "force" my sheep to eat every last bite in an area. So again, I keep the toxic plant information in mind and manage the sheep in a way to minimize controllable exposure.

 

Kim

 

Kim

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As will become clear shortly, this toxic plant list really ticks me off.

 

To a scientist, "toxic" means "contains toxins." Many, many plants contain toxins, and they generally fall into two categories: plants sheep won't eat and plants that have such a low concentration of the toxin that it has no effect on them. To a shepherd, "toxic" means "capable of producing illness or death." Very few plants that sheep will actually eat fall into that category. Wilted cherry leaves would be one example. Rhododendron, endophyte infested fescue, and ergot infested grasses would be a couple of others.

 

In my experience the vast majority of deaths that are blamed on the consumption of "something poisonous" are more likely the result of some other malady, ranging from parasitism to pneumonia to wasting diseases. In my opinion, the exhaustive lists of toxic plants that you can find on the Internet are partly to blame.

 

The Cornell site you linked to lists the following "toxic" plants: alfalfa, white clover, red clover, birdsfoot trefoil, several varieties of vetch, lamb's quarters, just about every maple, and tall fescue. It also contains the following disclaimer: "IMPORTANT:Just because something is on the poisonous plants list doesn't mean it can't be a good food or feed, and just because it is absent from the list doesn't mean it is safe!" I translate that as follows: "IMPORTANT: This list means NOTHING!"

 

Working off that list, you can just about always find something in your pasture that is "toxic" and blame an unexplained death on the consumption of that. I am not saying that you have done this, but I think a lot of small flock owners simply stop there and console themselves that there was nothing they could have done, or worse, lock their flocks up in a drylot to keep them from eating the deadly pasture plants like white clover.

 

Meanwhile, whatever actually killed the sheep continues to work away at the others, and appropriate management strategies are never adopted that would actually prevent the next "unexplained" death. For the record, it has been almost 15 years since I've had an unexplained death in my sheep flock. I have lost three sheep during that time to confirmed toxins: one to a broken branch of a cherry tree that I didn't find in time, and two to thiaminase linked to bracken fern. During those 15 years, about 7,000 sheep have passed through my flock. Every other death was explained by something else.

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I think you've twisted my words a little implying that if a death was unexplained it was due to lack of due diligence or that these unexplained deaths are somehow routine. By "unexplained death", I meant deaths that were isolated (a handful over 15 years), sudden and that all other causes of the death were ruled out. In other words, they were NOT "flock problems." Ironically, one of the "causes" you list was the one that I experienced -- bracken fern.

 

Back to my major point - I think shepherds need to use the information (indeed any information) keeping in mind what's practical/feasible for their siutation. If you look at the website, it contains much more than just a "list" of toxic plants. There is extensive information about the toxic compounds found in the plants and their effects that will provide context to weigh these factors.

 

Kim

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Thank you - I am reassured on many points. We scouted the area carefully and made the following decisions: The big cherry on the south end of the barn will still come down -- though out of the paddock, it's way too close to the in/out door the sheep will be using so that anything that fell from it would be an enticing bit of green in what will be a graveled area.

 

It is also undermining the foundation of the barn and it has pretty much reached it's zenith, given the limitations of space. We'll get a few board feet of good lumber out of it, perhaps enough to make a small table, which is nice. I'll plant something there that is more suited to the space. The trees along the south wall are less of a risk and will likely remain. The fence will be set back a considerable distance from the wall (more than enough to let a tractor and a brushhog pass through). The property is a family trust so I can't go willy nilly harvesting what might eventually become valuable trees.

 

Down in the meadows, the big patch of milkwood near the entrance to the orchard, that will be fenced off. It's too valuable for monarchs to mow down. The rest of the area seems pretty harmless...but I don't know all of the plants by sight.

 

The effects of putting livestock on the meadows have become quite debated but the "Golden Hoof" will hopefully become a part of an overall management plan that improves the meadows and helps to bring back the orchard while retaining the species that are necessary to support insect, bird, and wildlife populations.

 

 

Thanks for all of your advice -- keep it coming!

 

Liz

 

ETA - this is a more detailed explanation of how sheep are being used to restore and maintain natural habitat - so often it is thought that farming and environmental concerns are in opposition so this is a good example of how one supports the other...

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Kim I didn't mean to imply that that was what was going on in your case, and in fact I said that I didn't believe you wrote off unexplained deaths to toxic plants. Just that it does create the impression that there are a lot of dangerous things out there in the field that can cause lots of unexplained death, and that lots of small flock owners either take needless measures, avoid necessary measure, or both based on a poor diagnosis based on an list of toxic plants that essentially includes everything an animal might eat.

 

My point is that it's not even a matter of what's practical and feasible, but that if you were to take this resource at face value, you would cross a lot of the most valuable sources of forage off your list and/or worry needlessly about things that are not really dangerous to your sheep.

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