silvopasture

Poisonous Plants in Silvopastures

I was surprised in looking over the numerous past topics that we haven't had a discussion on plant toxicity risks to livestock in silvopastures. the following email came to Peter and I recently, and is representative of one of the more challenging native plants found in many parts of the Northeast: Mountain Laurel. The original emails are below. Would be interested to know what experiences others have had with Mountain Laurel and/or other "poisonous" plants.

From Craig in western MA...

I have been reading the Cornell Goats in the Woods information with interest and I am curious if this is still considered a viable method of raising meat goats.

I have a small goat operation in western MA that I'd like to expand. The main impediment to expansion is lack of pasture. However, I do have about 70 acres of woodland that is currently managed with occasional commercial thinnings. There is abundant underbrush on most of the property and when I let the goats in the woods, they have a field day. Although they love being in the woods, I am somewhat cautious due to the presence of Mountain Laurel. The use of electroplastic netting described in the workbook vs. letting them roam freely could mitigate potential poisonings. The goats seek it out as it is very palatable to them. Unfortunately it is also deadly poisonous to ruminants. The toxic effect is delayed 6-8 hours so the goats usually don't learn to avoid it.

My main questions are:

1. Is this still a viable strategy for meat goat producers with their own woodlots?

2. Is the method sustainable? I.e., will there come a point when all understory vegetation is destroyed leaving the animals without browse. Is there any information on a sustainable stocking rate?

3. What was done with the animals during the winter? Were they removed from the forest?

4. Is anyone in New England currently doing this?

I see several advantages to this method, especially in the control on intestinal parasites, haemonchus in particular as well as better hoof health from the exercise and browse they receive. My property is rugged and rocky, so my lazy goats would have to do some work to eat!

My response...

I worked for several years as a consulting forester in CT/MA and thus am familiar with the abundance of mountain laurel in those woods, but have no experience as a grazier with the plant (doesn’t grow in the Finger Lakes Region of NY where our family’s farm is). But yes, it’s one of those problematic plants that is both (reportedly) quite toxic and undetectable to livestock.

My theories would be to:

Try to control it to the extent possible in the areas being grazed. The www.forestconnect.info “publications” page has some bulletins on using herbicides and other methods to control undesirable vegetation). We used to encourage loggers to run it over as much as possible during harvests, but preventing resprouting would require treating the stumps with some sort of herbicide.

Make sure the goats are well-fed with other quality forages, and a balanced mineral supplement so that they’re not motivated to browse the laurel (at least not in significant quantities). Some plant poisoning issues, like prussic acid (wilted cherry and other Prunus spp.) appear to be aggravated when animals are deficient in critical minerals like selenium.

Allow a “natural selection” of goats that will learn not to eat it (those that don’t learn may die or need to be culled). This would probably be the most cost-effective method. Sounds harsh, but is the most commonly employed strategy in other parts of the world with livestock and problem plants.

Train the goats specifically not to eat the mountain laurel through negative reinforcement. For details: http://www.livestockforlandscapes.com

(very) gradually acclimate the animals to the Laurel and/or give them sub-lethal doses to learn that the plant will make them not feel well. This is generally how grazing animals learn to avoid certain plants. The trick is for them to not eat too much of the plant before they learn.