One of the reasons our pastures are so good is that they are actively managed. We do intensive rotational grazing, with our pastures subdivided into 10 smaller pastures that our two herds of geldings and mares rotate through on about a weekly basis. We also have two winter dry lots which we also use when the pasture grasses are stressed by drought, or need to build roots in the fall. We do regular annual over-seeding of barer areas in the pastures - gate areas tend to get bare - and also reseed our dry lots once the horses are out of them in the spring - this help extend the time when there isn't mud and also delays our need for round bales. Charisma's owner religiously measures the grass in the different pastures to make sure we aren't over-grazing. She also does a lot of hand-weeding of plants that reduce forage quality or that are poisonous to horses. She also does spot herbicide treatment from time to time of a few persistent perennial weeds like Canada Thistle and Multiflora Rose, paying very close attention to persistence and the time the horses should be out of the pastures. I help her with these jobs from time to time, and also just have an interest in plant identification. I've learned to identify a number of plants that can be hazardous to horses, but I'm always looking to learn more.
We were attending a 3-hour workshop put on by the University of Illinois Extension. There were probably about 20 people in attendance. For those of you not from the U.S., the public land-grant universities have extension services that provide much valuable assistance to farmers, ranchers and others with crops and animals - many of these services are also available to the general public. They do research and also publish many resources which we use on pasture management, hay and animal nutrition. The workshop was conducted by a vet, with assistance from the extension representative who we have worked with frequently on pasture issues.
We had a two-hour presentation on plants in our area that may be toxic to horses, which also included the clinical signs of eating (or in the case of Black Walnut, standing in contaminated shavings from) the toxic plant. Due to their different digestive systems, horse are sometimes affected different than other grazers such as cattle. Although there is a long list of plants, shrubs and trees that are poisonous to horses, fortunately horses will generally avoid toxic plants since they are much more selective grazers than cattle. The biggest problems occur where horses are not being fed sufficiently and are in pastures that are of poor quality, or are bored, say in a bare dry lot, and chew on what is there or reachable over the fence. Horses may also be affected by toxins that can develop in corn, hay or haylage, or due to plants or insects (such as Blister Beetles) that are included in hay.
There are also a number of ornamentals that are used around homes that are toxic (some extremely toxic) to horses, including Yew, Rhododendon/Azalea/Laurel, Foxglove, Oleander, Hydrangea, Delphinium/Larkspur and Lily of the Valley, as well as Red Maple. There are others and since horses are often stabled near homes, and there may be ornamental plantings around barns, this is good to know.
The level of toxicity of the various plants and agents varies, from ones where the horse would have to consume a large quantity to be affected to ones where even a small amount can cause severe effects or death. We had a show-and-tell with several complete - roots to flower - toxic plants to look at.
The presentation was held at the Chicago Botanic Garden, which is an amazing place to visit. After the formal presentation was done, we were given a map and directions how to find a number of the plants we had been discussing, and went out on our own to look at things.
We also got some lovely handouts and list of web sites that help with plant identification. (I did a post a while ago that included a list of my favorite identification guides.) There was also a good summary provided of the restrictions on grazing and haying following the use of various herbicides. I picked up a nice identification guide to pasture grasses. All in all, a very useful day!
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When I got home, Maisie and I took a short trail ride since our arena is still too wet to use. She was alert but much more relaxed. She mostly kept to a regular pace even as we returned to the barn, and we did some more of the "standing around" exercise. It was windy and cool, and also feeding time - she had to wait for dinner - so she did well.