Russian Thistle (Tumbleweed - Salsola kali, Salsola tragus) -
      I have not trained animals to eat this plant, but it has been used in the past as a forage during drought. This 2003 North Dakota State University Fact Sheet describes how to use it as a feed for sheep and cattle.
      This plant is a Eurasian native. The confusion in the latin name for this species is due to a variety of thistles that look very similar. Be prepared to look up information under both names for the best results. Currently the plant growing in coastal zones is known as S. kali, while the more prevalent species is called S. tragus. Because this plant is very salt tolerant and flourishes in conditions that would cause problems for most other plants, "it is an arid-lands forage of considerable value. When young and green, it is palatable and nutritous for sheep and cattle, but not necessarily for horses." (Toxic Plants of North America, Burrows and Tyrl, first edition, pg. 357.) Most resources suggest that as the plant matures, the spines harden, and they attribute the spininess to the plant's reduced palatability. In fact, it may simply be because nutritional value declines.
      Toxins: This plant can be a nitrate accumulator, and nitrate levels increase as the salinity of the soil it is growing in increases. Although diarrhea may be a consequence when sheep subsist on Salsola for several weeks, more important is a rare, acute neurological/metabolic problem following ingestion of large quantities of Salsola in only a few hours. This problem is a result of the oxalates in the plant. (Toxic Plants of North America, Burrows and Tyrl, first edition, pg. 357.) According to A Guide to Plant Poisoning of Animals in North America (Knight and Walter 1st edition, pg. 265-266), "Supplementary dicalcium phosphate in the diet before and during high-risk oxalate exposure is an efective means of reducing losses. High levels of dietary calcium bind oxalate in the rumen as insoluble, nonabsorbable calcium oxalate. Calcium may be provided to the animals in a salt mix (75 lb salt, 25 lb. dicalcium phosphate) or in pelleted alfalfa at a 5 % concentration and fed at the rate of .5 lb. per sheep/day. Livestock diets can also be supplemented with hay to help reduce the total intake of oxalate-containing plants."
      Grazing Prescription: You can graze this plant with the following, normal precautions:

1. Make sure hungry animals are not sent into large stands of this plant.
2. Make sure they have a variety of forages to choose from.

Additional Resources: U.S. Forest Service database