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The first step in the training process is knowing something about the nutritional value of the target weed and toxins it might contain. We will be collecting and adding more information here and in the , but here is a summary of what we currently know about our target species:
Distaff thistle
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Distaff thistle (Carthamus lanatus)
Other Common name(s): saffron thistle, false star thistle, woolly safflower, woolly star thistle, downy safflower
General Background: This native of the Mediterranean region is a spiny annual that can grow up to 3 1/2 feet tall. We know that efforts to control the thistle began as early as 1871 in Australia, but in spite of their ongoing efforts, it is still reported in every Australian state (1). For more on the plant itself, from Oregon.
Nutrients: Peggy Rathmann harvested a late-growing distaff thistle in October and had it tested for nutritional value at Utah State University. It compared favorably with the nutritional value of Alfalfa, and contained 17% crude protein, 34% NDF and 57% TDN.
Toxins: There are no known incidents of poisoning due to distaff thistle. Based on a report by San Feliciana, et al. (2) the plant contains sesquiterpene glycosides. This is similar to what is found in spotted knapweed which cows were successfully trained to eat at Grant-Kohrs Ranch national historic site. In general, animals are more successful eating terpene-containing plants when they have adequate protein. This could be a consideration as we enter the training phase.
Timing of Grazing: For complete details, visit the Library.
1. G.R.W. Meadly, J. Dept. Agric. W. Aust. 6, 197-201 (1957).
2. A. San Feliciana, A.F. Barrero, J.M. Miguel del Corral, M.V. Gacimartin, and M. Medarde, Phytochemistry 21, 2115-2117 (1982).
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 Italian thistle
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Italian thistle (Cardus pycnocephalus L.)
General Background: Carduus pycnocephalus, a vigorous annual thistle, originated in western and southern Europe. It arrived in California during the 1930s and has since become a serious weed problem. It occurs in a variety of disturbed habitats and germinates rapidly and in large numbers. It is most abundant in coastal areas and occurs as a weed of pastures, ranges, roadsides, rural areas, fallow cropland, railroad rights-of-way, field margins, and ditchbanks (Goeden and Ricker 1978). A variety of herbicides have been used on C. pycnocephalus, but they give only temporary control (Wheatley and Collett 1981). Ranchers report that if they cut the thistle, cows will eat it after it wilts.
Nutrients: We have not tested for nutrient content.
Toxins: Though some Carduus species are known to accumulate nitrates in toxic quantities, C. pycnocephalus has not been incriminated as a toxic weed (Goeden 1974).
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Yellow starthistle
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Yellow starthistle (Centaurea solstitialis):
General Background: Yellow starthistle is annual that grows 2 to 3 feet tall. The weed probably arrived as a contaminant in alfalfa seed in the mid-1800s to early 1900s. They are "allelopathic" meaning they produce chemicals in the soil which reduce the ability of other plants to grow in their vicinity. For additional information visit this UC Davis sponsored website about Yellow star thistle.
Nutrients: Based on what we know about how animals choose what to eat and the fact that cattle have successfully eaten it in research projects it is fair to assume that this plant will have good nutritional value.
Toxins: There are no known cases of poisoning of cattle eating yellow star thistle. In fact, cows goats and sheep have been successfully used to control the plant in research done at UC Davis. However, Yellow star thistle does contain an unidentified compound that causes chewing disease in horses. The compound damages the area of their brains that controls fine motor movements, including mouth and lip movements. According to Burrows and Tyrl "There seems to be cumulative storage of the toxins rather than cumulative effect or damage. Thus amounts of the plant that migh otherwise produce disease - .... 100% of body weight - may be eaten without deleterious efect if not consumed on a continuous basis."
Timing of Grazing: This information will be added shortly. See the Library for complete details.
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Purple starthistle
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Purple starthistle (Centaurea calcitrapa):
General Background: Purple starthistle is a biennial that sometimes acts as an annual or a short-lived perennial. Mature plants are 1 to 4 feet tall, have a stout taproot, and are densely and rigidly branched. Purple starthistle is native to Asia Minor from a region between the Black and Caspian seas. It was first detected in California near Vacaville in 1886 (1). Similar in some respects to yellow starthistle, this is an aggressive Centaurea, that is a problem on annual rangelands in the San Francisco Bay area. it tends to occur on sites more mesic (moist) than those occupied by yellow starthistle. When the two species occur together, purple starthistle grows on heavier bottomland soils. Grazing animals generally avoid purple starthistle, but may eat the young rosettes if other feed is not available.
Nutrients: We sampled purple starthistle with and without spines and its roots and found that in all cases, it is comparable to alfalfa in nutritional value. As the root was being dried it gave off an aroma similar to a sweet baked potato. A 2002 study showed that ethnic Albanians living in Italy gather and eat the plant's young whorls. Researchers have also found that extracts from the plant do a better job of degrading milk caseins and suggest that these extracts should be used as an alternative to commercial animal rennets in the manufacture of cheese.
Toxins: There are no known cases of poisoning of animals eating purple starthistle. We are gathering additional information.
Timing of Grazing: Based on the information about grazing Yellow starthistle, we are assuming that we should graze purple starthistle at the same growth time. We anticipate having to regraze the same plant more than once because of evidence that mowing older plants encourages development of multiple rosettes from one root base.
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Gorse and
gorse branch
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Gorse (Ulex europaeus):
General Background: This is a spiny, perennial, evergreen shrub in the Pea Family growing to over 2 metres. It has small leaves terminate in rigid spines, bright yellow flowers surrounded by a velvety calyx. Flowers develop into black seedpods with dark hairs.
Nutrients: Our November sample of gorse indicated that it is lower in protein than alfalfa and has moderate total digestible nutrients.
Toxins: There are no known incidents of this plant causing animal poisonings.
Timing of Grazing: Those in Australia who have had success using grazing to control gorse note that it is best to graze young plants that have not yet grown the large spines common on the mother plants. Since younger plants are generally protected by the mother plants, fire has been used to rid the area of the large plants and then animals have eaten young sprouts. For more information visit the Library.
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