34. MUSTARD FAMILY

Brassica (wild mustard)

Thlaspi (pennycress)

Lepidium (peppergrass), etc.

TOXICITY RATING: Low to moderate.

ANIMALS AFFECTED: Cattle, horses, sheep, poultry.

DANGEROUS PARTS OF PLANT: All parts, especially seeds.

CLASS OF SIGNS: Oral and gastrointestinal irritation, photosensitivity, breathing difficulty.

PLANT DESCRIPTION: Mustard family members have a pungent, sulfurous odor or taste. They may be annual, perennial, or biennial, with a basal cluster of leaves and alternate leaves on the stem that are usually smaller and shorter-stalked than the basal leaves. Flowers of most mustard species are yellow, but some are white, blue, or purple, and all have four petals in a cross-like arrangement (fig. 34A). The seedpod (silique) is dry and may be broad and flat (fig. 34B) or skinny and much longer than it is wide (fig. 34C). The mustard family includes weeds such as yellow rocket, black mustard (fig. 34), tansy mustard, peppergrass, and pennycress. These are found in fields, pastures, lawns, roadsides, waste areas, and sometimes in woods. Cultivated mustards, which may be harmful if eaten in large quantities, include cabbage, rape, broccoli, turnip, rutabaga, horseradish, and radish.

SIGNS: Mustard plants are capable of causing several types of problems. The most common is oral and gastrointestinal irritation primarily the result of the isoallyl thiocyanates and irritant oils. The plants are not palatable and tend to be avoided unless there is little else to eat or if the seeds have been incorporated into processed feeds. Clinical signs could include oral irritation, head shaking, salivating, colic, abdominal pain, vomiting (in those species capable of vomiting), and possibly diarrhea. Swine and younger animals (lambs and calves) appear to be more susceptible to the irritant effects of mustard seeds in processed feeds. In order to cause toxicity, fairly large amounts need to be consumed over a period of time.

Mustard plants can cause other problems, although these are not reported as often. Photosensitization has been reported in cattle after rape (B. napus) was consumed. There are also reports of abortions, goiter and blindness due to mustard consumption, but these are not major problems. Mustard plants may accumulate nitrates under certain fertilization conditions, and thus cause nitrate toxicosis.

FIRST AID: There is no antidote for mustard poisoning. Supportive care and providing adequate quality forage is necessary. For more serious signs, or if animals do not recover when mustard feed is withdrawn, consult a veterinarian.

SAFETY IN PREPARED FEEDS: Mustard plants retain their toxic components upon drying. The seeds in particular contain a high concentration of toxins, and may be incorporated into grain mixes or hay. Care must be taken to insure that these plants and seeds do not contaminate feeds, since they are toxic in any quantity. If small amounts have been incorporated into hay, animals are likely to voluntarily avoid the plants. However, if the hay is highly contaminated and there is no other forage available, the animals will eat the mustard out of necessity and suffer toxic signs as a result. Therefore, avoid feeding mustard, but if this is not entirely possible, provide for additional and more nutritious forage.

PREVENTION: Do not feed hay or other feeds that contain mustard plants or seeds. Do not let animals onto pastures that are overgrown with mustard plants without providing adequate edible forage. Use caution when feeding animals (especially swine) crop harvest leftovers from plants in the mustard family.