Nitrate poisoning of animals is actually nitrite poisoning occurring when nitrate is reduced to nitrite in the gastrointestinal tract. Mustard oil glucosides found in plants belonging to the Mustard family cause severe gastroenteritis. This form of glycoside is found in purple cockle, cow cockle, bouncingbet and pokeweed. If the saponin glycosides are absorbed into the bloodstream, they cause a breakdown of red blood cells and injury to the central nervous system producing convulsions and paralysis. Saponin glycosides produce a violent gastroenteritis with vomiting, diarrhea and colic. Wilting, frost and other forms of physical damage to plants may induce a rapid increase in HCN content.Ĭyanogenic glycosides occur in sorghums, sudan grass, marsh-arrow grass and wild cherries. Low soil moisture, high nitrogen and low phosphorus all favor HCN production. Climatic conditions, soil factors, shade and other factors that slow plant growth and development increase cyanogenic glycoside content. Some plant species normally have high levels, the highest levels occurring in early growth stages and decreasing as the plants mature. There are many factors that influence the amount of cyanogenic glycosides in plants. Often these are not seen because death occurs within minutes. The symptoms are muscle tremors, difficult, rapid respiration and convulsions. HCN interferes with the oxygen exchange from the lungs to the body tissues so that various tissues including the brain are starved for oxygen and are consequently injured. Cyanogenic glycosidesĬyanogenic glycosides are not themselves poisonous but in the presence of certain enzymes are hydrolyzed and produce hydrocyanic acid (HCN) which is highly toxic. They can be subdivided into three main groups. Glycosides are natural plant products that contain the sugar glucose. Toxic alkaloids are found in the following plants swamp and death camas, lupines, buttercups, marshmarigolds, larkspur, the nightshades, squirrel corn and Dutchman's breeches. The alkaloids generally are irritating to the gastrointestinal tract producing nausea, colic and diarrhea and also act on the central nervous system to produce blindness, muscular weakness, convulsions and death. AlkaloidsĪlkaloids are organic basic substances with a bitter taste, examples of which are morphine, atropine, nicotine, quinine and strychnine. ![]() However, most of the important poisonous plants in Ontario contain toxic agents from one or more of the following groups. Unfortunately for many plant species, the nature of the toxic substance has not yet been identified. There is a large variety of toxic substances that have been associated with plant poisonings. An animal that is hungry or has certain dietary deficiencies is more likely to eat toxic quantities of a poisonous plant than a well fed animal. Then, if a large quantity is consumed, they are resistant because their metabolism has already adjusted to handle the poison. Animals may build up resistance to certain poisons by being exposed to small quantities at first. Young animals are often more susceptible than older ones, but it isn't always the case. Different animal species are susceptible to different plants and poisons. The leaf stalk is eatable while the leaves are very poisonous.Īnimal factors also influence the ability of plants to poison. Certain parts of a plant may be poisonous and other parts not. In other cases, such as with buttercups, the poison is contained in the fresh plants but not dried ones. ![]() ![]() In some cases, damage to the plant or wilting may produce poisonous chemicals in the plant which were not present in the fresh material. The state of the plant when eaten may also be important. With some plants, there is an increase in their ability to poison with advanced stages of growth, whereas with others the danger lessens. Individual plant species and varieties may differ in their poisonous content from early growth to maturity. There are many plant factors that contribute to the toxic principles in plants. What may be a harmless plant species in one circumstance could be deadly in another. Unfortunately, this cannot be done for many factors are responsible for the toxic principles in plants. It would simplify matters if plants could be classified into two groups, poisonous and non-poisonous. For additional information on weeds that are poisonous, see OMAFRA Factsheet " Common Weeds Poisonous to Grazing Livestock", Agdex 130/643. It also describes plants which mechanically injure animals or may cause irritation of skin on contact. This Factsheet is an introduction to the ways and means that plants can poison livestock. The results of poisoning can range from minor irritations and slightly lowered animal performance to severe cases where the animal is in a great deal of distress and may die. There are many plants which contain chemicals or which accumulate chemicals that are poisonous to livestock.
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