Some Forages Can Cause Problems For Goats - Under Certain Conditions

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In response to last month's column about plants for goats I received several inquiries about the various problems that can occur with normally harmless plants under adverse conditions.

I will attempt to cover some of the more common problems here, but strongly encourage you to get with your local extension agent to review the plants present in your pastures that are toxic and/or conditions in your area that can cause normally harmless plants to become toxic.

I will not address the topic of toxic plants in this column. That would require more space, time, and expertise than I have. Your local extension agent should be able to help you identify the toxic plants present on your property, and help you develop strategies to prevent your goats from being poisoned by them.

I have several types of toxic plants on my own property, but I have found them to be no problem whatsoever because the types we have are not very palatable, there are not very many of them, and goats seldom eat enough of them to exhibit symptoms of toxicity. Goats eat a bite of this, and a bite of that, then a bite of something else. That browsing habit seems to protect them fairly well from native toxic plants.

Far more potentially problematic are the plants that under normal conditions are harmless, but which become toxic under the right conditions.

Many of the plants I discussed last month can, under the right conditions, make goats sick and/or kill them. The problem is compounded because those are plants that are palatable, and if you seeded your pasture with them they would compose a large enough portion of your goats' diet to poison them.

Following is a discussion of the types of problems that can occur, which plants cause them, the conditions under which they become toxic, and strategies for protecting your goats. For a description of symptoms and treatments I advise you to consult a vet, do an internet search on the topic, or look the illness up in a vet manual such as The Merck Veterinary Manual.

Grass Tetany

This is the most common problem observed when utilizing small grain pastures. Small grains contain high levels of potassium which can interfere with calcium and magnesium absorption.

The problem is most pronounced in mature does in heavy lactation on lush, fast growing pastures.

A mineral high in calcium and magnesium should be available to animals at all times when using small grain pastures. This is especially critical for lactating does because their calcium requirements are higher than dry does.

Nitrate Toxicity

Small grains, corn, sunflowers, sorghums, pigweed, lamb's quarter, thistle, Jimson weed, Kochia, smartweed, dock, and Johnson grass are all known to concentrate nitrate under the right conditions.

Those conditions include drought, frost, unseasonable or prolonged cool temperatures, hail, shade or cloudy days, disease, high levels of soil nitrogen, soil mineral deficiencies, or herbicide damage. Basically anything that stunts or slows plant growth. Nitrates are usually concentrated most heavily in the lower third of the stalks of affected plants making goats which tend to browse the tops of plants less likely to be affected.

High nitrate levels persist in hay cut from plants that were high in nitrate prior to cutting, so the problem can also occur when feeding hay of the plants listed above. High nitrate levels in drinking water can also cause or contribute to the problem.

Fortunately, it is easy to test plants for high nitrate levels. Your local extension agent should be able to assist you with this.

The following strategies may reduce problems for livestock exposed to high nitrate pastures/feeds; feed hungry livestock prior to exposure, graze or cut forages in the afternoon when nitrates have been converted to protein by plants, adapt livestock gradually to increasing levels of the suspect forage, and/or dilute by supplementing with low-nitrate feeds or grain.

Cyanide Poisoning

Certain plants contain compounds that can lead to cyanide poisoning in goats that ingest them under the right (wrong) conditions. These include arrow grass, velvet grass, Johnson grass, Sudan grass, sorghums, sorghum-sudan hybrids, most fruit trees, corn, and flax.

Browsing drought-stricken or frozen plants of the types listed above is the most common cause of cyanide poisoning in goats.

The best way to prevent problems is to remove goats from areas that contain these plants when conditions are such that the plants may become toxic. If you are planting these types of plants you should select varieties that have been developed to minimize the amount of toxic compounds they produce.

Mycotoxicoses

This is not really a single type of toxin but a category of toxins that can be consumed by goats in their feed. This category includes diseases caused by various fungi and molds such as: Aflatoxicosis from moldy peanuts, soybeans, corn, cottonseeds, rice and other grains; Ergotism from seedheads of grasses and small grains infected with fungus; Estrogenism and Vulvovaginitis from moldy corn and pelleted cereal grains; Fescue Lameness and Fescue Toxicosis caused by a toxic endophytic fungus and other funguses that live on fescue grass; and Perennial Ryegrass Staggers caused by a toxic endophytic fungus that infects perennial ryegrass.

These problems can be avoided by using varieties of seed that are free of toxic endophytic fungi, and avoiding feeding goats moldy grain and hay.

Selenium Poisoning/Deficiency

Plants in certain areas of Colorado, Nebraska, South Dakota, and Wyoming can contain toxic levels of selenium. If you are in one of these areas you should probably not produce livestock or will have to heavily supplement your goats' diet with feed grown in areas that are deficient in selenium.

Of larger concern are the areas that are considered copper and/or selenium deficient. This includes an area of the USA that includes all or part of many states (see attached map). Selenium/copper deficiency can cause severe reproductive problems for goats such as: failure of does to conceive, dystocia (difficult birth), retained placentas, and weak kids.

If you are in a deficient area or utilize legume pastures you need to be using a mineral supplement that contains both copper and selenium. Please note that most "Sheep and Goat" minerals do not contain any copper. Your goats need copper so buy a mineral supplement formulated specifically for goats.

Sweet Clover Poisoning

Spoiled sweet clover is the culprit in this disease. Normally harmless sweet clover becomes toxic when it is allowed to spoil. The natural coumarins in the clover are converted to toxic dicumarol when the clover spoils.

Varieties of sweet clover that are low in coumarin are available, but if these are not used then you should avoid feeding sweet clover hay or silage.

Plant Estrogens

Some plants naturally produce estrogen-like compounds that can cause fertility problems in does. Clovers (especially red clover), alfalfa, birdsfoot trefoil, barley and oat grain, and fescue grasses contain compounds with estrogenic activity and may delay or completely depress conception. Estrogenic Compounds are present in varying concentrations in most all legume plants during the entire growing season. This however, is not the case when the plants are mature and dry.

If you are going to use legume or fescue pastures, you may want to select plant cultivars that are known to have low levels of estrogens, avoid browsing does on those pastures during breeding season, and/or plant the legumes in a mixture with grasses or small grains to reduce the quantity of plant estrogen consumed.

That should give you an idea of the types of problems that can be encountered with common types of forages used in goat pastures. Again you should check with someone in your area that is knowledgeable about problems specific to your locale.

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This page updated 06/02/03

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