biology

Perennial ryegrass staggers

Perennial ryegrass staggers is a biology topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Perennial ryegrass staggers rather than just read about it. In short: Perennial ryegrass staggers is poisoning by peramine, lolitrem B, and other toxins that are contained in perennial ryegrass (Lolium perenne), and produced by the endophyte fungus Epichloë festucae which can be present in all parts of the grass plant, but tends to be concentrated in the lower part of the leaf sheaths, the flower stalks and seeds. This condition can affect horses, cattle, sheep, farmed deer and llamas.

Key takeaways

Perennial ryegrass staggers belongs to biology; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Perennial ryegrass staggers to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Perennial ryegrass staggers from memory before moving on to harder problems.

Reference excerpt

Perennial ryegrass staggers is poisoning by peramine, lolitrem B, and other toxins that are contained in perennial ryegrass (Lolium perenne), and produced by the endophyte fungus Epichloë festucae which can be present in all parts of the grass plant, but tends to be concentrated in the lower part of the leaf sheaths, the flower stalks and seeds. This condition can affect horses, cattle, sheep, farmed deer and llamas. It regularly occurs in New Zealand and is known spasmodically from Australia, North and South America, and Europe.

Ecology Perennial ryegrass staggers is caused by the ingestion of grass that is infected by the endophyte fungus Epichloë festucae var lolli, and this fungus produces a variety of toxins such as peramine, a pyrrolopyrazine alkaloid, and lolitrem B, an indole-diterpene compound. There is no external sign when perennial ryegrass is infected by this fungus. The Argentine stem weevil (Listronotus bonariensis) feeds on perennial ryegrass. When the grass on which they are feeding is infected by the fungus, the larvae of the weevil fail to develop fully. In an effort to breed perennial ryegrass that was resistant to the weevil, researchers in New Zealand inadvertently selected strains that were susceptible to the fungus. In fact the endophytic fungus forms a mutualistic association with the grass which grows more vigorously as a result and produces more tillers. With greater use of these susceptible cultivars, the fungus which is present in the seed, spread more widely with a consequent increase in perennial ryegrass staggers.

Symptoms Symptoms are neurological and may develop one to two weeks after exposure to infected pasture. Symptoms may include head shaking and irregular eye movements, changes in gait, stiffness, staggering and falling. Recumbent animals may display tetanic spasms and may die through misadventure, dehydration, starvation, loss of rumen function or predation. In the case of horses, the animal may quiver or tremble, be easily startled and be awkward to handle. More severely affected animals may repeatedly nod their head, show a tendency to splay their legs, and stumble and fall. The hind-quarters, moreover, may become paralysed.

Treatment Recovery usually occurs when the animal is removed from the contaminated pasture. The chief danger to stock at this stage is caused by their lack of coordination, which may result in accidental death by falling in awkward places such as ditches and ponds.

Prevention The disease is particularly prevalent in New Zealand. It may be prevented by avoiding grazing pastures containing perennial ryegrass, or seeding pastures with resistant strains of ryegrass. Horses are particularly prone to this disease because of their habit of biting close to the ground, and sparse pastures may encourage heavier grazing with greater intake of infected material. Supplementary feeding may help, but hay from infected pasture should not be used because it may contain further toxins.

References

Worked examples

Example 1 — a first encounter with Perennial ryegrass staggers

Start with the simplest possible case. Write down what Perennial ryegrass staggers claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Perennial ryegrass staggers before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Perennial ryegrass staggers ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Perennial ryegrass staggers

In research: Perennial ryegrass staggers appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Perennial ryegrass staggers in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Perennial ryegrass staggers is common in secondary-school and first-year university syllabi. It links to neighbouring topics Animal fungal diseases, Animal welfare and rights in New Zealand, Bovine diseases, so understanding it makes those chapters shorter.
In everyday life: Look for Perennial ryegrass staggers outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Perennial ryegrass staggers in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Perennial ryegrass staggers means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Perennial ryegrass staggers out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Perennial ryegrass staggers in simple terms?

Why does Perennial ryegrass staggers matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Perennial ryegrass staggers?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Perennial ryegrass staggers.