Buying and quarantining new livestock: a biosecurity guide for small farms

🐑 The short version

The cheapest time to investigate an animal's health history is before you own it.

Spring is when stock change hands. Some blocks are selling — lambs and calves have arrived, numbers are suddenly up, and nobody wants to carry surplus mouths into a dry summer. Others are buying, because they came through winter lightly stocked and the spring flush is getting ahead of them.

So animals move between properties. And a bought animal can arrive carrying things that were not part of the deal: worms, including drench-resistant worms, external parasites, foot problems, an unknown vaccination history, or something that simply was not visible on the day.

None of this requires a commercial operation to matter. A block with five sheep has less margin for a whole-flock problem than a farm with five hundred, not more.

❓ The case

Why does this matter on a small block?

Two reasons, and the second is the one people miss.

First, a small mob mixes completely. On a ten-acre block there is no far paddock. Whatever arrives is shared within days, and there is no realistic way to unwind it afterwards.

Second, some of what arrives can change your farm for years. A lame sheep gets treated and recovers. But drench-resistant worms introduced with bought-in stock can establish on the property and be extremely difficult to get rid of. At that point you are no longer dealing only with an individual animal — you may have changed the parasite population that every animal you run afterwards will encounter. That is a change to the farm, not an illness in an animal.

Set against that, the work in this guide is a few questions, a spare paddock and a fortnight of patience.

💬 Before you buy

What should I ask before buying sheep, cattle or goats?

Most sellers on the lifestyle-block end of the market are honest people who will answer plainly. The questions are not an accusation — a vendor who has kept good records will be pleased to be asked, and one who cannot answer anything has told you something useful too.

• Where have they been? Property of origin, and whether they have been through a saleyard or mixed with other mobs on the way.
• What have they been vaccinated for, and when? Check whether the primary course was completed and whether any booster is still due — an incomplete course is easy to inherit without knowing.
• When were they last drenched, and with what product? The active families matter more than the brand. "Recently" is not an answer you can act on.
• Has the property done any drench-resistance testing? A vendor who can show recent faecal egg count reduction test results is offering you something genuinely valuable.
• Any recent health problems in the mob? Lameness, scouring, coughing, skin or fleece problems, sudden deaths.
• Have they been treated for lice or external parasites? When, and with what.
• What have they been eating? A sudden feed change is its own risk, and knowing the current diet lets you transition rather than switch.
• Is there a declaration available? In New Zealand, an Animal Status Declaration. In Australia, a National Vendor Declaration and, ideally, an Animal Health Declaration.

👀 Inspection

What should I look at when I go and see them?

You do not need to be an expert. You need to look properly, and to look at the whole mob rather than only the animals being offered.

• Watch them move before you handle them. Lameness shows in the paddock and hides in the yards. Watch the whole mob walk.
• Condition, and evenness of condition. One thin animal in a good mob is a question. A mob where condition varies wildly is a different question.
• Back ends. Dags and scouring are worth asking about — they can indicate a worm burden, a feed issue, or something else.
• Fleece and skin. Rubbing, wool loss and irritation can suggest external parasites.
• Eyes, nose and breathing. Discharge, coughing, or animals that seem to be working harder to breathe than the rest.
• The place itself. The state of the yards, water and pasture tells you about the management the animals have had.

If something looks off and you cannot say why, that is a reason to walk away. There will be other stock. If you want a second opinion on a purchase that matters, a pre-purchase check by a vet is available and is usually cheap relative to the cost of getting it wrong.

🚧 Preparation

Set the quarantine area up before the trailer arrives.

This is the step that decides whether the rest of it happens. Deciding where new animals will go while they are standing on the trailer is how they end up in with everyone else.

What the area needs:

• Genuine separation. Not sharing a fence line with your resident stock if you can avoid it, and definitely not sharing a water trough.
• Water and feed already in place, so nothing has to be improvised on arrival.
• Somewhere you walk past. The whole value of the period is observation, and an area at the far end of the block gets checked less than one by the gate.
• Shelter and shade appropriate to the season.
• A plan for your own movements. Deal with the resident mob first and the new arrivals second, so you are not carrying anything back the other way on your boots.

On a small block "quarantine" may mean one spare paddock, a yard, or a pen. It does not have to be elaborate. It has to exist before the animals do.

📅 Duration

How long should new stock be kept separate?

There is no single quarantine duration that suits every bought animal. The right period depends on the species and on the risk you are trying to manage — and this is where most people get confused, because the published numbers look like competing answers to one question when they are actually answers to two.

There are two different clocks, and they run at the same time.

Clock 1 — the parasite holding period: 1 to 3 days

This is a short, specific step tied to a quarantine drench, and it exists for one biological reason: a drench kills worms but not the eggs already laid, so treated animals keep passing worm eggs for a period afterwards. Holding them off pasture during that window stops those eggs landing on your paddocks.

New Zealand's Wormwise puts the holding period at 24–48 hours. Australia's WormBoss puts it at 1–3 days, and gives a rule for choosing: one day if the feed is green and high quality, three if it is dry and low quality.

This clock finishing does not mean quarantine is over. It means one specific parasite job is done. That distinction is the single most misread thing in this whole area.

Clock 2 — the general health separation: longer, and judged rather than counted

This is the observation period, and it is what most people mean by "quarantine". It is there so you can watch for things that were not visible on the day you bought:

• illness developing after the stress of transport
• respiratory signs — coughing, discharge, laboured breathing
• lameness that only shows once they settle
• lice, mites and other external parasites
• scouring
• anything simply not thriving

How long depends on the species, where they came from, the disease risk in your area, local conditions and your vet's view. A concrete example where a figure is published: for poultry, New Zealand's Ministry for Primary Industries advises keeping new birds in a separate area away from other birds for 14 days, and being satisfied they are healthy before introducing them to the flock.

For sheep, cattle and goats there is no equivalent single published number, and a period measured in weeks rather than days is the usual practical advice. Ask your own vet what they recommend for your species and situation — it is a short conversation, and they know what is circulating locally.

🪱 The invisible risk

Worms, and why bought-in stock are the main way resistance arrives.

This is the part that changes your property rather than your animal, and it is worth understanding even if you never buy a sheep.

Both countries have a dedicated national programme for this, and they start from the same assumption. Beef + Lamb New Zealand's Wormwise says the aim of a quarantine drench is to prevent the importation of multi-drench-resistant worms onto your property. Australia's WormBoss is blunter still: assume that purchased sheep are carrying worms with some degree of drench resistance to one or more drench groups.

You almost certainly have worms with some level of resistance already. The goal is to avoid importing worse genetics than the ones you have.

Risk varies a lot by class and age of stock. Wormwise rates bought-in lambs and calves among the highest-risk introductions, and says anyone buying replacement ewes of unknown resistance status should also have a properly thought-out quarantine protocol. Individual sire rams, adult cows and adult bulls are rated lower risk, because animals of that class tend to shed far fewer worm eggs. That is a statement about stock class, not about numbers — it is not a general rule that one or two animals are safe.

The specific product protocol is technical, it differs between the two countries, and it changes as the resistance picture changes — so this guide points you at each country's authority rather than paraphrasing a recipe.

• 🇳🇿 New Zealand — Wormwise. Advises against relying on a triple or double combination drench as a quarantine treatment for bought-in sheep, unless the vendor has established very low resistance through recent testing — in which case you may not need a quarantine drench at all.
• 🇦🇺 Australia — WormBoss. Recommends a combination of no fewer than four unrelated drench actives, at least one from the newest actives, given concurrently rather than mixed together — and warns not to mix products unless the label allows it or a vet directs it. WormBoss gives separate advice for goats, where the registered options are more limited, particularly for dairy goats whose milk is for human consumption.
• Both: the protocol matters as much as the product. An excellent drench used badly achieves very little. WormBoss also suggests a follow-up worm test around 14 days after drenching for confidence that the treatment actually worked.

Read your own country's guidance in full and talk to your vet or animal health adviser before treating: Wormwise — quarantine drenching (NZ) or WormBoss — quarantine drenches (Australia). Our guide to drench resistance and worm management covers the wider picture of why resistance develops and how to slow it down.

🌱 The counter-intuitive bit

Where they graze afterwards matters as much as the treatment.

Here is the piece almost nobody knows, and it is the reason a quarantine drench so often fails to do its job.

A drench kills adult and immature worms. It does not kill eggs. So even after a highly effective treatment has cleared the gut, eggs already laid keep passing out in the dung for a day or more afterwards. Those eggs carry exactly the resistance you were trying to keep out.

1. Hold them off pasture first. Wormwise's gold standard is to hold new arrivals on a bare yard or grating, with feed and water available, for 24–48 hours, so eggs that pass out have no moisture and no grass blade to survive on. WormBoss says the same thing with a slightly different clock — hold in yards for small mobs, or a secure paddock for larger ones, for 1–3 days, choosing one day if the feed is green and high quality and three if it is dry and low quality. Both stress providing adequate feed and water throughout.

If a quarantine paddock is used rather than a yard, WormBoss advises keeping it free of sheep, goats or alpacas afterwards for at least 3 months in summer or 6 months in cooler months. Wormwise makes the same point in different terms, warning that repeatedly using one quarantine paddock over a long period risks creating a resistant-worm hotspot.

2. Then — the counter-intuitive part — put them somewhere dirty. Wormwise advises grazing new arrivals on well-contaminated areas of the farm for at least a few days. WormBoss says to release them onto a paddock likely to be contaminated with worm larvae from your existing stock — in practice, most paddocks grazed by your home-bred animals in the last three months.

Why it works: any resistant worms that survived the treatment are then vastly outnumbered by the ordinary, drench-susceptible worm population already living on your place. Their offspring interbreed with that population and the resistance genetics get diluted rather than concentrated.

Why the instinctive move is the damaging one: a clean, low-contamination paddock has no resident worm population to dilute anything. Put quarantine-treated stock onto it and the only worms seeding that paddock are the resistant survivors — you have created a pure population of exactly the worms you were trying to exclude, on your best ground.

The new animals feel like the ones deserving the best paddock. This is the one time that instinct is precisely backwards.

🇳🇿 Paperwork

Movement paperwork in New Zealand.

Keep this practical. Two things apply to most small blocks.

NAIT, for cattle and deer. If you own cattle or deer — OSPRI's own wording is "even if it's just 1 pet cow" — you must register with NAIT, tag the animals, and record movements onto or off your property within 48 hours. Buying two calves puts you inside the scheme. Our NAIT help page covers what the app holds and what you still do on the OSPRI side.

Animal Status Declarations — cattle, deer, sheep and goats. This one catches lifestyle-block owners out, because it is not only about sending animals to slaughter. MPI requires an ASD to be completed for movements of cattle and calves (including buffalo), deer, sheep and goats, and ostriches and emus from one property to another, or to a saleyard, where there is a different person in charge of the animals. Pigs use a different form.

In plain terms: if you buy sheep privately from someone else's block, that movement needs an ASD — and it is completed by the person in charge of the animals, not by you as the receiver. If you are buying, make sure the declaration comes with the stock and goes into your records. If you are selling, expect to fill one in.

The ASD carries the information the next person genuinely needs: withholding period status, TB status, and farming practices relevant to food safety and export eligibility. You can use a paper form (valid for all movements including saleyards) or electronic ASDs through MyOSPRI, and ASD form books are ordered from OSPRI.

One more thing worth knowing: when transporting NAIT animals, your livestock transporter may ask you to confirm in writing that the animals are tagged and registered. MPI publishes a Declaration to Livestock Transporter for exactly that.

🇦🇺 Paperwork

Movement paperwork in Australia.

Australia's National Livestock Identification System applies to cattle, sheep and goats, and it applies to small properties as much as large ones. The detail is state-based, but several things are national.

• You need a PIC — a Property Identification Code — issued by your state or territory authority.
• For private sales, it is the buyer who records the movement. Integrity Systems is explicit: for sales that do not go through a saleyard, the buyer or receiver records the livestock movement onto their property. The seller is not obliged to record it leaving. This catches new owners out constantly — the paperwork obligation lands on the person who just bought, not the person who just sold. If the sale goes through a saleyard, the saleyard records it.
• You have 48 hours. Integrity Systems states that the receiver of livestock has 48 hours to complete an NLIS transfer from the time of the physical movement. (Note the pleasing symmetry with New Zealand's NAIT window — same number, different scheme.)
• Movement documentation must accompany the consignment. For LPA-accredited producers that means an LPA NVD or eNVD; other forms may be used by non-accredited producers, and some states require additional documents. Keep your copies — they are checked in LPA audits, and for sheep or goats on visual tags you cannot complete a mob-based movement on the database without the NVD or waybill serial number.
• Sheep and goat eID. All sheep and goats born on or after 1 January 2025 must carry an NLIS-approved electronic identification device before they leave the property.
• Animals arriving without a tag should have a post-breeder tag applied — orange for cattle, pink for sheep and goats.
• Agistment counts as a movement if the destination has a different PIC.

Integrity Systems also notes that hobby farmers accredited through LPA keep the same records as anyone else. Our NLIS help page covers keeping the records straight; check your own state or territory authority for the local detail.

📝 Records

What to write down on arrival.

Next week you will remember that the five lambs were drenched. Six months from now, when one of them has a problem, you will not remember which product, what day, or which mob they joined.

The facts worth capturing at the moment they happen:

• Arrival date, and the date the separation period ends.
• Where they came from — vendor, property, PIC or NAIT number, agent if there was one.
• Movement paperwork reference — ASD, NVD or waybill number.
• What you gave them and when — product name, active family, dose, withholding period.
• Vaccination status as told to you, including whether a booster is still owing and when it falls due.
• Anything you noticed on inspection, even if it came to nothing.
• Which mob they joined, and on what date.

That last one matters more than it looks. If something turns up in the flock later, the question is always when did these two groups first mix — and that is a date nobody remembers and everybody needs.

✅ Checklist

Before you open the trailer.

• Know where the animals came from.
• Ask about vaccination and treatment history — the products used, not just "recently" — and whether any booster is still due.
• Check the movement and traceability requirements that apply to your species, where you are: ASD and NAIT in New Zealand, NLIS and an NVD in Australia.
• Have the quarantine area ready, with its own water, before they arrive.
• Inspect them properly, watching them move before you handle them.
• Have a parasite-management plan agreed with your vet before the day — the right approach differs by species, and what suits sheep or goats is not automatically right for cattle or poultry.
• Plan the immediate post-treatment grazing: hold them off pasture for the short parasite window, then onto contaminated ground rather than your cleanest paddock.
• Plan the longer health separation separately — it runs well past the parasite window, and it is the one that catches what you could not see at purchase.
• Record the arrival date, the origin, the paperwork reference and anything you did to them.
• Set the end date for the health separation on the day they arrive.
• Only mix them with your resident stock once you are satisfied they are ready.

📚 Further reading

Where the information on this page comes from.

• Beef + Lamb New Zealand — Wormwise: Quarantine drenching: the purpose of a quarantine drench, which classes of stock need one, the advice against relying on triple or double combinations for bought-in sheep, the 24–48 hour holding period, and grazing new arrivals on contaminated areas afterwards.
• WormBoss (ParaBoss) — Quarantine drenches: the Australian counterpart to Wormwise. The assumption that purchased sheep carry resistant worms, the four-unrelated-actives recommendation and the warning against mixing products, the 1–3 day holding period keyed to feed quality, keeping a quarantine paddock free of sheep, goats and alpacas for 3–6 months, releasing onto contaminated pasture to dilute survivors, the 14-day follow-up worm test, and the separate advice for goats.
• Beef + Lamb New Zealand — Livestock movement: on-farm biosecurity when stock arrive and leave.
• OSPRI — Lifestyle farmers and pet owners: NAIT registration for cattle and deer "even if it's just 1 pet cow", and recording movements within 48 hours.
• MPI — Animal Status Declarations: the species covered, the requirement for movements between properties where there is a different person in charge, who completes the form, MyOSPRI electronic ASDs, and the Declaration to Livestock Transporter. Page last reviewed 13 February 2026.
• MPI — Bird flu and protecting your birds: the 14-day separation advice for new birds joining a backyard flock.
• Integrity Systems — Buying, selling and moving livestock: the buyer records private-sale movements, the 48-hour NLIS transfer window, NVD requirements and record keeping, sheep and goat eID from 1 January 2025, post-breeder tags, and agistment.
• Animal Health Australia — Better on-farm biosecurity: general on-farm biosecurity practice, including introduced animals.
• MPI — Biosecurity on your farm or lifestyle block: the general principles this guide applies to buying stock.