FAQ: Lucerne Management – Animal

When should I vaccinate livestock grazing lucerne?

In Marlborough Doug Avery says “We give our lambs their first vaccine at weaning or soon after. Then a booster is given at about 6 weeks after weaning. From then on we give it just before lambing to the ewe once a year. This year lambs at ‘Bonavaree’ are also getting a B12 injection at tailing.”

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How important are vaccinations for livestock grazing lucerne?

The main issue with sudden death of fast growing animals is the cause of the death. This may be caused by clostridial bacteria – the bacteria use the sugar in the rumen to multiply in number quickly and overwhelm the animals. However, they also multiply quickly after death so the vet usually can’t tell if the infection was before or after death when making a diagnosis.

Step 1:

The first issue is that whatever vaccination programme you are using must be up to date and timely. With fast growing animals they may need a booster earlier than slower growing animals. So step one is make sure your current vaccination programme is up to date and timely. Many people use five in one and are having no problems. Make sure the final pre-lamb vaccination is at least two weeks prior to lambing so that the vaccine has time to get into the colostrum before lambing. This ensure maximum effectiveness for the lambs immune system from birth.

Step 2:

There are several strains of clostridial bacteria – seven of which are found in NZ and covered by the ten in one vaccine. The ten in one is offering protection from two additional strains than the five in one. However, there is debate about whether these extra two have actually been found to be infective and a problem in sheep. It depends on which vet you talk to as to which answer you get.

So, Step 1 would be the prudent course – make sure your current programme is up to date and on time – keep an eye on rapidly growing animals and vaccinate them. Some farmers swear by 10 in 1 – but it may be that the extra cost is making them more vigilant on getting their timing right and giving boosters when needed.

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What can I do to reduce the risk of red gut when grazing lucerne?

Ensure there is fibre (hay) and salt available at grazing and particularly when the lucerne is lush or after heavy rain. On occasion some farmers also report success from wilting lucerne in front of the grazing. The stand my have some strips cut in it about 48 hours before shifting stock onto the Lucerne (see photo below). Red gut is related to the twisting of the intestinal mass on sheep usually grazing lush pure lucerne and other lush pastures for at least a week. It may also occur 4-6 days after rain particularly in summer and autumn after dry periods. Weedy lucerne or lucerne with meadow hay available is less likely to results in red gut. Weaned lambs going onto lush lucerne are susceptible hence the move to have ewes and lambs grazing lucerne in spring. As with bloat, avoid putting hungry animals onto lush feed including lucerne.

Example of cutting strips in lucerne prior to grazing to wilt a proportion of the feed on offer at ‘Bonavaree’, Marlborough. Photo provided by Doug Avery (5/10/2015).

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How important are B12 injections for livestock grazing lucerne?

B12 injections are used to overcome cobalt deficiency. Most animals ingest some soil when grazing pastures and this is where the majority of cobalt needed to meet animal requirements comes from. The cobalt from the soil they eat while grazing stays in the rumen and makes cobalt available. However, if animals are grazing a taller stand/pasture and never putting their head down to graze near the soil surface then their intake of cobalt can be lower than usual. On occasion cobalt deficiency may show up in areas where it wasn’t traditionally used. B12 infections are a simple and effective way to minimise this concern.

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What causes scald in my brassica or lucerne and how can I avoid animal health issues?

Rape scald generally occurs when stock graze “immature” crops of rape in summer. “Immature” is actually not an agronomy term – what it actually means is there are high levels of nitrogen in the leaves that are not yet formed into structural or metabolic proteins. This often occurs early in the crops life because soil N levels are high because of mineralisation after full cultivation before sowing or the use of more than about 40 kg N/ha at sowing.

When nitrogen levels in the plant build up stock can’t cope with the high N levels in the ingested feed. Chlorophyll or other N based compounds get into the blood stream – this makes animals photosensitive. And hence regions with high exposure to the light and little wool covering are most sensitive (e.g. ears and face) effectively get sunburnt. The protein rich feed also enables them to eat without much foraging so the natural process of movement that would exert energy and allow waste from the blood stream to be removed also doesn’t happen.

Other complications with brassicas come from the use of sulphur based fertilizers- so these are not recommended for brassica crops but if cobalt or copper are limiting direct application (foliar or direct to animal via injections) is required. Copper and cobalt are required for animal health because plants do not take these up- they don’t need them to grow – so soil applications don’t help.

Importantly, iodine may be needed because brassicas produce giotrogens which affect the thyroid so iodine supplementation is potentially used. Again, not really plant available so a mineral lick is a cheap and easy option to avoid any potential issues.

In most cases the management of brassicas to avoid these problems is well known- it is well covered in Lincoln University’s animal science papers – but the practice of grazing brassicas on-farm has fallen down because a farmer is short of feed, weather has been overcast or low stock numbers are allowing too high an intake.

We have also had reports of scald from animals grazing lucerne in dull conditions in early spring when the lucerne has high N levels and these aren’t converted to proteins quickly enough. The easiest management is to remove animals from the crop for a few days for it to mature – and introduce them slowly to the crop at about 20% of diet for the first few days- basically restricting access and allowing time on a different feed source dilutes the compounds ingested on the rape/lucerne or other high N containing forage. This reduces the likelihood of an animal health issue developing – all things people know but tend to forget when under pressure.

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Can I reduce bloat in a cattle grazing system if lucerne was mown and left to wilt before it was grazed?

Yes – the issues around bloat can be dealt with in several ways. Ultimately, we never know when bloat is going to occur so we need to think about how to reduce the risk and have a range of strategies that we can put in place during periods when the risk of bloat increases.

Bloat seems to be more of an issue with young fresh lucerne that experiences a change in weather conditions, for example a cold day after several hot ones (or vice versa) or rain after heat leading to a rapid flush of young growth. This makes it difficult to research and so we try to minimise the risk. The strategies we can use include:

  • Ensure animals are not hungry when going on new lucerne – this may actually mean move them on a half day earlier than you though necessary so they are not empty. Grazing animals tend to stop eating knowing they will be getting a fresh break later so why bother eating low quality stalky feed? This means that there can be a mini empty period that we don’t realise and by moving them earlier you avoid it.
  • Bloat capsules for cattle that are older than about 15 months of age.
  • Bloat oils in water troughs.
  • Access to salt (sodium Na) – mineral blocks available at all times.
  • Mixed grazing of sheep and young cattle i.e. the sheep are more likely to grab the lush top leaves than the cattle.
  • Access to fibre – any sort of hay – but you may find only some animals will eat it.
  • Access to a neighbouring paddock or area with grass – preferred ruminant diet is 70:30 legume:grass.
  • Wilting the lucerne before grazing- this will reduce the water content and by definition increase the fibre percentage – a few hours is all that would be necessary.

You may not need to do all of these things and some people do none of them but even our most experienced farmers can occasionally get bloat. These are the strategies available to reduce the risk. Implement one or more of these strategies when there are sudden changes in weather conditions that could cause a change in the plant which increases the potential risk of bloat in your grazing stock.

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Is nitrate poisoning in lucerne killing my stock?

Background info:

Vaccinated, drenched sheep died while grazing a lucerne stand that was recovering after a summer dry period. Second year in a row that it has happened at about the same time of year. Autopsy shows no clear cause of death. A herbage test came back with a high N level. Animals had access to salt blocks but no supplementary fibre when moved to the new paddock.


Yes, deaths are most likely from nitrate given the environmental conditions at the time.

After a long dry spell the soil is usually warm. At the previous grazing the animals will have eaten the lucerne, which was high in nitrogen, and urinated onto the soil surface. This N is still present in the soil as growth slowed due to limited soil moisture.

During the dry period the lucerne is slowly accumulating shoots and nodes – these remain small and unseen with a lack of visible growth. When rain eventually falls the lucerne responds quickly. The internodes elongate so the lucerne is one of the first plants to respond to rainfall after a dry period. It looks green and lush and ready to be eaten. However, that rain fell in overcast (cloudy) conditions and, therefore, low sunshine conditions that are prone to cause high herbage nitrate levels.

Specifically, the rain stimulates leaf growth. This in turn increases demand for water and nutrients and results in high nitrate uptake from the soil (from the previously deposited urine and mineralisation) as water is taken in via the roots (nitrate is always dissolved in water). This high nitrate water then accumulates in the cells in the small leaves that were formed under summer dry conditions.

The problem of nitrate poisoning is exacerbated by overcast conditions – basically, there is a lack of energy (from sunshine) to convert the nitrate to protein. But … following dry conditions lucerne is often the only green material on the farm so there is a temptation to put the animals on it as the best ‘green pick’ for finishing lambs or flushing ewes/hoggets. This creates a potential disaster for the farmer as stock pick the small, lush, high nitrate content leaves which causing nitrate poisoning followed by rapid stock death. By the time the vet arrives the body has blown up so it looks like the death was a result of bloat.

It wasn’t – it was nitrate.

This situation is uncommon so once the farmer understands the danger conditions it is easy to avoid. In short, nitrate poisoning can happen once in awhile. It is not limited to lucerne. It occurs under the same environmental conditions for pasture species including red clover, phalaris, rape crops and cereals. It actually a less likely occurrence in lucerne than other crops except for the high N in the soil from the urine. The stand in question would have been grazed hard by a mob at some stage over that summer dry period.

The solution:

Avoid the problem by understanding the conditions which trigger it. Extreme care should be taken on lucerne growth produced following an extended dry spell followed by rain and subsequent overcast conditions with drizzle. While the drizzle is ideal for wetting the soil it means sunshine (energy) is reduced and the nitrate content will remain high in the herbage. As tempting as it may be to put stock on the lucerne the risk is too high, even if farm feed supply is below demand. Stay off the stand until sunshine returns and the plant can convert the nitrate to protein. Treat the stand as a winter brassica crop AND test the herbage nitrate level before grazing. This is the same recommendation we would make for a kale crop if we were concerned about nitrate. Test don’t guess – stock losses could have a major impact on next years income.

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Why am I getting so many bearings occurring in my hogget flock carrying singles which are set stocked on lucerne?

Note: In this case lucerne was set stocked with single bearing hoggets prior to lambing. Estimated 20-30% of the hoggets were bearings, with about 5% suffering prolapse in the 12-48 hrs after lambing.

Doug Avery replies:

“Bearings were once a huge problem at ‘Bonavaree’, but while we still get the odd one it is no longer seen as a significant problem. In recent years Fraser has managed feeding from scanning to lambing very closely, every day ensuring only the right amount of feed is issued to each sheep class. We would never lamb single lambing sheep on lucerne. We only lamb multiple birthing sheep on high power feed. Our single ewes and hoggets are held on very tight rations right through pregnancy and then fed better once the lambs are out.

Response from the LU dryland team:

We took a look at the published literature to see if we could get a bit more info on what might have happened in this case. Unfortunately, no one factor has been identified as the cause of prolapse and some reports are contradictory. The UK based NADIS (National Animal Disease Information Site) website gives great descriptions of the condition and outlines some of the factors implicated in the cause of vaginal and uterine prolapse. Beef + Lamb New Zealand R&D Brief 120 (Coping with bearings) also provides useful information.

Without further information our best guess would be the hogget flock set stocked on lucerne carried excessive body condition at lambing and large single lambs were produced. The NADIS site mentions prolapse at birth can be associated with prolonged 2nd stage labour resulting in the birth of a large single lamb. Bearings occurring in next the 48 hours after lambing were associated with those animals which required intervention during lambing and continued straining after birth in response to pain and swelling in the reproductive tract.

Excessive body condition has been mentioned as a possible factor leading to bearings. However, other research could not replicate the increase in bearings in a ewe flock due to increased feed supply but they mentioned gorging did not occur even though many stock has CS>3 at lambing (Litherland et al., 2000). Their work did show 20% of ewes which had bearings in the previous year prolapsed in the next pregnancy. Their recommendation was to identify and cull bearings.

Some reports also mention potential heritability of vaginal prolapse and recommend also culling progeny of bearing stock. The recommendation in this case would need to take account of whether grazing management lead to excessive hogget weights and large lambs to animals in their first pregnancy was the main factor influencing the number of bearings in the hogget flock on lucerne. Regardless, the hoggets which prolapsed need to be culled and their progeny identified. This way if trait proves heritable those progeny can be identified and culled to remove the trait from the breeding flock.

A range of factors have been implicated in the potential for stock to suffer prolapse. These include diet quality, exercise, short docked tails and other factors. It appears further research is needed to explain the impacts of these factors on the potential for prolapse up to and beyond lambing.


  • Litherland, A.J.; Lambert, M.G.; Knight, T.W.; Cook, T. ; McDougal, D.B. 2000. Incidence of bearings in ewes that had a bearing at the preceding lambing. Proceedings of the New Zealand Society of Animal Production 60: 44-46.
  • NADIS website: http://www.nadis.org.uk/ Beef + Lamb New Zealand website: http://www.beeflambnz.com/

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Why are my stock not performing as well as expected now they are grazing lucerne?

There can be several reasons for poor LWt gains in stock direct grazing lucerne. They can all be dealt with but it important to accurately identify why performance is poor so the appropriate action can be taken.

Ensure they have had a B12 injection – “Ill thrift” can occur if Cobalt levels are low and this can occur in regions when it hasn’t before because lambs are eating the top of the plant not the bottom near the soil surface. In most regions of New Zealand cobalt requirements are usually meet when stock ingest soil while grazing. B12 is essential for all lucerne grown on volcanic soils which are naturally low in cobalt. This has also been an issue on ex-forestry land in Canterbury.

Dull weather can lead to high protein levels in lucerne but not really a nitrate issue. The high protein diet can’t be effectively utilised to grow the animal. Ensure fibre is made available (supplement with hay).

Excessive N can actually lead to photosensitivity in ears and nose because green pigments can remain in the blood stream. This usually causes only cosmetic issues. A period off lucerne is the most important here and sunshine usually cures it.

The high protein can also mean the lucerne lacks sufficient energy in the diet – feeding grass or grain with the lucerne can balance the diet.

If it has been wet in summer the lucerne can get lush again, just like in spring, and rapid passage through the animals occurs so fibre should be offered.

Parasites are usually less of an issue on lucerne than grass but on wet herbage or areas where there may be a hot spot e.g. lambs can be vulnerable in a stock camp that ewes shed on in a previous rotation.

Another reason may be a lack of time grazing to allow for the rumen to adapt to a change in the quality of the feed (i.e. moving from grass to lucerne). This is more likely to happen on properties which have minimal lucerne and are unable to create the optimal 6-paddock rotational grazing system.

Empty gut syndrome: trying to get the stock to eat the last stemmy parts of a lucerne plant can actually leave animals “empty” for 1-2 days before shifting.

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Can I use my lucerne for ewe mating?

As always it depends; there are several farmers routinely mating all of their stock (ewes and hoggets) on lucerne and others report depressed scanning and lambing rates after doing so. It is important to understand why the answer is yes and no.

Lucerne that is fresh, young, leafy and free of insects (aphids) or foliar diseases has been used successfully to flush on. Equally in the grips of a major drought with only dry grass, wilting lucerne has been used with success. Stock that are not used to lucerne may experience a period of ruminant adjustment (similar to being moved onto a brassica) so consider this in the flushing period. Hopefully ewes coming off grazing lucerne have higher body condition which usually translates into higher scanning and lambing percentages.

Don’t use lucerne that is in full flower. At this advanced stage of maturity lucerne reportedly has high levels of coumestrans which can suppress ovulation rates. This creates a dilemma because autumn is the period when we want lucerne to flower to recharge underground reserves – so some planning in needed. If you have alternative feed available flush on that and put ram lambs or cattle. If not, use the freshest youngest lucerne during mating and allow stands to flower either well before (January/February) or allow a long period of growth after mating. If aphid levels are building up in autumn spray them prior to flushing.

Any negative effects on ewes are usually gone after three to four weeks of grazing other pastures and are not permanent. For more details on experiments check out our blog post or this report (300 KB).

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Can I graze dairy calves on my lucerne?

Note: this relates to 130 kg calves where the farmer was unable to use bloat capsules as the animals were below the 150 kg liveweight required for capsule use.

Give the calves about a three to four day break. Ensure they have easy access to a fibre source and salt and don’t put them into a break hungry. Irrigated lucerne, or after you’ve have a rain event, that is young and lush will be the most difficult time. Bloat is difficult to predict but sudden changes in weather (for example cool after hot or hot after cool) have both been mentioned anecdotally to cause the issue. In contrast, in dryland stands, by mid-summer the lucerne has usually dried off sufficiently that animal health issues are rare – until we get a rainfall event. I will never say you won’t get bloat but you should be able to avoid it particularly as we go later into autumn – except after a drought. Some dairy farmers use bloat oils in drinking water for clover rich pastures. Visit our blog for more information and for other advice that may be helpful.

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How risky is it to solely graze lucerne with yearlings through late spring and into summer?

It has been done successfully in many places – if you have concerns a bolus at 15 months is an option – but late summer the feed has usually hardened up (less lush, more fibre on offer) to the point where bloat isn’t an issue.

A couple of points to be aware of are the need to take care if grazing following a drought breaking rain when lush rapid growth occurs. Always make sure you have salt and fibre available – especially when the feed is lush and even when they don’t seem to be eating it.

Also ensure you move animals on a half day before you think they need it – that way they will never go on a new break hungry – but if you force animals to eat every last leaf some will actually not have eaten for 24 hours knowing the new break is coming and then gorge themselves and bloat can be an issue.

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Can I use lucerne to feed my dairy cows?

Much of South America grazes dairy cows with lucerne and lucerne grass mixes. There are several farmers in Canterbury who use it as part of their rotation – it is used both as a supplement – with some cropping farmers now growing lucerne for dairy and reducing their arable cropping. Lucerne makes an ideal protein rich supplement and is frequently used in total mixed rations in the United States and here in New Zealand.

Direct feeding of lucerne is also practiced provided you follow some rules – make sure animals have access to salt and fibre and for cows – Ensure the bloat issue is dealt with- either with capsules or oils. This is common practice for those who have clover rich pastures.

For those who have irrigation but insufficient water to fully irrigate lucerne provides an ideal buffer –it can be irrigated less than ryegrass. There have also been several studies done at Taranaki dairy centre and a couple by DairyNZ – that have shown mixed results but usually lucerne is as productive as grass based pasture in spring but higher in summer.

A simple way to start using lucerne in a dairy system would be to use the first spring regrowth, which is always the heaviest, to cut and carry for supplement. This would make sense for those systems that develop a grass surplus in spring and allow greater control of that grass surplus and reduce seed head production. From then on graze the lucerne as part of the rotation. In dry years it will harden off and the risk of lush lucerne causing bloat etc is not a problem. In wet years- you should have sufficient feed anyway from the grass pastures so use the lucerne as a supplement.

And finally if you are putting in pastures – you can add lucerne –it won’t like being rotationally grazed at 3 week intervals but in our experience it may still be better than white clover that losses its tap root after 18 months and therefore fails to thrive from then on. Grazing lucerne when it is 30-35 cm tall would be ideal so if you only have one or two paddocks – you may be able to drop them out of a rotation for a round and then feed them off. Lucerne as part of a grass based mixture is an option dairy farmers should consider when renewing pastures, particularly in areas where summer dry periods can occur.

There is a lot of straight agronomic advice on our website to get started – being unsure of the soils etc. We cannot guarantee success – but if you have one paddock going well – we would suggest more.

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