News & Events Pre-Lamb Seminar - Summary

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Pre-Lamb Seminar - Summary
24 July 2023 - John Meban (BVSc)
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The focus of the seminar was optimising ewe performance pre-lamb in the face of growing drench resistance and in the absence of controlled release capsules, such as Bionic, which have been a mainstay for many in the past.

The importance of regular FEC (faecal egg counting) and BCS monitoring, with good feed at critical times, to improve tail end ewe body condition was a recurring message.

The first speaker Hannah Wakelin (B. Ag) who oversees Eastland Vets FEC monitoring lab spoke about our database and current trends in the local parasite space.

Favourable wet weather in the recent seasons coupled with growing drench resistance has resulted in higher-than-normal parasite development and survival. This has led to a higher and ongoing pasture larval challenge.

Lamb growth rates and ewe performance have been below expectations in the face of these challenging parasite levels.

Worms depress appetite, cause physical damage to the gut reducing feed conversion efficiency and animal performance.

The main source of contamination is usually lambs. However, when larval challenge is high a percentage of ewes which normally have robust immunity against worms are showing higher than usual worm egg output. Hence a class of stock that is usually able to mop up larvae are in fact starting to fail to cope. A tail end of ewes is developing with lower-than-expected condition score.

We encourage you to do your own FEC monitoring before making drench decisions. The best information is you own information.

Drench checks 10 days after drenching are showing considerable leakage (developing resistance). Of the 70 triple Drench checks performed this season 73% have shown leakage. The average was >500 epg. Regular use of an ineffective lamb drench leads to a progressive build-up of resistant worm larvae on pasture overtime, especially when conditions are favourable as they have been for many seasons.

Eastland Vets has developed a recommended parasite monitoring programme which can be tailored for individual farms. In the early phase of understanding a farms status regular monitoring is required. Overtime a reduction to farm specific monitoring is recommended as a fuller understanding of the farm parasite situation builds.

The second speaker John Meban (BVSc) talked about the advantages and disadvantages of drench capsules.

In the past capsules have been very good at controlling the normal relaxation in resistance to worms that occurs in ewes around lambing known as the PPR (periparturient rise).

This results in increased egg output in ewes and this coupled with eggs and larvae overwintering from the autumn leads to the source of infection for new seasons lambs.

Due to the high current larval challenge overwintering of worms this year is likely to be significant and higher than usual.

In well fed good conditioned ewes the PPR is not as significant and is of shorter duration. The biggest tool in the box in the absence of capsules is to ensure all ewes are in CS 3 or more at lambing and go onto target pasture covers at spreading and during lactation.

If target feeding levels cannot be achieved animal performance and profitability will suffer. If this is the case lambing dates may need to be altered to better fit the pasture growth curve.

Production is driven by ewe CS. It has been shown that ewes that have a condition score of 2.5 or less pre-winter are twice as likely to be missing at weaning from all causes than ewes of CS 3 or greater.

Most gains are made by lifting these light ewes.

The main drivers of ewe feed demand at this crunch period (leading up to lambing and the during first weeks after lambing).

Essentially pre-lamb the main factors are ewe age, ewe maintenance costs, including immunity.

The number of lambs on board and their growth along with udder development increase feed requirements rapidly in the third trimester of pregnancy.

Feed demand peaks at three weeks after lambing to coincide with peak lactation.

Multiple bearing ewes cannot physically eat enough to meet peak energy demands pre-lamb and need to have CS reserves to utilise to buffer production.

Greg Tattersfield (BVSc) further discussed the importance of BCS to lock in top ewe performance.

There is still some opportunity to improve CS of light ewe’s post scanning but as winter encroaches this opportunity becomes less achievable. Greg showed how most gains occur from lifting light ewes to a minimum of CS 3. Gains drop off after this. CS is a hands-on process. Very poor ewes can often be identified by eye. Suboptimal ewes however, where the gains are to be made, can only be picked up by feel especially if they have more than 2-3 cm of wool. CS is simple, easy to learn and will return disproportionate rewards for effort.

Greg set some minimum targets around grazing residual covers as follows.

From scanning to a month from lambing >2 cm ( >1000kg DM residual).

At set stocking 3 weeks before lambing > 4cm (> 1200 -1400 kg DM).

To achieve these targets, it is a good idea to crunch some numbers and do a basic Feed Plan as soon as possible. Higher residuals will be needed for tail end ewes. Controlled winter feed allocation is essential with rotational grazing of the lighter ewes ahead of the main mob. Help with Feed Planning is readily available if required.

Greg gave an example of how strategic Nitrogen could be used to preserve ewe body condition if you got into a feed pinch. Despite current prices there was still a good return on investment.

Management tools to lock in ewe performance include reducing overall feed demand by exiting trade stock and at-risk light tail end ewes, that are unlikely to see the winter out, whilst they still had some value.

Foetal aging at scanning can help with late pregnancy feed allocation prioritising low BCS early ewes.

Appropriate targeted use of an effective drench after FEC monitoring in at risk ewes is still an option.

Diseases other than worms can also be a factor in limiting production at the same time and should be controlled. Of note are trace element deficiencies (selenium, Iodine and copper), liver fluke, lice, end stage FE livers, pleurisy, teeth abnormalities and feet issues. If in doubt some postmortems of tail end animals will help in the identification of the cause ill-thrift in these sheep.

It is accepted that these are best practice targets and may be removed from the reality of your situation. The long-term opportunity is to manipulate farm policies (systems) to remain productive, sustainable, and resilient into the future.

The final speaker Phil Ware (B.Ag) covered the treatment options available pre-lamb.

The first question to answer is what needs drenching. This can only be answered following the appropriate FEC monitoring.

Once this information is on hand a decision table can be used to prioritise age classes of animals for treatment. Included in this table are the farms drench resistance status, animal genetics (resistance, resilience), CS, likely nutrition, FEC’s, larval challenges, production goals, number of lambs (pregnancy status) and the need for refugia. We are happy to help you with these decisions.

Drench options range from oral’s- triples, novels, and mineral drenches.

Injectables- long-acting single actives, combined mineralised or plain vaccines with a short acting drench

Injectable trace elements

Trace element boluses (copper, B12 and Iodine)

Although the options are more limited this year without capsules tailoring a treatment for your animals may require different combinations for different stock classes depending on budget and goals.

Pre-lamb drench best practice should be based around realistic production objectives supported by knowledge of individual flock parasite challenge (FEC monitoring). Not all animals may require treatment.

Drench selection (correct active/s) is based on drench resistance status (use an effective drench), whole farm feed management and ewe CS.

Where possible use a short acting drench in combination with multimineral supplementation to support at risk ewe classes.


Pastures are more wormy than usual. Do your own FEC monitoring to identify at risk ewes/areas.

Many mobs have suboptimal CS ewes. Identify these and preferentially feed. Manage other diseases and cull unproductive non salvageable ewes before they die.

Do a feed plan and allocate feed to high priority ewes (younger, CS<3 and with multiples)

Consider drench use wisely and use an effective drench. Review your farm policies to build in resilience.

Ask the questions, talk to neighbours, advisers.

Look after yourself and each other in tough times.