Large Animal Newsletter – Autumn 2022

Faecal Egg Counts for Lambing Ewes

Faecal Egg counts around lambing are critical. The ewe’s immunity and their ability to withstand the burden of worms decreases dramatically at lambing, so we need to make a tight plan to help manage this period. Ideally, this involves planned paddock rotations to low risk pastures, larval cultures to ensure there are minimal barbers pole worm lurking around, and confirming the drench is effective.

• PRE-LAMBING: Be sure to bring your faecal egg counts into the clinic 8 weeks prior to lambing. This gives us time to do a count and a larval culture (please request this on submission form). Then we can have the data for appropriate drenching can occur on farm 4-6 weeks prior to lambing. We can also look to prepare sheep adequately if drench capsules are the preferred method of worm control
• LAMB MARKING: collect a sample from you ewes a week prior to lamb marking. This enables us to drench if required while the ewes are in the yards for marking, therefore saving on double handling. This is still critical, even if capsules are used, so we can give a cover drench if the capsule is not sufficient.
• If capsules are used, we need to be monitoring the worm burden as the capsule’s efficacy wanes (normally from about Day 90 post administration). Be sure to collect another egg count around this time and bring into the clinic. Capsules certainly need maintenance, and aren’t a “set and forget” option for worm control.

Drench resistance trialing

Do you ever wonder which drenches have resistance on your property? Aren’t sure which drench you should use when we say to use a highly effective drench for your property? Finding sheep aren’t responding to drenching like they should be? A drench resistance trial is the next step for your property.

This trial involves testing out major drench groups on young sheep on your property and monitoring response. This means we get real-time data about what drenches are effective for your property, and then can use it to make the best drench decisions possible, and help mitigate resistance. Our vets can use this information when giving you FEC reports to decide which drench to use.

Ideally, we conduct these trials every few years, as worm populations change. A trial includes two visits to your property, drenching sheep in their groups, sample collection, processing of faecal egg counts and larval culture. 

Pregnancy scanning sheep – what worries us?

Cattle scanning and pregnancy testing rates around the district on the overall, have been good. We touched on common causes of infertility in cattle in last quarter’s newsletter, and we’ve had numerous producers pursue testing for infectious causes of poor fertility in their herds recently.

With sheep scanning already underway or just around the corner for many of our sheep producers, we are hopeful for just as good rates in sheep as we have seen for many cattle producers. For those who experience less than ideal scanning rates, we have included some information about the most common causes of poor fertility in sheep.

Campylobacter

Campylobacter fetus is a common bacteria on sheep properties throughout Australia. When the bacteria is ingested by ewes with no immunity, abortions will result, which may spread to other ewes in the mob and cause an “abortion storm”. This commonly occurs in the last 6 weeks pre lambing, but there are reports of scanners noticing resorption of fetuses at scanning that have later shown to by campylobacter.

High risk factors for campylobacter outbreaks include pregnant ewes being exposed to other ewe’s membranes or abortion material, high stocking density, trail feeding at lambing, and cold and wet lambing pastures. It is important to remember that campylobacter can spread to humans, so if you are experiencing abortions or excessive stillbirths, please phone one of our livestock vets for advice on containing the problem. Diagnosis of campylobacter may involve performing post mortems on aborted lambs. Our livestock vets can then work with you to offer you options and create a sustainable prevention plan for your property and enterprise.

Cyclicity

Ewes are seasonally polyestrous, meaning that the day length and season affects when and how reliably they have oestrous cycles- rather than reliably having them at a set time interval. Many ewes being joined prior to Valentine’s Day (Feb 14th) are considered to be joined “out of season”. As a result, they rely on the presence of a ram to make them start cycling before they can start conceiving. This means the rams have to work to bring the ewes “on” before they can even get to getting them pregnant. If this is not addressed then we can see poor conception rates.

Using teaser wethers or vasectomised rams can do the hard work for your rams and have the ewes all ready to go to conceive when the rams arrive. This means that you get the most conception happening in the first 2-3 weeks of joining, and more lambs born in the first 2-3 weeks of lambing. What can this mean for you?