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.
To find out more information about a drench resistance trial, requirements to plan for, or to formulate a package and a cost estimate for a trial for your farm, please phone the clinic.
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 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.
Ovine Brucellosis is another bacteria that may infect rams, rendering them sub-fertile or infertile. It is sexually transmitted, but may be spread amongst rams when running together through domination behavior. Clinical signs may not always be apparent, but brucellosis may cause testicular deformities and lumpiness. Fertility results in brucellosis cases can vary, and may range from having extremely poor scanning rates, to having persistently sub-optimal rates in properties that have had it for a long time.
Brucellosis is diagnosed through a blood test. We will do this in an infertility workup, but is something we recommend for all producers to do routinely, frequency of which depends on the overall enterprise objectives. Biosecurity is key in preventing brucellosis on your property- ensure no stray rams or ewes come onto your property. Only buy rams from properties with Brucellosis Free accreditation, or who are blood tested negative prior to entry. This also goes for vasectomised rams (teasers), who may also be involved in spreading brucellosis.
Nutrition is critical when we are expecting a ewe to perform- both before and during joining. Be sure to routinely condition score ewes pre-joining to see where they are, and to give yourself time to bring them to optimum score if they aren’t already. A rising nutrition plane (in quantity and quality) is critical to optimize ovulation just prior to and during joining. This is the premise that “flush” feeding is based upon, which is one way to improve the number of twins and triplets born.
As this can be a complex venture, our livestock vets are happy to have a farm visit to assist with condition scoring and discussing feeding in the lead up to and during joining. For our sheep clients that sometimes struggle to find a reason to have us on farm for our annual visit, this can be an excellent visit that can provide you with a lot of real time data, and strategies planned to suit your property.
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?
- Shorter joining periods to get higher lamb percentages- no need to be joining for 8, 10, 12 or 14 weeks to ensure ewes are cycling, shorter joining will give them ample opportunity
- A more even line of lambs- for sale or for replacement
- More older lambs at sale date meaning greater maturity and greater growth potential
- Ewe lambs used as replacements will be more mature and have greater potential to reach growth targets by joining
Vasectomised rams are proven to be more efficacious than testosterone treated wethers, and this is a procedure we offer to do at our clinic. Utilise the upcoming “off-season” for the boys to organise your teaser plan- call the clinic for a discussion with our vets.
Please phone the clinic with further questions.