NSW WormBoss Worm Control Programs
NSW WormBoss Drench Decision Guides
Very few worm tests from the Coonamble district have been submitted through the state diagnostic laboratory, so information on worm burdens is limited. The few results seen were low, due to the dry conditions. It is expected that worm burdens will remain low as summer heats up, with (unfortunately) no rain events likely throughout spring. One thing to remember is that nutrition is important to worm resistance and resilience in sheep and cattle. The provision of good quality energy and protein sources will be necessary throughout the ongoing dry, especially to weaner animals. If nutrition is inadequate, immune systems will slip and worm burdens may rise despite the dry weather. Producers are urged to consider the commitment to supplementary feed in the coming months, including budgeting for this, and if it's not realistic consider selling surplus stock early.
There is very little to report in the Forbes area with regards to internal parasites. The few egg counts seen have been low and there were no clinical cases to be investigated. Conditions continue to deteriorate with regards to the season. During these dry spells producers should be worm testing before deciding to drench.
Currently it is looking rather worm-unfriendly in our region. Sheep are generally still looking healthy, but there is not a lot of feed in front of the ewes and lambs. Numbers are up at the saleyards.
In the region there is currently a lot of focus on farm biosecurity planning. It is opportune to remind sheep producers that this should also include quarantine drenching of introductions.
While Farm Biosecurity Planning tends to focus people’s attention on farm access, washing down facilities and commodity vendor declarations, the risks posed by chemical residues and chemical use remain important, as do routine management programs for vaccinations (especially the clostridials and CLA), internal parasites and blowfly prevention.
There have been very few worm test results this month.
In the east, one mob of one-year old merino ewe lambs in medium condition were drenched in January, and were not scouring. Their worm egg count averaged 12 eggs per gram (epg) of strongyle type eggs and 16 epg nematodirus type eggs.
In the west, there was only one wormtest submitted, which showed 204 epg strongyle type and 4 epg nematodirus type eggs. Interestingly the larval differentiation showed 69% barber’s pole worm, 8% black scour worm, 19% brown stomach worm and 4% large bowel worm. This is unusual for the far west part of the Murray region where scour worms are more commonly the predominant worm type. The samples also had low to medium amounts of coccidia present.
In the course of disease investigations in the west some sick sheep where investigated for worm burdens. One animal had a count of 400 epg strongyle type and low levels of coccidia while another only had 40 epg nematodirus type and low levels of coccidia.
The higher elevation basalt country stands out from the rest of the district, having received about double the rainfall to date. Pastures there are still green, and of reasonable quality. These same conditions are ideal for worms, as a recent investigation proved. Six full-wool two-year-old ewes with marked lambs at foot died suddenly, in a couple of days. From a distance, these ewes and lambs looked pretty good. The ewes had been drenched with a four-way combination between lambing and marking (apparently that's what the owner does as a routine), and were dying four weeks later. Up close, the ewes had lost a lot of condition (not easily seen under a full fleece), and a few lagged behind when mustered. Post mortem examination showed masses of recently acquired black scour worms in a badly damaged small intestine. The lambing paddock turned out to be a poor choice. It had been previously grazed by a mob of crossbred lambs in the autumn, and was heavily contaminated with worm larvae. As the amount of feed on offer declined, these highly susceptible young lambing ewes took the hit.
Elsewhere, winter has been drier and spring hasn't sprung. Worms have been pretty quiet as a result, so far. There is always a temptation to leave lambs on ewes a bit longer when conditions are tight, thinking that any milk they get is of better quality than the pasture available. But this is not the season to delay weaning. It won't take much spring rain to get worm larvae hatching, and for lambing paddocks to become too dangerous for poorly grown lambs. But remember to train lambs to eat supplementary feed before weaning.
One well-managed sheep enterprise with an unwelcome lice infestation is struggling to achieve eradication. There is an adage that "the best lice control product is a clean muster". But with lambing twice and four shearing dates in a year, lining everything up for effective treatment at the one time is proving difficult. Unfortunately, there is no leeway to allow use of lice control products "off-label". If the product label says "apply to unshorn lambs up to 2 months of age", we are not just being obstructive when we advise against using it in older lambs. Not only is there no work to support that extension, but you are legally bound to abide by the label on lice control products. In some cases, it is not possible to achieve lice eradication without altering annual management.
Conditions have generally remained dry in the district over the last month, although temperatures are on the rise. However, the 28-day rainfall forecast shows that showers are on the way.
Remember that worm eggs require warmth and moisture to develop into larvae (above 10–18°C depending on worm species and with usually more than 15 mm rain over 4–7 days). So, temperatures are adequate, but moisture is not. If the rain comes, it won’t take long for larvae to start accumulating on pasture. If sheep are carrying a reasonable burden of adult worms left over from the autumn break this initial challenge can catch producers off guard. Sheep that are nutritionally challenged due to the challenging winter and early spring conditions in the district are particularly vulnerable. If you’ve got a recent WormTest consider repeating it 3.5–4 weeks after the wet weather arrives— three and a half weeks is the minimum time it takes for roundworm eggs to develop into infective larvae and then for those larvae to be eaten by sheep grazing pasture, develop into adults in the sheep, and then start laying eggs. If you don’t have a recent WormTest, consider doing one now to see whether sheep are shedding significant numbers of eggs.
I’ve decided to include another case study that highlights the value of WormTests.
In September, six WormTest results were received from a producer running a number of separate mobs of Merino and cross bred sheep. The samples were submitted for WormTest Basic—Pooled egg count and worm typing. All larval cultures are still pending. The worm egg counts (WECs) are below:
This property had received some rain over the previous few weeks and therefore little can be said about whether the WECs reflect the larval burden on the previous or current pastures grazed. However, even without the larval cultures, mobs one, three, and four required drenching while the other three did not (as per the WormBoss Drench Decision Guide).
Once again, a bit of arithmetic. The cost of the WECs for all three mobs was $363. Assuming the producer would otherwise have drenched all six mobs with a combination drench containing three different actives he would have unnecessarily drenched mobs two, five, and six at a cost of $444 (740 ewes at 60 kg at approximately $0.60 per dose for the average triple combination drench), not to mention the producer’s time and the stress on the stock of mustering and handling. Once again WormTests for the win.
Dry conditions have meant worms are not a great concern for many sheep producers. A low number of WormTest samples have been submitted. Anecdotally, some have reported that sporadic rain events have appeared to increase Haemonchus burdens in mobs with higher stocking rates.