NSW WormBoss Worm Control Programs
NSW WormBoss Drench Decision Guides
The Coonamble district continues to experience extreme temperatures with many days above 40°C with frequent dust storms and no rain. Worm burdens are low, and larval contamination on pastures will also be extremely low due to the high ambient temperatures and lack of moisture experienced lately.
If you have sheep that are lethargic, sick or dying, it is critical to call a veterinarian and get a diagnosis rather than assume that it is ‘worms’. I have had many cases lately where farmers have unnecessarily stressed sheep by yarding and drenching them, only to find out they were suffering from hypocalcaemia, cathead staggers, or other diseases unrelated to worms. Simply drenching is a waste of money, can result in higher stock losses and contributes to drench resistance in your flock.
Fly burdens are also low due to the lack of moisture. Some producers have chosen not to join this year because of the ongoing drought; others have delayed joining until it rains, while others have joined and are awaiting scanning results. Whatever you have chosen to do, decision making, budgeting (feed and finances), and planning are imperative for ovine success until it rains.
The extreme heat in January would have decimated eggs and larvae on paddocks, so the only worms surviving are in the sheep. A WormTest to determine whether a second summer drench or a pre-lambing drench is needed will be very valuable as there is a fair chance worm egg counts will be very low. There are a few ‘pockets' in the district that continue to get storms and therefore, the potential for barber’s pole worm to become an issue. Producers should be regularly worm testing to ensure numbers are not building up.
In the eastern end of the Riverina LLS, there have been mixed results from worm tests with counts ranging from an average of 0 eggs per gram (epg) from some sheep in a drought lot to an average of 400 epg in some pasture-based sheep. This is a good example of the variability that occurs from farm to farm, and in some cases, mob to mob on the same property.
However, the majority of tests undertaken indicated burdens, on average, over 200 epg, and sheep with these levels of infections would be suffering some production impacts, at least at a sub-clinical level. Under the current seasonal conditions, this situation is not ideal. For instance, counts from some young sheep averaged 112 epg (0–320 epg range) of Nematodirus (thin-necked intestinal worm). The count is likely to be underestimating the true level of the Nematodirus infection because, if these sheep are carrying burdens of immature worms derived from mass hatchings that occurred after showers of rain, their presence will only be reflected in the egg count once they mature and commence egg laying.
In the few larval cultures that were undertaken the levels of Haemonchus (barber's pole) were above expected levels—26% in one case and 85% in another. This reflects the summer rainfall experienced in our region over the Christmas to January period and the warm weather. Producers are reminded to watch out for barber's pole infestations if this pattern of summer rainfall continues, and also to monitor stock in general in case a second summer drench is required. Doing a WormTest Gold or a Basic plus Type is a great idea to check what worm species you have on your property this season.
In the Western end of the Riverina there were significant variations in results from WormTests conducted in sheep over the last month. Results ranged from very high strongyle-type burdens (average 2,500 eggs per gram) to low or none at all. The clinical effects of these large burdens were seen in containment feeding situations, reinforcing the importance of an accurate drench history when purchasing stock. A WormTest before feedlot entry is also suggested to assess the requirement for a drench at induction.
There have been no clinical issues relating to worms in the western region of Murray LLS this month.
In the eastern region of the Murray LLS some WormTests were done with the highest average result being 124 eggs per gram (epg) strongyle-type and 32 epg Nematodirus. Some individual counts were much higher, the highest of which was 520 epg in a group of 400 pregnant Merino ewes. However, the majority sampled in this group had counts of 0 epg with an average for the group of only 84 epg. The mob was not scouring and in moderately good condition. Low levels of coccidia were present in a small number of samples.
Conditions: January brought patchy summer storms allowing us to reach our average monthly rainfall. A dramatic storm in February dropped 85 mm in a single shower in Braidwood with about 50 mm of that falling in 20 minutes. Evapotranspiration is currently still exceeding rainfall, and soil moisture is drier than it was a month ago.
Maximum daily temperatures are currently in the high 20s and above. It is likely that the average maximum temperatures will again be exceeded through March and April. Producers can make use of these conditions to create low worm risk paddocks either for ewes due to lamb or lambs that will be weaned soon. The method is particularly effective against barber’s pole worm, but less so against scour worms. When daily maximum temperatures are consistently above 25°C then 3 months without further contamination occurring (because it is too dry for the eggs to develop to larvae) will kill over 90% of the barber’s pole worm eggs, (see the graph of how temperature affects the survival of barber’s pole worm larvae).
Cattle: In young stock, worms are holding back weight gains and may be contributing to sporadic losses. Worm egg counts for a cohort of 3-month-old calves were over 400 eggs per gram. Young cattle have had a rough start to life as their undernourished mothers most likely would have produced poor colostrum and less milk. Usually, older cattle don’t need drenching, but protein deficiencies may have reduced their immunity, increasing worm contamination of pastures if there have been occasional falls of rain. Producers are encouraged to drench young cattle, especially if the body condition scores of the herd were below ideal, and pastures were short at the end of 2018.
Sheep: We had two worm tests recently that showed a remarkable contrast. The count in a large mob of maiden ewes last drenched in mid-December was 700 eggs per gram. At the same time, a small mob on another property drenched mid-December and using a rotational grazing system that focussed on worm management had a zero worm egg count. It is most likely the first property was unable to use pasture management for worm control due to feed pressure. A reminder that worm burdens are related to your flock, conditions and management systems. You can make informed, objective decisions when you have worm egg count results from your flock.
Many worm egg counts and larval differentiations were performed across the region in the last few weeks and have proved invaluable in making drenching decisions. Thunderstorms and warm weather producing short green grass have provided the right conditions for both scour worms as well as barber’s pole worm, and also Nematodirus (thin-necked intestinal worm) to thrive. Monitoring of weaner sheep identified average counts from 100 eggs per gram (epg) to 1,100 epg. Barber’s pole worm appeared to be present in all larval differentiations, but levels varied from 6% to 88% of the count.
WormTest monitoring has also been used in ewe and wether mobs to predict the necessity of a second summer drench. In many of these cases, the worm egg count averages were less than 20 epg.
Worm egg counts and faecal cultures have also proved valuable for determining whether scouring was caused by worms or bacteria or most commonly, a combination of both.
With pastures browning off at the end of summer, the importance of adequate protein intake in maintaining immunity against worms, particularly in the weaners, needs to be considered.
In the southern Shoalhaven LGA area, barber's pole worm is on the rise this month with mortalities and ill-thrift seen in both sheep and goats. In both these groups, animals that had been treated in the last 3–4 weeks were still doing poorly and with sporadic deaths. Signs observed in these cases included weakness, mild swellings of the jaw and face and varying degrees of anaemia of the eyes (pale lower inner eyelids) and gums. Anaemia ranged from pale pink to white. Remember, worm control is more than just relying on chemicals to do the job. Every farm has different needs, but an integrated program involves a combination of grazing management, nutrition, breeding, host immunity, and knowing what drenches do and don't work on your farm. Check your mobs now with a WormTest to see whether a drench is required. If your flock does not appear to be responding to a drench treatment, seek advice from your local District Veterinarian.
WormTest results from the district have been variable, but barber's pole worm remains a risk due to the regular rainfall from storms. There have been extremely high counts in some flocks, and very low counts from sheep that were not recently drenched, illustrating the role that grazing history and local weather play. Some producers have submitted faecal samples after drenching to check drench efficacy (DrenchCheck). This post-drench check is a simple and effective way to monitor your drenches and detect drench resistance early.