HOW TO USE THIS ONLINE MAGAZINE
by clicking the arrows at the side of the page.
by clicking anywhere on the page. A slider will appear, allowing you to adjust your zoom level.
and move the page around when zoomed in by dragging the page.
and return to the original size by clicking on the page again.
by entering text in the search field and click on "In This Issue" or "All Issues" to search the current issue or the archive of back issues
a PDF of this magazine.
by clicking on thumbnails to select pages, and then press the print button.
a page via email, Facebook, Twitter and more.
TO VIEW PREVIOUS EDITIONS
, click the
button at the bottom of the screen.
Beyond the Bale : March 2017
Survivaloflarvae(%) Days of survival Daily maximum temperature 0 03 06 09 0 120 150 180 210 10 20 30 40 50 60 70 80 90 100 Temp 10̊C Temp 15̊C Temp 20̊C Temp 25̊C Temp 30̊C Temp 35̊C It’s March. If you are in southern Australia’s moderate to high rainfall areas, you’ll be moving weaners onto a clean (low worm- risk) pasture when the season breaks. If you are in the northern, summer rainfall areas, you will have just started preparing clean lambing paddocks and be using cleaned weaning paddocks. If you are not doing that now, there is a real opportunity to be gained from implementing a well-proven strategy for effective and profitable worm control that decreases the exposure of sheep to worms. This reduces both production loss and the need for chemical (drench) intervention. In turn, fewer drenches result in less cost and labour and slower development of drench resistance – a winning combination all round. Strategically preparing low worm-risk paddocks – also referred to as ‘clean’ paddocks – for the most susceptible classes of sheep on the property also helps the remainder of the flock because there are fewer worms on pastures to infect other mobs being moved around the property. In summer rainfall areas, where barber's pole worm predominates (Qld and NSW north of a line through Sydney), prepare low worm- risk paddocks for lambs at weaning and lambing ewes. In winter and non-seasonal rainfall areas and Mediterranean climates (WA, SA, Tas, Vic and NSW south of a line through Sydney), prepare paddocks for weaners to use during their first winter. WHAT ARE LOW WORM- RISK PADDOCKS? To merit the description ‘low worm-risk’, these paddocks need to have such a low level of infective worm larvae on them that when sheep are introduced (after just being treated with an effective drench) at least a few months must pass before worm numbers build up to levels that cause illness in the stock. LOW WORM-RISK PADDOCKS HOW ARE LOW WORM-RISK PADDOCKS PREPARED AND USED? Two things must occur. Firstly, all of the existing worm eggs and most of the larvae on the paddock must die. Secondly, new larvae must be prevented from developing on that paddock during preparation. TIME FOR LARVAE TO DIE Generally, at least 90%, but preferably 95% of the worm larvae on a moderately to heavily worm-contaminated paddock must die. Less than this is rarely enough. In Australia, a 6-month period (over the coldest months) is sufficient for 95% larvae to die, and this can be reduced to a 2-month period during summer months in very hot locations. The graph below shows the rate at which barber’s pole worm larvae die, but is quite similar for scour worms that exist on pasture. Choose the temperature line that fits your location in the few months prior to when the low worm-risk pasture is required and find where larval survival (left side of graph) drops to 5% to show the number of days required for 95% of the larvae to die. PREVENTING FURTHER CONTAMINATION While the larvae on the paddock are dying, further contamination must be prevented. The simplest and surest way is to exclude sheep (and goats and alpacas, which share the same worms) from the pasture during the preparation period. However, this is often not the best use of the paddock. Where possible, utilise feed by grazing with cattle or horses (not sheep, goats or alpacas). Or use the paddock for growing a crop or making hay or you can graze heavily just before the preparation period and then leave the paddock empty during the regrowth period. You can, however, graze the paddock with sheep, goats or alpacas under very specific conditions. After they receive a drench proven to be fully effective on your property (see DrenchTests Whether you are in summer or winter rainfall areas, now is a key time to be taking action on low worm-risk paddocks – a cornerstone of successful worm control. SURVIVAL OF BARBER’S POLE WORM INFECTIVE LARVAE ON PASTURE AT VARIOUS DAILY MAXIMUM TEMPERATURES AND 60% RELATIVE HUMIDITY. PHOTO: Deb Maxwell 36 ON FARM
In the Shops - March 2017