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Beyond the Bale : June 2018
Serious worm issues have been reported on many properties across Australia where ewes and young lambs have grazed heavily worm-contaminated paddocks. Many producers, having experienced this problem, are now using a pre-lambing drench. In this article we present whether and when lambing ewes should be treated and their management for worms through to weaning. Apre-lambing drench is a time-honoured tradition, aiming to ensure that lambing ewes, whose immunity to parasites temporarily declines just prior to and after lambing, do not contaminate the paddocks with worms. If left untreated, lactating ewes can develop much higher worm burdens than when they are dry or pregnant, which in turn leads to a worm-contaminated lambing paddock and lambs becoming infected. As lambs and weaners have little immunity to worms, their growth, and even survival rates, can be affected. There are also further consequences with flow-on contamination to other sheep and paddocks on the property when sheep are later moved into and out of those lambing paddocks. To combat this, a pre-lambing drench may be warranted. You may be wondering if you need to give a pre-lambing drench, when to do it, which drench to use and whether a WormTest should be done first. REGIONAL AND STATE RECOMMENDATIONS • Tasmania / summer rainfall tablelands and slopes region of northern NSW / southern Queensland: The WormBoss regional experts recommend that a pre-lambing drench is mandatory. A pre-lambing WormTest is not required; instead, routinely give an effective, combination, short-acting drench and move the ewes onto prepared low worm- risk paddocks. A long-acting product is generally only warranted in wet, high worm-challenge seasons if the lambing paddocks are already heavily contaminated with worm larvae – that is, they have not been effectively prepared as low worm-risk. • Victoria / South Australia / other moderate to high rainfall areas of NSW and Queensland: A WormTest should routinely be carried out first to determine whether a pre-lambing drench is required. • Western Australia: WormTest late-lambing ewes (lambing later than mid-June), but in early-lambing ewes that received a drench in March–April no further WormTest or pre-lambing drench is required as this acts as a pre-lambing drench. • Pastoral region: A pre-lambing WormTest is not specifically indicated, especially in the drier areas, but if a drench before or during lambing has been required occasionally in the past on your property, a routine pre-lambing WormTest would be useful. Table 1 below shows the worm egg count thresholds above which a pre-lambing drench should be given. Some of these levels are below where ill-effects would be seen in the ewes, but are given strategically The information in the table comes from the WormBoss Drench Decision Guides. They provide more information to assist your day-to-day drenching decisions. See www.wormboss.com.au/drench-decision-guide TABLE 1: WORM EGG COUNT THRESHOLDS FOR PRE-LAMBING DRENCHES Drench if the worm egg count per gram of faeces is equal to or greater than the threshold shown in the table. IS A PRE-LAMBING DRENCH WARRANTED? LAMBING EWES: REGION ZONE/SITUATION PRE-LAMBING WEC THRESHOLD (EPG) Victorian Winter Rainfall Spring-lambing ewes Autumn-lambing ewes 100 South Australian Winter Rainfall South east 75 Higher rainfall Mediterranean 100 Lower rainfall Mediterranean: • early lambing ewes • late lambing ewes 250 150 NSW Non-Seasonal Rainfall • No culture OR less than 60% barber’s pole • Greater than 60% barber’s pole 150 250 Qld/NSW Summer Rainfall/Slopes and Plains 300 Pastoral 300 Western Australian Winter Rainfall High rainfall zone: • late lambing ewes (lambing starts from mid-June) • early lambing ewes (lambing starts before mid-June) 200 No drench is recommended as worm burdens will be low after the autumn treatment. Low rainfall cereal zone 200 to keep worm levels low during lambing. TIMING THE PRE- LAMBING DRENCH When a pre-lambing drench is recommended, it is ideally given within the three weeks before the start of lambing. Giving a drench sooner than this – particularly in the higher rainfall areas – allows more time for the ewes to acquire a substantial burden of worms before lambing starts. Time the drench with the move to the prepared lambing paddock. If WormTests are used, allow enough time for samples to be posted to the laboratory and results to come back – usually about a week. 46 ON FARM