Cattle worm control in NSW November 2017, Primefact 419, second edition Dr Stephen Love, Veterinarian / Research Officer (Parasitology), Extensive Livestock Industries, Armidale Dr Gareth Hutchinson, formerly Parasitologist, Elizabeth Macarthur Agricultural Institute, Menangle This Primefact outlines the basics of worm Other gastrointestinal roundworm species, control for grazing beef cattle in New South including barbers’ pole worm (Haemonchus Wales. placei), small intestinal worm (Cooperia spp.), stomach hair worm and black scour worm Cattle worms (Trichostrongylus spp.), nodular worm and related worms (Oesophagostomum spp.), and Following is an overview of internal parasites hookworm (Bunostomum spp.), add to the total (‘worms’; endoparasites) of cattle. This includes impact on host animals. gastrointestinal nematodes, liver fluke (Fasciola hepatica), stomach flukes, and lungworms. Lungworms Cattle can be infected with lungworms Figure 1. Calf with ‘bottle jaw’ (submandibular (Dictyocaulus viviparus), but these parasites are oedema) due to Fasciola hepatica (liver fluke). usually not a problem in extensively grazed beef Haemonchus, also a blood-sucker, can cause this cattle in NSW. too. ‘Lumpy jaw’ (‘actino’; usually in older cattle) causes a firm rather than a soft swelling. Flukes (Trematodes) Liver fluke (Fasciola hepatica) is an important parasite of cattle in certain areas, where conditions are suitable for the intermediate host, an aquatic snail. (The presence of the snail does not necessarily mean fluke are present, however). ‘Flukey’ areas occur mainly in the eastern third of NSW, but also in some western irrigation areas. More information: Boray, 2017; Love, 2017. (See references). Stomach fluke (such as Paramphistomum spp. or Calicophoron spp.) occasionally cause disease, mainly in coastal areas. Adult stomach flukes do little damage; most problems are caused by large numbers of migrating immature flukes in the small intestine, resulting in enteritis, scouring (diarrhoea) and weight loss. More information: Lloyd, 2007. Image credit / source: Boray JC, 2017 Coccidia Round Worms (Nematodes) Coccidia are microscopic protozoal parasites, not Gastrointestinal worms. The ones of relevance here are the Small brown stomach worm (Ostertagia ostertagi) species (e.g. Eimeria spp) that inhabit the is the most important roundworm of cattle in intestines of grazing livestock, including cattle. temperate regions worldwide, including NSW. Cattle worm control in NSW As with sheep and goats, coccidia in cattle occur Immunity and nutrition in the intestines of normal, healthy animals, and Well-fed animals develop immunity faster and are coccidian oocysts (‘eggs’) can be seen during better able to expel parasites and to withstand microscopic examination of faeces from animals, the effects of those that remain. as in a ‘WormTest’ (faecal worm egg count, or WEC). Young cattle are most susceptible to worms, but usually develop useful immunity by 20–24 When disease (coccidiosis) due to large numbers months of age. Generally cattle develop much of coccidia occurs, it is often in young animals better immunity to worms than sheep and goats. that are stressed, and in wet, overcrowded Although adult cattle often require little or no conditions. Signs include weight loss and drenching for roundworms (as opposed to liver scouring, sometimes with the passage of blood fluke), some individual animals can become as well as faeces (dysentery). However, similar wormy. Susceptible adults may include bulls, signs can be seen in scours due to bacteria, first-calf heifers, and severely-stressed viruses, or worms. individuals, especially on ‘cattle-only’ properties Note that drenches for worms (anthelmintics) are in higher rainfall areas. not effective against coccidia. Antimicrobials such as sulphonamides are required. Seek veterinary Pasture/grazing management advice. ‘Worminess’ of pastures and animals - Table 1. Harmful cattle worms and their seasonal patterns distribution (Source: Love and Hutchinson 2003, Dung pats can provide shelter for worm larvae for adapted from Cole 1986) several months, even in very dry conditions. Therefore, paddocks continually grazed in Common/significant - NSW autumn and winter by young cattle - which shed Summer rainfall / subtropical areas e.g. North Coast more worm eggs than adults - can become very Haemonchus placei (barber’s pole worm) wormy. The highest numbers of Ostertagia eggs are shed by cattle from 6 to 10 months of age, Ostertagia ostertagi (small brown stomach worm) with the numbers falling markedly, due to host Cooperia punctata – C. pectinata (intestinal worm), resistance, as they approach one year of age. as a complex, often with Ostertagia and sometimes Larval availability (Ostertagia) on pasture is Bunostomum phlebotomum (hookworm) highest from late winter until spring, peaking Oesophagostomum radiatum (nodular worm) around September, then declining rapidly in summer. Through spring, worm burdens can Fasciola hepatica (liver fluke) – in ‘flukey’ areas increase rapidly in young cattle (12-15 months Non-seasonal to winter rainfall / temperate areas old). Inhibited Ostertagia larvae in these young Ostertagia ostertagi cattle can increase from early spring, peaking in October-February (‘pre-type 2 infections’). From Trichostrongylus axei (stomach hair worm) late summer to autumn, these larvae in the Cooperia oncophora (intestinal worm) abomasum can resume development to adult worms in 18 month old cattle, causing severe Fasciola hepatica (liver fluke) – in ‘flukey’ areas symptoms of Type 2 ostertagiosis, even when dry Occasionally significant, mainly subclinical, or weather prevails (Smeal, 1995). sometimes present in large numbers Preparing ‘safe’ pastures for young cattle Paramphistomum spp. and Calicophoron calicophorum (stomach flukes) – especially NSW Preparing a number of ‘worm-safe’ pastures, North Coast (immature stage sometimes imporant). particularly in higher-rainfall areas of NSW, T. axei (not of major importance) should be considered. This is so young, Strongyloides spp. (threadworm) (not of major susceptible cattle can be moved every few importance) months to paddocks with fewer worm larvae. Aim to graze weaners from late July through to summer on the least contaminated pastures Integrated parasite management available. (IPM) Smeal (1995) advocated preparing ‘safe’ or ‘low Manage worms by using ‘non-chemical’ as well worm-risk’ pastures for spring 4-5 months as ‘chemical’ control options. ‘Non-chemical’ beforehand. options include improved nutrition and providing ‘worm-safe’ (low worm-risk) pastures for young cattle. 2 NSW Department of Primary Industries, November 2017 Cattle worm control in NSW Table 2. Low worm-risk pastures for weaners Smeal states these grazing systems have been highly effective in reducing numbers of Ostertagia Rank Pasture management ostertagi and other nematodes over whole farms Best New sown pasture or crop after 1 to 2 years, and says they should be used Pasture spelled or grazed by sheep for in ‘wormy’ environments’ if cattle raising is a previous 4 - 5 months major enterprise. He also noted (in 1995) that beef producers in eastern parts of the northern Pasture not grazed by any cattle for tablelands have successfully used the Double previous 4 - 5 months Paddock Grazing System since 1978. Good Pasture grazed by adult (>2 years old) dry cattle But, for many if not most beef producers, regular Pasture grazed by cattle older than 18 use of relatively long-acting endectocides is more months of age attractive than using grazing management and Higher risk Pasture grazed by young cattle such as short-acting drenches. Endectocides weaners (macrocyclic lactone-based pour-on (topical) drenches with activity against endo- as well as ectoparasites) have certain advantages. In In Smeal’s plan for the NSW tablelands (where weighing up the options, even an informal cool, moist conditions in spring favour benefit-cost analysis would have to include Ostertagia), there is the option of a Single or issues such as sustainability and selection for Double Paddock Grazing system. resistance, a matter on which opinions will vary, as well as production gains per unit input (cost of In the ‘Single’ system, a ‘safe’ paddock is drench, labour, other management costs); in prepared between March and July by spelling, or short, productivity. grazing with untreated adult cattle (>2 years old) and / or sheep at low stocking rates. Ten month ‘Drench and move’ and ‘refugia’ old weaners are drenched and moved into the Note that drenching cattle immediately before or ‘safe’ paddock in late July, where they remain after moving onto very clean pasture, for example through spring into early summer. Smeal (1995) ungrazed cereal stubble, can result in greater reports that, in trials where ‘safe’ grazed weaners selection for resistant worms. This is because were compared to those remaining on pastures there are few worms ‘in refugia’ on the clean contaminated in autumn and winter, the former paddock relative to worms remaining in the cattle. had significantly lower worm burdens, as well So, there are fewer drench-susceptible worms to higher weight gains - 30-60 kg extra per head - ‘dilute’ the progeny of resistant worms surviving by spring and early summer, 9-12 months after the drench. ‘Safe’ pastures (as described here) in weaning. tablelands areas, for example, will likely have In Smeal’s ‘Double’ system, two ‘safe paddocks more worms in refugia than ungrazed cereal are prepared for 4 months over