Tasmania worms, flies and lice update - December 2018

Perth: Paul Nilon, Nilon Farm Health (pandonilon@bigpond.com)

Season’s greetings from Tasmania, where the weather has been coolish, except when it’s warmish, with rain over most sheep grazing areas, but not the biblical falls recorded at Ingham (coastal, north Queensland) and such places. Nevertheless, the South Esk should be flooding in the next few days, although we’ve only received 20 mm. The long-suffering Fingal Valley has had good rain.

It’s no surprise that the rain in November and December will keep the worms ticking over. Further, it’s not hard to see flies irritating sheep when they are confined. Indeed, since the weekend rain (15^th–16^th), I’ve seen fat crossbred (XB) sheep with less than six weeks wool struck on the back and shoulders.

So, recommendations are:

• Complete weaning before Christmas. Pasture stimulated by the rain will provide good grazing for the newly-weaned. Do not use it as an excuse to delay weaning.
• Many, if not all Merino producers will need to give a second summer drench in February–March. This is not usual for producers south of Campbell Town.
• Flies are active. Monitor diligently. If you cannot, treat before Christmas or enlist Santa’s helpers to dag and treat on Christmas day. Early weaned lambs that may not have been treated at marking will be vulnerable.
• Heavy rain may wash out fly chemicals, reducing the protective period. Dicyclanil sticks like a tax auditor. Others may be removed. Beware.

Monitoring Prime Lambs: In February, I wrote a piece suggesting that a lot of monitoring is useless because it’s done too infrequently or too late. There is no point waiting till the lambs are scouring before doing a count. So, to reiterate: if you rely on monitoring for drenching decisions do a count every 2–3 weeks. If you are unwilling/unable to do this then drench to the calendar.

Figure 1. Removing fodder without appropriate periods of spelling may not reduce the numbers of worm larvae on pastures. Source: Paul Nilon.

The picture is of a late-cut paddock that should provide such good fodder that I’ve asked the client to keep a ‘cupla’ rolls for me to eat for breakfast. Regardless, these are often regarded as (parasitologically) safe grazing, but it’s not always so. I frequently see wormy lambs within four weeks of being weaned onto these paddocks. Here are some thoughts:

• The worm cleansing effect is due to spelling, not removal with the fodder. Short spelling periods (e.g. opportunity haymaking when the season kicks on) may not lead to decontamination.
• Even with a good destocking time (say, 10 weeks) cool springs such as the one just past allow larvae to live longer.
• Experience suggests that grass and clover seed paddocks are generally safe, perennial pastures are much more capricious.
• The best paddocks are those that have been grazed by cattle in early spring, or paddocks that have had at least 10 weeks without sheep before being cut.

When all is said and done these paddocks provide good grazing for weaners when resources are scarce. It’s often a case of suck it and see. Monitor closely rather than assuming safe grazing.

Pox and Pestilence: Differences in animal health status between the States and regions is often a matter of political consideration, rather than a reality. However, the tens of thousands of sheep, and more than a few cattle that are entering Tasmania pose at least one real health problem: the risk of introducing hydatids. It would beggar expectation that imported sheep and cattle did not (occasionally) carry intermediate stages of hydatid tapeworms. Endemic infection is extremely rare in Tasmania. So, a few hints to keep it that way:

• Dispose of carcasses by burial or burning. This is a legal requirement.
• Worm your dogs with a compound containing praziquantel.
• Importantly, places that allow hunting with hounds and dogs should insist that their owners worm the hounds with praziquantel. Native lore—that these dogs increase the transmission potential—is correct. This applies to hydatids (which is essentially exotic) and to sheep measles (which is definitely endemic).

Season’s Greetings: As the sun sets on 2018, have a great Christmas and New Year. Keep the comments coming. I always prefer positive ones, but a few brickbats do not hurt (since the kids left school there is enough in the kitty for therapy).

Finally, if you are on the road during the holidays, stay safe.
 

Figure 2, below. Sunset over the ruins of the old jetty at Trial Harbour on the West Coast of Tasmania. Source: Paul Nilon.