Local disease watch - June 2016
Animal exports active
Livestock export opportunities for South East producers have expanded greatly. Cattle, sheep, goats and alpacas have headed for destinations such as China, Israel, Turkey, Middle East, Japan, Malaysia, Bangladesh, Vietnam, Uruguay and New Zealand.
Freedom from diseases such as Foot and Mouth Disease, Bovine Tuberculosis and Brucellosis, BSE (“Mad Cow” disease) and Scrapie make Australia a preferred source of livestock for world markets. Certification and testing regimes are set by the importing country, and vary greatly.
One disease on the radar of some importing countries is Bluetongue. Bluetongue is a viral disease of ruminants which causes serious disease in sheep. Up to 100% of the mob becomes ill and 30% may die. Symptoms include fever, drooling, breathing difficulty, mouth ulcers, and red/blue muzzle and feet. Cattle show few signs of infection, and deaths are rare.
Local Land Services veterinarians routinely collect blood samples from sentinel cattle herds strategically located across the region. These blood tests help map the annual movement of important insect-transmitted viruses including Bluetongue, Akabane and Three-Day Sickness.
There are more than 24 strains of the Bluetongue virus worldwide, and ten of these occur in the Northern Territory. Some of these ten strains could cause deaths in sheep, which is one reason for restrictions on sheep ownership in the Territory. Two strains have occasionally found their way into NSW when summer air currents carry south the biting midges that spread the virus.
This has implications for south east livestock producers looking to export to Bluetongue-sensitive markets. Our region is bisected by a line on a map (Australian Bluetongue Zone Map) which delineates the extent to which these midges might migrate. Being on the wrong side of the line excludes sales to lucrative markets such as China and Turkey.
Three-Day Sickness in cattle
Further cases of Three-Day Sickness have been reported from farms south of Kiama.
Affected animals develop fever and lameness, lose their appetite and are reluctant to move. Most recover within a few days with routine nursing.
Worms in sheep
Several weeks of dry windy weather, interrupted briefly by widespread falls of about 40mm and only one decent frost, did little to change the pattern of worm infection in Tablelands sheep. Barber's pole worms still dominate egg counts on about half our properties, with averages of several thousands common regardless of sheep age. Some properties remain free of barber's pole worms, and have little worm activity of any sort at present.
Producers are trying to decide on their best strategy for ewes pre-lambing, knowing that feed conditions are far from ideal. You will need some essential information: a current worm egg count and culture for worm type to know how many and what type of worms are present; and the grazing history of the proposed lambing paddock, from as far back as when it rained around Australia Day. Much of our barber's pole hassle arose from eggs hatching after that rain event, and larvae were allowed to build up because producers then thought it became 'too dry' for worms.
It is now not unusual to see the protection period from drenches containing closantel reduced as a result of developing resistance. Many closantel products had sustained activity against susceptible barber's pole worms, controlling re-infection and pasture contamination for up to six weeks after drenching. This was useful where sheep were returned to contaminated pastures after drenching. Loss of this protection period is often the first indication that the worms in your sheep are becoming resistant to closantel.
Continued use of that same drench results in adult worms surviving drenching as well. One local property recorded a worm egg count of 5,800 eggs per gram (epg) in ewes twenty five days after closantel, and 1,000 epg after 18 days in wethers. The worms in both mobs were 100% barber's pole worms.
Operation Mary looks at sheep in saleyards
Sheep consigned to saleyards, and particularly the paperwork that accompanies them, has been the focus of a joint Local Land Services/Department of Primary Industries campaign.
Dubbed Operation Mary, biosecurity staff found the most common error when sheep are sent to sale is omitting to list all the Property Identification Code (PIC) ear tag numbers of sheep in the consignment. If you didn’t breed all the sheep in the sale lot, you must record all non-vendor bred PIC numbers on the National Vendor Declaration (NVD).
Being able to trace sheep from any property, saleyard or abattoir all the way back to the property of birth is fundamental to Australia’s reputation for producing certified clean agricultural products. It only works if the PIC ear tags of all sheep are recorded on the NVD.
Victoria already uses electronic ear tags for sheep, similar to cattle, and is urging national up-take of that more expensive tracing option.
Our only way to avoid it is to prove that our existing system based on visual ear tags and accurate paperwork is just as good. According to Mary, we still have some way to go.
Liver fluke widespread
Surveys show liver fluke are present on about one third of properties in eastern NSW. Liver fluke are showing up more frequently in tests of both sheep and cattle from our region. A blood test on cattle grazing fluke-prone paddocks containing creeks or springs may be a useful way to monitor for fluke on your property, if you run sheep and cattle.
Some producers are taking full advantage of their vet by collecting blood samples from cows during preg testing.
Work is continuing on commercialisation of a new dung test for sheep and cattle, which will identify fragments of fluke DNA in faeces. One drench company has already used this test extensively for cattle, finding it more accurate and able to detect fluke earlier than existing tests.
The new test will also be a great help in identifying those properties where liver fluke are resistant to drenches, which is an increasing problem. More information: Treat for liver fluke
Sudden deaths on cereal crops
Nitrate poisoning has killed both sheep and cattle grazing oats, winter wheat and triticale crops recently. High levels of nitrogen in the soil, derived from fertiliser at sowing time, or applied as in-crop urea, lead to dangerously high nitrate levels in crop plants. Overcast weather or foggy days add to the problem, as the plant struggles to use the nitrogen for growth.
Most affected stock die within hours of introduction to a new paddock, before beneficial bacteria have a chance to multiply in the paunch.
Many cases of nitrate poisoning could be avoided if hungry stock were filled up on hay or alternate pasture before having first access to crop. Delay introduction to the crop until after lunch, especially on overcast or foggy days, to allow plants time to use some of the excess nitrogen they absorbed overnight.