Rains in March and April have initiated variable pasture response for many producers throughout Queensland. In some areas the rapid growth of green feed after these rain events has brought associated risks. Issues are occurring predominantly in flocks introduced to the area from other pasture types or drought affected areas. This includes stock that have been bought in, agisted or moved from drier/grassier country to country dominated by herbage. Being aware and mindful of some of these issues will help in maintaining stock health.
One issue that has recently arisen in Central West Queensland is pulpy kidney (enterotoxaemia). This has caused a number of deaths in sheep that have travelled from drier areas and then been turned out onto high quality pastures. The disease is caused by a toxin produced by the bacteria Clostridium perfringens Type D. This bacteria, which normally lives in sheep or cattle intestines causing no harm, can proliferate under favourable conditions and produce a highly lethal toxin. A sudden change in diet through a change in paddock or even supplementary feeding can create conditions in the gut favourable for the bacteria to grow and to produce its toxin, resulting in acute disease.
Signs that pulpy kidney is occurring in your flock can be hard to observe. Lambs in good condition are often just found dead on their side with limbs extended and head thrown back. It can look similar to tetanus or other neurological conditions. Adult sheep may stagger or scour before dying, which can look similar to some common plant poisonings.
Vaccination can prevent the disease and given treatment is impractical, expensive and has a poor prognosis, vaccination is usually the best option. Vaccinations typically take 7–10 days to take effect and provide protection, however previous vaccination history has a significant impact on protection. If the animal has had two shots as a lamb, then one booster shot will be protective. If the animal hasn’t had the vaccination before, then it will need a booster shot 4-6 weeks after the first administration, and full protection may not occur until after the booster shot. When buying in stock, ask for prior vaccination history before purchase to allow assessment of possible vaccination requirements upon arrival. Vaccine protection periods vary depending on the type used, so please consult the manufacture or product label to ensure protection is still valid or to check the appropriate vaccination regime.
Toxic plants are another issue to consider given the wide variety of grass and herbage available to stock in some areas. While this is good news on most fronts, there has also been significant growth of potentially toxic species, such as pigweed and button grass. Pigweed, while nutritious as part of a mixed diet, can cause oxalate poisoning which causes muscle weakness, staggering or an inability to stand. Animals are often found lying on their chests or lie down when pushed. They are sensitive to the touch and often lie quietly without paddling or struggling. Treatment will vary depending on the situation, so please contact your local Department of Agriculture and Fisheries (DAF) inspector/veterinarian or private veterinarian for advice.
To prevent plant poisoning, management practices can be put in place to give the animals their best chance.
When moving stock through yards it is essential to check for dominant plant species in the yards. Experienced graziers recommend either removing them or trampling them quickly with a large mob. Before turning animals out of the yards onto lush herbage, allow them to fill up with safe roughage. This reduces the likelihood of animals going into the paddock and gorging themselves to a dangerous level. When letting animals out into the paddock, local graziers have found tailing animals out onto the safest areas of high grass content helps with reducing incidences of toxicity.
Many of these conditions can look similar. Please contact your local DAF officer or private veterinary surgery to discuss possible diagnostic investigation, treatment or advice —the cause might not be what you think.
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