Smoko session 5

Changes to the vet team

You might have heard, there’s been a few changes in the vet team. Our wonderful DV at Nyngan, Erica Kennedy has left us, but never fear she hasn’t gone far! She and her partner Robbo have bought the Western Rivers Vet Clinic at Warren and Nyngan so they’ll be sticking around long-term which is great news for our area.  This means that we have a vacancy at our Nyngan office, so if you’re a vet looking for a move, or you know of a vet who might like a job with us, please get in touch.  In the short term while we have that vacancy, if you are in the Nyngan area and need a vet, please call one of our other DVs – myself if you’re north of Nyngan, Georgia (Condo DV) if you’re south or west of Nyngan, and Sarah (Dubbo DV) if you’re east of Nyngan.

We’ve also had Kate Atkinson start in the DV Coonabarabran role in a part-time capacity.  Kate is local to Coolah and previously worked in private practice there, so give her a call if you need a vet in the Coonabarabran area.

All of the District Vet contact details are available here.

Weaner anaemia still lurking

We are still seeing cases of M.ovis or weaner anaemia in sheep, right across central west NSW. After a few years’ hiatus where we didn’t see this problem, presumably due to drought, we are now seeing it cause disease in not just weaner sheep, but even hoggets.

Due to the onset of the wintery weather, we are now more often seeing it linked to management procedures that involve blood transfer between sheep on equipment such as mulesing, ear tagging or shearing, but earlier on we believe it was being spread by the high mosquito burden.

M.ovis is a blood parasite, which enters the bloodstream and attaches to a red blood cell which alerts the body that the red blood cell is now damaged or defective, causing it to be chewed up by the immune system. Typically it is seen in the six weeks after management procedures and usually starts appearing around the district in May, continuing through winter.

The clinical signs of M.ovis are anaemia (pale gums), weakness and a preference to lay down rather than walked when mustered.  In fact, it looks a lot like Barbers Pole Worm! However, instead of reaching for the drench gun, reach for the phone to call your vet to call for advice and a proper diagnosis first.  If you yard sheep that have M.ovis to try to drench them, you will often cause deaths.

There is no treatment for M.ovis – the mob will need to be left alone to recover in their own time, which they should do if kept on a good plane of nutrition, free of other diseases and stress free.

Drench resistance studies planned for Spring

The District Vet team is busy preparing to conduct some drench resistance studies on farms across the region in spring.  This is important information that can be really useful when choosing a drench on your farm.  We last did drench trials north of Dubbo around Nyngan and Coonamble in 2013, and the results were astonishing with plenty of resistance found, and stark differences between individual farms in the same locality.

A drench resistance study is also called a Faecal Egg Count Reduction Trial. The way it works is that we need access to around 100 undrenched weaner sheep. It is really important that they are under 10 months of age and that they definitely undrenched and that they have a worm burden of at least 200 eggs per gram.  We then categorise them into groups of 10 animals (identified by different coloured ear tags) weigh each animal and give each group a different drench.  We then run them all together for 14 days, and then revisit and take faeces from each individual animal for a faecal egg count.  If the drench has done its job with 100% efficacy, the faecal egg count should be 0.  If there is drench resistance to that particular compound, eggs will remain in the faeces.

If you’re interested in learning about drench resistance on your farm, get in touch with your local District Vet and let them know to keep you in mind for spring. It’s really important that if you’re interested in being involved in a trial that you don’t drench your weaners before the trial.

Too much of a good thing - Photosensitisation

I’ve been receiving calls about photosensitisation in stock (mainly sheep, but cattle can also be affected) grazing cereal crops or brassica.  It’s also been a cause of abattoir condemnations, reported as “jaundice” on feedback sheets.

This is most likely secondary photosensitisation due to huge amounts of chlorophyll, or the “green” substance in these plants, although there is some suspicion that there is an unknown compound present in brassicas that causes primary photosensitisation.

The green pigment in the plants is metabolised to a light sensitive compound that overwhelms the liver and builds up in the blood stream.  If a sufficient amount of this compound is present at the surface of exposed skin, sunlight will cause skin damage.

Affected animals lose hair and look scabby and swollen on hairless areas. This can be around their face, ears and udders.

Treatment involves removing animals from the feed source and getting them to eat something that is not as green.  So putting them on a native pasture paddock is a good idea, or putting out hay. Individuals who are affected can be treated with anti-inflammatory medications from a private veterinarian, and should be moved to a shady paddock or shed until recovered.

More information about photosensitisation can be found here  https://www.dpi.nsw.gov.au/__data/assets/pdf_file/0016/111157/photosensitisation-in-stock.pdf

Take care when grain supplementing cattle on crop

I thought that the end of the drought meant that I would stop seeing dead cattle from grain poisoning, but I’ve seen a few lately!

Farmers are putting out cereal grain feeders to stock on crops, either to improve feed conversion efficiency, or to make the crop last longer. This is completely reasonable, however some care needs to be taken.

Some feedtests done on cereal crops lately showed the energy to be 11-13MJ ME/kg DM and the protein to be anywhere from 14-26%. While they are full of water in most cases, the dry matter component is really readily fermentable, and packed with energy and protein.  Put simply, these crops are “rocket fuel”.

Once you put this “rocket fuel” into the rumen, the rumen microbes go to town on it and metabolise it really quickly into Volatile Fatty Acids (VFAs).  This is awesome, as it ultimately leads to weight gains. However, as their name suggests, these VFAs are “acids”, so if you get enough of them produced all at once you get a slight drop in the rumen pH.  It’s usually not enough to notice any changes in your animals, and it’s not enough on its own to cause death like all of the drought feeding disasters involving cereal grains did.

However, once you then put a self-feeder full of cereal grain in the paddock it doesn’t take much more carbohydrate or starch from the grain to make the rumen pH plummet and death results from lactic acidosis.  I find that the deaths normally occur in paddocks where there are a large number of animals and few self-feeders. This causes a lot of competition at the feeder and some animals will over eat.

So if you’ve got cattle on crop, do a feedtest on the crop and work out what the energy and protein content is, you may not need to supplement with grain!  If you are going to put out grain feeders, put out plenty of them so that the intake of the animals can be as controlled and as low as possible. We don’t want animals sitting at a grain feeder near a watering point and overeating.

And of course, don’t forget to buffer your rumen with an appropriate lick and give them some minerals as well to balance the deficiencies in the crop.  Our livestock officer Sue Street wrote an excellent article on introducing stock to crops which is available here

Until next month, enjoy the green feed, and if you have any animal health enquiries give your local District Vet a call.

Jillian

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