Smoko session 2

The season has turned around across most of the central west, with green feed, mosquitoes and flies abundant!

Nuisance flies and mosquitoes

The insects are driving animals (and humans) mad, and I’ve been asked a lot lately, is it worth treating stock for nuisance flies and mosquitoes?  Studies have shown that insects do cause a production loss to some degree. One study from the UK in cattle showed that fly worry caused 0.3kg of growth rate loss per day, and milk loss of 0.5L/day.  There are products on the market that are registered for use in cattle for nuisance insects, however you will need to weigh up the cost and effort of yarding the animals for treatment, and the relatively short protection period the products offer.

If you decide you’d like to treat your stock for flies, please try to use an insecticide that is just for external parasites, rather than a dual product. If we start to use our precious drenches as fly control products every few weeks, we will quickly contribute to drench resistance developing for internal parasites.

There are also other ways to control flies, which are probably more relevant around intensive livestock areas such as feedlots, but still a good idea. There is some really good information on this topic from the Department of Primary Industries here and Meat and Livestock Australia here.

Mycoplams ovis (M.ovis) in sheep

Mosquitoes are also really good at spreading M.ovis in sheep flocks. This blood parasite is also known as E.ovis or weaner anaemia.  The organism enters the bloodstream, 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. Weaners are most commonly affected, and typically it is seen in the six weeks after management procedures such as shearing, marking or mulesing.  While we have not seen any cases of weaner anaemia yet, we may come winter time when lambs get bigger and these sorts of management procedures are undertaken.

Clinical signs

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 have mortalities occur.


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.

Barbers Pole Worm

While we haven’t seen any cases yet, we are also on the lookout for Barbers Pole Worm, considering the ideal conditions, particularly in the north of the region.  Did I mention that Barbers Pole Worm has very similar signs to weaner anaemia? If in doubt, don’t guess, call your District Vet for advice and to get a diagnosis.

While the drought probably did a great job of killing any Barber’s Pole Worm larvae on the ground, there will be small numbers of adult Barbers Pole Worm living in the fourth stomach of some of the sheep in your mob. Each of these adult worms can lay 10,000 eggs per day! They are built to withstand a drought and multiply rapidly when conditions are ideal.

It takes about 21 days for the lifecycle of the worm, so about 3-6 weeks after the rain event is when we expect to see clinical signs in sheep.  But please don’t reach straight for the drench gun - do a wormtest first – you can pick up a wormtest kit from the LLS office, collect some sheep poo and send it to the lab. In a few days, you’ll know if your sheep are wormy enough to need a drench.
In 2012, the District Vets did a series of drench trials on farms in the central west area to look at our levels of drench resistance.

The results were surprising and they are all outlined here.

Button Grass feed test

We recently did a feedtest on some of the button grass that is growing around Coonamble. It was 84.3% moisture, had an energy content of 8.7MJ ME/kgDM, a Neutral Detergent Fibre (NDF) of 62 and a Crude Protein of 19.3%.  
The high moisture content, high fibre and the low-ish energy content will mean that heavily pregnant twin bearing ewes will struggle to eat enough to maintain themselves, and this is worth considering as lambing rolls around. These girls will need supplementation with cereal grains to avoid pregnancy toxaemia.

The other thing to note is that the protein is pretty high relative to energy (remember from the Managing Drought Handbook, page 45, we want protein to be about two higher than energy, so for an 8.7MJ grass, we’d like the protein to be around 10.7% for a perfectly balanced rumen).  This energy to protein balance is not high enough to be causing clinical problems – what is probably happening at the ruminal level is that the extra protein is being broken down and the carbon skeleton is being used as an energy source, and the N part of the molecule is being processed by the liver into urea, for excretion by the kidney in urine.

The most important thing to recognise and understand is that we shouldn’t be supplementing stock grazing this type of pasture with any form of protein – they are getting more than enough. So remove any licks that contain urea, and if you’re supplementary feeding make sure it is energy based (eg cereal grains) rather than pulses or protein meals.

In other news

There are new versions of LPA NVDs for all species available from 1 July 2020. Changes will include the removal of the agent’s declaration and the inclusion of a destination PIC.  For six months, from 1 July 2020 to 31 December 2020, both updated and current NVD versions will be accepted.  From January 2021, everyone who uses a hard copy NVD book will need to ensure they have the correct most up to date version (0720).

Until next month, enjoy the green grass and the lovely weather!

Jillian Kelly

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