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Animal Health Update May 2018

May 2018

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Local disease watch

Kate Sawford, Palerang district vet

Long-acting drenches – maybe not this season

A case of ‘mectin or ‘ML’ drench resistance was reported recently on the tablelands, with ML efficacy less than 50 percent. The property has a history of limited use of WormTests and drenched mainly according to the season. There was a bit of long-acting ML used on property, with no primer and exit drenches.

The assumption is that long-acting drenches were likely used at times when adult worm burden and larvae pasture contamination levels were low. In these instances long-acting drenches strongly select for drench-resistant worms. The reason is that while there is likely to only be a small number of resistant worms in the sheep and resistant larvae on pasture, they will contribute a relatively high proportion of eggs, leading to an increased proportion of resistant larvae on pasture.

Long-acting drenches are a great tool, particularly when pasture contamination with larvae is high, conditions are ripe for worm eggs to hatch, the class of sheep is particularly vulnerable to infestation, and there is a need to avoid handling sheep, like during lambing. It is worthwhile to ensure they remain effective on your property. Only use them when worm burden and/or pasture contamination with larvae is high – in other words, consider the grazing history of the paddock and make sure you’ve got a current WormTest. Always use a primer and an exit drench. Reserve them for use in vulnerable classes of stock during good pasture-growing seasons. For more information, consult Australia’s authority on worm control – www.paraboss.com.au.

NLIS compliance for cattle producers

A few producers have had questions about filling in their National Vendor Declaration (NVD) correctly. In particular, ‘what do I do when I’m selling homebred and non-homebred cattle in a single consignment?’

The answer is not obvious, though pretty simple – you must either tick NO at Q3 and answer the subsequent question on how long they have been owned for OR use two NVDs, one for the vendor-bred (i.e. homebred) cattle and another for the non-vendor bred (i.e. non-homebred) cattle. The reason is that the answers to the important food safety questions on the NVD will vary depending on whether the cattle were vendor-bred or non-vendor bred. Remember that any non-vendor bred cattle that lose their NLIS tag while on your property will need to have a new NLIS tag before they leave. This tag must be a post-breeder tag (in other words an orange tag that has your PIC printed on it) so that they are identified as not having been bred on your property. This distinction is very important for traceability, particularly if a residue is detected at an abattoir.

J-BAS 7 and 8 cut off approaching quickly

Now that all of the excitement has died down, many cattle producers may have forgotten about J-BAS.

As a reminder, beef herds with an on-farm biosecurity plan that incorporates the JD Biosecurity Checklist are a J-BAS 6. If your market demands cattle from a property that is J-BAS 7 or 8 you need to get testing done.

Producers that are now J-BAS 6 have the opportunity to get their herd to J-BAS 7 by getting a ‘Check test’ done with results available by 30 June 2018. Miss this deadline and your herd will likely require a series of ‘Sample Tests’ to lift it to J-BAS 7. ‘Sample Tests’ have the potential to be far more expensive than ‘Check Tests’ depending on the size of your herd so make sure you don’t miss out on this deadline if a higher J-BAS score is important for your enterprise. Contact your private veterinarian to arrange a test.

For information on Johne’s Disease in cattle refer to https://www.animalhealthaustralia.com.au/jd-cattle-tools/

Agisting cattle down the coast? Don’t forget about Theileria

A few cattle producers in the tablelands have been fortunate enough to secure agistment on the coast, reducing the grazing pressure on severely drought-affected properties. If that includes you, don’t forget about the risk posed by Theileria.

Theileria is recognized to be transmitted by bush ticks, but other vectors are likely to be involved. For those agisting cattle, the biggest risk of clinically significant infection is in heifers and cows in late pregnancy.

If you’re agisting cattle the first step is to consider the Theileria risk in the area. For up-to-date information contact your local district or private veterinarian.

If Theileria is known to occur where you’ve got agistment, the next step is to reduce the challenge to those cattle. To do so, treat cattle on arrival with a product containing deltamethrin and then treat them again 12 hours later with pour-on Cydectin®. Repeat treatment every 28 days with a product containing deltamethrin.

The other thing to consider is that you don’t want to bring Theileria back to your home property, either in the agisted cattle or the insects they carry. To play it safe, treat agisted cattle 24 hours before loading or when they come off the truck at home with a product containing deltamethrin, as well as all cattle already at home.

Buying in vetch hay? Don’t forget that some varieties can cause toxicity

Many producers in the region have had to search far and wide for suitable hay. Though not cultivated commonly in this region, some hay may contain vetch.

Vetch species are high-protein legumes that can add considerable nutritional value to hay. However, the woolly pod and pompany varieties of vetch have been associated with toxicity, particularly if they dominate the hay. The microhairs on them can cause an allergic-type reaction leading to skin lesions, diarrhea, and ill-thrift.

When buying hay containing vetch, as with all bought-in feed, it’s important to ask for a Commodity Vendor Declaration (CVD). Make sure to ask what variety of vetch is in the hay to ensure you won’t have an issue.

Bovine respiratory disease

Alex Stephens, Yass district vet

Bovine respiratory disease (BRD) is the most important cause of clinical disease and death in feedlot cattle in Australia.  It also occasionally causes disease and death in weaner and yearling cattle in the backgrounding and grazing industries. Producers ask how cases should be treated, how deaths can be prevented and whether they should have a vaccination program to prevent disease this year or in future years.  The answer lies in understanding the factors that contribute to respiratory disease outbreaks as management decisions can help to minimise disease occurrence and deaths.

The disease may initially present as sudden death because often there is rapid progression from mild clinical disease to death with initial signs going unnoticed. When the first case is confirmed with a post mortem, producers are then on high alert for its more subtle symptoms including depression, not eating, coughing, increased rate of breathing and nasal discharge.  Animals need to be checked daily and those affected should have their temperature taken. Any animals with a fever should be treated immediately with antibiotics.

BRD is caused by a combination of predisposing factors including stress, adverse environmental conditions, and circulating viruses and bacteria. Typically it is a disease of young cattle between weaning and two years of age. Stress plays a very large role in the disease. It weakens the immune system making cattle more susceptible to circulating viruses and bacteria. Cattle become stressed by weaning, trucking, saleyards, unfamiliar handling, dehydration, time without feed, confinement in close spaces, new social groups, surgery and injuries.

The viruses involved with BRD, with the exception of bovine herpesvirus 1 that causes Infectious Bovine Rhinotracheitis (IBR) and pestivirus (BVDV), are generally considered normal circulating viruses of cattle, which usually do not cause clinical disease. They include bovine respiratory syncytial virus, parainfluenza-3 virus and bovine coronavirus. Disease results especially when cattle become infected with two or more viruses simultaneously. The bacteria involved with BRD are also often considered normal inhabitants of the back of the throat. The list includes Mannheimia haemolytica, Pasteurella multoicida and Histophilus somni. These bacteria multiply in damaged tissue rapidly causing severe bacterial pneumonia. Histophilus somni can cause disease without prior viral damage.

This long list of potential disease-producing agents demonstrates the difficulty in vaccinating against BRD. You can vaccinate against some of the viruses and bacteria but not all. The other difficulty with vaccination is that disease most often occurs within the first fortnight or month of purchasing young stock, often prior to the development of protective immunity from any vaccines given on arrival. It is for this reason that feedlots will pay a premium for vaccinated stock. As the cost of vaccination is relatively high compared with occurrence of clinically detectable disease in most backgrounding situations, the decision to vaccinate is commonly driven by a premium paid by the feedlot with its benefits extending to the backgrounding operation.

The vaccines available are:

  • Bovilis MH ®, a vaccine against the bacteria Mannheimia haemolytica. Two shots are required 3-4 weeks apart.
  • Pestigard®, a vaccine against bovine viral diarrhoea virus (BVDV), or pestivirus. Two shots are required at least 4-6 weeks apart.
  • Rhinogard®, a live vaccine against bovine herpes virus 1.  A single dose intranasally is required.
  • Bovilis MH + IBR®, a vaccination against the bacteria Mannheimia haemolytica and bovine herpesvirus 1. Two shots are required 3-4 weeks apart.

Management decisions to reduce BRD involve identifying and minimising as many concurrent stressors as possible:

  • Preferably purchasing weaners that have been yard weaned. These stock have learnt to handle being held in close proximity to other stock, have experienced drinking from troughs and alternative feed sources. They also have more chance of previous exposure and immunity to some of the viruses.
  • Keep cattle in established social groups.
  • Provide stock with adequate nutrition.
  • Ensure parasite control is up to date.
  • Minimise dust in the yards and provide good quality water.
  • Purchase weaners directly from farm rather than through calf sales. In doing so the huge stress of a large calf sale is avoided and the likelihood of exposure of previously unexposed calves to pestivirus persistently infected (PI) calves is decreased.

Pestivirus plays an important part in BRD as it weakens the immune system, making PI and previously unexposed calves more vulnerable to other respiratory viruses. Try to avoid buying PI calves with your consignment by following these guidelines:

  1. Preferentially buy from a known vendor who you know has a Pestivirus management plan in place.
  2. Avoid buying weaners through saleyards.
  3. Avoid purchasing ‘the tailenders’. This practice is not a guarantee, but poorer doing calves are more likely to be PIs compared to healthier calves from the same mob.
  4. Collect tail hairs from all introduced cattle to identify any PIs. This process can be done yourselves, without a vet, using the kits supplied by the NSW EMAI laboratory or your district veterinarian. Immediately cull any PI calves.

Condition scoring cattle & sheep

Helen Schaefer, Far south coast district vet

What?

  • A condition score (CS) is an assessment of an animal’s condition, or “nutritional wellbeing”, based on estimated fat reserves on certain body parts.  Condition scoring is more useful than live weight in that it is independent of such factors as frame size, pregnancy, wool growth.
  • Condition is scored on a scale of 1 to 5 for beef cattle and sheep (refer to tables 1 & 2):
  • 1 = extremely poor condition/underweight
  • 5 = extremely over conditioned/overweight
  • Managing CSs helps to manage feed requirements.
  • The CS of your cow or ewe is a key indicator of her reproductive performance. The ideal CS to optimize production and profitability is 2.5-3.5 for breeding cattle and sheep.
  • Maintaining an appropriate CS of bulls/rams is critical for their fertility. Overfatness (CS 4-5) decreases fertility as excessive fat interferes with heat exchange in the testicles. Poor condition (CS 1-2) in the months prior to mating decreases fertility due to poor quality semen.
  • Monitoring the CS of your herd/flock helps inform management decisions (e.g., is the CS of your ewes/cows 3, and falling? Consider early weaning/supplementary feeding/herd or flock segregation to prevent CS falling below 2.5).

Why?

  • Managing CSs helps to manage feed requirements.
  • The CS of your cow or ewe is a key indicator of her reproductive performance. The ideal CS to optimize production and profitability is 2.5-3.5 for breeding cattle and sheep.
  • Maintaining an appropriate CS of bulls/rams is critical for their fertility. Overfatness (CS 4-5) decreases fertility as excessive fat interferes with heat exchange in the testicles. Poor condition (CS 1-2) in the months prior to mating decreases fertility due to poor quality semen.
  • Monitoring the CS of your herd/flock helps inform management decisions (e.g., is the CS of your ewes/cows 3, and falling? Consider early weaning/supplementary feeding/herd or flock segregation to prevent CS falling below 2.5).

How?

  • CS depends on how easy it is to feel the short ribs, behind the ribcage and next to the backbone (refer to table 3). In cattle it is also useful to assess the fat reserves around the top of the tail.

Scoring 1

Important points to remember

  • You may not notice cattle losing 2kg/day but over a month this equates to losing one CS i.e. 50-80kg.
  • It is far more economical to maintain appropriate CSs in your stock than to let CSs fall and then build them back up again.
  • It is a producer’s responsibility to ensure that the CSs of their livestock are maintained above minimum guidelines to meet welfare and health standards, even in dry conditions.
Table 1: Cattle Body Condition Scoring (www.daf.qld.gov.au)

Table 2: Sheep Body Condition Scoring (www.daf.qld.gov.au)

Table 3: How to Condition Score (http://www.lifetimewool.com.au)

Is it fit to load?

Fiona Kelk, Yass district vet

This article is a gentle reminder for livestock owners and agents of their responsibilities when making the decision to send stock to market or abattoirs.

The saleyard is a place to buy and sell fit and healthy stock. There are many different conditions that may affect livestock, causing them suffering and compromising their ability to move freely and cope with the rigors of transport.

Examples where livestock should not be selected for transport to saleyards or abattoirs are:

  • weak and emaciated stock (starved, in very poor condition)
  • lameness – transported stock should be able to walk normally and bear weight evenly on all four legs
  • deformed stock
  • stock showing any visible disease, injury or tumours
  • stock unable to keep up with the mob both at loading and unloading
  • immature or weak stock - with particular reference to bobby calves
  • stock in late pregnancy

If the animal is unfit to transport – do not load it. Individual animals that are unfit for travel should be managed appropriately, treated as required or destroyed humanely on-farm.

Some saleyards within the South East charge for carcass disposal. Fees for stock that are not fit to load are doubled.

The fit to load guidelines from the MLA are an excellent resource.

District vet for Palerang departing

Kate Sawford district vet Palerang

I am off to New Zealand to assist MPI with the Mycoplasma bovis emergency response. My last day in the Braidwood office will be 8 June 2018.

I will be replaced by Dr. Louise Baskind at the beginning of July. Dr. Baskind grew up on a mixed enterprise in South Africa that included a 200-head milking cow herd. She graduated from the University of Sydney in 2009 with a Bachelor’s degree in Veterinary Science. Since that time she has worked in private clinical veterinary practice in Alice Springs, the UK, Bungendore and Braidwood. She very much looks forward to joining the South East LLS vet team.

Thank you to all of the landholders, veterinarians, agents, and rural store staff I have worked with over the past three years. I wish you all best in the future.