1999 December

Johnes Disease - Don't Ignore It!

We are all involved in an industry that is undergoing continual change. When I commenced veterinary practice more than 20 years ago I had no idea that we would be routinely visiting herds of over 400 cows. When cell counts were first available, few of us realised how large a role they would play in everyday management of the herd.

Attitudes of the farming community to Johnes Disease have undergone a significant change over the last few years and without doubt will undergo significant change in the very near future.

It is now rare to see any group of cattle sold without a reference to the JD status of the herd.

Dairy manufacturing companies are beginning to receive orders for product that is sourced from animals that are free of diseases such as EBL and JD.

The majority of people purchasing cattle are now asking for an indication of the JD status of the cattle they intend to buy. Anyone who is selling cattle needs to be able to provide information indicating whether or not their herd is likely to be infected.

At the moment there are three broad groups of herds.

  1. JD Market Assurance Herds
    These herds have undergone a voluntary assessment that includes testing of the whole herd. They conduct strict control measures and have a nil or very low risk that any cattle are infected. There are two dairy herds in Western Victoria in this category.

     

  2. Known Infected Herds
    1. Control Program Herds:
      These herds conduct control measures of varying levels on farm but do not test.
    2. Test and Control Herds:
      These herds have audited control programs and do annual whole herd tests. A number of these herds have a very low prevalence of disease and groups of animals within the herd are of very low risk of being infected.

     

  3. Non-Assessed or "No Known JD Herds"
    This includes the majority of herds. Some of these herds are JD free. It is also certain that a lot of these herds are infected, mostly without the owners knowledge. We continue to diagnose JD in these "No Known Johnes" herds.
JD is a slowly developing disease and can be present for a number of years before it makes itself apparent. As the test and control program progresses we are finding a significant number of infected cows in these herds that have been introduced from "No Known JD Herds". The good news is that JD can be controlled.

Diligent calf rearing practices alone will control JD in the majority of herds. Next year an official program, probably called "The Calf Accreditation Program" or CAP will be introduced. This program will be voluntary and producer funded and will be available for very low prevalence of JD, or non assessed herds.

The program consists of:

  • The herd owner/manager establishes a set procedure for rearing of replacement calves. This procedure will implement the known disease control measures for JD.
  • The program will be documented and monitored to ensure no "short cuts" are taken.
  • External auditing will be undertaken to provide confidence for intending purchases.
If JD is present at a low level in these herds, the CAP will minimise spread to other cattle.

If JD is inadvertently introduced into a herd on the program, spread to other cattle will be minimised.

What if your herd is already infected with JD?

A diligent calf rearing program is essential to reduce the continued infection of young calves. We strongly advise anyone who has JD in their herd to reassess their calf rearing practices and to implement an effective disease control program. This is particularly important if you intend to sell cattle for breeding purposes, eg at a dairy sale, within the next few years.

Summary

  1. JD can be controlled.
  2. The ability to sell cattle for their true value in the future will rely on purchasers being confident of the JD status of the herd and property.
  3. This can only occur if active steps are taken to control the disease; document the methods used and monitor their effectiveness.
  4. Anyone who wishes to set up and effective program can contact one of our JD accredited vets.

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Deregulation - Does the Victorian Dairy Industry Need It?

Farmers have been given the opportunity to vote on whether they wish to see a planned dismantling of the regulations for sale of liquid milk throughout Australia or conversely to vote to maintain these regulations indefinitely.

In recent weeks there has been much discussion by industry representatives that has shed light on the issues relating to deregulation. Deregulation is about the share of liquid milk which is biased heavily away from Victorian and Tasmanian dairy farmers. The dismantling of the domestic market support scheme for manufacturing milk is predetermined and is not a consideration in the deregulation vote.

The federal government's proposed deregulation package is dependent on the Victorian Government passing legislation to dismantle the current regulation controlling liquid milk sales. If such legislation is not passed by early next year, the deregulation package will not be available.

There is almost a guarantee that any regulation put in place to control the sale by farmers, processors or retailers of liquid milk, will be ignored. It is unlikely that such regulations will convince the federal government that they are in the public interest. This is apart from jeopardising what would, for the first time, be free trading, in a protected dairy commodity market in Australia.

To have a better understanding of the need to deregulate the dairy industry, it is worthwhile forecasting the likely future structure of the Australian Dairy Industry. In the next 20 years, farm size will continue to increase. It is most unlikely that milk returns on the export market will rise since a sustained price rise will entice entry of other dairy producing countries to capitalise on the profits. The EU and USA have huge potential to expand production in this event.

Farmers will be faced with continuing deterioration in terms of trade. Those who have embraced new technologies and efficiencies will have a competitive advantage. Their business management expertise will also be high.

The processing industry will also have undergone significant change. The traditional cooperatives will have been forced to float their shares to better respond to market forces. Mergers will be likely and small companies will need to secure niche markets to survive. The sale of large quantities of semiprocessed unbranded products typical of the bulk of todays exports will not attract large profits. Multinational companies, which already have a strong presence in Australia, will utilise the low milk prices in Australia to process and export branded products overseas.

Domestic demand for dairy products will not change significantly however due to a continuing increase in total production; the percentage of milk consumed in Australia will decrease. Any regulated domestic market would become less significant. It is possible that a small proportion of entrepreneurial dairy farmers will secure a portion of the liquid milk markets of major population centres at prices which reflect the world commodity price plus a margin to cover the extra cost of non seasonal production. There are moves already between processors and farmers for this to commence after deregulation. Existing processing companies will have to compete with these farmers for this market.

There is also a strong possibility that UHT milk sales will grow at the expense of the short shelf life pasteurised milk. In many countries in Europe, UHT is the only liquid milk available. Modification to treatment which reduces the taste differences, more friendly packaging, competitive pricing and better positioning in supermarkets, will assist this change.

For Australian farmers to be able to stay competitive, it is imperative that they produce milk at a price which allows them a margin for profit. We have the advantage of a very low cost industry with a sound processing system to support it. If the government were prepared to subsidise the value of export milk by imposing a regulated price on liquid milk above that which is reflected in the world market, it would send incorrect price signals back to farmers. This has been demonstrated by the farmers in the north and the west where many have dairy farms operating at much higher costs and lower efficiencies. Although it could be argued that regions in Victoria are more suited to dairying, most of the higher costs on these farms are related to lack of uptake of modern farming technologies. The high milk prices received by these farmers has allowed them to farm with higher costs. To maintain their status quo by supporting the current regulations would perpetuate the inefficient farms. The farms operating efficiently in these regions are achieving high returns subsidised by Victorian farmers who do not have access to their markets.

The future of the Australian dairy industry is bright for those with enthusiasm and dedication to take on the challenges faced not only by dairy farmers but all Australian agriculture. There is no option for government and farmers other than to support a deregulated industry.

It is perhaps incorrect to suggest that the proposed package will remove regulation from the dairy industry. It will, in fact, impose a further eight years of regulation.

 


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Human Behaviour & Milk Production

Do you want to get extra milk for no extra cost?

A recent DRDC funded study performed by Professor Paul Hemsworth of the Animal Welfare Centre has shown that milk production can be increased significantly when stock people undergo extra training in stock handling. The study was run in 94 dairy herds in northern Victoria during 1998/1999 with milk production (volume, fat and protein) and BMCC being used to monitor the effects of the program. Half of the herds received training in animal behaviour (the treatment group) with the other herds being monitored only (the control group).

A process called cognitive-behavioural intervention was used on the Control group. Stock people were intensively trained to identify what aspects of human behaviour influenced cow behaviour. The underlying belief in this system is that human attitudes to animals influences the way that humans behave towards animals. This in turn has a direct influence on the way the animals behave towards humans. All of this has an effect on production. Cognitive-behavioural intervention has been used in the pig and poultry industries resulting in gains in production and reductions in health problems. Improvements in reproductive performance have also been shown in piggeries that have adopted this technique.

The farms that were trained in cognitive-behavioural intervention produced an average 1 litre/cow/day more than the Control herds. Fat and protein production was also increased. The BMCC of the treatment group was lower than the control group, however this result was not significant. The majority of the stock people trained believed that their attitudes towards their stock had improved and that the stock were easier to handle as a result of their training. A majority of the females in the treatment group also believed that they were less likely to lose their temper with the cows. This was not the case with the male participants.

It is clear that improvements in human behaviour and attitudes towards cows and a reduction in the fear responses by cows is associated with improvements in milk yield. Continual, even mildly aversive behaviour towards cows teaches cows to be fearful. Improvements in the comfort of cows and people in the dairy environment have other spin off effects including increased job satisfaction, improved labour productivity, improvements in animal health and welfare.

 


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Heat Stress In Dairy Cattle

Having experienced our first few days of summer, now may be a good time for you to consider the effect that heat stress is having on your cows and whether it is feasible for you to take preventative measures to minimise its consequences.

Cows are adversely affected any time the ambient temperature is outside their thermoneutral zone, which ranges from 16 to 25ºC. The effect of humidity is just as important as that of temperature. Recent work has combined the effects of both temperature and humidity into a single index, called the temperature-humidity index or THI. The effect of various THI values are explained in the following table:

 

There is a table available here which gives the THI for a given temperature and relative humidity. As an example, at a temperature of 32ºC and relative humidity of 70% (similar conditions to the hot days we have had already had this season) the THI is 85. So these days have had a significant effect on your cows' production.

The most significant effects of heat stress on cattle are illustrated in the above diagram. From a clinical perspective, the signs of hyperthermia in order of increasing severity are as follows:

  • Seek shade, refuse to lie down, increased water intake
  • decreased food intake, reduced or absent rumination (chewing of cud)
  • Crowding around water sources, increased respiratory rate
  • Body splashing
  • Open mouthed and laboured breathing
  • Excessive salivation
  • Incoordination, inability to move
  • Collapse, convulsions, coma
  • Organ failure and death
Limiting the effects of heat stress

In this region it is not economically feasible to spend large sums of money to minimise the effects of HS, given the number of days where the effect is severe. But with a limited budget and by adjusting some simple management routines, the economic losses associated with HS can be reduced.

    Options to consider include:
  1. Adequate shade - in the form of trees, shade cloth, canvas coverings or shed cover (in order of increasing cost and effectiveness). If trees are chosen, consideration must be given to the orientation of the plantation, and the species of tree and the shade it provides. Shade cloth and canvases are often appropriate for dairy yards during the time of maximum stress (corresponding to the PM milking). Shed cover is far superior if roof height, ventilation, orientation to the sun, and insulation are all appropriate, but costs considerably more. Some farmers in northern Victoria have build sheds which can be also used as both shade and as cover for a calving pad in winter - which helps justify the expense.

     

  2. Fans - large industrial fans are used further north but are unlikely to be feasible here.

     

  3. Sprinklers - are a very effective means of lowering cow temperature if used correctly. They must wet the skin of the cow to be effective, rather than just applying a mist to the cows coat. The latter will occur if droplet size is too small. Mists will lower air temperature near by, but will actually further retard heat dissipation from the cow by acting as a form of insulation. Continuous or 2 minute on / 5 minute off cycles are preferred, with the latter saving water and allowing warm air to escape from beneath the herd between spraying times. The duration required is usually a minimum of 30 to 60 minutes. There is little expense involved in sprinkler systems, they are very effective and there is no reason why they cannot be installed even temporarily on the top rail of a dairy yard.

     

  4. Cow management - having a shade paddock close to the dairy is the ideal situation so movement and hence further stress during the worst time of day can be minimised. When yarding, cows should not be rushed and water points should be numerous and sufficiently large so enough cows can get access at the same time. For larger herds it may be wise to yard and milk the herd in 2 or 3 groups so cows can remain under shade for longer rather than waiting unnecessarily on yard concrete.

     

  5. Nutrition - the ideal situation is to feed lower quantities or higher quality feed. On hot days cows will eat concentrates in preference to other sources of feed, so to avoid acidosis you must ensure they still get adequate roughage. You can feed slightly more concentrate but avoid large abrupt changes. There is evidence emerging which also supports feeding your cows the majority of their daily allocation (of all feeds) during the cool of night. This makes sense given few of you cows will graze at all as the temperature approaches the mid thirties. So allotting more pasture/crop for the evening grazing may be of benefit.

     

  6. Water - Obviously, your trough water supply should be capable of supplying adequate volumes (up to 120L/cow/day) at sufficient volume flow rate.

     

  7. Breed selection - White cows do cope better during the heat of day, but are more prone to developing various types of skin cancer. Black cows do feel the effects of HS earlier but radiate heat better at night and hence recover more rapidly.

     

Treatment of individual cows

If an individual cow shows signs of severe heat stress as described earlier, then immediate action should involve hosing the cow down with large volumes of cold water, minimising stress/physical exertion, placing her in the shade and provide air movement. Some cows may also benefit from large volumes of intravenous fluids, rectal enemas and stomach tubing with water.

So next time you begin feeling the effects of a hot day, take time to consider your cows level of comfort and the money you may be loosing. Simple strategies such as sprinklers, changing paddock selection and delaying the afternoon milking for even a couple of hours may make a huge difference.

The Queensland DPI has a publication and CD-ROM package titled Managing hot cows in Australia, which is an excellent source of information for those interested.

 


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