1999 SeptemberBloat Control Update
Clover growth on most farms has been better this year than for many years. It would be wise to consider the options for bloat control prior to problems occurring, as there is always a panic to institute a control program in a hurry when the first sign of clinical bloat occurs.
Some important considerations are:
What is the current nutritional status of the herd?
Herds feeding a large amount of grain (6 kg or more) will have a lower proportion of
the diet as pasture. This has some dilution effect as well as making the cows less
hungry as they leave the dairy. They are less likely to eat as aggressively or as much
pasture. Bloat will be less likely and less severe.
How well are cows eating paddocks out?
In situations where grazing management is lax, cows will be more able to selectively
graze. They will eat more clover from between clumps and less higher fibre pasture.
Apart from other pasture management problems bloat will be more prevalent in these
cases.
What are the effects of subclinical bloat?
If clinical bloat is occurring in the herd subclinical bloat will be causing production
losses. It is estimated that subclinical bloat will cause as much as a 15% loss in
production.
Modes of treatment
Numerous products have been around for a long time. These have certain merits but most have their drawbacks. One newer group of treatments is the ethoxylated alcohol products. Two brands are Bloatmaster and Bloat Enz. These are low volume treatments with more extended protection periods than the more traditional oils. They can be administered on top of bale feed relatively easily at only a slightly higher cost.
Administered this way they provide protection during the main danger periods and ensure every cow is treated. They need to be used at both milkings to ensure 24 hour protection.
Other products available are bloat capsules, flank applied oils, roller drums and licks. All have varying levels of protection depending on route of administration. They may be more applicable in low risk situations.
More information on products available and prices can be obtained from resellers. It may be wise to source an appropriate treatment sooner rather than later to prevent any problems related to heavy demand over the next couple of months.
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Nitrate and Nitrite Poisoning
Bloat Control Update
Clover growth on most farms has been better this year than for many years. It would be wise to consider the options for bloat control prior to problems occurring, as there is always a panic to institute a control program in a hurry when the first sign of clinical bloat occurs.Some important considerations are:
What is the current nutritional status of the herd?
Herds feeding a large amount of grain (6 kg or more) will have a lower proportion of
the diet as pasture. This has some dilution effect as well as making the cows less
hungry as they leave the dairy. They are less likely to eat as aggressively or as much
pasture. Bloat will be less likely and less severe.
How well are cows eating paddocks out?
In situations where grazing management is lax, cows will be more able to selectively
graze. They will eat more clover from between clumps and less higher fibre pasture.
Apart from other pasture management problems bloat will be more prevalent in these
cases.
What are the effects of subclinical bloat?
If clinical bloat is occurring in the herd subclinical bloat will be causing production
losses. It is estimated that subclinical bloat will cause as much as a 15% loss in
production.
Modes of treatment
Numerous products have been around for a long time. These have certain merits but most have their drawbacks. One newer group of treatments is the ethoxylated alcohol products. Two brands are Bloatmaster and Bloat Enz. These are low volume treatments with more extended protection periods than the more traditional oils. They can be administered on top of bale feed relatively easily at only a slightly higher cost.
Administered this way they provide protection during the main danger periods and ensure every cow is treated. They need to be used at both milkings to ensure 24 hour protection.
Other products available are bloat capsules, flank applied oils, roller drums and licks. All have varying levels of protection depending on route of administration. They may be more applicable in low risk situations.
More information on products available and prices can be obtained from resellers. It may be wise to source an appropriate treatment sooner rather than later to prevent any problems related to heavy demand over the next couple of months.
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Nitrate and Nitrite Poisoning
It has become increasingly frequent to hear of animals suffering from this syndrome in recent years. Feeding of crops and nitrogen applications on pastures have been incriminated as causes of such cases
It is important to put into perspective the importance of this disease in Western Victoria. Nitrates when ingested in reasonable quantities cause inflammation of the gastrointestinal tract and subsequent diarrhoea. Often this is associated with a milk fever like syndrome since absorption of calcium is impaired by damage to the bowel lining. This is not fatal and cows will recover uneventfully after treatment with calcium.
The disease of more concern however, is nitrite poisoning. This occurs when the condition in the plant prior to ingestion or in the rumen is conducive to conversion of nitrates to nitrites. This is a much more potent poison, which ties up haemoglobin in the blood causing respiratory distress. Severe cases can die within one hour of ingestion of toxic feeds and can involve a significant percentage of the herd. This is a rare disease in this district and very occasionally is the cause of more than one or two deaths in a herd.
Plants That Potentially Cause Nitrite Poisoning
The most likely plants in this district to cause nitrite poisoning are young oats, rape and turnip crops, capeweed, thistles and annual rye grasses.
It is much more likely that nitrate levels will build up in plants:
- After spraying with herbicides (wilted plants).
- In late autumn after a long dry spell.
- In fast growing nitrogen boosted brassicas or rye grass crops.
- Following frosts or cloudy cold weather.
Treatment of nitrate poisoning usually only requires removal from likely sources of nitrates and calcium to reverse the metabolic disorder.
Nitrite poisoning can be deadly. To reverse the effects of nitrites on blood, methylene blue is injected intravenously along with calcium. Cows are suffering respiratory distress so extra stress needs to be avoided to minimise losses,
Avoiding Nitrate and Nitrite Poisoning
Just as it would be unreasonable to suggest that clovers be avoided because of fear of bloat, it would be unreasonable to avoid feeding brassica and nitrogen boosted rye grass crops because of the fear of nitrite poisoning. It is a rare event given the considerable amount of nitrogen use in the district. In our experience the most likely causes of nitrite poisoning will be rape crops, especially regrowth in late autumn and capeweed. After the initial growth following the autumn break, there is less likelihood of uptake of nitrates and nitrates by plants. Avoid feeding hungry animals with these crops by supplying hay or silage before grazing.
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Feed Costs
The next three months are potentially the most crucial months of the year in determining how much value we will get from the investment we make in feed. An excellent spring provides ad lib pastures, silage and hay followed by quality regrowth. Crops are can be readily established and production will decline slowly. A bumper grain harvest brings more grain onto the market at cheaper prices and a good hay crop has a similar impact on hay prices.
Fertiliser, cropping, harvesting, grain and hay represent a significant part of dairy farm expenses. It is worth dissecting these costs and examining the expense and value of each feed
Nitrogen Boosted Pasture:
In spring, responses to nitrogen can exceed 20:1 under favourable conditions. At a more conservative response of 15:1, this provides 15 tonnes of extra feed for $750 (1 tonne N = 2.2 tonne of urea at $340 spread) which is $50 per tonne
Silage:
The out of pocket expenses for silage making on farm will vary from $90 per tonne where a contractor is employed to mow, rake, bale and wrap to $20 per tonne when a contractor only needs to cart silage to a pit. Because most farmers will contribute some time and machinery to their silage making, the out of pocket cost will usually be less than $50 per tonne.
Hay:
The cost of hay making once again varies from less than $10 to $50 per tonne depending on how much contracting is involved.
Crops:
The cost of lime, fertiliser, contractors and seed for re establishment will vary from $300-$700 per hectare. For farms with their own cultivation equipment and minimal requirements for lime and capital fertiliser, the cost will be closer to $300.
When poor quality paddocks are cropped, there will be a loss of 2-3 tonnes of feed foregone whilst crops are grown. A yield of 5-6 tonnes per hectare of crop will produce a net surplus of feed of 3 tonnes per hectare. This will cost $100-$200 per tonne. An excellent crop (12 tonnes) and low establishment cost could drop this cost to $30 per tonne.
Purchased Feeds:
Wheat $150/tonne whole $165/tonne dry matter
Clover Hay $140/tonne wet matter $155/tonne dry matter
Pasture Hay $100/tonne wet matter $110/tonne dry matter
| Feed | $/tonne DM | MJ/Kg | % CP | Cents/MJ |
|---|---|---|---|---|
| Nitrogen Boosted Pasture | 50 | 12 | 20 | 0.4 |
| Silage | 50 | 10.5 | 16 | 0.5 |
| Hay | 30 | 9 | 12 | 0.3 |
| Crop | 100 | 12 | 14 | 0.8 |
| Wheat | 165 | 13 | 13 | 1.3 |
| Clover Hay | 155 | 10.5 | 16 | 1.5 |
| Pasture Hay | 110 | 9 | 12 | 1.2 |
There are a number of factors to consider when choosing where to spend on feed. If nitrogen is used to grow extra silage the cost is $100 per tonne or 0.9cents per megajoule. If cropping is a well managed procedure on the farm with a proven track record and is part of a pasture improvement program it can be very useful. The benefit of spring pasture quality management following an intensive silage and hay program will lengthen the season and keep up milk production into summer. The availability of crops as a highly digestible feed in summer is hard to beat with silage and grain. The ease of management when relying on purchased fodder and grains also has its benefits.
There is no doubt from these figures that if cows are well fed with a mixture of home grown pasture, silage, hay and crops, the cost will on average be significantly cheaper than purchased feeds.
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