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Know Your Nitrate Risk

posted by Horse Owner Today    |   September 14, 2012 12:19


Chelsey Carruthers, M.Sc., AAg
Regional Livestock Specialist, Saskatchewan Ministry of Agriculture
Watrous

Every fall with the first frost looming, livestock producers worry about nitrate in their forages. What is nitrate, where does it come from and what can you do about it?

What is nitrate?

During normal growth, plant roots take up nitrogen from the soil in the form of nitrate and the plant converts it to protein. When plant growth is stopped by an event such as hail, frost, drought or chemical damage, this normal process is affected and nitrate accumulates in the plant.

When ruminant animals eat plants containing nitrate, their rumen microbes convert it to nitrite, which is much more toxic. At low levels, nitrite is handled by the rumen microbes and used for protein production. However, at high levels, the microbes can’t keep up. Nitrite is absorbed into the blood stream where it can cause problems by decreasing the oxygen carrying capacity of the blood. Animals can die due to lack of oxygen. Symptoms of nitrate poisoning include trouble breathing, weakness, diarrhea, muscle tremors and death. At lower levels, nitrate poisoning can cause decreased productivity and abortions.

How can you tell?

Nitrate accumulates in the stems and leaves of plants following periods of stress. However, not all plants are equally affected. Nitrate tends to accumulate in annual forages, such as those used for swath grazing and green feed, and some weeds, and is usually higher in immature plants. Legumes such as alfalfa rarely accumulate high levels of nitrate. Crops that have been fertilized with nitrogen will be at higher risk of nitrate accumulation.

After a stress that kills the plant, such as a hard frost, the crop should be harvested as soon as possible. The plants will not recover, and cannot clear the nitrates. Because the plant roots will continue to absorb nitrate from the soil for a few days following plant death, the nitrate level in the plant will continue to rise during this period.

If the stress to the plant has been mild enough for the plant to recover and continue to grow, harvest should be delayed about ten days. This will give the plant a chance to use up the stored nitrate and convert it to protein.

If you suspect your harvested forage is high in nitrate, a feed test can be done to determine the nitrate level. This will give you an idea of what you are dealing with, and what you can do about it.

What can be done?

Not all frozen forages will be high in nitrate. Testing is the only method for determining the nitrate level and developing a plan to deal with high nitrate feed. Most of the time, the risk to livestock can be decreased by diluting high nitrate feed with low nitrate feed. Water can also be high in nitrate, and should be tested as well. A combination of feed and water both high in nitrate can be a more serious problem. Livestock should be maintained in good body condition, and provided with a diet well balanced in energy, protein, vitamins and minerals. Livestock should also be introduced to higher nitrate feeds very slowly, and monitored carefully.

Understanding the process of nitrate accumulation, the risk factors, and the importance of feed testing can help you to plan ahead and deal with high nitrate feeds to protect the health and productivity of your livestock.

For more information on this or other topics please call me at (306) 946-3237, the Agriculture Knowledge Centre at 1-866-457-2377 or visit our website: http://www.agriculture.gov.sk.ca/

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Feed

Forage Alternatives

posted by Horse Owner Today    |   January 26, 2011 16:25

Hay is hard to find in some areas. Because of a scarcity of hay in many regions, can you just skip feeding hay this winter and make up the deficit by doubling your horse’s grain ration? The answer is an emphatic NO.

Consider availability, cost, and practicality when choosing ways to provide adequate fiber.

 

Hay, or some other source of fiber, is absolutely necessary to the health and function of the horse’s digestive tract. Overconsumption of grain is characteristically followed by colic, gastric ulcers, or laminitis, so this is not an option to consider. Aim for an average of 1.5% of the horse’s weigh in hay or equivalent forage each day (approximately 15 pounds of hay for a 1000-pound horse, or 7 kg for a 450-kg horse), adjusting up or down depending on the horse’s age, use, and metabolism.

 

Why is fiber so important in the equine diet?

Consumption of grass, hay, and other forage fulfills both physical and psychological needs. Horses have a strong desire to chew, and also to have the full-gut feeling that comes from eating a lot of fiber. Deprived of adequate forage, horses tend to chew on trees, fences, stalls, and anything else that is available. A steady supply of forage helps to maintain the optimum types and numbers of microorganisms in the hindgut. These bacteria and other organisms transform fiber into energy the horse can use for growth or performance. The proper balance of beneficial bacteria prevents an overgrowth of harmful organisms that may upset digestion. As well as aiding the passage of food through the digestive tract, adequate fiber provides bulk and weight in the intestines. This helps to keep them from twisting and looping around each other, possibly leading to tissue damage and colic.

 

Is there a particular need for forage during cold weather?

A near-constant supply of forage is an important factor in keeping horses warm in the winter. The vast fermentation vat of the horse’s hindgut steadily produces heat that can’t be supplied by an all-grain diet.

 

My local hay dealer doesn’t have hay for sale this year. Should I buy hay from outside my region?

Obviously, not all hay is the same, but with some precautions, you should be able to use hay that is shipped in from other regions. Things to look for include:

Blister beetles. Alfalfa hay may contain these small insects that are highly toxic to horses. Signs of ingestion may include colic, depression, loss of appetite, and straining to urinate.

Unfamiliar weeds or plants. Hoary alyssum, a pasture weed, has been found in alfalfa hay baled in Michigan. Horses consuming the plant showed diarrhea, swollen legs, fever, and signs of laminitis.

Selenium levels. The amount of selenium in hay is influenced by the level of the mineral in the soil where the hay was grown. Horses need a certain amount of selenium, but high levels are toxic. Hay from some western states may have this problem. Signs of selenium toxicity include laminitis and a loss of mane and tail hair.

• Vitamin content. Levels of vitamin A and E drop slowly as hay ages. Hay baled last year, or even very early in the current year, may not contain enough vitamin E to keep horses in good health through the winter; signs of deficiency include muscle weakness, tremors, and weight loss. Vitamin E level depends less on the hay’s place of origin than on how long it has been in storage.

• Quality. Ask hay brokers for a nutrient analysis before making a purchase, and examine the hay before accepting delivery. Good hay will smell fresh and clean without a moldy odor. Check the center of a few bales; hay that appears dry and yellow on the outside of the bales may still be green and fresh inside.

 

I still don’t have enough fresh hay to supply my horse all winter. What can I do?

If at all possible, some hay should continue to be fed. Owners can use alternative fiber sources to round out the diet if the amount of traditional hay must be reduced. Ideas for stretching your hay supply include:

Feeding chopped hay, available at some feed stores in 50-pound (23-kg) bags. Palatability is an asset; expense and storage may be problems.

Adding some hay cubes to the horse’s diet, soaking the cubes if necessary before feeding. Alfalfa, timothy, and mixed cubes may be available, and in some parts of the country a hay cube fortified with vitamins and minerals is available. Many horses can get along well on mixed cubes, and selection should match the horse’s needs. Because there is less waste with cubes than with loose hay, you often do not need to feed an equivalent weight. Don’t put all the cubes out at one feeding, as the horse will probably gobble them up quickly and then have nothing to eat for hours.

Adding beet pulp to the ration. This “super-fiber” can make up a maximum of 20% to 30% of the diet, is easily digested, and can be bought in bulk at feed stores. Many people advocate soaking beet pulp before feeding, so use of this fiber takes a little more time and management than some other choices. Beet pulp is low in phosphorus and some other minerals and vitamins.

Feeding a “complete” or “fiber-included” feed that incorporates both the forage and grain portions of the diet. Be sure that the feed actually includes forage; some companies use the “complete” designation to indicate a fortified grain mix, not a product that offers forage. This type of feed should be offered in several small feedings throughout the day rather than as one large meal.

Using clean older hay. Even if last year’s hay doesn’t have optimum levels of some vitamins, it gives the horse something to chew on. Older hay that is clean but very dry can be moistened before feeding to make it more palatable, and the nutritional shortfall can be made up by adding a vitamin-mineral supplement.

Feeding straw, either baled or chopped. Clean, non-moldy straw is palatable to many horses and contains nearly as many calories as some grass hays, although it is lower in protein and phosphorus.

Allowing horses more access to pasture. If non-grazed fields are available, horses will continue to eat grass all winter even though it is not actively growing. In fields that have been grazed all summer and fall, horses may be forced to eat brushy or toxic plants as the only choice. Before counting on this source of forage, owners should walk the fields to make sure there is something to eat.

 To view  the complete article go to:  http://www.equinews.com/article/forage-alternatives

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