Do I Need to Test For Nitrates?

Last week I attended both the Colorado Cattlemen’s Annual Convention and the Sandhills Ranch Expo at the Ward Laboratories Inc tradeshow booths.  At both locations, producers had concerns about nitrates.  The climate and weather however were contrasting conditions.  Colorado producers wondered how drought stress might affect the nitrate levels in their forages, while Nebraska and South Dakota producers were concerned if too much precipitation might have affect nitrate levels in forages.  Here are 5 factors that affect how nitrates accumulate in forages.

  1. Plant Species

Some plant species accumulate nitrates more than others.  These species should be tested for nitrates regularly before feeding to animals.  These species are: sorghum (milo), sudan grass, millet, oats, johnson grass, broadleaf weeds, corn and sunflowers.  There are other species which also accumulate nitrates but not to the same extent as those listed above: wheat, rye, and triticale fall into these categories.  Finally, under extreme stress alfalfa and soybeans can accumulate nitrates, however the stress must be extensive, and this situation is very rare.

  1. Maturity of the Plant

Young plants and regrowth take up nitrogen from the soil faster than it can be converted to protein.  Older more mature plants take up nitrogen at a slower rate and have had plenty of time to convert nitrogen to protein.  Therefore, younger plants and regrowth tend to accumulate more nitrates than older mature plants.

  1. Plant Part

The lower 1/3 of the stock of the plant is where the most nitrates are stored.  Leaves and stems do not store nitrates in the plant. When grazing, leaving the last third of the stock might be a good idea to avoid any nitrate toxicity issues.

  1. Environmental Conditions

Stress due to weather or climate may increase nitrate accumulation.  During drought stress, the plant may be able to take up nitrogen but not have enough moisture to convert it to protein.  On the other hand, coming out of a drought a dramatic increase in moisture may cause the plant to take up more nitrogen than it can convert to protein in a timely fashion.  Frost and freezing temperatures also cause stress to the plant and nitrate accumulation.

  1. Management

Nitrogen fertilization is a common cause of nitrate accumulation in forages.  Nitrogen fertilization may increase yield, but it also increases risk of nitrate toxicities.

Nitrates are tricky.  I often run into producers who want to tell me their situation and management practices and ask if they need to test.  The truth is no one can determine the nitrate levels based on an antidote.  Testing is the only way to have full confidence.  If there are concerns, send forage samples to Ward Laboratories, Inc for a nitrates test and use the table below as a guide to interpert your report.

Nitrates

4 Considerations of Water Quality for Beef Cattle

Typically, livestock water access and quality are considered during the summer months when heat stress is a concern.  I am choosing to address this topic during the cold winter months because as the temperature drops, below the thermal neutral zone animals consume more feed to increase metabolic heat production and water intake requirements increase with feed intake.  Water is often an overlooked nutrient during the winter months although access to quality water is important for maximum health and production.  Additionally, I have received a concerning inquiry regarding adding salt to water to keep it thawed during the winter months.  This could have deleterious effects on animal health. If a high salt water is provided with no alternate fresh water source, it could eventually lead to the animal’s death.  It is important to remember that water serves many functions in the mammalian body including making up 70% of the body’s mass, regulating temperature, growth, reproduction, lactation, digestion, metabolism, and many other functions we typically take for granted to function properly.  Therefore, access to quality water is important throughout all seasons, including the winter months.  Cattle can substitute snow if water availability is sparse but, access to quality water promotes maximum growth and reproductive performance.  Cattle are not particularly fond of cold water and therefore, while they can use snow in place of water, they prefer a heated water tank. Below are 4 items to examine when determining water quality:

  1. Total Dissolved Solubles (TDS).

This measures the minerals broken down within the water. Sodium chloride (NaCl), bicarbonate (HCO3­), sodium sulfate (Na2SO4), calcium (Ca) and magnesium (Mg) are some of the common solubles present in water.  Less than 1000 ppm TDS indicates safe water and will not cause any animal health concerns.  If the TDS is greater than 1000 ppm then further guidelines found in either the Ward Guide page 148  (http://wardlab.com/download/WardGuide.pdf) or Table 9-2 of Nutrient Requirements of Beef Cattle 8th revised edition page 156 should be referenced for Total Soluble Salts (TSS) guidelines

  1. Nitrate.

Health risks including abortion can occur in cattle drinking greater than 133 ppm NO3-N over long periods of time.  Nitrate poisoning and death can result from cattle consuming water greater than 221 ppm NO3-N.

  1. Sulfates.

High sulfate water can result in health risks from diarrhea to Polioencephalomalacia (PEM), a disruption in thiamin metabolism resulting in a neurological disorder.  It is recommended that calves are provided with water less than 500 ppm sulfate and mature beef cattle are provided with water less than 1000 ppm sulfate.

  1. Contaminants.

Other compounds can be found in water which are detrimental to cattle health. Below is listed common contaminants Ward Laboratories, Inc. tests for, but we are always happy to send samples out to other labs if you suspect another compound may be causing issues.  We commonly send out for selenium and lead.

Contaminant Toxic level (ppm)
Aluminum 0.5
Boron 5.0
Copper 1.0
Fluoride 2.0
Manganese 0.05
Zinc 5.0

 

In conclusion, it is important to provide quality water low in soluble salts, nitrates, sulfates and other contaminants to cattle in order to maximize production performance and ensure healthy animals.  Addition of salts to beef cattle water to keep it thawed during the winter months can increase the TDS thereby, having negative effects on cattle performance and health.  If you are struggling with keeping waterers thawed, remember cattle can substitute snow for water when necessary, and options such as heated tanks should be considered. If you are really struggling and need to get creative, put a salt water solution in water bottles and allow them to float at the top to prevent ice formation.

 

6 Cautions When Grazing Cover Crops

Grazing cover crops can be a cost-effective way to achieve multiple productions goals.  Cover crops can provide ground cover to prevent erosion, improve soil health over time, and provide nutrition to beef cattle.  However, cover crops are not a fool proof feed.  Turning cattle out onto cover crops to graze without proper feed tests can lead to a wreak due to improper management.  Recently, I had a producer lose 12 head of growing cattle to polioencephalomalacia, a neurological disease in cattle consuming too much sulfur.  After the incident, that producer wanted to test his cover crops to ensure he did not experience another tragic loss.  My advice, is to test cover crops before grazing for protein, energy value, minerals, nitrates, and under some circumstances, prussic acid to ensure proper management and prevent undue losses. These are the 6 cautions to consider when grazing cover crops:

  1. Nitrates

Cover crop mixes include several plant species known to accumulate nitrates for example: brassicas, such as turnips and radishes, or small grain plants, such as oats, millet, or grain sorghums. When cattle consume high nitrate feeds, the microbes in the rumen convert that nitrate to nitrite.  The nitrite is then in the gas, which the cattle belch and then inhale.  The nitrite then binds to the blood hemoglobin preventing oxygen from binding.  At levels between 1,400 – 2100 ppm NO3-N this can cause spontaneous abortions with no warning signs or symptoms.  At levels between 2,100 – 4,000 ppm NO3-N sudden death may occur and therefore, animals grazing cover crops should be slowly acclimated to consumption of nitrates and offered a low nitrate roughage to fill up on first.  Never allow hungry cattle onto a high nitrate field.  Nitrate levels above 4,000 ppm NO3-N should not be grazed as sudden death will likely occur.

  1. High sulfur

The toxic level of sulfur in a cattle diet is 0.40 ppm on a dry basis.  Brassicas are sulfur accumulators, that occasionally test above the maximum tolerable level, and are often included in cover crop grazing mixes.  When sulfur intake is above the tolerable level, thiamin metabolism is impaired in a condition known as polioencephalomalacia (PEM). Head pressing, blindness, and muscle tremors are all clinical symptoms of PEM which, untreated, results in death.

  1. Low magnesium

Grass tetany is a condition commonly associated with lush spring pastures.  These pastures are known for having low magnesium due to rapid growth conditions. Cover crops also tend to have low magnesium.   The magnesium requirement for a beef cow is 0.2% of the diet at peak lactation and 0.1% of the diet for growing cattle.  When cover crops contain less magnesium than is required, a magnesium deficiency can develop resulting in grass tetany.  The signs of grass tetany are cattle stop grazing, become overly alert, and appear uncomfortable, they will then begin to stagger until they finally lie down with their head pulled back into a “star gazing position”.  Untreated, this condition will result in death.  To prevent the development of a magnesium deficiency, many producers grazing cover crops feed a mineral between 8-12% magnesium to be consumed at a rate of 2.5-4oz per head per day.

  1. Prussic acid

In cover crop mixes there are species of plants which accumulate hydrogen cyanide, a poisonous gas commonly known as prussic acid, in their leaves under stressful growing conditions.  These plants include sorghum grasses, sudan grasses, and flax.  Stressful growing conditions includes drought or frost.  Plants grown in drought conditions should be tested for prussic acid prior to grazing because consumption of high levels of the gas is sudden death.  Contrarily, frost typically breaks cell walls allowing the release of the gas and therefore should be safe to graze after 4 days.  Regrowth after a frost however, should be tested prior to grazing because the plant is stressed from the previous frost, but the cell walls have not been broken to allow the gas to escape.

  1. Bloat

A frothy bloat is often attributed to legumes or high protein grasses.  Cover crop mixes high in legumes such as clover, beans, or cowpeas may result in some animals over indulging in the legumes resulting in frothy bloat issues.  These legume plants are high in soluble protein and sugars which allows the microbes to ferment and grow at a rapid rate resulting in a high rate of gaseous by-product accumulation.

  1. Choke

Brassicas such as radishes and turnips may be pulled from the ground to be consumed by cattle grazing cover crops.  If they are swallowed without proper mastication the animal may choke on the large root.  This is typically more of a problem for young cattle who are inexperienced in grazing brassicas.

Overall, grazing cover crops can be a great way to provide nutrients to cattle, prevent soil erosion and improve soil health.  However, the producer should be aware of the risks they are assuming feeding these diverse forages.  Testing for nitrates, minerals, and potentially prussic acid is highly recommended to avoid unnecessary losses due to grazing cover crops.

 

4 Considerations For Feeding Hail Damaged Forage And Crop Residues

 

Here in Central Nebraska we have experienced several mid-summer thunderstorms. These hail producing storms have wreaked havoc on crops and forage productivity, particularly in the Broken Bow and Ansley areas. As producers move forward with crop insurance, they will also be scrambling to utilize what is left of their standing row crops and forages. There are three laboratory tests I would recommend to make an informed decision about the remaining forage. Then depending on the results of your laboratory tests, you can determine what your most economical option is.

1. Nitrates

Defoliation due to the pounding hail results in decreased photosynthesis within the plant. This means that the plant can not convert nitrates to protein. The root system of the plant still continues nitrogen uptake, although the plant cannot utilize these nutrients, resulting in the potential accumulation of nitrates in the plant. Nitrate (NO3 – N) levels between 1400 – 2000 ppm can result in abortions while levels higher than 2000 ppm can result in sudden death if not diluted with other sources of roughage. Therefore, nitrate testing of hail damaged forages is highly recommended before making a decision to graze, hay or ensile the forage.

2. Mold and Mycotoxin Potential

Hail damages the outer cell wall of the plant. The cell wall is an immune defense similar to skin on animals. It prevents infectious agents from penetrating, proliferating and using the plant as a food source. When the cell wall is damaged, opportunistic molds may infiltrate and grow. Consequently, when haying or ensiling forage, testing for mold counts is important. Mold counts above 1 million cfu/g impact animal health and lower production potential.
If the forage is a grain producing forage such as corn or milo, a producer may want to inspect the crop to determine if grain has been produced. If there is grain and it is damaged by the hail, mycotoxins become a potential risk when feeding to livestock. Mycotoxins presence may be present even in the absence of a high mold count. If you suspect mycotoxins may be an issue, remember mycotoxins and molds are often produced together however, the absence of one mycotoxin does not mean conditions were not ideal for another mycotoxin to emerge. If haying the hail damaged forage, proper drying can cut down on mold and mycotoxin presence. If ensiling, proper fermentation and additives may reduce the risk of having these agents in the feed.

 

 

3. Relative Feed Value

The relative feed value (RFV) will be less in a hail damaged forage or crop than its intact counterpart. Defoliation caused by the hail results in the removal or the leafy mass of the plant and what remains is the stocks and stems. These parts of the plant are lower in protein and higher in fiber, which results in a lower relative feed value. Additionally, this also means lower total digestible nutrients (TDN), and net energy of gain (NEg), lactation (NEl), and maintenance (NEm). Therefore, when feeding hail damaged forage, testing the protein and energy of the feed is important to determine how much energy and protein supplementation will be needed to meet production goals.

4. Economics

The last thing to consider, and the most important to your bottom line, when determining how to feed a hail damaged forage is what is the most cost effective delivery system based on the results of feed reports. If the nitrate reports came back low and you have the means to supplement cattle in the field to meet energy and protein needs, grazing may be the most cost effective option. Haying may also be an option under that scenario, however, if selling the hay profit margins may be small do to the lowered feed value and potential mold risks associated. Additionally, when haying you must input equipment and fuel costs associated with cutting, windrowing, and baling. If the nitrates levels have been reported between 2000ppm and 3000 ppm ensiling the damaged forage may be a good option as the nitrates can decrease by up to 50% and then be fed back to the animal. Equipment, fuel and storage costs must also be taken into account for ensiling the feed. In the case of moderate nitrates, haying and mixing with a high quality forage, such as alfalfa, to both dilute the nitrates to the appropriate level and meet the difference in protein and energy provided by the damaged forage and the animals requirements, may also be a viable option. Finally, if the nitrates report is high, utilizing the forage as a fertilizer for next years crop may be the only option.

When determining how to best utilize hail damaged forage, always take nitrates, mold and mycotoxin risks into account as well as the lowered feeding value. Consider the man power, equipment, fuel and supplementation costs associated with each option. This will allow you to make the most informed and cost effective decision possible.