Nitrate Toxicity in Beef Cattle

Written by Megan Van Emon, Extension Beef Cattle Specialist, Montana State University

Elevated nitrate concentrations can be found in forages that have been grown under stress, such as severe drought conditions.  Nitrate toxicity is caused by animal consuming feeds and water that have elevated levels of nitrate or nitrite.  Care should be taken when feeding cattle cereal grains/hay, corn stalks, orchardgrass, and other feeds known to contain high nitrate levels.

Nitrate is not toxic to animals unless consumed in excessive levels.  When nitrate is consumed in excessive levels, nitrite poisoning can occur.  Normally, forage nitrate is broken down in the rumen to nitrite by microbes, and then to ammonia.  The ammonia is used by rumen microbes for protein.  However, when nitrate is consumed in elevated levels, nitrite accumulates within the rumen faster than it can be converted to ammonia.  The nitrite then enters the small intestine and is absorbed into the bloodstream.  The high levels of nitrite in the bloodstream convert hemoglobin to methemoglobin, which cannot carry oxygen, ultimately limiting the body’s oxygen supply.

Acute nitrite poisoning is caused by animals consuming a large amount of high nitrate forage over a short period of time.  Chronic nitrite poisoning occurs when animals consume small amounts of high nitrate forage over a long period of time.  Chronic nitrate poisoning is only treated by eliminating the consumption of the high nitrate feed or by diluting the high nitrate feed with low nitrate feeds.  Acute nitrite poisoning can occur rapidly after consuming high nitrate feeds, in these severe cases, an immediate intravenous injection of methylene blue by a veterinarian may save the affected animal.  However, due to the rapid onset of acute poisoning, treatment may not be the best option.

Testing forages to ensure safe levels of nitrates (Table 1) is the most effective way to minimize the potential of nitrite poisoning in livestock.

Table 1. Effect of nitrate concentration on livestock (100% DM basis).
NO3 – N (ppm) NO3 (ppm) Comments
<350 <1,500 Generally safe
350-1,130 1,500-5,000 Generally safe for nonpregnant livestock. Potential for early-term abortions or decreased breeding performance. Limit feed to 50% of ration for pregnant animals.
1,130-2,260 5,000-10,000 Limit feed to 25-50% of ration for nonpregnant animals.  DO NOT FEED TO PREGNANT ANIMALS.
>2,260 >10,000 DO NOT FEED.
Hibbard et al., 1998
0.1% NO3-N = 0.44% NO3 (0.1 x 4.4)
0.44% NO3 = 0.1% NO3-N (0.44 x 0.23)
0.1% = 1000 ppm


Diluting high nitrate feeds with low nitrate feeds can reduce the potential for nitrite poisoning by using the following equation (Glunk et al., 2015; MT200205AG):

WL = (WH)*(%H – %B) / (%B – %L)

WL = weight of low nitrate hay required

WH = weight of high nitrate hay

%H = nitrate concentration of high nitrate hay

%B = nitrate concentration needed in final blend

%L = nitrate concentration of low nitrate hay


For nitrate testing, contact your local extension agent.  You can also find additional information in the MontGuide, “Nitrate Toxicity of Montana Forages.”

Time to Survey for Alfalfa Weevil

Written by Kevin Wanner and Emily Glunk

Alfalfa weevil is the key insect pest of alfalfa, causing variable levels of economic damage across Montana each growing season. After mating the female weevils lay their eggs in alfalfa stems, and newly emerged larvae crawl up to the developing terminal buds where they chew small “pin” holes in the leaves. The larvae develop through four instar stages (Figure 1); the larger 3rd and 4th instar larvae feed openly on unfurled leaves and cause the largest economic loss. Severe feeding damage will give the field a “frosted” appearance. Mature larvae develop into the next generation of adults that leave the alfalfa field to find overwintering sites. In Montana there is one generation per year. The majority of crop damage occurs prior to the first cutting as a result of feeding by larger larvae. Management decisions are based on surveying the number of weevils to determine if their population will exceed the economic threshold, the point that warrants action to be taken.

Alfalfa weevil sampling should begin in the spring when the stand is about 8 to 10 inches tall. Weevil populations can be estimated using sweep nets (net with a 15 inch diameter, can be purchased online) or by shaking alfalfa plants in a bucket. An average of 20 alfalfa weevil larvae per sweep meets the economic threshold for action. Ten sweeps are taken at each of 3-5 five sites in a field (30-50 sweeps per field) and the total number of weevil larvae counted to determine the average per sweep. An alternative is to cut 10 stems from each of 3-5 different sites in a field (30-50 stems per field) and shake the stems in a bucket to collect the larvae. An average of 1.5 – 2.0 larvae per stem meets the economic threshold for action. To get an accurate average more samples are required for larger fields. A minimum of three samples are recommended for fields up to 20 acres, four samples for fields up to 30 acres and five samples for larger fields. Based on historical weather data, sampling for alfalfa weevil in Montana typically begins between May 24 and June 16, depending on the location and the seasonal weather.

Typical dates that alfalfa weevil monitoring begins in Montana:

Sidney – May 24.    Glasgow – May 29.   Lewistown – June 13.   Kalispell – June 7.   Dillon – June 10.   Bozeman – June 8.   Red Lodge June 16.

When the economic threshold has been met (more than an average of 20 larvae per sweep or 1.5-2.0 larvae per stem) action is required to preserve yield. If stand growth is sufficient early harvesting is the most effective and economic action. If early harvesting is not an option then an insecticide can be used to reduce weevil populations below economically damaging levels. Additional management information including insecticide options is listed online in the High plains IPM guide:

Additional video resources:

Tips When Considering Cull Cows

Written by Dr. Megan Van Emon, MSU Extension Beef Cattle Specialist

One area of the beef cattle market that is easily overlooked is the cull cow market. Most cows are culled because they do not re-breed or produce a small calf at weaning. It is important to remember that cull cows have potential to provide an additional source of income for the ranch. Here are a few tips to consider when culling your cows.

  1.  Cull Cow Market. The cull cow market varies throughout the year, with the lowest prices occurring between September and December. This occurs as many producers are weaning during this time period and flooding the market with cull cows. If it is economically viable, selling cull cows early in the summer or hold them over winter and selling in the early spring may improve cull cow prices.
  2. Feeding Cull Cows. Feeding cull cows after weaning can improve body weight, body condition, and quality grade. Determining feed costs and cost of gain for cull cows will determine if it is economically viable to keep cull cows to receive a better market price in the early spring.
    1.  Feed Sources. Cows should be adapted to a high energy diet over a 2 to 3-week period. Additional feedstuffs can be used, such as crop residues and additional pasture space.
    2. Length of Feeding. Type of diet has a significant impact on fat color of beef cattle. A high forage diet leads to yellow fat, which is not as desirable as white fat. Some research suggests that feeding a high concentrate diet for a little as 56 days can change yellow fat to white. Feeding thin cows to a moderate condition, will take time, and determining average daily gain will aid in determining how long it will take a body condition score 3 cow to move up to a body condition score 5.
  3. Second Pregnancy Check. When retaining cull cows after weaning, it may be beneficial to conduct a second pregnancy check. It is not uncommon for “open” cull cows to be carrying a calf, which can be retained to calve with the herd or sold immediately as a bred cow.
  4. Implants. Cull cows being fed to improve body condition and weight after weaning may benefit from an implant. The cost of implants should be considered when determining if they will be used and how they will impact weight gain and feed efficiency, and the potential to reducing days on feed.

These are several tips to consider when feeding cull cows, but the most important is economic viability. Deciding to sell or feed cull cows is a decision each producer must determine and how will that decision impact potential profits.

Cow Sense Chronicle: Early Weaning As a Drought Management Strategy

From Cow Sense Chronicles by Rachel Endecott, Beef Cattle Specialist

I’ve been hearing from folks experiencing drought and fires throughout the state. Other regions are in good shape, but some are ready for winter to come to the rescue! This month, I’ll give a brief overview of early weaning as one drought management tool for ranchers.

The majority of spring‐born beef calves are weaned at 6 to 7 months of age, typically in October or November. This timeframe will vary based on calving season, location, and marketing scheme. As dry conditions result in limited forage availability, producers may consider early weaning to ease some of the demand. By the time a calf is 6 to 7 months old, he or she consumes about half of the amount of forage that a mature cow consumes.

Weaning calves removes the lactation demand for nutrients. Cow requirements and intake will both decrease after weaning. A rule of thumb I use in my beef cattle management class is that for every day calves are weaned earlier than normal, 0.6 grazing days worth of forage are saved. This incorporates both the decrease in calf consumption of forage and the lower intake of a non‐lactating cow. This thumb rule was developed with a 1300‐lb cow weaning a 600‐lb calf at 7 months of age. If for‐ age is of adequate quantity and quality, we expect cow body condition to improve post‐weaning, which can pay dividends for the next breeding season. Weaning earlier gives the cow more time during mid‐gestation when her requirements are the lowest to put on weight going into winter and next year’s calving season.

Early weaning does come with some challenges. What are you going to do with the early weaned calves? In a drought situation, you might not have forage available to wean them on pasture. Do you have harvested feedstuffs you can feed to them? Can you send them to your buyer early? Will they stay in pens built for larger calves? Are you prepared to deal with calf health issues that may arise? Do you have the resources to have them backgrounded on‐ranch or elsewhere?

There are a couple of schools of thought when it comes to early weaning. “Traditional” early weaning might be August or September instead of October or November for many spring calving herds, like what I’ve described on the previous page. Research has shown improvements in cow condition that could make a positive difference in reproductive performance next year. If, however, we are in a bad enough drought situation that we feel we need to make a positive difference in reproductive performance THIS year, calves need to be weaned before the breeding season. Cows will increase body condition and breed up well in this system. The disadvantage is that you now have a bunch of 80‐day‐old calves to manage, and that’s not for the faint‐hearted.

Don’t forget the upcoming Veterinary Feed Directive short courses around the state. We’d love to see you and visit about the implications the new rule has for livestock producers, so RSVP to the appropriate local county Extension office listed below. All meetings start at 1 pm.

VFD Short Course Schedule Summer 2016

August 3 Miles City – Fort Keogh – 406-874-3370

August 4 Billings – County Courthouse – 406-256-2828

August 9 Glasgow Cottonwood Inn – 406-228-6241

August 10 Havre – MSU NARC – 406-231-5150

August 11 Lewistown – Eagles – 406-535-3919

August 16 Sidney – Extension Office – 406-433-1206

August 24 Butte – Public Library – 406-723-0217

August 25 Missoula – Extension Office – 406-258-4200

September 12 Great Falls TBD 406-454-6980

September 21 Dillon UM-Western 406-683-3785

Veterinary Feed Directive Informational Meetings

The Montana State University Extension Beef Cattle Program is holding Veterinary Feed Directive educational meetings throughout the state this summer. These courses are free to the public and will be a great way to learn more about the VFD. For more information about the courses please contact Megan Van Emon, Extension Beef Specialist at 406.874.8286 or

All Meeting Flyer (002)

Veterinary Feed Directive Impacts Feed-Grade Antibiotics

by Megan Van Emon, Ph.D. – MSU Extension Beef Cattle Specialist

The new Veterinary Feed Directive (VFD) rule will change how medically important antibiotics are fed to livestock.  The rule does NOT include the use of injectable antibiotics.  Previously, feed-grade antibiotics have been labeled for control, treatment, prevention, growth promotion, and feed efficiency.  The VFD rule results in the removal of the statements and uses of feed-grade antibiotics for growth promotion and feed efficiency.

Guidance for Industry proposal #209 concerns the use of medically important antibiotics in food-producing animals.  Guidance for Industry proposal #213 focuses on the drug companies and recommending they voluntarily align their products with GFI #209.  Medically important antibiotics are those that are used in both human and animal medicine.

The two main proposals of GFI #209 are: 1. use of medically important antibiotics will be limited to therapeutic uses only; and 2. use of medically important antibiotics for food-producing animals will be limited to those that have veterinary oversight.  The main proposal of GFI #213 asks the drug companies producing medically important feed-grade antibiotics to voluntarily remove production (ie. growth promotion and feed efficiency) claims from the labels and moving the over-the-counter products to VFD or prescription status.

Additionally, a valid veterinary-client-patient relationship (VCPR) is required for veterinarians to issue a VFD.  A valid VCPR includes: 1. the veterinarian assumes the responsibility for medical judgements and animal health and the client agrees to follow veterinarian instructions; 2. the veterinarian has sufficient knowledge of the animal(s) to initiate medical treatment and makes timely visits; and 3. the veterinarian is available for follow-up care and evaluation.  If you currently do not have a valid VCPR, building this relationship prior to the VFD implementation may be a good idea.

A valid VFD consists of paperwork filled out by the veterinarian that contains the veterinarian information, clients information, description of animals and location, VFD drug information, why is the VFD being issued, level of VFD in the feed, duration of use, date, and withdrawal time.  All VFDs will require the statement: “Use of feed containing this veterinary feed directive drug in a manner other than as directed on the labeling (extra label use), is not permitted” and the veterinarian’s written or electronic signature.  The veterinarian is required to maintain the original VFD form with copies being provided to the feed distributor and producer.


As we move closer to the implementation of the new Veterinary Feed Directive (VFD) rule, the MSU Extension Beef Cattle Program will be conducting educational meetings throughout the state this summer.

Date City Location
July 26 Kalispell Flathead Co. Fairgrounds
August 3 Miles City USDA-ARS Fort Keogh
August 4 Billings TBD
August 9 Glasgow Cottonwood Inn & Suites
August 10 Havre MSU-NARC
August 11 Lewistown Eagles
August 16 Sidney TBD
August 24 Butte TBD
August 25 Missoula TBD



To learn more about the VFD and the informational meetings please contact Megan Van Emon at 406.874.8286 or at

MSU Extension and MSGA announce 2015 Steer of Merit certifications

montana state extension logoMontana State University Extension and the Montana Stockgrowers Association (MSGA) distinguished 108 “Steers of Merit” out of 903 entries for 2015. Out of 589 steers entered in the Carcass Division, 70 were deemed Steers of Merit. In the Ultrasound Division, 38 out of 314 entries received the distinction.

The exhibitors and breeders of the top five steers in each category were honored at MSGA’s Annual Convention, Dec. 5 in Billings at the MetraPark Rimrock Auto Arena. The number of Steer of Merit certifications for 2015 decreased by 10 steers, with 27 fewer entries submitted compared to 2014.

The top five steer entries in the Carcass Division were:

  1. Isabelle Lowry, Lewis and Clark County (Isabelle Lowry, breeder);
  2. Haven Meged, Custer County (Bart Meged, breeder);
  3. Sam Kearney, Ravalli County (Troy Griffin, breeder);
  4. Cheyenne Hawbaker, Daniels County (Steve and Kristi Vorhees, breeder); and
  5. Trenton Braaten, Broadwater County (Butch Gillespie, breeder).

The top five steer entries in the Ultrasound Division were:

  1. Trey Nansel, Yellowstone County (Barry Kruger, breeder);
  2. Parker Cook, Yellowstone County (breeder unknown);
  3. Spencer Lepley, Yellowstone County (breeder unknown);
  4. Kallie Candee, Richland County (Asbeck Brothers, breeder); and
  5. Bill Bender, Yellowstone County (Northwest College, breeder).

Megan Van Emon Steer of MeritThe Montana Steer of Merit program was initiated in 1967 as a joint effort between the Montana Stockgrowers Association and Montana State University Extension. The program was designed to measure, record, and improve carcass characteristics in beef cattle. Data from these carcasses has been summarized and analyzed statistically. Over time, significant increases have been made in quality grade and in yield grade, or cutability, indicating that cattle can be selected for leaner carcasses with higher cutability and still maintain high quality grade as reflected by marbling.

To be designated a Steer of Merit, carcasses are evaluated by a qualified individual using information that relates to yield of lean meat and eating quality. Beef carcasses must meet criteria set by the Steer of Merit Committee in the areas of hot carcass weight, dressing percent, fat thickness over 12th rib (back fat), total rib eye area, yield grade, percent cutability, and quality grade. Computer software programs help compile data and rank carcasses for state and county awards. Data is also analyzed periodically to track genetic and feed management progress. The minimum standards for Steer of Merit are reviewed each year and the program is updated to meet the changing industry standards.

For more information about the Steer of Merit program call Megan Van Emon, Montana State Extension Beef Cattle Specialist at (406) 874-8286.

Click here for more 2015 Annual Convention coverage from Montana Stockgrowers.

MSU Extension Survey on Noxious Weeds

montana state extension logoMontana State University Extension Specialists Drs. Jane Mangold and Kate Fuller are working on a survey to help gain a better understanding of how noxious weeds affect livestock producers on private rangeland in Montana. As a part of their project, they are surveying livestock operators.

Please take a few minutes to fill out their short survey, here:

Any questions or comments, or requests for survey results, should be addressed to Kate Fuller at or Jane Mangold at  Kate and Jane thank you very much for your time!

Tips for Interpreting Forage Analysis

montana forage analysisBy Dr. Megan Van Emon, MSU Extension Beef Cattle Specialist

Having your hay and pasture quality analyzed prior to feeding or turnout is one of the most important and effective tools for cattle feeding management. Forage analysis allows for more precise feeding of supplements and other feedstuffs to meet requirements throughout the year. Forage analysis becomes especially important during drought and the possibility of limited forage intake while on grass. Therefore, accurately interpreting that forage analysis is crucial.

As Received Basis

These values represent the content of nutrients with the moisture included. Due to dilution, these values are lower than those in the dry matter basis column. These values can be converted to a dry matter basis by dividing the as received values by the percentage dry matter.

Dry Matter Basis

The values in this column give the nutrient profile after the water is removed. These values will be greater than those in the “as received” column. The removal of water allows for direct comparisons to be made between feed ingredients. The dry matter basis gives the best indication of the nutritive value of the feedstuff because we report animal requirements on a dry matter basis. Dry matter values can be converted to an as received basis by multiplying the dry matter value by the percentage dry matter.

Crude Protein (CP)

Labs measure the Nitrogen (N) content of the forage in order to estimate CP (% CP = % N × 6.25). Crude protein will include non-protein nitrogen and true protein. Crude protein provides the total protein within the forage and does not indicate if any heat damage has occurred, which could alter the availability of the protein.

Acid Detergent Fiber (ADF)

The acid detergent fiber encompasses the cellulose and lignin portions of the cell wall. This number is crucial in determining the ability of the animal to digest the forage. As ADF increases, forage digestibility decreases.

Neutral Detergent Fiber (NDF)

The NDF includes the ADF portion plus hemicellulose. The NDF value is important for determining forage dry matter intake. As NDF increases in the forage, dry matter intake decreases.

Total Digestible Nutrients (TDN)

This is the sum of the digestible fiber, protein, lipid, and carbohydrate components of the forage. In most laboratory analyses, TDN is usually calculated based on ADF and NDF and can vary by region and diet type. Typically, high quality forages range from 50 to 60% TDN and low quality forages range from 40 to 50% TDN. Using TDN in ration calculations is best for rations that are primarily forage. The net energy system should be used in diets that include high concentrations of grain because TDN tends to underestimate the feeding value of concentrate relative to forage.

Net Energy of Lactation (NEl), Net Energy of Maintenance (NEm), and Net Energy of Gain (NEg)

The Net Energy system accounts for the energy losses from digestion of feeds and forages. Net energy estimates the portion of energy in a forage that is useable to the animal to meet the needs of body maintenance and production. Net energy is partitioned into the net energy of maintenance (no body weight gain or loss), net energy of lactation (milk production), and net energy of gain (body weight gain). The net energy system should be used for diets containing high concentrations of concentrates. Net energy values are usually calculated from TDN values, which are calculated from ADF. Therefore, as ADF increases in the forage, net energy values will decrease.


This represents the total mineral content of the forage and typically ranges from 3 to 12% on a dry matter basis. Grains and concentrations usually contain range from 1 to 4% ash. Excessive amounts of ash indicate soil contamination.

Other analyses can also be conducted, such as nitrates, molds, yeasts, and mycotoxins, and individual minerals. These analyses are not typically included in a standard test and must be requested at an additional cost.

Forage Considerations For Fall Grazing

From “Pastures for Profit: A guide to rotational grazing”. University of Wisconsin Extension. 2014.

From “Pastures for Profit: A guide to rotational grazing”. University of Wisconsin
Extension. 2014.

By Dr. Emily Glunk, MSU Extension Forage Specialist and Assistant Professor

There are a lot of questions regarding whether or not it is safe to graze your fall pasture, and to what extent. Fall is a tricky time to manage grazing on pastures, as there is a lot going on with the plants below-ground, which we can’t always see. Grazing too hard in the fall has the potential to be very detrimental to forages, and should be managed accordingly.

So what all is happening right now in our forages? Cool-season grasses are trying to grow more new roots to replenish those that had been shed earlier in the summer. Right around June 21, the summer solstice, a lot of our introduced cool-season grasses shed their roots and begin to grow new ones, contributing to what is known as the “summer slump”. If you trek out to your pasture and dig up a couple plants, you should see quite a few new white roots and tillers forming, indicating a healthy plant and a healthy stand. Our legumes don’t shed their roots, as they have one well-defined taproot, but they are trying to store up enough carbohydrates to serve as any energy source for regrowth in the spring.

It is important that we don’t graze our pastures too heavily in the fall, as we can significantly impair the plants ability to store carbohydrates, or energy, which will help in the regrowth and recovery process. Plants go through a process called photosynthesis, which transforms sunlight into a usable energy source. The plants ultimately convert the sunlight (in the form of photons) to carbohydrates, which are stored in the roots or lower parts of the stem in some grasses. By grazing heavily, and removing most of the leaf area which is required for photosynthesis, we are limiting the plants ability to capture sunlight, and therefore create and store energy. This will be evidenced by slow growth in the spring, creating an opening for weed invasion, or if bad enough, winter kill over the winter.

So what can we do to manage these plants and prevent this from happening? Number one is to not graze very heavily in the fall. Allow those plants enough leaf area to continue photosynthesis, while not trying to use too much of their carbohydrate reserves for regrowth prior to winter. That is not to say don’t graze at all, but try to maintain an adequate stubble height for those forage species. You can contact myself or your local county agent to get species-specific recommendations. Number two, you can wait until after the plant has gone dormant to graze it down lower, because at this point the plant is no longer going through photosynthesis and accumulating carbohydrates, and it will no longer be using its energy reserves for regrowth before spring. You still should take care and be mindful of the impacts of hoof traffic on plant roots, especially in muddy conditions. While the plant may be healthy and have plenty of carbohydrates, if the animal physically injures the plant or its roots, this too can have a negative impact on regrowth ability and plant survival.

From the figure below, we see that carbohydrate reserves are at their lowest around internode elongation phase, a time when we have to be very careful in our management. This is when reserves are being used for primarily for plant regrowth and leaf production. Once there are enough leaves present, and the plant has begun the stem elongation phase, we see an accumulation of carbohydrates. The plant will be able to start storing carbohydrates at this point for regrowth in the spring. We want to make sure that the plant has the ability to store enough carbohydrates before a killing frost, so that we don’t see a problem in the spring.

Another thing that we see happening in the fall is the development of growing points for next spring’s growth. Those are the tillers that we can hopefully see when we dig up some plants. Old tillers may appear brown and dead, but they still serve an important role to the plant. They are a form of stored nutrients, as well as provide protection to the new, developing tillers. We also want to avoid allowing animals the ability to graze off these new tillers, which will be helped by leaving adequate stubble height. Another benefit of leaving some stubble in the field is that it increases the amount of snow that is caught, insulating the soil, and decreases the potential for ice sheeting. This too will help increase plant survivability over the winter.

For any questions or forage recommendations, contact Dr. Emily Glunk at or 406-994-5688. or contact your local county extension agent.