Non-Protein Nitrogen and Soybeans: a Deadly Combination

Every once in awhile I get asked if soybean plants or stubble should be tested for nitrates.  Soybeans are legumes like alfalfa, and like alfalfa, under stressed conditions can accumulate a toxic concentration of nitrates.  Soybeans are listed as nitrate accumulators by the Iowa Beef Canter.  Therefore, if you are having doubts, send a sample to Ward Laboratories, Inc. for a test to make the best possible feeding decision.  Having received inquiries about nitrates in soybeans, I was reminded of a cow that got out into a soybean field and died of suspected nitrate poisoning last year.  However, when the soybean plants were tested, low nitrate concentrations were found.  Upon review of the animal’s diet history, non-protein nitrogen was consumed before the cow got out into the bean field.  Concluding that the more likely cause of death in the case of that specific cow was non-protein nitrogen poisoning.

Non-protein nitrogen poisoning occurs when the urea cycle is overloaded.  First, the ruminant animal consumes non-protein nitrogen typically in the form of urea in a supplemental feed.  If fed at high concentrations urea itself can be toxic.  Once in the rumen, urease produced by rumen microbes converts the urea to ammonia.  Ammonia is a form of nitrogen that microbes can use to produce amino acids and ultimately protein for their own population growth and production.  When too much ammonia is present in the rumen, it is absorbed through rumen epithelia and transported through the blood stream to the liver.  In the liver, ammonia is converted back to urea and transported to the kidneys for excretion.  When the kidneys are overloaded with urea and ammonia it continues to circulate around the body in the blood stream.  As a result, animals begin to have facial muscle spasms, frothy salivation, bloat or abdominal pain, labored breathing, frequent urination and weak staggered walking.  Often urea poisoning results in death.

UreaPoisioning

So, what does this have to do with a cow getting out in a bean field?  Soybeans produce the enzyme urease.  When a ruminant animal consumes urea in combination with raw soybeans, the concentration of enzyme is no longer a limiting factor in the rate that urea is converted to ammonia.  The rumen microbes can not keep up and the urea cycle becomes overloaded with ammonia and urea circulating in the blood stream even though the animal did not consume toxic levels of non-protein nitrogen.

This is one of the reasons why soybean meal is often sent to Ward Laboratories, Inc to check the activity level of the urease enzyme.  Soybean meal is processed and heated to high temperatures denaturing or melting the enzyme, thereby deactivating it.  So, if you plan to feed whole soybeans, which can be a great source of crude protein (approximately 40% crude protein on a dry basis) either ensure they have been heat treated or do not also feed a non-protein nitrogen supplement.  Additionally, do not feed a supplement containing urea when feeding a baled soybean stubble containing lots of leftover beans, ensiled soybeans or if cattle are grazing a cover crop mix which includes soybeans. Soybeans and urea rarely cross paths because both are used as protein sources, but when they do death losses are likely to occur.

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6 Nutritional Strategies to Alleviate Heat Stress in Beef Cattle

Summer has arrived! For most that means backyard BBQs, boating, fishing, mowing the lawn and enjoying the sunshine, but for livestock producers heat stress is something they face each year.  Cattle not well equipped to handle heat stress and are usually grazing or in a feedlot during this time of year.  Unlike swine and poultry who are housed in a more controlled indoor environment with fans and sprinklers to help keep them cool.  Cattle sweat and pant to combat heat stress.  However, they only sweat 10% as much as humans do and depend mainly on respiration to cool themselves in the hot summer months.  As heat stress increases, feed intake levels decrease and thereby so does performance during those hot spells.  Here are 6 ways producers can adjust their diet to help alleviate heat stress:

1.Replace low quality roughages and grains with high quality forages.

This may decrease the energy density of the diet which has been shown to alleviate so of the heat stress factor on the cattle. The heat increment of digestion is higher when consuming feeds high in fiber.  Feeding high quality forages can reduce this extra feed source of heat.  However, be cautious not to choose a forage without enough fiber as that will result in poor rumen health and potential acidosis or bloat.  Look for a forage that is low in ADF and has at least 20% NDF.

2. Add buffers such as sodium bicarbonate to total mixed rations.

If you are going to continue feeding a mixed ration with grains, adding a buffer can reduce the incidence of acidosis. When feed intake has decreased, cattle will sort out the grain and consume little high fiber forage resulting in acidosis.

3. Increase the concentration of minerals and vitamins in the diet.

Three minerals that should specifically be increased as they are lost through perspiration are sodium, potassium, and magnesium which should be fed at a rate of 0.6%, 2.0% and 0.4% of the dry matter content of the diet respectively. Chromium may also have some benefits, however more research is needed on how this micro-mineral may provide some relief from heat stress.  Niacin a B vitamin may also have benefits on cooling the skin, but again there is little research to back up this claim.

4. Add water to dry rations.

If the ration is dry cattle will not want to consume it on a hot day. Just like us on a hot day they would choose a Popsicle over a bowl of dry cereal.  Therefore, a producer may be able to increase feed intake by keeping rations moist and appetizing to the cattle.

5. Provide plenty of cool water.

Never limit water. During a heat wave, animals will consume extra water to keep cool and replace water losses through sweat and respiration.

6. Feed in the evenings.

Animals are not going to want to eat when it is hot out and if they eat in the early morning the heat increment of digestion will coincide with the hottest part of the day, thus adding to the heat stress. By feeding animals in the evening, the temperature may have cooled enough that they will want to consume feed, and the peak heat increment of digestion will occur during the overnight low temperature.

The above are recommended adjustments to make during the summer months when raising beef cattle.  If you graze cattle, be sure to acknowledge that they do most of their grazing at night when it is cool.  So, make sure if you need to move them you wait until the evening when it is not too hot, but not too late as to interfere with their feed intake.  There are other environmental strategies to combat heat stress, and what can be implemented from operation to operation is very different for example providing shade or keeping them in open air flow areas and away from wind breaks.  As always, if you are looking to test forage to replace grain with quality hay or if you need help with the addition of minerals, Ward Laboratories INC. is here to help with those decisions.

Test Forage Make More Money!

Soon we will be entering forage grazing and harvesting season. Although many producers test their hay or silages when buying and selling, there is still a group who either only test for nitrate when they believe they may be having an issue or do not bother to test at all.  There are many benefits to testing feed, such as improving animal health and production, but a major benefit from a business perspective is the potential to improve profitability.  Testing forages can help producers improve their bottom line.

I have attended several conferences where Dr. Aaron Berger from University of Nebraska Lincoln has spoken about profitability and costs to ranches.  The first point Dr. Berger always drives home is the unit cost of production.  It is important to keep track of all input costs to each enterprise on an operation to know what is profitable and what is losing money.  It is also a helpful tool to see where improvements can be made.  In his presentations, Dr. Berger also points out that the number one cost to produce beef cattle is feed.  Therefore, improvement in feed cost would increase profitability.  This can be done through selecting for cattle that consume less feed and gain the same, sourcing cheaper feed, and precise ration and diet formulations.

Precise ration and diet formulations improve profitability by reducing the occurrence of over or under supplementation to reach animal production goals.  To produce a precise and accurate ration or diet, forage testing must be done, otherwise producers are just guessing about the nutrient content of the forage.  Forages are variable plant material.  As the feed and NIR reviewer at Ward Laboratories Inc., I have seen alfalfa hays and grasses vary from a crude protein level of about 15% to 25% and 4% to 18% on a dry basis respectively.  The fiber content of various forages is also variable.  Acid detergent fiber (ADF) is used to calculate the total digestible nutrients (TDN) of the feed, so variation in ADF affects energy supplementation.  Neutral detergent fiber (NDF) affects how much of a forage or hay the animal will consume.  Minerals are also variable in forages and obtaining an idea of the mineral content may also affect mineral supplementation strategies, such as which mineral to feed or possibly creating a custom mineral mix.  If you would like to learn more about forage variability read Quarrels About Quality: 14 Sources of Variation in Forage and Hay Testing.

Testing hay and forage to formulate rations and diets can reduce underfeeding and overfeeding of animals.  When a producer overestimates the nutritional value of his forage, it can negatively affect the animal’s health.  Thereby impacting performance, reducing reproduction rates, decreasing lactation, or growth.  While the feed cost of an overestimated diet is lower, not meeting the nutritional requirements of that animal results in reduced performance and impacts the producer’s profitability.  An oversetimated nutitional value mresults in less protift. When a producer underestimates the nutritional value of a feed, overfeeding the animals results in increased feed costs and decreased profitability.  Additionally, if overfeeding is extreme, cows can become obese, which also can negatively impact reproductive performance.   In the case of underestimating a forage’s nutritional value, the cost of a NIR forage test ($15) at Ward Laboratories, Inc. is quickly made up in feed costs in just a few days of feeding.

 

So, to improve profitability, at a minimum forage testing is a necessity.  If cattle are grazing a pasture, crop residue, or cover crops, there is variation and a simple NIR test can provide information to make an informed supplementation strategy.  If cattle are consuming a total mixed ration, I would advocate to test all ingredients for the most profitable feeding ration possible with those ingredients.  Using feed testing to make decisions can increase an operations profitability through meeting animal nutrient requirements and therefore performance goals, as well as not wasting feed and money overfeeding animals.

Here are some other resources if you are still doubting the merit in hay testing for profit:

Test, Don’t Guess

The Importance of Forage Testing

Profit Tip: Understanding a Forage Analysis

There’s Money in Testing Your Stalks and Hay

A $50 Hay Test Can Save Producers Money

Carbohydrates and Forage Quality

The function of carbohydrates in any animal’s diet is to provide energy.  Some carbohydrates are more easily digestible and provide energy to the animal, or in the case of the beef cattle, to the rumen microbes more rapidly.  These carbohydrates are Non-Fiber Carbohydrates (NFC). Examples of NFC are starch and sugars, such as glucose and fructose, which are measured at Ward Laboratories Inc. as Total Sugars Invert (TSI).  Starch is also analyzed at Ward Laboratories Inc.  by breaking down the polysaccharide into simple sugars.  An example of a high starch forage is good quality corn silage.  An example of a high sugar forage is high quality alfalfa hay or haylage.

Samples dissolving into buffer on the hot plate with stir bars for starch analysis

 

 

 

Fibrous carbohydrates such as cellulose, hemicellulose and lignin are slowly digested.  In ruminant nutrition the two fiber types we typically use in formulation of feed rations and in evaluation of forage quality are Neutral Detergent Fiber (NDF) and Acid Detergent Fiber (ADF).  The indigestible and slowly digestible portion of feed is represented by NDF which contains cellulose, hemicellulose, and lignin.  The least digestible portion of feed is represented by ADF and contains cellulose and lignin but not hemicellulose.  Therefore, ADF is always less than NDF when represented as a percentage of the feed or forage being analyzed.

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ADF and NDF are measured using Ankom bag technology.

The Neutral Detergent Fiber of a feed makes up the floating mat of feed in the rumen.  This floating mat physically stimulates the animal’s digestive processes, specifically rumination.  A high NDF feed typically forms a mat that exists for a longer period of time in the rumen resulting in the animal feeling full longer due to the physical gut fill and consequently consuming less feed.  In summary, high NDF feeds, typically low-quality forages, are predictive of low dry matter intake, while low NDF feeds are predictive of a higher dry matter intake.

Acid Detergent Fiber is used in predictive equations to calculate the energy content of the feed.  Total Digestible Nutrients (TDN), Net Energy of Gain (NEg) and Net Energy of Maintenance (NEm) can all be calculated using the ADF value.  Feeds with a higher percentage of ADF have a lower percentage of the high energy sugars and starches.  Therefore, high ADF feeds and forages have lower energy values and low ADF feeds and forages have high energy values.

At Ward Laboratories Inc. I receive phone calls inquiring about why certain forage reports have higher Relative Feed Values (RFV) or Relative Forage Qualities (RFQ) than others or why those two index values do not match for the same feed.

Relative Feed Value was created to quickly compare the quality of legume hays such as alfalfa or clover. We often apply this index to other forages, or feeds forgetting the original purpose and loosing the understanding that it was not originally meant to be applied to grass hays, corn stalks and especially not corn grains and other non-forage feeds.  Therefore, non-legume forages typically have lower than expected RFVs and animals consuming this hay perform better than the index value would predict.

Relative Forage Quality was created to be inclusive of most forages and is a quick way to fairly compare one forage to another weather it is a grass hay or legume.  The values for RFV and RFQ on the same feed often are separated by as much as 20 points because RFV uses ADF and NDF to predict digestible dry matter and dry matter intake while RFQ uses crude protein, fat, NDF, NDF digestibility among other factors to predict dry matter intake and total digestible nutrients.  South Dakota State University Extension has put together a great resource for better understanding of RFV and RFQ.  Below are the simplified equations for each index:

RFV = Digestible Dry Matter × Dry Matter Intake / 1.29

RFQ=Dry Matter Intake × Total Digestible Nutrients /1.23

    In conclusion, carbohydrates provide energy to the beef cow and support the growth and role rumen microbes play in ruminant digestion.  The higher percentage of the forage or hay is made up of fibrous fractions, such as ADF and NDF, the less NFC are available to rapidly provide energy.  Therefore, as ADF and NDF increase the forage quality decreases due to lower energy values and declining feed intake.  So, when feeding low quality forages such as old cane hay or corn stalks it is important to provide energy supplements in the form of beet pulp, distillers grains, corn grains or molasses based liquid supplements for example. However, on low ADF and NDF, high quality forages little to no supplementation is needed to support animal maintence and production performance.

Feeding the Bugs Part 2: 7 Feed Additives to Modify Rumen Metabolism

The two most common issues that occur when feeding ruminant animals are bloat and acidosis.  Bloat is the result of gases not being able to escape from the rumen.  It can occur on a forage-based diet due to rapid fermentation of soluble protein and readily available carbohydrates resulting in a frothy entrapment of rumen gases.  In the feedlots, bloat is typically a secondary symptom to rapid starch fermentation and acidosis and froth may or may not be present. Acidosis occurs on grain-based diets and is the result of decreased pH in the rumen due to rapid starch fermentation and excess lactic acid presence in the rumen. While bloat is an issue on forage diets, ruminants were adapted to consume a mostly forage diet, but it is not conducive to efficient animal production.  Therefore, cattle are often placed on high grain diets for growing and finishing at a high rate of efficiency. Along with increased production on a grain-based diet comes the increased incidence of acidosis and bloat.  Here are how 7 feed additives modify the fermentation process in the rumen to prevent bloat and acidosis.

 

  1. Proanthocyanidins also known as condensed tannins, are found in plants such as apples, tree bark, grapes and cranberries. These compounds when present in the rumen at 1-5ppm DM intake, can precipitate soluble protein thereby preventing the accumulation of froth decreasing the incidence of bloat. We are in the day and age where crop improvements are often from manipulation of genetic material to suppress unwanted plant characteristics such as in low lignin varieties of alfalfa and corn. Currently, the consortium for alfalfa improvement is researching the possibility of varieties expressing condensed tannins to prevent legume bloat.  This variety may be available in 8 to 10 years if the process proceeds in a similar way to the low lignin varieties.

 

  1. Poloxalene is a surfactant which breaks up the soluble protein froth thereby preventing pasture or legume bloat. It can top dress a ration or be offered in a molasses lick.

 

  1. Ionophores are a chemical compound that inhibits the growth and activity of gram-positive bacteria in the rumen. Gram-positive bacteria only have one outer cell membrane as opposed to gram negative bacteria that have two and are therefore not susceptible to the effects of ionophores on the bacterial cell. Common gram-positive bacteria in the rumen include cellulolytic bacteria and methanogens.  Therefore, the fermentation pathways in the rumen are shifted so that less methane gas is produced and more useful compounds such as volatile fatty acids, which can be utilized by the animal are produced.  Ammonia producing bacteria in the rumen also tend to be gram-positive and consequently less protein is degraded to ammonia and by-pass protein increases.  Ionophores were originally fed because they change the feed intake habits of the animal to consuming smaller amounts throughout the day which decreases acidosis occurrence.  The ultimate result of feeding ionophores on animal production is decreased feed intake, increased rate of gain and thereby improved feed efficiency.

 

  1. Buffers include bicarbonate, limestone and magnesium oxide. These compounds increase rumen pH, decreasing acidity. When animals are fed buffers, cellulolytic bacteria populations increase, amylolytic bacterial populations decline and the rate of starch fermentation decreases resulting in less incidence of acidosis.

 

  1. Direct Fed Microbials (DFM) are just as they sound, the purposeful feeding of specific microbial species to alter ruminal microbe populations. When feeding DFM the bacterial population is meant to shift from lactic acid producing bacteria to lactic acid using bacteria thereby preventing acidosis. With this feed additive results vary, and they do not always exhibit an impact on acidosis.

 

  1. Enzymes that are meant to break down fibers are sometimes fed to increase forage utilization in the rumen.

 

  1. Essential Oils are naturally occurring plant secondary metabolites. They are not well understood, and research results are varying. They are currently thought to have the potential to alter rumen fermentation pathways, but the mechanism is not known.

 

Although the above feed additives can help prevent bloat and acidosis, they can not replace a properly formulated step-up ration and diet or production practices such as backgrounding.  One of the best ways to prevent these aliments is to test feed ingredients and formulate a diet plan that moves animals from a low energy forage-based diet to a high energy high-grain diet gradually.  This allows those intermediate acid utilizing bacteria with a slower turn over rate to catch up with the diet and reduce the chances of acidosis.