April Snow Showers Bring Stress and Scours

This spring we have had some very untimely snow storms.  Some have even been historical, such as the blizzard that hit most of the midwest including Minneapolis as I was traveling to the Montana Nutrition Conference and Livestock Forum.  Unfortunately, I was not able to attend the conference as my airplane was diverted and the rebooked flights canceled, TWICE! So now here I am some how stuck over a thousand miles from my destination (Bozeman, MT) in the upper penensula of Michigan.  However, this was a minor inconvenience for me compared with the obstacles cattle producers face this season.  Through social media I have read countless stories about ranchers doing all they could to save calves and help cows in these snowy, windy, unseasonably cold conditions.  I have read about ranchers who were out rounding up newborn calves that were struggling as the storm began to roll in.  Some of those producers wrote of feelings of sadness and failure as they lost visibility and it became unsafe for them to be out in their pastures attending to their livestock. Other farmers, were able to get their calves in a hoop house shelter or barn to ride out the storm.

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Joeseph Skroch’s calves in a barn riding out the blizzard in central Minnesota.

While the storm has past, producers are not in the clear just yet.  Weather events such as this blizzard put extra stress on cattle.  The increased levels of cortisol in the animal’s system suppresses the immune system leaving them more susceptible to other infectious agents.

In mature cattle, the suppressed immune system is often taken advantage of by infectious agents resulting in a respiratory disease.  Bovine Respiratory Disease Complex (BRDC) can be caused by viral infectious agents (Bovine Respiratory Syncytial Virus (BRSV), Parainfluenza 3 (PI3), Infectious Bovine Rhinotracheitis (IBR)), bacterial agents (Pasteurella multocida, Mannheimia haemolytica, Histophilus somni, Mycoplasma bovis) or a combination of any of the above.  

In calves, this increased level of stress and suppressed immune system culminates as diarrhea, or calf scours.  With the storm, chances of calf scours increases if the dam is shortchanged nutritionally resulting in poor quality milk for the calf.   If the dam is low on protien and energy, she cannot produce milk containing the nessicary antibodies to protect the calf.  Therefore, especially after this storm event it is important to ensure a well formulated diet for the cow.  Opportunistic infectious agents can also play a role in calf scours and can be bacterial (Escherichia coli, Salmonella, Clostridia perfringens), viral (Rotavirus, Coronavirus, Bovine Viral Diarrhea (BVD), IBR) or parasitic (Cryptosporidium, Coccidia).

When cattle are already under extra stress due to the weather, it is important to not add any additional stress through poor nutrition.  Be sure to formulate precise and accurate diets for both the cow and calf through feed testing and consulting at Ward Laboratories Inc.  A good ration to avoid nutritional stress will provide ample protein, and energy to meet physiological requirements of the animal.  It is also important to provide minerals in the diet to support the immune system. When the immune system is supressed from stress due to the changing weather, absorption of minerals vital to immune function such as magnesium, selenium, copper and zinc are supressed.  A combination of stress and imporper nutirition can render a good vaccine schedule useless.  In addition to providing a high quality diet, avoid feeding questionable feeds containing mold or aflatoxin as these agents may not directly cause illness or death, they can contribute to the suppression of the immune system resulting in respiratory symptoms and reduced reproductive productivity.  While no one can truly be prepared for all adverse weather events.  Producers can always utilize all their knowledge and resources to move forward after an event such as this spring’s blizzard and snowstorms.  Now hopefully I will have made it back to Kearney, NE by the time you are reading this post and we are done with all of this cold weather and on to summer forage production!

 

Spring Calving and Magnesium: 5 Risk Factors for Grass Tetany

As they say, “spring has sprung!” That means the birds are out chirping, summer is on its way, baby calves are on the ground and lush, green pastures ready for grazing.  While this does paint a picturesque image, cattlemen know there’s a danger in those beautiful, green spring grasslands: a nutritional disorder known as Grass Tetany, Grass Staggers or Hypomagnesaemia.  Grass Tetany is a deficiency of magnesium in a cow’s body that causes them to stagger, look alert and become easily excitable and often results in death.  Magnesium is a required mineral for beef cattle.  It is involved in many enzyme activations and therefore important biological processes.  Magnesium is particularly involved in nerve and muscle impulse transmissions. There are 5 risk factors for developing this deficiency:

  1. Age or Maturity of the Cows

Older cows that have produced 2 or more calves in prior calving seasons are more at risk to develop a magnesium deficiency during lactation.  As a beef cow moves from the gestational to the lactational physiological state, magnesium requirements increase from 0.12% to 0.2% of the dry matter intake.  Older cows have a more difficult time mobilizing stored magnesium from bone to meet these increased requirements.  In beef cattle 65-70% of the body’s magnesium is stored in the bone. While the diet may technically meet requirements, without mobilization of stored magnesium grass tetany can develop.  More mature cows have more difficulty with this biological process.

  1. Fertilization Protocol of the Pasture

In soils, the fertilization protocol can greatly affect the minerals available in the grasses grown on that pasture.  High levels of potassium, nitrogen and to a lesser extent phosphorous in the soil can interfere with a plant’s ability to absorb magnesium.  This creates a forage that is low in magnesium and high in potassium and nitrogen.  Therefore, it is recommended that pasture fertilization protocols be managed with the use of soil testing at Ward Laboratories Inc. to prevent over use of nitrogen, phosphorous, and potassium (NPK) fertilization.

  1. Manure Management on the Pasture

Similar to over fertilization of pasture ground, over accumulation of manure from previous grazing seasons can also result in decreased magnesium in the grasses produced. Manure is going to add nitrogen, organic acids, and long chained fatty acids to the soil, which will also decrease the absorption of magnesium by growing grasses.  Resting a pasture,that has a high manure load, can help alleviate this risk for the next grazing occurrence.

  1. Species of Grasses

Plants deficient in magnesium tend to be rapidly growing cool season grasses.  Some species commonly involved with magnesium deficiency are orchard grass, rye grass, timothy grass, fescue grass, crested wheatgrass, brome grass, and small grain producing varieties such as oats, barley or triticale.  To decrease the risk of developing Grass Tetany, it has been recommended that producers introduce legumes to the pasture at a rate greater than 30% since species, such as alfalfa, are not typically deficient in magnesium with the NRC average being 0.37% of dry matter.

  1. Forage Nutrients

Pasture grasses with dry matter mineral concentrations of less than 0.2% magnesium and greater than 3.0% potassium are known to cause Grass Tetany.  Just like in soil, excess potassium in the diet interferes with magnesium absorption and forces cows to rely on mobilization of stored magnesium for lactation.  You can send your forage samples to Ward Laboratories Inc. to test for mineral concentrations to determine if your forage matches that profile.  If so, feeding a high magnesium free choice mineral may be necessary.  Magnesium concentrations in those minerals typically range from 8-12%.  Magnesium Oxide is typically the compound added to the mineral mix and is unfortunately unpalatable and therefore, as a producer if you may need to get creative with how you are going to get that magnesium into those cows, for example mixing it in with a protein supplement if free choice mineral intake is low.

In conclusion, there are 5 risk factors for development of Grass Tetany: maturity of cows, fertilization protocol on pasture, manure on pasture, species of grasses and forage mineral concentrations.  Ward Laboratories Inc. can help you manage your pasture with soil testing and your forage with feed analysis.

 

 

Forage Creativity: Soy-Corn Silage

Here at Ward Laboratories Inc., we often encourage producers to be creative and try newapproaches to agricultural production.  A couple of weeks ago at the American Society of Animal Science Midwest meeting in Omaha, I listened to a talk about getting more creative with corn silage: “Production of High-Quality Forage through Unique Forage Blends” presented by Dr. Ishwary Acharya.  Ward Laboratories Inc. tested 1,451 corn silage samples and 2,197 total silage samples of all types in 2016.  So, I have seen the range and variation in the nutrient quality of silages used in the area.  Dr. Acharya’s research focused on making the best possible silage for a dairy operation, as he stated in his talk, “the ultimate measure of forage quality is milk production”.  Being in central Nebraska, I think his research could not only increase the nutritional content of the silages produced, but also the value of grazing the cornstalks by a beef enterprise after harvest.

The idea behind Dr. Acharya’s presentation was to double crop corn and vining soybeans to produce high protein low fiber silage without sacrificing yield.  First, to produce the best possible corn silage, the crop was chopped higher than producers typically chop corn silage.  This resulted in less stock and more leaves, husks, and cob in the silage.  Therefore, yield was compromised for higher protein and lower fiber concentrations.  The second part of the presentation explained that to overcome the sacrifice of yield, vining soybeans could be intercropped with the corn.  Therefore, when chopping for silage at a higher level, the soybean plant material made up for the loss of stocks in the yield.  In this study, the resulting silage had increase yield, forage quality, and protein compared with typical corn silage.  Dr. Acharya interseeded the vining soybean at various rates and determined that the optimal rate was somewhere between 67% corn 33% soybeans and a 50:50 mix.  The study also looked at the optimal time for fermentation based on pH and presence of volatile compounds that have affect on rumen function and animal performance.  At 60 days of fermentation Dr. Acharya determined that fermentation had not gone to completion and the silage should be ensiled for at least a 90-day period.  This finding agrees with other literature I have read on the topic.

Dr. Acharya’s idea of double cropping to create a high-quality forage source for dairy cattle could also be of benefit to beef cow calf pairs grazing the remaining corn stalks.  If soybeans were intercropped, I would predict that there would be some beans and vining materials left in the field which would be higher in protein and lower in fiber than the corn stalks alone.  Of course, I would advocate that producers test both their silage and try to get a representative idea of what has been left on their field to provide necessary supplementation.  For the silage, I would recommend testing crude protein, acid detergent fiber to predict energy values and neutral detergent fiber to predict dry matter intakes at a minimum noting that the sample would need to be ran as a wet chemistry feed test and that the addition of soybean to the silage would not allow for a reliable and accurate NIR scan.  For the grazing stocks and soybeans, I would run the same test to get an idea if protein or energy supplementation are necessary.  I would also caution that soybeans do contain urease and we typically do not graze cattle on soybeans fields as they risk urease toxicity if they have recently consumed non-protein nitrogen (NPN), therefore when considering supplementation strategies for cattle grazing a field of cornstalks intercropped with vining soybeans, lick tubs or mineral mixes with urea could not be utilized.

As, with any novel feed, always monitor animal body condition, production and health to ensure it is providing the nutrients required.  Don’t be afraid to try something new.  It might be of benefit to your operation weather it is vining soybean corn silage or grazing cover crops or feeding from the waste stream, feed testing and good ration and diet formulation can lead to success of a livestock operation.

2018 KSU Cattlemen’s Day

The highlights of this year’s KSU Cattlemen’s Day were the tour of the Feed Intake Measurement Facility given by Dr. Bob Weaber and the necropsy demonstration given by DVM A.J. Tarpoff.  The take away I want to reiterate to any livestock producers is that a post-mortem exam is crucial in determining the cause of death to an animal and identifying how we can prevent it from happening again.

Feed is the number one input cost to raising beef cattle, and improvements in the feed conversion to product can result in increased profits for beef producers.  This makes the research on feed efficiency at KSU very important and promising to steakholders.  The difficulty with improving feed efficiency, is that is is dependent on feed intake and gain, therefore to impact efficiency or feed conversion rate, cattle need to be selected to either gain more than average while consuming the average amount of feed, consume less than average while gaining weight at an average weight, or both gain more and consume less at the same time.  Touring the Feed Intake Measurement Facility was like a trip down memory lane for me.  When I was working on my masters’ project at the US Meat Animal Research Center, my steers feed intake was monitored using the same Insentec feeding system that is featured at the KSU facility.  The Insentec system uses RFID tags to keep track of each animal each time they come to the feeder.  The feed bunk is automatically weighed before the animal begins consuming feed and then after the animal is finished.  This results in many data points for each feeding event for each animal which is then condensed into average daily feed intake over the trial period.  What sets this research facility above others is their ability to also monitor water intake as well as the ability to put cow calf pairs on the lot and monitor their feed intakes as well.

The presentation by Dr. Tarpoff, Using Postmortem Examination to Enhance Heard Health Management, is a presentation I wish all producers could have attended.   All too often I receive a phone call with someone asking to test their feed to determine what killed their cattle, without having consulted their vet first.  A necropsy is a vet bill worth paying.  Dr. Tarpoff stressed the point that even if you believe it was a death due to bloat, you must first use necropsy findings to rule out other possibilities.  He said that even if a death appears to be a bloat that could just be the feed fermenting in the animal after the animal’s systems have begun shutting down.  Using information from a post-mortem exam can aid in making the best possible production decisions to prevent death losses in the future.  It is imperative that you work with your vet when problem solving animal health issues.  At Ward Laboratories Inc.  we can test for several animal health issues in feed such as nitrates, prussic acid, high mold and aflatoxin, but often all of these come up without answers and it is too late to perform a necropsy by the time our results are sent out. Use our lab tests to confirm what your vet determines. Dr. Tarpoff recommends a necropsy on a dead animal be performed as soon as possible and at a minimum within 24 hours of death.

This year’s KSU Cattlemen’s day, did not focus on nutrition, however I believe it was very valuable for producers who attended, and I would encourage any beef producers looking to make improvements to their production to attend this event in the future.

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Trade Show

Cattlemen’s Day 2018 Beef Cattle Research

 

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.

Feeding the Bugs Part 1: Exploring the Interactions of Rumen Microbes

Soil microbes are all the buzz these days, but what about rumen microbes?  Currently, it is very common to go to a ruminant nutrition meeting and hear about feeding the microbes first.  This is especially the case with the NRC Nutrient Requirements of Beef using the microbial protein and bypass protein system.  There are four groups of microbes that can be found in the largest compartment of the four-chambered stomach, the rumen.  These groups are bacteria, protozoa, fungi, and archaea. These microbes make up a diverse microbial community that behaves synergistically to prevent feedback end-products of fermentation, and to ensure rapid fermentation and digestion of feed.  Understanding how these microbes perform and interact in the rumen can help producers to understand why certain feeds have the effects that they do in the rumen, for example why acidosis or bloat is more likely to occur on certain diets and how a step-up ration can help prevent these digestive issues.

Bacteria are small in size and replicate quickly making them the most populous microbe in the rumen at about 100,000,000,000 cells / mL of rumen fluid.  Therefore, they play an important role in ruminal fermentation.

Cellulolytic bacteria are important to the breakdown of the fibrous structure of the plant material.  They adhere to forages to avoid predation by other microbes and utilize cellulase, a membrane bound enzyme, to breakdown plant fibers.  Populations of cellulolytic bacteria are highly affected by rumen pH.  On high forage diets, lots of ruminating is needed to breakdown the feed into small particle sizes for fermentation resulting in lots of buffering saliva present in the rumen allowing cellulolytic bacteria to thrive.  On high grain diets, cellulolytic populations decline as pH decreases and the rumen becomes more acidic. Important species of cellulolytic bacteria include Fibrobacter succinogenes, Ruminococcus albus, and Ruminoccuc flavefaciens.

Hemicellulolytic bacteria degrade hemicellulose into sugars, which can be used as a substrate of fermentation by other microbes in the rumen.  Most Ruminococcus bacteria fall into this category.

Amylolytic bacteria can utilize ammonia as a nitrogen source, and amylase, a secreted enzyme, to breakdown starches.  Like cellulolytic bacteria, their populations are also regulated by pH.  Inversely to cellulolytic bacteria, amylolytic bacteria are more prevalent on a high grain diet and decline with increasing pH and rumen buffers.  Amylolytic bacteria produce lactic acid which sometimes results in lactic acidosis.  Streptococcus bovis is an important species of amylolytic bacteria.

Intermediate acid utilizing bacteria are also very important to rumen fermentation.  These species utilize lactic acid, and succinyl acid as a fermentation substrate.  Intermediate acid utilizing bacteria are key to adaptation to high grain diets, however their reproductive rate is significantly slower than other bacteria, making production management such as backgrounding or implementing a step-up ration that much more important in the prevention of acidosis.  Important species of intermediate acid utilizing bacteria are Megasphaera elsdenii and Selenomonas ruminantium.

Proteolytic bacteria are very important in the rumen as they breakdown protein into peptides, amino acids and ammonia for growth by other rumen microbes. They also produce branched chain fatty acids which stimulate the growth of cellulolytic bacteria.  Some important proteolytic species are Peptostreptococcus and Clostridia.

Ureolytic bacteria only make up 5% of the rumen microbial population and are associated with the rumen wall.  These bacteria can break urea into ammonia and carbon dioxide allowing other microbes to utilize the ammonia as a nitrogen source.

Lipolytic bacteria use both secreted and membrane bound lipases to breakdown fat.

Protozoa make up a smaller proportion of the rumen microbe population than bacteria, but 50% of the microbial mass due to their larger size.  Protozoa cannot utilize non-protein nitrogen in the form of urea or ammonia.  They also predate smaller microbes such as the bacteria discussed above.  Most protozoa digest non-structural carbohydrates such as sugars and starches.  They play a role in acidosis prevention by sequestering some starch away from amylolytic bacteria. There are two classes of protozoa associated with fiber digestion.

Holotrichs have a long replication time, and are very sensitive to low pH, acidic environments. Therefore, exist mainly on a high forage diet and are not present in animals fed a high grain diet.

Entodiniomorphs have a short replication time and a greater population than Holotrichs.  They are also more tolerant of low pH environments. Therefore, Entodiniomorphs are present in the rumen on a high grain diet but are less prevalent.

Fungi have very low populations in the rumen but are very important to fiber digestion.  Fungi utilize their hyphae to physically separate strands of fiber.  Picture the stem of a mushroom as the hyphae and the log it is growing out of as the cellulose bundle it is breaking down.  Fungi also produce cellulase, an enzyme for breaking down the fibrous portion of the plant.

Archaea are not very populous in the rumen, but their impact on the efficiency of fermentation is very important. Archaea are the major methanogen producers in the rumen.  They utilize hydrogen produced by cellulolytic bacteria to produce methane gas, which is eructated by the animal.  This eructation, is considered an air pollutant by staunch environmentalists and a source of decreased production efficiency by producers.  The ionophore Monensin can be utilized to decrease methanogen numbers.  Important species of archaea are Methanobrevibacter and Methanomicrobium.

The four groups of microbes present in the rumen, bacteria, protozoa, fungi and archaea, play a major role in how ruminants utilize various feeds especially forages and high starch concentrate.  An understanding of microbial roles and interactions in the rumen can help a producer understand the importance of feed testing when formulating a new ration, changing the ruminant’s diet from forage-based to grain-based, and preventing acidosis or bloat.

Get the Scoop on Using Your Poop

Phewy! Smell that? From an early age, we are often told the old phrase “That’s the smell of money!” Although this phrase is often used to indicate cattle profits, the manure in those pens also holds a wealth of resources that can help enrich and strengthen your soil. Once used routinely in integrated farming systems, manure plays a critical role in returning nutrients to the soil. With the shift from integrated livestock and row crop farms to separated specialized operations, the natural cycle of many nutrients has been disrupted. This separation of practices has led to an overabundance of manure in some areas and a lack of nutrients in others, causing a shift to synthetic fertilizer use. So, what does manure do to our soil?

Manure is an important source of raw or partly decomposed organic matter. The nutrients in manure can vary depending on the animal type, health, age, feed ration, bedding and water content. In addition, the various management practices associated with handling manure, manure storage, duration of storage, application amount, application technique and weather can all dramatically alter the nutrient content in manure and thus the amount of nutrients available in the soil and for future crop use. Understanding and applying the correct amount of manure to your fields can be accomplished by testing your manure prior to application. You would be surprised how much it can vary! The table below highlights the difference in nutrient levels found in beef cattle manure that we have processed at the lab in the past five years. Want to see how swine, poultry, dairy cattle, or compost fared? You can check it out here.

Beef Manure

 

First, let’s set the stage. Before manure ever touches the soil, soil fauna (e.g. ants, earthworms, arthropods etc.) and microbial populations (e.g. bacteria, fungi, viruses) naturally exist in your soil. These populations, or communities, are incredibly diverse and have varying community structures that reflect your soil quality, or “soil health”. The majority of the microbial populations exist within the top few inches of your soil, clustered around the root structures of plants, known as the rhizosphere. Soil microbial activity is responsible for the main decomposition of all litter inputs into the soil. Larger fauna in the soil are important for the preliminary break down of residue into small pieces, creating greater surface area for microbial activity. They also move fragments of litter throughout the soil structure, exposing the litter to larger microbial communities, which provides a natural incorporation without resorting to mechanical methods. When food is scarce (e.g. winter months when no living plant is present), microbes have the natural ability to enter a low energy requiring comatose-like state to preserve their nutrient supply until food is readily available again.

Initial introduction of manure is a feeding frenzy for soil microbes. Manure not only contains a large amount of macro and micro soil nutrients but also inoculates the soil with microorganisms excreted by livestock. The nutrients in manure, although processed by the host, require a suite of soil microbe activity to alter the chemical structure of nutrients to make them available for microbe and plant use. Much like hungry teenagers at a buffet, microbes attack the most easily accessible forms of food first: sugars, starches and other soluble nutrients. This initial process is often rapid. Once these resources have been used, the breakdown of more complex soil compounds begins and is a slower process like preparing a box of mac and cheese. It takes time and a little bit of effort. This process includes the breakdown of cellulose and hemicellulose, both found in plant tissues. Lastly, complex compounds, such as tannins and lignins (found predominantly in woody plant species) are broken down. This process occurs over a long period of time and with a lot of help. It’s almost like preparing a Thanksgiving feast. This process requires the specific activity of select microbes (e.g. White Rot) to breakdown these compounds.

Microbes are very similar to people in the way they act. Although the main end product of aerobic (or oxygen loving) microbial activity is to release carbon dioxide (CO2) and water, microbes require nutrients to support growth, maintenance and reproduction. Thus, microbes make a living by harvesting carbon and other nutrients from the soil organic matter. Microbes are responsible for converting many minerals from organic to inorganic forms (often referred to as “mineralization”) that are easy to take up for both the microbe and plants. For instance, microbes need N to meet many microbial needs (e.g. protein building). If there is an abundance of N in the organic matter, extra microbial processed N, in the form of ammonium-N (NH4+-N), is released into the soil environment. Due to the close proximity of microbial communities and plant roots, the released, easily available N is taken up by the plant. Increases in nutrient sources, such as the addition of manure, stimulates microbial growth and reproduction, resulting in a larger, more active microbial community. Larger populations lead to greater microbial turnover, in which the death of the microbe releases nutrients gathered during its lifetime and can now be utilized by plants.

In addition to the minerals microbes liberate for plant use, manure and microbes can also help build your soil structure. Increased presence of organic inputs promotes microbial activity and decomposition. During this process, polysaccharides are produced as a by-product and help bind macroaggregates together in the soil. Polysaccharides  are sticky, glue-like substances that form bridge-like structures between aggregates and are resistant to degradation in the soil. The accumulation of this activity creates a snowball effect in the soil. Stabilized aggregates create tunnels that increase soil porosity, soil water holding capacity, nutrient cycling and nutrient availability to microbial communities. In turn, these characteristics support an improved soil drainage system, a decrease in bulk density and compaction, and a decrease in soil crusting and erosion.

The rate at which decomposition occurs in the soil is dependent on the quality and composition of the manure, the microbial community structure, weather and time. This rate causes manure to act like a slow release fertilizer, ensuring all the nutrients are not lost during initial application or shortly after. A manure analysis report often provides a “First Year Availability” value to help you understand and apply the correct quantity of nutrients needed for your crop. These manure mineralization approximated values are calculated based on similar mineralization rates found in research for each manure type. If you like to apply manure in the fall but are concerned about potentially losing nutrients due to soil moisture and microbial activity, consider incorporating cover crops into your rotation to help cycle nutrients in the soil. As they breakdown in the winter and spring, they will release the nutrients consumed from your manure application while supporting a healthy, thriving soil microbial community.

Applying manure to your soil can be an efficient way of stimulating an active, healthy microbial community while providing nutrients to your crop. Manure quality is dependent on various factors that contribute to the dominate microbe community and nutrient forms. Be sure to properly analyze your manure before you apply to ensure you are getting the most out of your valuable resource. Understanding and properly applying manure could help save fertilizer costs in the future while boosting your soil microbial community resiliency and soil health. So go ahead and take a deep breath. That’s the smell of money.