West Texas Rangelands
West Texas RangelandsWe hope to provide a variety of information from current news stories, prescribed burning, wildfires, brush control, and cow-calf management!

Why I Ranch…Dr. Jake Landers

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Dr. Jake Landers

After a 30-year career with Extension, I hope I have half the brains, sanity, and passion that my dear friend and colleague, Dr. Jake Landers possesses.  Dr. Landers set the bar pretty dang high and it is an honor to learn from him in the pasture and in the classroom.  As I said in an earlier post, Dr. Landers morphed into a Range Father of mine overnight.  The second I met him he was my hero.

Dr. Jake Landers served as an Extension Range Specialist at the Texas A & M Research and Extension Center, San Angelo in 1979.  He developed techniques and procedure for individual plant treatment of brush and prickly pear cactus for ranchers in 17 counties.  He initiated prescribed burning as a procedure for managing rangeland to reduce undesirable species and stimulate grasses.  He wrote short articles for newspapers and magazines and continued writing after his retirement from the Extension Service.  He was recognized as the outstanding person in Range by the Texas Section of the Society for Range Management in 1990 and Sustained Lifetime Achievement Award by the parent society in 2016.

Jake described himself as a gentleman rancher at best, but I beg to differ.  His Dad was in full charge until Jake was 60, and his brother Fritz assumed the duties until they divided up 20 years later. Since then Dr. Landers has helped decide when and where to graze and when and where to burn, control mesquite and pricklypear. Dr. Landers is not trying to make a profit, but he is still learning and operating by experiment.  Most of which I am convinced is adaptive management, but Jake makes it look so dang easy, fun, and effortless that it is more stewardship than anything.

How did you get your start in ranching?  I learned a lot about raising sheep, goats and cattle growing up on the ranch until I was 18. I had intended to get a degree and come home to ranch. But the drought and other interests kept me in school until I was independent of making a living  on the ranch.

How important is agriculture to your family?  Agriculture was important growing up because it was 95% of our income. Now it is important as an enjoyable experimental hobby.

What makes ranching in West Texas so unique? Speaking more of the Edwards Plateau, the mix of vegetation allows raising of cattle sheep and goats while keeping a viable white tailed deer herd for hunting.

Do you feel like there is enough emphasis on agriculture in K-12 education? Not in the least. My experience with teachers in conservation workshops indicates that most do not have an adequate background in agriculture to provide the information.

Who did you learn the most from along the way? I learned about plants mostly on my own. I learned a lot working on programs with county agents and a lot about burning from Larry White, Range Extension Specialist at Uvalde.

Outside the Fire…Duff Hallman

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The Duff Ranch, located in Tom Green, Schleicher and Irion counties, received the Texas Department of Agriculture’s Family Land Heritage Award last fall for continuous operation by the same family for 100 years. The Duff Ranch was established in 1904 by Sam Houston Henderson 13 miles east of Eldorado. Sam accumulated more than 100,000 acres during his lifetime, where he ran 6,000 head of cattle. Today, Duff Hallman and Trip Hallman have operated the ranch since 1975.

Duff is a licensed and insured private prescribed burn manager through the Texas Department of Agriculture.

How did you get introduced to fire? Dr. Jake Landers at a field day at the San Angelo Research and Extension Ag Center

Do you make special plans for fire in your management plans well in advance, or take advantage of good fuel and weather conditions as they come? It is a combination of both; planning ahead for proper fire guards is ongoing whether it is a summer or winter burn and if fire is one of your methods of range improvement you seize opportunity when it knocks.

What’s the hook for you on fire? The hook for me is cost and results.Customary methods of conservation work are not cheap and cost share is fading. Burning must be a long term systematic approach.

In your opinion, what makes a successful fire? A successful fire is one that accomplishes the goals set out in the planning of the burn. I have never had a bad one. 

Who in your burn circle/crew would you never burn without?  My weather monitor and one of my sons who I am teaching this practice to. 

Why I Ranch…

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Frank and Sims Price Ranch

In 2012, Price Ranch was recognized for their range management when they were presented the Outstanding Rangeland Stewardship Award by the Texas Section, Society for Range Management and Texas and Southwestern Cattle Raisers Association. And it was recognized as a 2013 regional Environmental Stewardship Award Program (ESAP) winner during the 2013 Cattle Industry Summer Conference.

How did you get your start in ranching? The Price family began ranching in 1876. Frank Price has managed his family’s ranch for 40 years, first in partnership with his father, and then in partnership with his son Sims in 2011. Together, they run their cow-calf operation on 68,000 acres. Sims and his wife Krista are the fifth generations of Prices on the ranch, which they operate in four counties. The ranch operates with three primary income enterprises including sheep, cattle, and hunting. 

How important is agriculture to your family?  The Price family has two primary goals. First, the ranch is operated as a separate business, self-sustaining, and is expected to show an annual profit. Second, but equal, their goal is to leave their natural resources in the best possible condition for the next generations.The family is dedicated to these goals. They have recently started using Environmental Quality Incentive Program (EQIP) dollars to make continuous improvements to the ranch, and they also use controlled and prescribed burning to their benefit by adjusting their livestock grazing charts to include speed of moves, flash grazing, animal density and total deferment.

What makes ranching in West Texas so unique? In a normal year, they receive 18 inches of rainfall. These last two years have been abnormal, with exceptional drought and devastating wildfires, particularly in their area,” said Texas and Southwestern Cattle Raisers Association President Joe Parker, Jr. “Even though they had to reduce their herd to protect their land, they still found lessons in flexibility during the adversities. The Price family’s experiences with wildfire lead them to be a leading voice in Texas on inter-agency cooperation in fighting wildfires. We are glad to have his practical and sound leadership in such an important area.” The father-son partnership at Price Ranch represents the fourth and fifth generations of Prices to ranch in west Texas.

Jimmie Powell – Thee Man

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Mr. James L. Powell accepted the Foy Proctor Memorial Cowman’s Award of Honor in Midland last week and some of the greatest stories of West Texas were shared.

I first met Mr. Powell on a prescribed burn south of San Angelo and the man is just cool.  He is humble, gracious, hard-working, not to mention, a legend. He even has his own chapter in the Texas Cattle Barons book.  But in my book, he is right up there with John Wayne and other cowboy heroes. img_5557

The following is a story he told while at the 20th Fall Gatherin’.

“WWII was underway and all the cowboys who were in their 20s had been drafted if they hadn’t already enlisted.  We were rounding cattle in Reagan and Crockett County.  It encompassed about 64 sections.  The corrals where they loaded the cattle on the train were right in the city limits of Big Lake.  Back then we gathered the calves and weaned them as we worked a pasture.  We had all the calves grouped in a four-section pasture leading in to the corrals.  Now keep in mind it was just myself, my dad, and the foreman on that place and three boys that my dad got out of school that day.  We were handling about 400 head of fresh weaned calves, and we had started mov
ing those calves up the fenceline.  We had them grouped up on the north fenceline about a mile or so from the pens, and about the time they got those calves to the corrals, the train came by.  That engineer blew his whistle three or four times, and there was no way in the world we could hold those calves together.  They went between us and under us and before we knew it they were scattered all over that pasture again.  I know if my father could have caught that engineer, he would have talked to him about that.”

Dr. Jake Landers’ Thoughts on Mesquite

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Dr. Jake Landers morphed into a Range Father of mine overnight.  The second I met him he was my hero.

Dr. Jake Landers served as an Extension Range Specialist at the Texas A & M Research and Extension Center, San Angelo in 1979.  He developed techniques and procedure for individual plant treatment of brush and prickly pear cactus for ranchers in 17 counties.  He initiated prescribed burning as a procedure for managing rangeland to reduce undesirable species and stimulate grasses.  He wrote short articles for newspapers and magazines and continued writing after his retirement from the Extension Service.  He was recognized as the outstanding person in Range by the Texas Section of the Society for Range Management in 1990 and Sustained Lifetime Achievement Award by the parent society in 2016.

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Below, are Dr. Lander’s thoughts on mesquite.  Have a laugh, enjoy the irony, and appreciate the life-long hobby of brush management 🙂

“SOME OF MY DEEPEST THOUGHTS, SOME ON MESQUITE

  1. People who have a kind feeling toward Mesquite, by and large, have not had to make a living on Mesquite-covered rangeland.
  2. Mesquite trees, like West Texas ranchers, have roots deep in the land where we tend to admire and respect tenacity.
  3. Mesquite on rangeland reminds me of athlete’s foot; you can live without treating it for a long time, even a lifetime, but it is aggravating, and it tends to get worse if ignored.
  4. Mesquite shade is a poor excuse for shade.
  5. In a forest of Mesquite trees, none of them grow straight.
  6. The inside of a Mesquite tree when polished is prettier than the outside, unless it’s rotten.
  7. The smell of meat cooking over Mesquite wood coals is as pleasurable as opening a fresh can of your favorite coffee.
  8. I’ve never chewed on a Mesquite bean that I really liked, but it gives you something to do if you don’t have tobacco.
  9. Mesquite doesn’t seem to have any enemies except humans.
  10. A wooden nickel made of Mesquite is worth a lot in China, I’ll bet on it.
  11. If we came up with a sure-fire, cheap method of killing Mesquite, there would be at least one rancher who would complain about losing the beans for his cows during the next drought.
  12. I started making wooden nickels out of Mesquite to get rid of it, now I might have to replant some or borrow from my neighbors.
  13. I keep a few old Mesquite trees just to grow beautiful Mistletoe for Christmas decorations.
  14. Goats have been bred up to consume Cedar, why not breed up a llama to eat Mesquite leaves.
  15. There’s no thorn like a Mesquite thorn; it even hurts when you pull it out.
  16. When Algerita berries don’t make a crop, the Mockingbirds have to depend on Mistletoe berries on Mesquite and Hackberry.
  17. I almost disabled my pickup hitting a Mesquite stump hidden in the grass that grew after the tree was cut down.
  18. If you cut down a Mesquite and don’t paint the stump to keep it from sprouting, you are not going to Heaven when you die.
  19. Real old Mesquite are as rare as real old people, a tiny percent of the whole population.
  20. You would think there would be a disease like Oak wilt that could wipe out Mesquite.”

Thank you Dr. Landers!

Why I Ranch.

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This October we are featuring Mr. James K. Rooter Brite, Jr. from Bowie, Texas.  Rooter is a father, rancher, conservationist, and my friend. The Brite Ranch has been a member of the Texas and Southwestern Cattle Raisers Association (TSCRA) for Rooter’s entire life. He has been a director of the TSCRA since 1999, and has served on their Agriculture and Research and Natural Resources and Environmental committees since 1994. He has served as a director of the Upper-Elm Red Soil and Water Conservation District since 1979. He has served on the Association of Texas Soil and Water Conservation Districts board and on the Texas State Soil and Water Conservation Board. He represents the National Association of Conservation Districts on the National Grazing Lands Conservation Initiative steering committee. Additionally, he serves on the National Cattlemen’s Beef Association, Natural Resource and Environment Committee.

rooter1How did you get your start in ranching? I am a third
generation on this ranch.  I was born and raised on the ranch where my grandfather J.A. Brite purchased in 1929. I took over my dad’s cow herd in the mid-1960s and purchased the ranch from dad in 1974, when I began full-time management of the ranch with my wife, Lynda, and eventually my son, J.K.

How important is agriculture to your family?  Agriculture is about one third of my income.  You have to look at the cumulative value of everything you do on the land. Management decisions you make now will make a difference 30 years from now. It all adds up, whichever direction you go. At an early age I learned the cause and effect of different land management practices. These first-hand lessons I learned from the land stimulated my desire to learn more and be diversified in my management. I apply land management practices that are practical, using common sense. I don’t do things because they are what somebody else thinks might be good. I do things because they work on this land, and that’s what makes the difference.

What makes ranching in West Texas so unique?  The only constant is inconsistency  with the weather and markets. 

Do you feel like there is enough emphasis on agriculture in K-12 education?  There needs to be a much greater attention on ag, but it must be taught by qualified and experienced teachers.

Who did you learn the most from along the way?  By college age, I was intrigued by the land so I enrolled in Texas Christian University’s two-year Ranch Management program. TCU Professor Chip Merrill inspired me to try new things and not be afraid to try something different. I approached the resource management of the ranch using a short-term reactionary response to changing forage, production, and anticipated market condition. My long-term management is of a continuing upward trend in success of native forage. I feel like we can utilize our current management methods and maintain, or in areas of need, improve the productivity of this ranch in an economically and environmentally sustainable manner.

Thank you Rooter!

Are Cows Athletes? -Dr. Travis Mulliniks University of Tennessee

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Dr. Travis Mulliniks, Assistant Professor in beef cattle nutrition and energy nutrition University of Tennessee, poses a very interesting question.

Read below for his incredible insight!!!!  Excellent work by Dr. Mulliniks!

 

Beef cattle in the United States graze a variety of unique environments, which differ in climate, topography, and forage quality and quantity. These differences are accentuated by dynamic and unpredictable weather patterns and thus impact forage production and subsequently increase variability in cow performance. Animals commonly react to these variable conditions by initiating adaptive responses to cope with extreme conditions such as stress (Stott, 1981).  To date, a tremendous amount of research has shown the benefit of adapted breeds of animals to certain environmental stressors.  However, production practices that modify the production environment with purchased or harvested feedstuffs can buffer the coping mechanisms that livestock express. Furthermore, these production practices may start leading to less desirable and stagnant responses to environmental and physiological stresses. 

Dr. Mark Petersen with the USDA-ARS Fort Keogh Livestock and Range Research Laboratory in Miles City, MT has preached that cows are athletes and should be managed accordingly. For most people, that seems like a crazy concept, but when you think about the amount of environmental pressure a cow is expected to perform under coupled with nutrient demands of lactation and reproduction, this concept becomes clearer. If athletes train to have an increased adaptive capacity and tolerance to stress, why don’t we manage cows in a similar methodology to increase their adaptive resilience to environmental stresses?  However, common livestock practices tend to manipulate livestock’s nutritional environment to a degree that may completely buffer their capacity to become more adaptive and ultimately less energy efficient.  In human fitness, an interesting aspect of skeletal muscle is its adaptability. If a muscle is stressed (within tolerable limits), it adapts and improves function.  Conversely, if a muscle receives less stress than it’s used to, it atrophies. Therefore, adaptation requires a systematic application of environmental stress that is sufficient enough to elicit an adaptation, but not so severe that a loss in production occurs.  If the stress is insufficient to overload the body, then no adaptation occurs, which is where a lot of our cow-herd management practices leads us.  So can we use a model for capacity adaptability and environmental stress to increase energy efficiency and longevity of the cow herd?  Is the “feed them to breed them” mentality decreasing efficiency and/or the cow’s inherent capacity to cope with environmental stress?

Research

Adaptive capacity confers resilience to nutritional insults, given that livestock have the ability to modify their nutrient requirements with minimal losses of production.  Petersen et al. (2014) illustrated that cows experiencing a dynamic environment are coping with the change by altering nutrient requirements compared with those that are in relatively static surroundings. Conversely, cows managed in the more controlled situations or static environment have a decreased aptitude for energy utilization efficiency.  To illustrate this, Mulliniks et al. (2015) utilized datasets from research stations in New Mexico and Tennessee.   Although, nutritional supply during the breeding season is much greater in TN, pregnancy rates were significantly less (88 vs 96% in TN and NM; respectively) in TN than in the nutrient restricted environment of NM.  Input cost to achieve these production measures has to be taken into account in calculating efficiency differences.  Current annual cost of production in Tennessee is $800/cow; whereas New Mexico is roughly half at $440/cow.  In addition, Mayfield (2012) reports that longevity in the Tennessee herd was only 3.5 year, which is quite a bit lower than the 61% retention rate of the heifers remaining in the herd after 5 year of age (Mulliniks et al., 2013a).  Thus, illustrating short- and long-term effects of adaptive capacity on cow-herd productivity. 

So what happens if we take environmentally adapted heifers out of their dynamic environment and develop them in a static nutritional environment?   In New Mexico, Mulliniks et al. (2013a) showed the impact of programing animals to fit their given production environment. These researchers developed yearling beef heifers on native range receiving one of two protein supplements (low-rumen undegradable protein vs high-rumen undegradable protein) or a control set of heifers developed in a feedlot.  During the developmental treatment period, heifers developed in the feedlot had increased average daily gain (1.5 lb/d) from the initiation of treatments to the start of breeding compared with range-raised heifers consuming low-quality range with protein supplementation (0.58 lb/d).  Even with the low average daily gain until breeding, retention rate through 5 years of age for range-developed heifers fed a high-RUP supplement was 68% compared with 41% heifers fed a lower-RUP supplement and 42% for heifers developed in a feedlot (see Figure 1 below).  This study indicated the short- and long-term impact that developing heifers to fit their environment can have on biological and economic efficiency.

 

Figure 1. Retention rate of heifers grazing native dormant range with two types of protein supplementation (36RUP and 50RUP) or fed a growing diet in a drylot. Values shown in breeding yr 1 are heifer pregnancy rates.  Breeding years 2 through 4 are proportion of the original heifers treated that were remaining at end of breeding in yr 2, 3, and 4. Retention tended (*P > 0.08) to differ among treatments in breeding yr 1 and 2, but was greater for 50RUP than 36RUP and DRYLOT cows in breeding yr 3 and 4 (**P < 0.01). 36RUP = 36% CP cottonseed meal base supplement fed 3 d/wk supplying 36% RUP; 50RUP = 36% CP supplement fed 3×/wk supplying 50% RUP; DRYLOT = corn silage diet fed in drylot to gain 0.68 kg/d. Adapted from Mulliniks et al. (2013).

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Flexible and opportunistic strategies are necessary for successful management in variable environments. Successful strategies have to be engrained in a clear understanding of the challenges facing the grazing animal and its natural abilities to meet and adapt to these challenges.  For example, Mulliniks et al. (2012) illustrated over a 6 year period that not all animals need to be fed to achieve a target body condition score, which allows for utilizing body storage as a nutrient source during periods of energy deficiency to maintain reproductive competence.  The cows from this study were offspring of cows that were managed in a low-input ($35 to 50 per cow per year in feed inputs) production system for multiple generations.  Thus, pre-planned management strategies to allow for body weight loss during periods of moderate feed restriction followed by nutrient realimentation during period of increase nutrient supply can be used to improve efficiency of energy utilization (Freetly et al., 2008).

The capacity for animals to cope with environmental changes depends on the degree of their metabolic flexibility (i.e., the phenotypic response to an environmental change).  Having a high metabolic flexibility may be significantly tied to the adaptability to dynamically changing nutrient supply levels.  Mulliniks et al. (2013b) illustrated the ability of livestock to modify metabolically in response to changes in nutrient availability was correlated to their timing of conception. Cows with elevated blood ketone concentrations, manifested from metabolic imbalance, prior to breeding season had a prolonged interval from calving to conception.  Therefore, ketone concentrations may be a useful indicator of adaptive capacity during metabolically challenging physiological periods.

Bottom Line

Livestock are expected to survive, grow, reproduce, and cope in dynamic and unpredictable weather patterns that create diverse environmental challenges or a combination of challenges.  However, if adaptive, flexible management is not utilized, static management in the face of a dynamic problem will not yield the most favorable long-term results.  With that being said, adaptive management is similar to the “bend but don’t break” philosophy.  You allow a defined amount of stress to elicit an increased capacity to respond positively to the stress.  With dynamic swings in environmental conditions, exploiting the natural ability of livestock to adapt in response to periods of nutrient imbalances may be an alternative strategy to manipulating the production environment. Implementing this approach may subsequently enhance adaptive capacity to environmental stresses, while increasing economic and biological efficiency. 

References

Freetly, H. C., J. A. Nienaber, and T. Brown-Brandl. 2008. Partitioning of energy in pregnant beef cows during nutritionally induced body weight fluctuation. J. Anim. Sci. 86:3703-77.

Mayfield, W. M. 2012. Evaluating the relationship between ultrasound-derived carcass characteristics and the production traits in Angus cattle. MS thesis. University of Tennessee, Knoxville.

Mulliniks. J. T., A. G. Rius, M. A. Edwards, S. R. Edwards, J. D. Hobbs, and R. L. G. Nave. 2015. Improving efficiency of production in pasture- and range-based beef and dairy systems. J. Anim. Sci. 93:2609-2615.

Mulliniks, J. T., D. E. Hawkins, K. K. Kane, S. H. Cox, L. A. Torell, E. J. Scholljegerdes, and M. K. Petersen. 2013a. Metabolizable protein supply while grazing dormant winter forage during heifer development alters pregnancy and subsequent in-herd retention rate. J. Anim. Sci. 91:1409-1416.

Mulliniks, J. T., M. E. Kemp, R. L. Endecott, S. H. Cox, A. J. Roberts, R. C. Waterman, T. W. Geary, E. J. Scholljegerdes, and M. K. Petersen. 2013b. Does β-hydroxybutyrate concentration influence conception date in young postpartum range beef cows? J. Anim. Sci. 91:2902-2909.

Mulliniks, J. T., S. H. Cox, M. E. Kemp, R. L. Endecott, R. C. Waterman, D. M. VanLeeuwen, and M. K. Petersen. 2012. Relationship between body condition score at calving and reproductive performance in young postpartum cows grazing native range. J. Anim. Sci. 90:2811–2817.

Petersen, M. K., C. J. Mueller, J. T. Mulliniks, A. J. Roberts, T. DelCurto, and R. C. Waterman. 2014. Potential limitations of NRC in predicting energetic requirements of beef females with western U. S. grazing systems. J. Anim. Sci. 92:2800-2808.

Stott, G. H. 1981. What is animal stress and how is it measured? J. Anim. Sci. 52:150-153.

 

 

 

Why I Ranch.

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I have decided to dedicate a series on West Texas ranchers called “Why I Ranch.”  Each month I will highlight a rancher in West Texas and ask them to share their story about the ranch life.

This September, Mr. John Treadwell will share with us his story on “Why I Ranch”.

John ranches in Tom Green, Menard, and Schleicher counties.  John is the recipient of the 2006 Statewide Lone Star Land Steward and Leopold Conservation awards.  John has a mix of sheep and cattle on his operation and holds resource stewardship at the top of his priorities.

How did you get your start in ranching? I grew up as an unpaid cowboy during the peak of the screwworm infestation. Getting rid of those flies is one thing the Government did correctly. Later, after college and the Navy, I got a lot of pleasure from gardening, producing food for my family and neighbors when I lived in Dallas and gardening was also a stress reducer from my corporate job. Years later, after I sold my business, my son Brian asked me to assist him in his guiding/outfitting hunting business based on the family’s 4000 acre ranch in West Texas. We soon outgrew the home ranch and needed to lease other properties for hunting, but were appalled at the condition of the available ranches. We decided to look for a block of land that would enable us to manage the deer, quail and turkey populations to ensure sustainable and controllable numbers for our hunting operation. He eventually found two adjoining ranching properties for sale and we had 8000 acres in Eastern Menard County. Hunting alone would not float the note so we added cattle and began dividing the existing pastures to apply our version of high intensity/short duration rotation system so that we could bank grazing and would not need to feed our stock during the winter.

How important is agriculture to your family?  I think my family is more aware of what goes into the food we consume, and are appreciative of the work we go to in order to produce it. But, a lot of gardening is not fun and the same goes for chickens, sheep and cattle. So often there is recognition but not commitment.

What makes ranching in West Texas so unique?  West Texas ranching causes one to be cautious in his planning because nature is so unpredictable and we are so near the desert as far as rainfall’s reliability. We need to be continuously grateful for what we receive because it could easily be worse.

Do you feel like there is enough emphasis on agriculture in K-12 education?  I think that some exposure to plant and animal growth and behavior could be part of Biology but since no university has a degree in sustainable ag or organic ag, where would the instructors come from?

Who did you learn the most from along the way?  I’d have to credit Rodale, Allan Savory, Walt Davis and Jimmy Powell and of course Holistic Ranch Management. I observed my Grandfather and Father as being the opposite but still influential. Make a plan, observe, and re-plan.

Thank you John!

 

Prussic Acid Misconceptions – Dr. Ted McCollum

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Dr. Ted McCollum, Extension Beef Cattle Specialist with Texas A&M AgriLife Extension Service, explains that prussic/cyanide levels when there is a frost/freeze event is one of the most confusing and misleading statements in most extension and popular press articles.  Here’s the skinny on the actual facts brought to you by thee Dr. McCollum:

“The cyanide(prussic acid) in plants does not exist in a free, liberated state.  The cyanide is part of a larger molecule called a cyanogenic glycoside. In members of the sorghum family this compound is Dhurrin; in chokecherries, wild cherries, mountain mahogany, among others, and the kernels of almonds, peaches,  apricots and apples this is Amygdalin (laetrile) and Prunasin; in cassava, white clover, flax and lima beans this is Linamarin.  These compounds themselves are harmless; the breakdown and liberation of the cyanide is the insult.  

A hand grenade represents a “potential” explosion.  As long as the pin is in place and the lever (trigger) has not been released that “potential” is not realized; the grenade is harmless.  But when the pin is pulled and the trigger is released and the fuse activates and catalyzes the explosion, the potential is realized and potential harm ensues.  The cyanogenic glycoside is like the hand grenade.   As long as the cyanogenic glycoside remains intact there is only the potential for toxicity; this is sometimes referred to as “cyanide potential”.  In order for the potential to be realized, something has to trigger the enzymatic action to liberate the cyanide molecule from the glycoside.   The beta-glucosidase enzymes that liberate cyanide from the parent glycoside are found in the plant tissue. In the intact plant tissue, the cyanogenic glycosides are found in vacuoles while the enzymes are found in the cytosol.  In order for the cyanide to be released the plant tissue must be damaged so that the glycosides and the enzymes come together. The enzymes are also produced by ruminal microbes.  Cutting, crimping, mastication, trampling, hail damage, and frost/freeze disrupt cellular structure and allow the glycosides and enzymes to mix and liberate cyanide from the parent glycoside.  Introduction into the ruminal environment presents the glycosides to the microbial enzymes and releases cyanide. 

So back to the grenade, the cyanogenic glycoside is the grenade and represents “potential toxicity”.  The damage to the plant tissue or introduction to the ruminal environment pulls the pin and releases the trigger.  The subsequent mixing of the glycoside with the enzymes activates the fuse and catalyzes the release of cyanide and a possibly toxic insult.  

Back to the freeze/frost — 

First, freeze/frost causes tissue damage and will indeed result in an increase in the “free” cyanide present in plant tissue (In fact, when analyzing cyanide in the lab, the forage samples are first frozen in order to release all of the cyanide; simply analyzing cyanide on fresh samples only indicates what is “free” in the tissue).  But remember, when the animal bit, chewed and swallowed that same forage into the ruminal environment just hours before the freeze or frost, the same cascade of events occurred as when the standing forage was exposed freeze/frost a few hours later.  The potential for toxicity was always there, different events pulled the pin and released the trigger. So, in order for a freeze/frost to increase toxicity for ruminants (more later) as is stated in the many pubs, the freeze/frost would have to actually stimulate dhurrin (cyanogenic glycoside) synthesis by the plant.  In other words, the freeze/frost would have to stimulate the plant to make more hand grenades. I have searched for research to prove that freeze/frost increases dhurrin synthesis (specifically dhurrin since that is the glycoside in sorghums, sudans, johnsongrass) in the plant.  It is not there.  I recently contacted Dr. Ros Gleadow from Australia who works in the area of cyanogenensis in plants and her response to my query was quote “Dhurrin is not synthesised in response to frost.” 

So, the plant does not make more hand grenades in response to frost/freeze which goes back to Dr. Halliburton’s comment which I have reworded with my interpretation of his meaning – The potential toxicity after the freeze was the same as the day before the freeze.

I think some of the misinterpretation and source of information in the pubs stems from studies of long ago where the researchers collected plant samples before and after a freeze and analyzed the cyanide content of the forage tissue.  However, they did not freeze the samples before they analyzed them.  So, they did not release all of the cyanide before analyses.  They found that the amount of “Free” cyanide was higher after the freeze.  This is indeed true. BUT, they did not measure “cyanide potential” which is the real concern and as far as I have discerned, if they had measured cyanide potential they would have found no difference before and after the freeze.

We typically deal with ruminants in these grazing forage situations.  Ruminants are typically more susceptible to cyanide toxicity because (1) ruminal microbial beta-glucosidase activity, (2) ruminal pH near neutrality – the optimum pH for beta-glucosidase activity.

What about nonruminants?  Typically less susceptible to cyanide toxicity (1) no microbial activity in the first stage of digestion (2) acid pH in first stage of digestion slows/eliminates beta-glucosidase activity in ingested forages.  So when the nonruminant is ingesting forage with “cyanide potential”, they have some protection because the enzymatic activities that release cyanide are suppressed or absent.

BUT, following a freeze/frost, the possibility for toxicity in a nonruminant may increase.  The frost or freeze has liberated the cyanide and the animal will be ingesting free cyanide.  The other “protective” mechanisms – no microbial digestion, acid pH in stomach – have been circumvented.”

 

Fire Appreciation Day

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A HUGE thank you to Dr. Dale Rollins for organizing Fire Appreciation Day at the Rolling Plains Quail Research Ranch on May 24th!  We had over 80 participants and a healthy mix of stakeholders, agencies, and Prescribed Burn Association members!  Thank you to Dr. Robin Verble-Pearson, Zac Wilcox, Lloyd LaCoste, Matt McEwen, Mark Moon, Chris Ellis, Kent Mills, Barrett Koennecke, Brad Kubecka, Seth Pearson, Ethan McJames and all the other others who helped put this show on!  Thank you for your support in prescribed burning! Click here for more information on the talks presented at Fire Appreciation Day! And check out this link for the radio broadcast presented by Texas Farm Bureau!
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