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March 2012
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Archive for March, 2012

Drought and Its Impact on Your Pond

Tuesday, March 27th, 2012

Seems like a handful of things are inevitable…death, taxes and drought. Drought? Yep, drought…if you haven’t been through a drought (and which of us haven’t?), you will. As a pond owner and steward of your water, understanding what happens in drought conditions with a pond helps us understand how to cope with it.
When someone asks me, “How deep should my pond be?” I always think about drought. Always. A pond needs to be deep enough that it doesn’t go dry during a drought. In areas normally subject to regular high annual average amounts of rainfall, ponds don’t need to be quite as deep. In eastern Texas and Louisiana, for example, those good folks can expect 45-55 inches of rain yearly. Coupled with average annual evaporation rates of 40-50 inches per year, theoretically, a pond only needs to be as deep as six or eight feet. But, travel a couple hundred miles west, beyond Abilene, Texas, and the equation changes. Out there, 20-24 inches is more normal, on top of 88-90+ inches of average evaporation over a year. So, a pond in that part of the world is better suited to being 15, maybe 20 feet deep, just to maintain storage capacity so the pond won’t go dry during the hottest seasons.
Here your pond sits, perched somewhere in an area destined for drought. What impacts might drought have on your favorite body of water?

There are several facts about water that we all need to understand.

  1. Water always moves…always. It can’t sit still. Gravity takes it, it percolates through soils, moves laterally, leaves through the bladders of animals or disappears upwardly, through evaporation. We don’t keep it, we borrow it. Understand this and you can understand your roles as a steward.
  2. Water is the universal solvent. Anything that can dissolve into water, will. Minerals, metals, nutrients, the atmosphere, old cars, cardboard…lots and lots of stuff dissolves into water. That’s important to know, especially in the throes of a drought.
  3. Water is necessary for multitudes of reasons, but remember it is a stable compound. Water comes, water goes. It’s what’s dissolved into that precious substance that can leave us shaking our proverbial heads.
  4. Water is harmonious in its environment. When water needs oxygen, its absorbs the gas from the atmosphere…so long it can contact the atmosphere. As a balance, water returns the favor to the air…dry air is a sponge, absorbing water as needed. Remember, water works in a continual balancing act in its natural cycle of cleansing and re-distribution. Physics play a role.

With an understanding of the facts, what do you, dear pondmeister, will help you understand the meaning of “drought” for your pond.

As your precious pond is sucked down during torrid heat and not enough rainfall, here’s what happens. There are biological effects, physical changes and chemical consequences.

The fishery will change. It has to. For most ponds, the top three or four feet constitute about half the volume of the pond. As the water draws down, fish slowly become congregated. Big fish eat smaller fish, especially where largemouth bass live. It’s Nature’s way. What’s happening, biologically, is that as the volume and size of the pond diminishes, the fishery tries to adjust. As long as there are fish which can eat other fish, the population makes those necessary adjustments. When full, a ten acre lake supports whatever that ten acre lake can support. But, when that lake shrinks to four acres during a drought, the fishery adjusts to what a four acre lake can support. Some of the fastest growing fish a biologist often sees happen to grow as a pond shrinks. Baitfish are flushed away from their safe havens around the shoreline and often end up as morsels trying to make their way in a shrinking environment.

That new bare ground which used to be pond bottom makes some changes, too. Aquatic plants lose their foothold and terrestrial plants take advantage of the opportunity. Depending the length of the drought, these former-pond-bottom soils respond accordingly. When this dirt is exposed to air and heat, it cleanses itself by composting organic matter accumulated under water. For composting to occur, oxygen must be present. In essence, the soil goes through something of a cleansing, setting itself up for a fresh new start when flooded again.

Speaking of flooded…it will rain again. Trust us on that. It won’t necessarily rain when we want it, but it will rain again. When your four acre drought-induced lake blossoms back into the ten acre lake you remember, changes will occur…again. Refreshed soils now have plant life that grew during the drought. That stuff becomes habitat for fish. Your adjusted four acre fishery now has new opportunities in its “new” ten acre environment. With fresh water and newly inundated habitat, your fish will respond by spawning. They’ll want to fill this new environment with lots and lots of new inhabitants. This move creates the opportunity for a new food chain. Existing predator fish will have new opportunities to grow rapidly…again because they have much more food and plenty of space. All this is, like Martha Stewart might say, is “A good thing”.

What about water quality during a drought? As water evaporates, all that leaves is pure water. Everything dissolved in it stays behind. To understand simply, hear this. Let’s say you have your water tested and the lab results show alkalinity in terms of calcium carbonate is 150 parts per million. CaCO3 is limestone. That’s one of the most common minerals dissolved in water. The drought ensues, your pond level drops and half the water is gone over a period of months. With half the water gone, the alkalinity doubles from 150 ppm to 300 ppm. Over those months, your fishery adjusts to this slow change. Keep in mind, in this example, we’re only talking about one parameter. In your pond, many different compounds are dissolved. You have nitrogen, probably some phosphorus, some salts, some organic matter, different minerals and metals, based on what lies in the soils beneath and surrounding your pond. As the water makes its droughty exodus, these other hangers-on stay behind. Meaning? Your water quality changes. As the quality of the remaining wet stuff changes, nature makes other adjustments. When it rains, if you get lots of rain quickly, those different chemical parameters can drastically change…sometimes within hours. All those concentration changes can be drastic enough to stress…or kill…your fish. Monthly or quarterly water chemistry analyses could be a wise move during drought.

Here’s another important rule of thumb of nature. She won’t let nutrients go unused. Where there’s food, something will grow. In most pond cases, that growth ends up being plankton. That might be a good thing, might not. Pay attention to the visibility depth of your plankton bloom. Too much bloom spoils the fun with a fish kill. Remember, hot water and dense bloom are ingredients for fish to die. As your pond recedes, the nutrients stay behind and often become more concentrated. Watching your water change color and seeing the visibility depth change is part of your due diligence.

Are there many answers, short of a daily rain dance, during drought? Yes, there are. Move the water. Aeration allows water to continue its dynamic changes, moment by moment. Seek help from someone who knows more about aeration than you do. Don’t just go online, buy a system, toss it in and turn it on. Learn first, act next. Pay attention to the water chemistry, too. Have a lab check it, compare your results. It might look like Greek at first, but the more you study, the more sense it makes. Watch the plant life. Too much of a good thing is a bad thing…especially when looking at rooted plants or mid-summer plankton blooms. If the drought persists beyond “ordinary”, consider harvesting some of your precious fish. They’ll better if you fillet them BEFORE they float up.

Here’s the bottom line. Droughts happen. There’s a drought somewhere on the planet every minute of every day. Be aware, learn about what happens during that spate of time and be prepared to react. That’s the part of stewardship that pays dividends.


Author: Bob Lusk, Pond Boss

Are Sugars, Starches and Grains “Evil” in Horse Diet

Tuesday, March 27th, 2012

Have you ever watched a pendulum swing? It swings way to the right, and then goes back to center. Then it swings way to the left, then returns to center again. In human nutrition, the sugar and starch pendulum appears to be returning to center. In equine nutrition, however, that sugar and starch pendulum seems to be hung up way off to the side.

Before we talk about the “evil” nature of sugars and starches (and therefore grains since they usually provide the majority of starches in a horse’s diet), we need to talk about carbohydrates. Sugars and starches are carbohydrates, but fibers are also carbohydrates. Fiber carbohydrates (structural carbohydrates) are important in a horse’s diet, and are primarily provided by the forages (grass or hay) that the horse eats. When people talk about feeding a “low carb” or “no carb” diet to horses, that implies that we need to reduce or eliminate the hay
or grass in the horse’s diet as well as the concentrate (or grain-based) feeds. That is usually not what we want to do, because fiber is essential to maintain the health of the horse’s digestive tract. The sugars and starches are nonstructural carbohydrates or NSC (sometimes referred to as soluble carbohydrates). In some situations it may be beneficial to reduce the NSC in a horse’s diet.

Are nonstructural carbohydrates “evil”? In the horse’s small intestine, most nonstructural carbs are broken down into glucose, a simple sugar. The glucose is then absorbed into the blood stream, and is carried to various tissues where it is used as fuel, or stored as glycogen (in the muscle or liver, where it later used as fuel) or as fat. Glucose is very important for the horse to function properly, as it is the only fuel that can be used by the brain, it is used to a large extent by the hooves, and it is the only substance that can be used for making glycogen. Studies have shown that horses that use up all their glycogen and are not provided glucose to replenish the glycogen stores show greatly reduced performance capabilities. So glucose is vital to the health and well-being of the horse. Again, glucose comes primarily from NSC.

So, again, are nonstructural carbohydrates “evil”? We know that too much NSC (particularly starch) in a horse’s meal can cause problems. We want the NSC to be digested in the small intestine, but if we feed a large meal that contains so much starch that it overflows from the small intestine into the large intestine, it may cause digestive disturbances such as colic or laminitis. Studies have shown that feeding no more than about 0.5% of a horse’s bodyweight of grain in one meal will reduce the risk of grain overload into the horse’s hindgut, therefore reducing the risk of colic or laminitis.

For laminitic horses (horses that have been previously been diagnosed with laminitis) feeding less NSC may be helpful in reducing the chance of a recurrence. Horses with chronic laminitis may be more susceptible and more sensitive to NSC in the diet.

There are some horses that suffer from disorders such as Cushing’s Syndrome. This disorder may cause a problem in the regulation and use of glucose in the body. The hormone insulin helps regulate glucose, by causing it to be removed from the blood into the tissues where it is used or stored. In horses that suffer from Cushing’s Syndrome, the insulin may not function properly to regulate the glucose, and we see high levels of glucose in the blood. We call these horses “insulin resistant”. In these situations, it may be beneficial to feed less NSC so that there will be less glucose provided by the diet.

Another situation in which low NSC diets are recommended is for horses diagnosed with “Equine Metabolic Syndrome”. These horses are usually obese, and blood tests show them to be apparently “insulin resistant”. However, in many cases if the horses are put on low calorie diets and lose weight, their glucose and insulin values return to normal.

Once again, are nonstructural carbohydrates “evil”? In my opinion, the answer is a firm “NO”. There are some situations in which some horses may benefit from lower levels of NSC in their diets. However, we need much more research to determine where the level of NSC needs to be, because the horse still needs glucose for brain, muscle and hoof function. We don’t know at this point where the lower limit of NSC in the diet is to ensure adequate glucose to supply the body’s needs. We also do not know where the upper limit is to reduce the potential for NSC in the diet to cause problems for insulin resistant horses. As an equine nutritionist, I try to ensure that the total diet includes
all the essential nutrients to meet the horse’s nutritional needs without exacerbating any medical conditions. For most typical horses, the amount of NSC in a standard diet of grass or hay and concentrate feed will cause no problems. In situations where the NSC may be an issue, there are factors to consider other than just how much grain is in the horse’s diet.

Horse owners almost always look at the grain portion of their horse’s diet to reduce the NSC. However, just because a feed contains grains, it does not mean that the feed is high in NSC. Conversely, just because a feed does not contain whole grains does not mean that it is low in NSC. Different ingredients in a feed contain different amounts of nonstructural carbohydrates, and it is the total mixture of ingredients that determines the NSC content of that feed. Purina Mills has several feeds available that are low in NSC. And more importantly, those feeds are formulated to contain all the nutrients necessary to meet the horse’s nutritional needs.

Further, we need to keep in mind that fresh grasses and some hays can contain fairly substantial amounts of NSC. When dealing with a horse that is suffering from a disorder that may be aggravated by high levels of NSC, it is vital to look at the forage portion of the ration as well as the concentrate to determine the best total diet for that horse.

Finally, it is essential to keep in mind that each horse is an individual with individual needs. When we start looking at individuals with special needs such as those with Cushing’s Syndrome, or obese horses, or laminitic horses, there is no cookie cutter approach to meeting the horse’s nutritional needs as well as the medical needs.

At Purina Mills, we have a large variety of feeds available to meet the needs of horses in many different situations. We have a number of equine nutritionists and veterinarians involved in current research to determine the best blends of all ingredients and nutrients to provide the safest and most effective ways to feed horses. Our goal is to provide the best nutrition for your horse by supplying the nutrients necessary to support your horse’s health, performance, and longevity.


Katie Young, Ph.D., Consulting Equine Nutritionist

Formulating Horse Feeds

Tuesday, March 27th, 2012

When choosing a horse feed, looking at the guaranteed analysis can help you determine if the nutritional content of that feed is appropriate for the age and activity level of your horse.  You’d think that two products that both contain 14% protein, 6% fat, etc. would be pretty much the same feed.  However, products with similar guaranteed analyses may be manufactured using different formulation strategies and have very different formulas.  This can affect the nutritional value for your horse.  The most common formulation strategies are “Least-cost” formulas and “Fixed” or “Locked” formulas.  Both strategies have benefits and drawbacks.  There is a formulation strategy that Purina uses for premium horse feeds, “Constant Nutrition” formulation, which is more nutritionally accurate than either of the other strategies.

Least-cost formulation allows a manufacturer to adjust the ingredients in the formula based on cost.  As long as the formula still meets the guaranteed analysis, the manufacturer can change the ingredients used in the formula.  In some circumstances, the change in ingredients doesn’t change the effectiveness of the diet so it makes sense to meet the nutritional needs of the animal in the least expensive way.  There would be no benefit to making a more expensive ration to achieve the same results.  For instance, if you are feeding cattle and being paid for weight gain and a least-cost formula will not change the rate of gain or feed efficiency of the cattle, but will be less expensive to feed, that just makes good business sense.  However, in some cases, especially when feeding horses, a major change in ingredients can dramatically alter the effectiveness of the diet, even when the nutrient levels don’t change.  A good example of this would be substituting cottonseed meal for soybean meal in a diet for growing horses.  Soybean meal and cottonseed meal may both have similar total protein content and could be interchangeable in a formula to meet the protein guarantee.  However, cottonseed meal does not provide the same quality of protein to support growth as soybean meal, and young horses will not grow as well eating a feed with cottonseed meal as the protein source.  So, in this case, the least-cost formula may be less expensive per ton but the loss in animal performance will negate any cost savings.  In addition to potential for reduced performance, there is always the potential for reduced palatability or digestive upset in horses when large shifts in ingredients occur in their feed.

With fixed or locked formulas, the same ingredients and amounts of ingredients are used every time the feed is made, regardless of price or nutritional variation of those ingredients.   This sounds like the most consistent way to make horse feed; however, there is a significant drawback.  All ingredients, even high quality ingredients, have variation in nutritional content.  For instance, all oats will not have the same protein or mineral content.  If the formula is completely locked and not taking into account the nutritional content of the individual ingredients, the level of nutrition provided in the finished product will vary.  Horses do benefit from consistency in their diets, but they don’t have specific requirements for certain ingredients.  The purpose of ingredients is to provide nutrients the horse needs. So, while a fixed formula does provide the same amount of ingredient in every bag, it may not provide the same level of nutrition.  For example, a horse feed made of 49% oats, 20% beet pulp, 16% corn, 8% alfalfa and 7% soybean meal would average 14% protein, using the average book values for these ingredients.  However, with the typical range in protein content of these ingredients, the end product could range from 12.4% to 21.1% protein.  Other nutrient levels will vary as well.  So, while a fixed formula does insure a consistent ingredient profile, it won’t provide the most consistent level of nutrition for the horse.

“Constant Nutrition” formulation is a key component of the Purina FeedGuard™ Nutrition System.  This strategy provides consistent, reliable nutrition in every bag of premium Purina horse feed.  Under the Purina FeedGuard™ Nutrition System, stringent quality standards are set for ingredients which are purchased only from an approved list of suppliers that meet those strict criteria.  Then, when ingredients arrive at a manufacturing facility, the ingredients are inspected, sampled and analyzed for nutrient levels.  This is more accurate than using published book values or supplier averages for nutrient levels of ingredients.  If an ingredient is approved, then the tested nutritional content is entered into the formulation system, which then makes small adjustments in amounts of ingredients to maintain consistent nutrient concentrations in the finished product.  There are strict restrictions for how much adjustment is allowed to ensure consistency in formulation.  For example, the amount of soybean meal may be adjusted slightly to compensate for lower protein in another ingredient, but cottonseed meal could not be substituted for soybean meal.  This formulation strategy ensures that horses always receive the most consistent nutrition possible, and that horse owners always get exactly what they pay for.

Karen E. Davison, Ph.D.
Manager- Equine Technical Services
Land O’Lakes Purina Feed

Horses and Water Comsumption

Sunday, March 25th, 2012