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Rehydrate. Recover. Perform.
A nutritional solution for mitigating the effects of heat stress.
Since 1983, TechMix has been innovating, manufacturing and marketing, nutrition products designed to help improve animal health, performance and maximize profits around the world. Our portfolio of more than 70 all-natural products is specifically engineered to address the time-sensitive nutritional needs of animals when they undergo periods of stress due to life cycle, diet changes or other stressful events. Each product is validated through research to provide the right nutrition at the right time and it’s a concept we call our Timed Event Nutrition (T.E.N.) program. T.E.N. makes recovery easier and quicker by supplying critical nutrients during these times.
TIMED EVENT NUTRITION
One such critical period is heat stress. During periods of heat stress, a cow’s body will attempt to self regulate through its own thermal regulation system. This means the cow may exhibit some of the following behaviors or responses: • Drooling • Panting and heavier breathing • Eating less • Sweating These are just a few of the thermal regulating triggers that can negatively affect health and performance without proper management. While most dairymen utilize heat abatement equipment and facilities protocols, nutritional solutions are often overlooked even though the cow experiencing heat stress has very specific nutritional needs.
How heat stress can negatively affect cows. Defining heat stress
Heat stress occurs when a cow’s heat dissipation is exceeded by heat load from metabolic heat production, heat increment of feedstuffs, and heat gain from environmental sources. Combined, these conditions can compromise a cow’s ability to dissipate excess body heat. Note that temperature alone is not the determinant for heat stress conditions. Humidity plays a role as well. Temperatures as low as 68º F with a relative humidity of 85% can work to create heat stress conditions. The Temperature Humidity Index (THI) Chart (see Fig. 1), can be used as a guide for determining when conditions are right for heat stress events. Fig. 1
Cows with an elevated body temperature consume less dry matter intake (DMI) and produce less milk and, in fact, make milk with less efficiency. The result is less production profitability and myriad potential health issues that may add treatment expenses to rectify. There are four ways a cow can cool herself: 1. Conduction: occurs when a cow lies on a cooler surface. 2. Convection: when air moves past the skin’s surface 3. Radiation: heat losses occur when the ambient temperature is cooler then the animal’s body temperature. 4. Evaporation: what the cow relies upon most for cooling during heat stress. As you will see on the following pages, each of these methods can lead to negative effects on cow physiology. It should be mentioned that genetic variation in cattle can also play a role in cooling capability. Cooling systems and heat abatement programs are important. However, their efficiency can be challenged in extremely arid or humid climates and often cannot help the cow maintain thermoneutrality. As a result, nutritional strategies which support yield, but also address metabolic and physiologic challenges induced by heat stress, are needed to help the cow maintain or re-establish health and performance.
Collier and Zimbleman
Stress Threshold Respiration rate exceeds 60 BPM. Milk yield losses begin. Repro losses detectable. Rectal Temperature exceeds 38.5°C (101.3°F) Mild-Moderate Stress Respiration Rate Exceeds 75 BPM. Rectal Temperature exceeds 39°C (102.2°F) Moderate-Severe Stress Respiration Rate Exceeds 85 BPM Rectal Temperature exceeds 40 °C (104°F) Severe Stress. Respiration Rate 120-140 BPM. Rectal Temperature exceeds 41 °C (106°F)
Four key heat stress issues that impair milk production Heat stress is a challenging time for all livestock. For the dairy cow, heat stress can trigger a cascade of behavioral and physiologic responses as coping mechanisms to maintain health. Responses to heat stress affect not only energy balance, but also water, sodium, potassium, and chlorine metabolism—all of which are temperature regulating mechanisms used to dissipate excess body heat. In fact, high-producing dairy cows may enter heat stress much earlier than lower-producing cows due to higher metabolic heat, especially in the warmer months.
1. Dehydration For the dairy cow, total body water content is about 65% of their body weight. Of this total body fluid, 66% is contained within cells and the remaining third is found in the soft tissue compartments, digestive and vascular systems. Combined, these body systems and cells carry and distribute nutrients, along with disease fighting cells and compounds, to maintain balance, and provide fluid for the fetus. The chart below (Fig. 2) shows how much water is required by a cow based on milk production, dry matter intake and temperature. Fig. 2
Water Intake (gallons/day)
Milk prod. lbs./day
DMI lbs./day 40oF
Mean Min. Temp.a 60oF 70oF 80oF
40 60 80 100
42 18.4 48 21.8 54 25.1 60 28.5
20.2 23.5 26.9 30.3
22.0 25.3 28.7 32.1
Avoiding lost milk production Nearly all dairy cows tend to respond to heat stress the same way—lower milk production. This is due to a number of reasons but reduced feed intake is a key reason. Fig. 1 below demonstrates milk yield when cows experience heat stress. So while managing cow comfort is important, meeting their nutritional needs is equally as important. The good news is that nutritional strategies exist and are effective.
Milk Yield (lb/d)
100 90 80 70 60 50 0
25.5 28.9 32.2 35.6
A cow will drink nearly 30 percent more water at 80°F than at 40°F. However, water consumption can actually decrease when the temperature is over 90°F due to inactivity and decreased dry matter intake (DMI). At this stage, water intake is utilized for managing heat stress first, while any remaining water is used for body maintenance requirements and milk production. Therefore, access to quality water without restriction is important when managing heat stress.
Underfed Heat Stressed
23.7 27.1 30.4 33.8
Source: Water for Dairy Cattle. Guide D-107. New Mexico and Oklahoma Cooperative Extension.
The rumen serves as a reservoir that releases consumed water to the body fluid compartments via osmotic pressure. As cells require fluid for metabolism, electrolytes and other nutrients exert osmotic pressure in order to continuously supply the cells with fluid for normal functions. If the body does not have enough
Rhoads et al., 2010
As hard as the cow tries, and mother nature allows, behavioral and physiological management of heat stress alone does not always prevent serious health and performance issues. Therefore, it is incumbent upon the dairyman to help a heat stressed cow by having a better understanding of how her body is reacting and what nutritional requirements need to be met during this period. To help with this understanding, what follows are 4 key outcomes of a cow experiencing heat stress. Note that these are not necessarily isolated challenges, but are interrelated.
Fig. 3 14 Milk Yield (kg/day)
Effect of Dehydration on Milk Yield 25% restriction 50% restriction
12 11 10 0
Baseline Water restriction Rehydration 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 Time (d) Source: Am J Physiol Regul Integr Comp Physiol 280:R418-R427, 2001.
fluids then the amount of nutrients transferred to the cells (for metabolism etc.) is greatly reduced. Therefore, managing the water content in the rumen is important for maintaining both normal rumen fluid volume as well as other body fluid reserves. Beware that not all situations of dehydration in cattle are easy to recognize. The rumen acts as a fluid reservoir by which body fluid balance can be maintained for a short period of time. This will cause “shrink” of the animal’s normal body weight and, if not corrected, will lead into clinical dehydration as identified below. Identifying levels of dehydration Severely challenged cattle can dehydrate in excess of 10 percent of their body weight. This degree of dehydration is potentially life-threatening and clinical signs include the following: • Eyes sunken into orbits • Skin remains tented indefinitely • Mucus membranes are dry • Depressed attitude is evident Cattle with dehydration of 5 - 10 percent of their body weight will exhibit • Partial sunken eyes into the orbit • Skin tenting that is 4 to 8 seconds in duration • Tacky mucus membranes • Reduced dry matter intake • Decreased productivity It should be noted that university studies indicate cattle with 7 - 8 percent dehydration levels show impaired immune response. Cattle with 2 to 4 percent dehydration or less will have minimal observable clinical signs but physiological and performance efficiency can be reduced. Water loss during heat stress can be quite evident by observing the cows body condition. But even in periods when heat stress is not a factor maintaining proper hydration is important as cows continually lose water via:
• Milk production (25-35% of total water intake)
• Freshening (fluid loss equal in weight to the calf )
• Fecal (30-35% of total water intake)
• Urine (15-21% of total water intake)
• Vapor loss from the lungs
• Disease, diarrhea, malabsorbtion
Rehydration Rehydration and hydration maintenance for dairy cattle can be accomplished in three ways: 1. Parental through IV or subcutaneous administration 2. Oral rumen drenching/pumping with large volumes 3. Combination of parental and oral volume of fluid or supplementation of electrolytes.
Electrolytes can be added to the ration on an as-needed basis to improve fluid efficiency due to their role in helping promote nutrient flow and balance. When calculating replacement fluids it’s important to consider maintenance requirements, production needs, and fluid losses due to heat stress, sweat, sickness or other challenges. To maintain normal cellular functions, a 1,000 pound cow requires 12 gallons (96 pounds) of water on a daily basis. Some of this water comes from their feed ration (10-30%) and the balance from daily water volume intake (usually 8 to 9 percent of their total body weight. For a lactating cow, each 10 pounds of milk produced requires an additional gallon of water over maintenance requirements.
2. Circulatory and Nutrient Disruptions During heat stress, a dairy cow uses convective cooling where blood flow, normally used for digestion, is directed to the surface layers of the body to cool. As a result, blood normally utilized for digestive functions, is now redistributed to the skin and puts the digestive system at risk of becoming hypoxic (low in oxygen). Consequently, intestinal toxins can enter circulation and cause inflammation and poor health. In addition, the flow of nutrients and energy away from the digestive system means they are not making it to the cells and tissues where needed… like the mammary gland for milk production. However, these cells and tissues require more potassium, energy, and adequate fluids to maintain health and prevent production losses during heat stress. Convective cooling involves sweating which greatly increases the secretion of potassium and is one of the major reasons that supplemental potassium is required during heat stress. Without supplementation, this cooling mechanism ultimately puts the cow at risk of an energy imbalance and other metabolic challenges and can have a negative impact on the reproductive system. Cows do not have the built-in mechanism to manage potassium levels in their blood stream and therefore rely on dietary input along with urine and fecal output to regulate. Potassium is the primary electrolyte responsible for intracellular energy mobilization and utilization. Responsible for proper fluid balance within cells, potassium is a requirement for proper body function. The combination of low feed intake, sweating, and dehydration from heat stress, leave the cow deficient and therefore potassium supplementation is required to ensure proper cell functioning. Other nutrient disruptions as a result of heat stress include:
• Elevated insulin levels (hypersensitivity)
• Depressed glucose levels are especially present with restricted feed intake during heat stress. Muscle and other tissues are requiring more glucose, limiting glucose avail-
ability to the mammary gland resulting in lower milk production.
• Insulin and glucose may also be limiting factors for ovarian function especially in dairy cows genetically selected for high milk yield. Studies suggest that insulin is involved in follicular maturation.
Nearly all stress events including heat stress and freshening, among many others, lead to nutrient disruptions which cascade into circulatory or digestive challenges. Awareness of a cow’s feed intake, and need for proper supplementation in accordance to that feed intake, can help reduce the negative impact and help maintain health and performance.
3. Reduced Feed Intake
A cow’s feeding behavior will change during periods of heat stress. For instance, cows will eat less partly due to lethargy but also in order to avoid creating additional body heat generated from digestion. Fig. 5 shows the relationship in feed intake during heat stress relative to cows that may be underfed. Bout feeding during the cooler periods of the day, like morning or evening, is very common. These feeding bouts, however, can create broader fluctuations in rumen pH levels and leave the cow at risk for acidosis. In fact, the risk of acidosis is compounded by heavy drooling because the cow loses rumen buffering benefits that salivation supplies under normal conditions. Add it all up and heat stressed cows are at significant risk of rumen acidosis (both subclinical and clinical). Data has shown that heat stress accounts for a 50% drop in feed intake while decreased feed intake accounts for 50% of the drop in milk yield. Conversely, as DMI goes down, the cow’s nutrient requirements actually increase due to the physical mechanisms of cooling. The dairyman needs to encourage consistent feed intake and watch for feed sorting where cows sort concentrates, getting more nutrients from grain which contributes to blood glucose, however, they don’t typically get enough fiber.
Fig. 5 50
40 35 30 25 20 0
Hypocalcemia, high body condition score at calving, and deficiencies in vitamin E and selenium are nutritional risk factors that cause retained placenta and lead to the risk of endometritis. This means that metabolic disorders predispose cows to physiological disorders, thereby reducing reproductive efficiency. Research has shown that cows developing hypocalcemia, ketosis, acidosis, or displaced abomasums have lower conception rates and take longer to become pregnant. Low feed intake can lead to hormonal and metabolic profile changes that result in decreased milk yield. Encouraging feed intake then, is key to managing these changes and an important component for optimizing fertility outcomes.
4. Reproductive Compromises
One of the most significant, and frequently overlooked, outcomes of heat stress challenges centers on how physiological and nutritional changes impact factors related to reproduction. In fact, vitamin A deficiency has long been known to affect reproductive function in cattle and vitamins and minerals both are linked to reproductive function. A nutrition deficit contributes to prolonged postpartum anestrus. The interaction with genetic, environmental, or management factors also influence the duration of anestrus. There is a inverse relationship between energy balance and the time ovarian activity resumes postpartum such that inadequate nutrient intake results in loss of weight and body condition score, and finally cessation of estrous cycles.
Underfed Heat Stressed
Magnesium is one nutrient critical to the cow’s ability to metabolize calcium and therefore, critical to helping prevent hypocalcemia. Since the cow’s magnesium level is dependent on diet alone, a deficiency can occur when DMI is low.
Rhoads et al., 2007
Follicle health and gestation Alleviating the energy deficits of high-yielding dairy cows in early lactation by supplementing dietary fat can reduce the interval to first estrus but subsequent fertility can be impaired. In highyielding dairy cows, negative energy balance and/or reduced nutrient intake in the early postpartum period can have the
following outcomes: • Reduced body condition scores • Reduced dominant follicle diameter • Altered biochemical concentrations in fluid surrounding the follicle In normal conditions, each of these contributes to reproductive success, but when proper nutrients are not available they can also lead to impaired fertility. The cumulative effects of heat stress events, and even dramatic variations in weather, can compromise the success of gestation during both winter and summer. In recent studies of high producing cows, an elevated rectal temperature decreased the probability of pregnancy. Heat stress can compromise the success of gestation during the preimplantation period, such that high temperature humidity index values for the period 21-30 days of gestation are a risk factor for early fetal loss in the future. Retained placenta Vitamin E supplementation during the dry period is associated with a reduced risk of retained placenta. Dietary supplementation with vitamin E and selenium may reduce the incidence of retained placenta, but these nutrients may also affect reproductive function. Calcium and phosphorous deficiencies affect reproduction, and vitamin D may directly affect reproductive function in addition to its role in calcium and phosphorus metabolism.
Cows with retained placenta can have longer postpartum intervals to first ovulation and more uterine infections, foot problems and mastitis than cows without retained placenta. It has been determined that combinations of short gestation length (<270 days) and low birth weight (<81 lb) are associated with the highest risk of retained placenta. Uterine involution and ovulation A normal postpartum cow prevents uterine infection by rapid involution of the estrus and cervix, discharge of uterine content, and mobilization of natural host defense. The greatest influences on uterine involution are post natal condition and parity. The two most important factors that determine the start of ovulation is the daily level of total digestible nutrients at time of postpartum ovarian activity, and post natal condition. Prolonged postpartum anestrus is a main factor limiting reproductive efficiency. However, during anestrus, ovulation does not occur despite ovarian follicular development, because growing follicles do not mature… largely due to inadequate
nutrient availability. Calcium, potassium and vitamin A are important for recovery. Vitamin A specifically works to maintain and repair epithelial tissue. Cows will become anestrus when they lose about 23% of their initial body weight. In fact, heifers undernourished by about 40% of their requirement, lose dominant follicle growth and diameter thereby inducing anestrus in 60% of heifers within 14 days of this undernourishment. Body condition and embryonic survival • Improving body condition scores at calving and AI • Minimizing losses of body condition after calving • Hastening onset of estrus cycles early postpartum All of the above are seen to help increase conception due to enhanced embryonic survival. The majority of pregnancy failures occur during the embryonic period. Reports indicate that approximately 5% of detected pregnancies are lost during the fetal period. In one study, only 12% of 25 embryos recovered from heat-stressed heifers were normal compared with 68.4% of 19 embryos from thermoneutral heifers. Stressed heifers also had a higher incidence of retarded and/or abnormal embryos. Repeat breeder syndrome Embryonic mortality also contributes to repeat breeding in dairy cows where reproductive chemical malfunctions are the cause of embryonic mortality. In primiparous cows the risk of repeat breeder syndrome increases with postpartum metritis, stillbirth, and when it takes many more days to reach peak milk yield. Abnormal calving, retained placenta, and postpartum uterine infections may be associated with an increase in prevalence of subclinical endometritis and subsequently, subclinical endometritis may decrease reproductive performance and increase the incidence of repeat breeder syndrome. Excess rumen degradable protein and high feeding levels can also reduce embryo survival, the latter by suppressing circulating progesterone concentrations. Insulin may also be important in relaying information on nutritional status to specific neurons thereby initiating the cascade of events required for successful reproduction.
As you can see, nutritional challenges due to heat stress lead directly to many health and performance issues cooling equipment cannot affect. The chart on the next page shows how these challenges can be categorized and demonstrates their interrelatedness. 7
Heat stress challenge flow Like building blocks, this chart shows how behavioral responses to heat stress set a foundation for resulting biological adaptations. Those biological adaptations correlate with negative results leaving a cascade of issues for the dairyman. The nutritional solution to this cascade lies with electrolytes, vitamins and energy sources.
• Reduced feed intake digestion creates additional heat
• Increased respiration rate (Panting) - >80 breaths per minute - Attempt to cool and enhance oxygen intake - Reduced blood HCO3
• Bout feeding during cooler periods of the morning and evening • Feed sorting may not be getting all required nutrients • Lethargy reduced activity and energy • Increased water intake attempt to cool
• Increased body temperature - >102.2º F (rectal) • Drooling - Reduces rumen buffering affect • Sweating - Evaporated water loss increases to help cool - Potassium loss through the sweat • Altered blood flow - F rom digestive system to cooling system at skin surface • Fluctuations in rumen pH - Swings in feed intake alter pH levels
• Reproduction issues -N utrition deficit slows ovulation time line and risks embryo mortality
• Promotes further dehydration due to expelling of vapor • Attempts to decrease body temperature
Specially selected electrolytes and energy sources are proven to help: • Encourage water intake
• Promotes lethargy, reduced feed intake, and milk yield • Jeopardizes fertility
• Improve dry matter intake
• Without the contribution of this buffering effect the rumen pH can drop to dangerously low levels
• Re-establish positive energy balance
• Dehydration of cells and tissues - cells cannot efficiently transport fluids or nutrients • Immune system at risk
• Improve milk production
• Blood is no longer available for proper nutrient flow • Intestines are at risk of becoming hypoxic
• Replenish electrolyte balance
• Reduce production losses • Transition cows faster for higher peak milk
• Potential for subacute or clinical acidosis • Further encourages low feed intake • Reduced milk production and components • Potential for metabolic issues • Hoof/laminitis problems
• Compromised follicle health and gestation • Delayed uterine involution and ovulation • Reduced body condition and embryonic survival
Heat abatement practices alone are not enough Abundant water and ventilation, shade, and even sprayers are excellent heat abatement tools for the “outside” of the cow, however they cannot overcome the physiologic challenges present during heat stress. Only nutritional solutions to the challenges outlined in this manual will provide heat stress relief “inside” the cow. Adding supplements Studies at University of Florida as far back as 1987, found that adding electrolytes to the diet improved feed intake and water consumption. Current trials have expanded upon these studies and support the need for supplementation. When a cow sweats, potassium is lost and sodium is excreted to compensate for the potassium reduction. Therefore, potassium should be provided as a supplement or in the diet, to provide the cow a reserve capacity for mild heat episodes. Additionally, one of the most significant, and frequently overlooked, outcomes of heat stress challenges centers on how the physiological changes impact reproductive factors. Due to low nutritional intakes, dehydration, and metabolic imbalances, cows are more prone to reproductive issues. The low availability of electrolytes and key vitamins account for the core nutritional needs. Without these nutrients reproductive health risks climb significantly. This is especially true when considering embryos, where mortality could prove quite costly to the dairyman in terms of delayed conception. 10
Vitamin A, vitamin E, calcium, potassium and magnesium are essential for optimal reproductive health. Calcium, for instance is directly related to healthy smooth muscle contraction and low levels of calcium can result in hypocalcemic cows that are prone to retained placentas. Calcium propionate provides a rapid source of absorbable calcium. The propionate is converted to blood glucose as an energy source which is critical for recovery. A heat stressed cow can also experience low blood vitamin E levels due to excessive drain into the colostrum. Vitamin E is essential for proper immune function; therefore it’s important to maintain adequate levels on a continual basis. Even with routine summertime diet and cooling techniques already in place, there are times when a cow can experience heat stress for which she cannot cope. During these times the use of yeast/fungal cultures and water or feed hydration electrolyte products can be very beneficial in reducing the effects heat and humidity has on health and performance. In fact, current trials with patented electrolyte hydration products have indicated less milk loss and the observation of better cow comfort.
Engineered for heat stress Hydration is the key component to herd health and performance. A palatable, buffered, electrolyte product like Bovine BlueLite provides the right nutrition at the right time to aid recovery from dehydration.
Rehydrate. Recover. Perform. Bovine BlueLite® is chock-full of electrolytes such as potassium, sodium, magnesium and calcium to name a few. Added energy sources come from dextrose, sucrose, fructose and more. Bovine BlueLite® contains betaine, an osmolyte that helps to maintain cell volume and fluid balance thereby helping improve protein synthesis, cell division and maintain gut integrity. And finally, Bovine BlueLite® is vitamin fortified with antioxidant vitamins necessary for combatting toxins.
Beyond heat stress Veterinarians, nutritionists and dairy producers agree that Bovine BlueLite can be used in many ways and is one of the most effective hydration products on the market. Bovine BlueLite has been engineered to make it the ideal nutrition supplement not only for use during heat stress events but also close ups, freshening, post-freshening, cold stress and in calves. For Cows and Calves • Encourages water intake and maintain proper hydration • Replenishes electrolyte balance • Help re-establish positive energy balance • Supports hydration during heat- and cold-stress events • Promotes feed intake during changes in feed • During health challenges or any stressful event • Calves - Eases transition to weaning • Calves - Helps inhibit pathogen growth • Calves - Enhances digestion and optimizes nutrient utilization
For more than twenty years nutrition from Bovine BlueLite® has been supporting the proper hydration and balance of electrolytes and energy in stressed cows. Exactly the kind of nutrition a cow experiencing heat stress needs — delivered at just the right time. Bovine BlueLite: • High potassium electrolyte for quick replacement
• Highly palatable and buffered electrolyte formulated for dehydration
• Contains multiple energy sources
• Easy-to-administer for individual or whole herd treatments
Fig. 1 70 68
Florida heat stress trial
Total economic loss to the American dairy industry due to heat stress is calculated between $897 million to $1.5 billion. Clearly, heat stress is one of the surest ways for a dairyman to lose milk production and thus profits. Combine milk loss with the detrimental effects on a cow’s health and it’s clear that heat stress is a challenge that needs to be addressed to maintain production and profitability. Managing for heat stress with proven nutrition solutions is critical, just like ventilation and other equipment solutions. When considering the cost of treatment for a retained placenta at $315 or the treatment costs of some metabolic disorders, doing as much as possible to avoid such expenses makes economic sense for the dairyman. If you have any questions regarding information contained in this manual please contact TechMix directly at 877-466-6455.
Fig. 2 70 68 Milk, lbs
The economics heat stressed cows
p < .02
The temporal effect of Bovine BlueLite® on milk yield. BlueLite®
Week Fig. 3 70
P = NS
Effect of parity on the milk yield response to Bovine BlueLite1
68 Milk, lbs
In a commercial and controlled experiment, Bovine BlueLite® fed at a 6 oz. feeding rate increased milk production by 2.2 lbs for both multiparous (M) and primiparous (P) cows (Fig. 1). For both parities, the increase in milk production (Fig. 2.) occurred within the first week of treatment. This increase was more pronounced in the primiparous cows as they had a 3 to 5.4 lb milk response (Fig. 3) throughout the trial and the increase became more pronounced with advancing weeks. Heat stressed cows receiving Bovine BlueLite® produced more milk compared to untreated control cows resulting in minimal production losses due to heat stress.
Effect of Bovine BlueLite on milk production1
BlueLite® has been the industry’s leading electrolyte rehydration product for more than 25 years. TechMix partners closely with university research departments, independent researchers, and veterinarians to ensure documentation for efficacy. What follows is data reported from a recent trial conducted on cows experiencing heat stress.
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TechMix, LLC • 740 Bowman St • PO Box 221 • Stewart, MN 55385 • 877.466.6455 • techmixglobal.com 12