Posts by Rob Costello, Dairy Technical/Business Support Manager, Milk Specialties Global

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Sunday, November 13, 2011

Calf Feeding - Bottles vs. Pails



This is always an interesting and sometimes passionate subject. There are advantages to either feeding system, and I have personally been in both camps. This post is based on research evidence and looks at anatomical, physiological, nutritional and behavioral aspects and responses to feeding milk or milk replacer with bottles/nipples and open pails.

Effects on the Esophageal Groove

When a calf swallows, solid food such as starter grain moves down the esophagus and passes through an opening called the esophageal groove just before it enters the rumen. Prior to weaning, milk and milk replacer take a different route. Factors such as suckling, anticipation, and a variety of sensual and neural stimuli cause muscles around the esophageal groove to contract. This contraction closes the groove, allowing milk and milk replacer to bypass the rumen and flow directly into the abomasum for digestion.

2 week old calf
The objective is to keep milk out of the rumen. When calves suckle milk through a nipple, little if any milk ends up in the rumen -- typically less than 3 milliliters. Although effective esophageal groove closure also occurs with open pail feeding, there is much more variability. Milk enters the rumen more frequently and varies from a few milliliters to well over 50% of the milk consumed. Large volumes of milk repeatedly entering the rumen can lead to serious metabolic problems resulting in low rumen pH, growth of yeast rather than normal rumen microbes, small distorted rumen papillae, poor production of volatile fatty acids (VFAs) and low cellulose digestion. Obviously calves are successfully reared on pails every day, but feeding milk through a nipple provides consistent, efficient groove closure, minimizing the chance that milk will enter the rumen.

Water drinking and the esophageal groove. If things go to plan, water and solid feed enter the rumen. Water provides the medium for starter feed digestion in the rumen and encourages feed intake. When water is consumed immediately after milk feeding, the esophageal groove may still be closed, causing water to directly enter the abomasum. If this happens on a regular basis, starter intake and rumen development may be delayed.

Water temperature may also affect closure of the esophageal groove. When calves are accustomed to drinking milk from an open pail, drinking warm water from an open pail can cause efficient closure of the esophageal groove after weaning -- up to at least 16 weeks of age.

Body position and the esophageal groove. The more natural suckling position of a calf's body when it drinks from a bottle is often cited as a benefit for the calf, promoting efficient esophageal groove closure. However, the esophageal groove is a functional part of the reticulo-rumen and is not part of the esophagus. Moving the calf's head and neck up and down in response to pail location does not affect the position or reaction of the esophageal groove -- unless the position is extreme. Although nursing from a bottle is a more natural position, it does not affect esophageal groove function.


Effects on digestion

When suckling a cow, a two-week old calf ingests two quarts of milk in about 3.5 minutes. At eight weeks of age it takes about 2.4 minutes. Observations obtained at a calf research facility show that suckling a nipple bottle is about 35% faster than suckling the cow, and drinking milk from an open pail is about 85% faster than the cow.

The rate at which a calf consumes liquid feed affects the rate with which the liquid moves through its digestive tract. The slower consumption rate associated with nipple feeding enhances several physiological processes associated with digestion. Saliva production is around three times greater with nipple feeding, resulting in more salivary lipase being mixed in with milk as it is swallowed. This begins the process of fat digestion in the calf's abomasum. Nipple-feeding also results in secretion of more abomasal enzymes and greater enzymatic activity in gastric solutions, resulting in more effective stimulation of protein digestion activity in abomasal fluids.

With the secretion of more enzymes and digestive acid, more fats and proteins are digested in the abomasum when feeding with nipples. More digested nutrients flowing from the abomasum into the small intestine means there are more nutrients ready to be absorbed.

With open pail feeding, more digestion is delayed until the small intestine. The increase in undigested nutrients reaching the small intestine results in greater secretion of pancreatic enzymes which enter the upper portion of the small intestine to digest the additional nutrients. In other words, the pancreas responds to the higher level of undigested nutrients reaching the small intestine by increasing lipase and enzyme production. Even so, there are some physiological functions that are of concern, such as the fact that most fat absorption is limited to the first 30% of the small intestine. Open pail feeding narrows the time window for effective digestion and absorption of nutrients.


Effects on Animal Health

Some studies show more episodes of diarrhea, more persistent and more severe diarrhea with open pail feeding, while some studies found no difference. Although research specifically designed to evaluate the possible effects of feeding method on calf diarrhea provide mixed results, there does not appear to be evidence showing that nipple-feeding leads to more diarrhea issues than open pails. In other words, when undesirable results occur, they occur with pails.

A specific health reason cited by many large calf raisers for using bottles and nipples instead of pails is the tendency of some calves to aspirate milk into their air passageway and even into their lungs when drinking from a pail. The telltale sign of the problem is coughing and a raspy or "rattling" sound during breathing after calves have finished drinking. These operations relate the use of bottles and nipples to fewer cases of pneumonia and fewer treatments.


Other Physiological and Behavioral Effects

Behavioral differences in calves have been reported between the two feeding systems. In calves housed individually, nipple-feeding reduces non-nutritive oral activities such as sucking objects, sucking and nibbling on parts of the pen, self-licking or licking calves in adjacent pens. Nipple-fed calves have shown lower heart rates during and just after feeding and returned to a resting state more quickly after a meal than calves that drank from an open pail. In group feeding situations, sucking from a nipple may reduce cross-sucking that occurs in group housing situations.



There are other interesting management areas to compare and contrast, such as feed delivery & clean-up and the spread of disease, but they are a bit more subjective and beyond the scope of this post.

In summary, research shows that calves can be efficiently and effectively raised using either bottles and nipples or open pail feeding of milk or milk replacer. This same research, however, demonstrates a greater potential for variability and an undesirable animal response with pail feeding compared to nipple feeding. When all is said and done, nipple feeding methods appear to be the gold standard against which pail feeding must be evaluated.


Saturday, October 1, 2011

2011 Junior Dairy Management Contest

Here's a shout-out to all of the competitors, coaches, organizers, volunteers and sponsors whose efforts made the 25th Junior Dairy Management Contest at All-American Dairy Show such a success! Teams from Pennsylvania, Ohio, New York, New Jersey and Delaware recently arrived in Harrisburg, PA to compete in 4-H and FFA divisions.

Students judged and placed dairy cows, evaluated forages and other feed ingredients, calculated feed costs and tested their knowledge in other dairy management areas such as herd health, milking management, animal
housing and ventilation, animal wellbeing, calf management and farm finances. Participants competed for over $5,000 in prizes awarded for team and individual performance, with a $1,000 scholarship going to the highest scoring individual to be used for post-secondary education.

The Junior Dairy Management Contest requires a more diverse understanding of the dairy industry than traditional cattle judging and quiz bowl competitions. In the individual competition, contestants must be able to think on their feet. The five highest placed individuals
demonstrate their ability to think and speak on different subjects, providing insight into their depth of knowledge in dairying as they respond to and interact with interview judges.

Congratulations to all of this year's contestants for all of your efforts and hard work. If you are a 4-H or FFA coach and are interested in participating in the Junior Dairy Management Contest, or if you just want more information, you can visit www.allamerican.state.pa.us, or contact one of the contest superintendents:





Thursday, September 1, 2011

Calf Feeding - How Long Should a Calf Feeding Nipple Last?



Well, that depends...

Certainly there are formulation differences among manufacturers that contribute to differences in nipple life. For example, each brand of nipple has a hardness characteristic that affects its performance. Put simply, the softer the nipple, the easier it is for newborn calves to suckle. The down side of softness is that it leads to shorter life. On the other hand, a hard nipple may last longer, but can be quite challenging for newborn calves. The material formulation used by each nipple manufacturer places their product somewhere along this spectrum, imparting characteristic ease-of-use and durability qualities.

Beyond basic formulation and manufacturing differences, there are other factors that have a big impact on nipple life. It is quite intriguing that even though two farms use the same brand of calf nipple, one farm manages an average life between 350 to 400 uses per nipple while the other achieves an average of over 600 uses. Both farms use the same product, and they even receive the same batch or manufacturing lot of the nipple. The possibility that this difference in life span is due to manufacturing issues is pretty remote.


Factors that cause wear

As nipples are used they are subjected to two primary forces on the farm that cause them to wear. One is chemical, caused by cleaning and sanitizing solutions; the other is physical or mechanical resulting primarily from calves sucking and chewing on the nipples. To combat these forces and improve resistance to degradation, calf feeding nipples are typically made with natural rubber compounds. As mentioned earlier, each company has their unique formulation which affects nipple wear.





Before & After
The picture on the right shows typical wear: swelling (more pronounced at the tip), thinning of the wall and elongation of the body of the nipple, loss of material strength.


Mechanical effects. Rubber compounds help to reduce these effects, but the nursing activity of calves causes the wall of the nipple body to thin and elongate, eventually wearing out. The amount of time that a calf has access to the nipple after it has emptied the bottle can be a big component of life expectancy. Consider a situation where the farm allows calves to routinely suck and chew on nipples for two minutes after draining their bottles before they get around to collecting the bottles from the hutches. If the farm averages 450 uses per nipple, these innocent two minutes translate into 15 hours of idle sucking time on each nipple. That's a rather sizable entertainment expense. A slight adjustment in management practices could go a long way toward improving nipple life on this operation.

Chemical effects. A wide variety of products and procedures are used to clean nipples -- some good, some not so good. Many cleaning and sanitizing chemicals have a harsh effect on nipples. They remove the natural, protective oils from the rubber, causing it to dry out and become more susceptible to degradation. Even water itself causes rubber to swell, so immersion times in cleaning and sanitizing solutions should not go beyond the minimal time required for effective action. Nipples should be removed promptly and allowed to air dry.

A recent laboratory evaluation took a look at the effects of various sanitizing/disinfecting solutions on nipple material. This study was concerned with the chemical effects of these solutions on swelling and material strength. The least damaging were chlorine products. The most damaging was iodine, with chlorhexidine products testing slightly better than iodine. These effects were more pronounced as the solution temperature increased. The results are certainly interesting and informative, but they do not mean that you should switch your sanitizing product. They do, however, indicate a relative potential for undesirable effects on nipple life. Good cleaning and sanitizing procedures can minimize these effects.

a word of caution ~
solutions of sanitizing/disinfecting products need to be mixed according to label instructions. That list of organisms the product is 'effective against' doesn't describe watered-down solutions. Trying to cut costs or reduce harmful chemical effects by diluting sanitizing solutions is actually a waste of money.

______________________________


Odd, but True...


Tuesday, July 26, 2011

A New Direct-Fed Microbial For Calves


Late-breaking Original Research

Some new and exciting research in the world of direct-fed microbials was recently presented at the 2011 ADSA-ASAS Joint Annual Meeting in New Orleans. By adding an anti-inflammatory lactic acid bacteria to a pathogen reducing Bacillus-based DFM, researchers demonstrated a significant improvement in calf performance, namely a 13 lb (5.9 kg) weight gain advantage.

In this trial, calves less than a week old were randomly assigned to 3 treatments: Control, Control diet plus a Bacillus-based DFM, or Control diet plus a Bacillus-based DFM with the anti-inflammatory lactic acid bacteria Enterococcus faecium ID7.  The control diet was a non-medicated 20% protein, 20% fat all milk protein milk replacer fed at a rate of 1.25 lb (0.57 kg) per day until weaning at 6 weeks. Calves received free-choice starter and water throughout the 8 week trial. Table 1 shows that calves receiving milk replacer containing the Bacillus DFM plus E.faecium ID7 had increased average daily gain over weeks 5-6, 7-8 and overall during the 8-week trial compared to control calves.



    Superscript letters indicate significant differences within rows. Values within a row that share the same superscript are not statistically different. For example, during week 5-6 both the Control calves and the Bacillus DFM calves have the superscript “a”. This means that the difference between the two is not statistically significant. On the other hand, the 5-6 week values for the Control and Bacillus DFM plus ID7 groups have different superscripts, which means the difference between those two treatments is significant (that’s at the P < 0.05 level if you’re interested).  

A thirteen pound weight gain difference is certainly a substantial result for a milk replacer additive. This is even more impressive when you consider the varied results on calf performance generally reported for DFM products. The recent BAMN publication, Direct-Fed Microbials (Probiotics) In Calf Diets, reports that adding direct-fed microbials to milk or milk replacer may support calf intestinal integrity and overall health and concludes that most research has reported little effect of direct-fed microbials on animal growth or feed efficiency. The publication also suggests that companies marketing direct-fed microbial products should research specific organism(s) in the product.

Well, this current research is part of a continuing effort to develop specific, targeted DFM products for calves that utilize selected bacterial strains, evaluated for desirable characteristics and effects. This research actually began over a decade ago, when...
  1. 1,500 bacterial isolates were obtained from the digestive tracts of young calves. Bacterial strains were evaluated for their colonizing ability, their ability to prevent the growth of pathogens and their compatibility with common antibiotics. The six superior strains were further evaluated in calf trials for their ability to reduce scours and treatment costs and were ultimately selected for inclusion in the DFM product BRELACTIS, marketed by Merrick's, Inc.
  2. Next, a Bacillus-based DFM selected for its effects in the intestinal lumen, especially under diarrheic conditions, was put to the test in a series of calf trials. This DFM was added to an oral electrolyte and evaluated as a therapy for scours. Pathogen shedding, treatment costs and the severity of scours were all reduced. This is the first report demonstrating efficacy of a DFM used therapeutically to mitigate calf scours.
  3. This Bacillus-based DFM was then evaluated as a milk replacer additive and a bolus supplement. The objectives of the study were to quantify the effects of the DFM as a bolus or incorporated into a 20% protein, 20% fat milk replacer on calf performance. Bolus treated calves received two boluses -- one on Day 0 and another on Day 6. Both the bolus supplement and the milk replacer additive improved ADG, fecal score and feed efficiency.
  4. Prior to the current research, Enterococcus faecium ID7, one of the six bacterial strains of BRELACTIS, was selected for further evaluation. E. faecium ID7 was found to have an anti-inflammatory response on intestinal epithelium. By reducing inflammation, E. faecium ID7 allows the immune system to respond to challenges, while helping to partition energy more effectively for calf growth.
    An important characteristic to notice from these trials is that the Bacillus-based DFM not only survives the different environments of electrolytes, milk replacers and boluses, it also withstands the associated manufacturing processes. This characteristic greatly enhances its application.

The research studies discussed above are not the complete list of evaluations that went into the development of the Bacillus-based DFM with Enterococcus faecium ID7 -- it's commercial name is Omni-bos® CB Plus -- but they clearly demonstrate a systematic, focused approach to developing and evaluating an effective calf DFM product. That makes it pretty special.





Monday, May 23, 2011

INTRODUCING: Electrolyte and Water Balance In Calves





The original Electrolyte and Water Balance in Calves has undergone a complete makeover, and now includes many new graphics and additional text...

This updated publication contains six chapters. The first describes the routine process of water movement into and out of the digestive tract, and sets the stage for discussions about water loss, rehydration therapy, and electrolyte formulation and function that follow in later sections.

The second chapter provides a detailed look at how the body regulates the chemical composition of blood, and maintains control over electrolytes, water and acid-base balance. These principles form a solid foundation for assessing actual situations and developing successful, cost-effective treatment and prevention protocols.

Chapter 3 explores water loss mechanisms through the digestive tract and discusses the process of dehydration and the clinical signs associated with progressive water loss.

The amount and timing of electrolyte replacement therapy is critical for rapid recovery from dehydration. Chapter 4 describes the relationship between the degree of water loss and the amount of electrolyte solution required to offset the loss. The focus is on oral rehydration therapy.

Common components of electrolyte solutions are presented in Chapter 5. Electrolyte products can serve a variety of functions: rehydration, electrolyte replenishment, gut repair and support for improved function.

The recently completed 4-part electrolyte blog series has been added to the publication as an entirely new Chapter 6, Electrolyte Formulation and Function.

Here is a link to the new and improved Electrolyte & Water Balance In Calves  Check it out!



Posts in the 4-part electrolyte series:
Jan 18, 2011, Electrolytes - Product Comparisons
Feb 15, 2011, Electrolytes - Dissociation of Strong Ions
March 23, 2011, Electrolytes - Alkalinizing Agents
May 4, 2011, Electrolytes - Dependent & Independent Variables

Wednesday, May 4, 2011

Electrolytes - Dependent and Independent Variables


(this is the fourth and final post in a series on electrolytes and how they influence acid-base chemistry)

From a clinical evaluation standpoint, it's fairly easy to gain insights into an animal's acid-base status from a blood sample. A pH measurement gives an estimate of the hydrogen ion concentration, [H+], which can be used along with a CO2 measurement from a blood gas analyzer to calculate the concentration of bicarbonate, [HCO3-], present in the animal's bloodstream. Even better, these values can be used to develop an effective treatment protocol. It would therefore seem logical that variables such as pH, [H+] and [HCO3-] must be central to a problem and that they are determinant forces in acid-base physiology.

In reality, this assumption is at the core of much of the difficulty and confusion that so often accompanies a developing understanding of acid-base mechanisms. The first three posts in this series demonstrate that acid-base adjustments occur without regard for variables such as bicarbonate. This post will be no different in that regard, and will explore how acid-base variables relate to each other and what that means to acid-base balance.

Dependent & independent variables. An important consideration when evaluating variables and their acid-base relevance is whether changes in their concentration occur independently or whether they depend on changes and interactions among other variables. The concentration of a dependent variable is governed by the concentrations and changes of independent variables. In other words, dependent variables change only as a result of changes in independent ones. Variables such as pH, hydrogen ion concentration [H+] and bicarbonate concentration [HCO3-] are all dependent variables. As such, they cannot cause changes in each other or in independent variables. Their concentrations are simply the results of other factors.

On the other hand, independent variables are subject to independent variation. Their concentrations are not under the control of other variables.  As such, independent variables are amenable to change, and as a result, changes in their concentrations influence acid-base status. This has important implications when attempting to correct an acid-base disturbance. There are three independent variables:

  • [SID]: the strong ion difference
  • PCO2: the partial pressure of carbon dioxide
  • [ATOT]: the total amount of weak acid in plasma

Figure 1 provides a description of each of these independent variables. Feel free to read about PCO2 and [ATOT], but this discussion will focus on [SID] -- we are already familiar with strong ions, and adjustments to [SID] are how electrolytes products affect acid-base status. [SID] is simply the sum of all positive strong ions and all negative strong ions. Normal plasma [SID] is around +40.



        Independent Variables



Figure 1.         



For the sake of argument, let's say that it is possible for us to add bicarbonate, a dependent variable, to plasma without the associated sodium. What would happen? The general effect is that the added bicarbonate would travel to the lungs where it would combine with hydrogen to form CO2 and H2O, which would then be exhaled. Each bicarbonate would remove a hydrogen ion from the body. But,since the independent variables have determined the plasma hydrogen ion concentration, we would expect those forces to generate a hydrogen ion to replace each one removed by the added bicarbonate.

But in reality we don't add bicarbonate by itself -- we also add sodium. And sodium concentration is a part of [SID], an independent variable. While bicarbonate is heading off to the lungs to be processed, the added sodium is raising [SID] which lowers the hydrogen ion concentration and raises pH. 

So, the notion that bicarbonate is an alkalinizing substance is obviously incorrect. The same can be said for literature that touts bicarbonate's acid buffering benefits. Nonetheless, sodium bicarbonate is an alkalinizing compound and is frequently used as a low-cost formulation tool to generate an alkalinizing effect. Formulators often choose not to use sodium bicarbonate in oral electrolytes because of its potential for causing undesirable effects in the digestive tract - bicarbonate does not behave the same way in the gut as it does in plasma. From a formulation standpoint, there is not a requirement that an alkalinizing compound must be used for an electrolyte to provide an alkalinizing effect. Having an alkalinizing compound on the label is no guarantee either. That's up to the person doing the formulation. 



This ends the series on electrolytes and acid-base chemistry. On a personal note, I have always found this subject matter both challenging and fascinating. I hope these discussions have proven interesting and informative, not too painful, and provide some useful insights the next time you evaluate an electrolyte product.

Other posts in this series:

May 4, 2011, Electrolytes - Dependent & Independent Variables

Wednesday, March 23, 2011

Electrolytes - Alkalinizing Agents

What They Are and How They Affect Acid-Base Regulation

(this post is the third in a 4-part series on electrolytes and how they influence acid-base chemistry)

Earlier in this series, we saw that strong ions fully dissociate from other substances when they dissolve in water. This dissociation not only affects the electrolyte solution being fed to the calf, it also has profound effects within the animal itself. Each strong ion forms an oriented complex with water molecules, isolating the ion and preventing it from entering into reactions within the body. And, by attracting either OH- or H+ from surrounding water molecules, these oriented complexes have a big effect on plasma pH. The important thing to remember is that you don't have to add or remove OH- and H+ from the body to change the acid-base status of the animal. Water readily forms and dissociates into OHand H+ in response to changes within the system. If this doesn't sound familiar, you may want to review the first two posts in this series before reading on.

Acidosis, Electrolyte Formulation and Alkalinizing Agents
Electrolyte products can be formulated to capitalize on the relationships between strong ions and water to bring about a change in the acid-base status of an animal. Sodium and chloride are the primary strong ions in plasma, they play an integral role in the body's acid-base control processes and they are fundamental components of electrolyte solutions for calves. 

As described in the previous post, the kidneys use sodium and chloride as they make acid-base adjustments. Simply put, they remove chloride to raise pH or remove sodium to lower it. Since the plasma pH of a calf with acidosis is below normal, it stands to reason that by providing more sodium than chloride in our electrolyte solution, we should be able to positively affect the acid-base status of the calf and increase pH. 

The normal ratio of sodium to chloride in plasma is about 4:3 (140 mmol/L sodium:103 mmol/L chloride). Using sodium chloride as our only source of these two ions provides one chloride ion for every sodium, slightly over-representing chloride in terms of normal plasma concentrations. To achieve an appropriate ratio of sodium to chloride, especially if we want to have a chance at correcting acidosis, ingredients other than sodium chloride must also be used in the formula. Ingredients that provide sodium without an accompanying chloride ion include sodium bicarbonate, sodium acetate and sodium lactate, and can be used to replace a portion of the sodium chloride in the formula, thereby achieving an alkalinizing effect.

Research Study. Many research studies have been conducted to evaluate the alkalinizing capabilities of different compounds under a variety of circumstances. But one in particular fits well with this discussion and provides an excellent demonstration of acid-base adjustments in action. In this clinical study, Kasari and Naylor evaluated sodium bicarbonate, sodium lactate and sodium acetate for the treatment of acidosis in diarrheic calves. (The complete reference is provided at the end of this post).The criteria for calves in this study were:
  • under 30 days of age
  • clinical signs of diarrhea
  • greater than 8% dehydration
  • venous blood pH less than 7.25

Calves that satisfied these criteria received one of four electrolyte treatments intravenously. The Control group received an electrolyte solution where all sodium and chloride ions were provided by sodium chloride. This solution contained 146 mmol/L of sodium and 151 mmol/L of chloride. To make room for the test compounds in the other three treatments, one third of the sodium chloride was removed from the Control formula and was replaced by enough sodium bicarbonate, sodium lactate or sodium acetate to provide a total of 146 mmol/L of sodium, 102 mmol/L of chloride and 50 mmol/L of either bicarbonate, lactate or acetate. In other words, the sodium level was maintained throughout all four treatments, chloride was reduced in the three test formulas and another substance was substituted for the chloride that had been removed. All treatments were administered intravenously so that a total of 7.2 L of fluid was given over a four-hour test period. The four treatment formulas are shown in Table 1.


Table 1. Treatment Group Formulations

Results. There were no differences observed between treatments in their ability to rehydrate calves. They all did a good job and performed equally well. However, when it came to correcting acidosis, only the reduced chloride treatments improved plasma pH and brought about a change in the acid-base status of the animal. At the onset of each treatment, plasma pH averaged 7.05. At the end of the four-hour test period, average pH for all but the Control calves was between 7.20 and 7.28 (pH > 7.28 was considered normal). The pH of Control calves at the end of the treatment was still around 7.05.

Considering the acid-base concepts presented so far in this series on electrolytes, the results of this study provide evidence of the roles of sodium, chloride and water in acid-base regulation and of the importance of proper electrolyte formulation to correct acid-base disturbances. Ingredients that provide sodium separate from chloride are necessary components of well-balanced electrolytes, and are part of a group of compounds collectively referred to as alkalinizing compounds or alkalinizing agents.

I must point out though, that a common interpretation of this and other acid-base research is that bicarbonate, acetate and lactate are considered to be the alkalinizing agent of these alkalinizing compounds.The thought is that metabolism and other reactions involving these substances results in hydrogen ions being removed from the body, thereby bringing about alkalinization. If that seems like the most probable scenario, then I encourage you to review earlier posts. In any case you will certainly want to read the fourth and final post in this series which will explore the relationships among these variables from a cause-and-effect standpoint. Is bicarbonate, for example, an independent or a dependent variable -- is it in the driver's seat, or merely along for the ride? I encourage you to read on.


Reference:
Kasari, TR; Naylor, JM: Clinical evaluation of sodium bicarbonate, sodium L-lactate, and sodium acetate for the treatment of acidosis in diarrheic calves. JAVMA, Vol 187, No. 4, August 15, 1985


Curious minds want to know...

So which is it, "alkalinizing" or "alkalizing"? A search of Wiki-Docs found the following:
  • alkalinizing: used 1376 times in 733 documents
  • alkalizing: used 16 times in 15 documents


Other posts in this series:

Jan 18, 2011, Electrolytes - Product Comparisons
Feb 15, 2011, Electrolytes - Dissociation of Strong Ions
May 4, 2011, Electrolytes - Dependent & Independent Variables


    Tuesday, February 15, 2011

    Electrolytes - Dissociation of Strong Ions

    And the Role of Water in Acid-Base Regulation

    (this post is the second in a 4-part series on electrolytes and how they influence acid-base chemistry)

    A curious thing about electrolyte ingredients is that even though they are listed on the label, many of them don't end up in the solution we feed to the calf. There is no sodium chloride. There is no sodium bicarbonate, or sodium acetate, calcium lactate, potassium chloride or a number of other ingredients.

    So...what happens to them? It's actually quite simple. They dissociate, or separate into their basic components when they dissolve in water -- or any aqueous medium such as blood plasma and other body fluids. As was pointed out in the previous post, not accounting for this dissociation can lead to sizable miscalculations when evaluating electrolyte products. This dissociation also has a profound effect inside the calf, which is the subject of this post.

    A good indicator of whether or not an electrolyte ingredient will dissociate is the presence of one or more strong ions. Sodium, chloride, potassium, calcium and magnesium are all strong ions. It's pretty easy to identify which ingredients contain strong ions since their presence is indicated in the ingredient name.

    Fig 1. Orientation of Water Molecules Around Strong Ion
    Let's take a closer look at what happens when sodium chloride is mixed with water. Sodium and chloride provide the backbone of most electrolyte solutions - they are the major electrolytes in plasma and play a fundamental role in the metabolic regulation of acid-base balance.

    Sodium has a strong positive charge associated with it while chloride has a strong negative charge. On their own, both ions would readily react with other substances - but water molecules prevent this from happening. Figure 1 shows how water molecules orient themselves around the dissociated sodium (Na+) and chloride (Cl-) ions. By orienting themselves in such a manner they isolate the ion and its charge, and prevent it from reacting with other substances. The negatively charged oxygen of the water molecule orients toward the positive sodium ion, while the positively charged hydrogens orient themselves toward the negative chloride ion.

    By forming complexes with water, strong ions become chemically inert and don't enter into reactions within the body. It's easy to imagine the serious consequences that could result if strong ions were free to react and form compounds within plasma and cellular fluids -- it would certainly add a new dimension to kidney stones.

    Fig 2. Attraction of OH- and H+ ions to Strong Ions In Solution
    The orientation of water molecules around strong ions does more than just prevent unwanted reactions. The outward facing hydrogens of the water molecules around sodium have positive charges that attract hydroxyl ions (OH-). The water molecules around chloride have negative charges that attract hydrogen ions (H+). These attractive forces are illustrated in Figure 2.

    Where do these OH- and H+ ions come from? They are the result of dissociation of nearby water molecules. Not only does water react to the presence of these strong ions by orienting themselves around each ion, water also responds to the attractive forces of the resulting strong ion/water complex by providing OH- or H+ ions depending upon which complex is present.

    This is why sodium and chloride are so important to the kidneys as they work to regulate acid-base balance. By selectively removing sodium, for example, the kidneys lower the plasma OH- concentration. In effect, this increases the relative concentration of chloride and H+ in plasma, lowering pH. Conversely, by removing chloride, the kidneys lower plasma H+, which raises pH. The latter scenario is an important part of resolving acidosis.

    Water readily dissociates into H+ and OH- and readily re-forms in response to changes in the solution, generating or destroying  H+ and OH- in the process. Water is the perfect medium for this purpose. No other substances are required to supply or to remove OH- or H+. No other reactions need to take place.


    These characteristics of water are fundamental to acid-base chemistry. Much of the confusion and conceptual difficulties surrounding acid-base mechanisms arise from the mistaken idea that OH- and H+ must be added to or removed from the solution from the outside in order to bring about a change in acid-base status. Water is the perfect medium. It is an inexhaustible reservoir of OH- and H+ within the body and is constantly adjusting to changes within the system.


    Sodium chloride is an important electrolyte ingredient, but its inclusion in the formula as the sole source of these two ions results in little change in the acid-base status of an animal. This is due to the counter-balancing effect of the two ions.  Each sodium ion added to the solution is offset by a chloride ion. To bring about a change in acid-base status, this relationship would need to change.

    Electrolytes are formulated for a variety of purposes and functions. Calves that are dehydrated due to diarrhea may also suffer to some degree from acidosis, where plasma pH is below normal. To help remedy this situation and bring about an increase in plasma pH, the electrolyte should provide more sodium than chloride.

    Unfortunately, strong ions cannot be added to a solution by themselves. In dry form, they are bound to some other substance which must be added to the solution along with the strong ion. In this case, where we are interested in replacing chloride, ingredients like sodium bicarbonate, sodium acetate and sodium lactate can be used to replace a portion of the sodium chloride in the formula. This provides sodium without the counterbalancing effect of chloride. Bicarbonate, acetate and lactate do not have the effect within the body that chloride does. They do not form complexes with water, they do not have the same attractive forces and they do not have the same effect on hydrogen ion concentration. They are also free to enter into reactions in the body. Sodium bicarbonate, sodium acetate and sodium lactate are sometimes referred to as alkalizing agents, which will be the subject of future posts.



    Other posts in this series:
    Jan 18, 2011, Electrolytes - Product Comparisons
    Mar 23, 2011, Electrolytes - Alkalinizing Agents
    May 4, 2011, Electrolytes - Dependent & Independent Variables

    Tuesday, January 18, 2011

    Electrolytes - Product Comparisons


    (this post is the first in a 4-part series on electrolytes and how they influence acid-base chemistry)

    Electrolyte comparisons show up in articles and publications from time to time, and are typically based on information found on the label of each product. Although probably unintentional, these comparisons usually contain a fair amount of incorrect or misleading information. These profiles may be convenient and are intended to be informative, but caution needs to be exercised when using these comparisons.

    To begin with, the product profiles in these comparisons use values that have been calculated from the actual numbers of molecules of the different ingredients that make up each electrolyte product. What?!  For many of us who ventured into high school chemistry class, thinking in terms of molecules can lead to flashbacks of Avogadro's number and the incomprehensible "mole". Talk about a panic attack. But don't fret, you are in good company. 

    It's actually the use of these principles that leads to problems with electrolyte evaluations and comparisons - not just in published comparisons, but across the board. The intent of this post is to shed some light on how these problems are generated, and how to avoid the pitfalls they create.



    The term or unit of measure most commonly used in electrolyte evaluations is millimole, abbreviated mmol. Simply put, this is a measure of the concentration of a substance, such as sodium, chloride, or glucose that is dissolved in a solution. The term osmolarity is often used when talking about mmol concentrations.

    To evaluate an electrolyte product, we need to work with the solution the calf actually consumes, not just what's in the package on the shelf. We start with the dry product, add water according to the label instructions and then evaluate. This is all figuratively speaking, of course -- we do this on paper, not in an actual bucket. The label provides a list of ingredients and a guaranteed analysis. The Ingredient List is an accounting of the ingredients used to make the product, whereas the Guaranteed Analysis states the concentrations of various ingredients or specific nutrients provided in the dry product. Sometimes the details in the Guaranteed Analysis can be a bit skimpy, especially if a manufacturer is protecting a proprietary formula. That's understandable since they may have a significant investment in the product and don't want to give the formula away. In such cases, a few phone calls or emails to manufacturers may be necessary to provide sufficient detail for each product.

    The example electrolyte product shown below contains six ingredients which are listed in the left-hand column. The right-hand column shows the mmol/liter concentration of each ingredient in the final solution. The other columns are mathematical steps along the path to our mmol objectives. (If you're interested in the math, a sample calculation is provided at the end of this post.)

    Electrolyte Example


    This is the standard approach to evaluating electrolytes. There is, however, one slight problem. Several of the ingredients (sodium chloride, sodium citrate, sodium bicarbonate and potassium chloride) don't exist in the electrolyte solution that the calf drinks. Once these substances come into contact with water, they dissociate into their base components. In this case, we're left with sodium, chloride and potassium (which are called strong ions) as well as citrate and bicarbonate.

    This dissociation has profound effects on acid-base balance in the body (and will be the subject of future posts) as well as having profound effects on the osmolarity of the solution. For example, the actual impact of the sodium chloride in this formula on osmolarity is 114 mmol/L, not 57 mmol as shown in the table. Sodium citrate, sodium bicarbonate and potassium chloride actually contribute 16, 154 and 44 mmol/L, respectively. Dissociation of sodium citrate yields four molecules (three sodium and one citrate), whereas sodium chloride, sodium bicarbonate and potassium chloride dissociate into two molecules each. Glucose and glycine stay the same since they don't dissociate.

    Some electrolyte comparisons go further and provide a total mmol/L value for the different electrolyte products being compared. These values can be quite inaccurate and misleading. Our example electrolyte shows a total mmol/L value of 354. The actual osmolarity of the product is 522 mmol/L. So be cautious about using these numbers.

    The following table accounts for ingredient dissociation and provides a more accurate description of the electrolyte solution consumed by the calf. It allows for correct assessments of osmolarity, and results in a higher degree of accuracy when evaluating electrolytes.



    Example Calculation

    g/L: (% formula/100) x (oz. powder/(liquid vol. x 0.95)) x 28.35
    mmol/L: (g/L/molecular wt.) X 1000

    glycine: (4/100) x (3.2/(2 x 0.95)) x 28.35/75.07 x 1000 = 25.4mmol/L

    Note: The molecular weight of dextrose/glucose listed in the table is greater than the actual molecular weight of this sugar, which is typically listed as 182. The larger number accounts for the high moisture level of commercially available dextrose/glucose used in electrolyte products. Using the higher molecular weight provides a more accurate assessment of the osmolarity of this ingredient in the final solution.


    Other posts in this series:
    Feb 15, 2011, Electrolytes - Dissociation of Strong Ions
    Mar 23, 2011, Electrolytes - Alkalinizing Agents
    May 4, 2011, Electrolytes - Dependent & Independent Variables