POTASSIUM CHLORIDE SUPPLEMENT IN LACTATING ANIMALS

Introduction

Nutrition is the most important aspect of animal production, as it has direct effects on health and productivity. Proving well-balanced diets according to the stage and body condition can enhance productivity and prevent common disorders of dairy cows. Animal nutrition is one of the most researched subjects and great advances have been made in the past on nutritional management of dairy animals. With the increasing productivity there have been proportionate increase in the requirements of different nutrients of dairy cows. High-yielding dairy cows require a particular composition of nutritional ingredients depending on their production status. The optimal supply of nutrients in the diet are indispensable for the prevention of imbalances. Potassium is one of the crucial macro-minerals in dairy cow nutrition that plays a vital role in numerous physiological functions. However, it is often underappreciated in the cows’ ration and its requirement varies according to the lactation stage. Research suggests that high yielding cows frequently deficient in potassium during their early lactation period due to higher excretion of potassium in milk and low dry matter intake. NRC indicates that extreme potassium deficiency in lactating cows’ results in substantial reduction in feed intake, decreased weight gains and diminished milk production. To overcome the deficiency, it is therefore important to provide diet with potassium supplements. Potassium helps in different body functions as below – 

1. Electrolyte Balance: Potassium is a key electrolyte, which helps maintain fluid balance and osmotic pressure in cells and tissues.
2. Nerve and Muscle Function: It is necessary for proper nerve impulse transmission and muscle contraction, including the smooth muscle contractions involved in digestion.
3. Acid-Base Balance: Potassium helps regulate the acid-base balance in the blood and tissues, which is crucial for overall health.
4. Support for Metabolic Health: Potassium is involved in many biological processes and thereby supports proper metabolic function. This balance is crucial during periods of stress, such as lactation, when the cow’s physiological demands are high.
5. Milk Production: Potassium is involved in the production of milk, affecting both the quantity and quality of milk produced.

Potassium regulation

The potassium regulation has carried out by two functions:

1. External potassium balance
2. Internal Potassium balance

External potassium balance is difference between dietary consumption of potassium and its elimination through different route like renal, salivary and gastrointestinal route. In dairy cattle the dietary potassium usually gets completely absorbed (>85%). The main source of potassium are forages rich in potassium contain and potassium balance is maintained through elimination of excessive potassium. Maximum potassium excreted via urine i.e. 75%, followed by faeces -13% (mostly unabsorbed dietary potassium) and 12% in the milk. The excretion of potassium is higher in lactating cow compared to non-lactating animals, because those animals are adopted to fed forages and hence eliminate excessive dietary potassium.  

Internal Potassium balance is defined as the shift of potassium ions between the intracellular and extracellular space. Alteration in the equilibrium between intracellular and extracellular potassium can result in hypokalaemia or hyperkalaemia without altering the actual concentration of potassium in the body. Internal potassium level commonly influenced by disturbed acid base balance in the body. In metabolic acidosis the increased extracellular fluid concentration of hydrogen ion enters into the cells and then potassium ions present intracellular compartment enter into extracellular which increase the plasma concentration of potassium.  Similarly, in metabolic alkalosis, extracellular potassium enters intracellular compartment which results into condition called hypokalemia.

Hypokalemia

Hypokalemia is a condition characterized by low levels of potassium in the blood. Animal with normal appetite usually do not suffer from potassium deficiency. One of the primary causes is inadequate intake or absorption of potassium-rich feed. Animals with hypokalemia have generalized muscle weakness, depression, and muscle fasciculations. Severely affected animals are unable to stand or lift their head from the ground. A serum potassium concentration <2.5 mEq/L reflects severe hypokalemia; most animals will be weak, and some will be recumbent. A serum potassium concentration of 2.5–3.5 mEq/L reflects moderate hypokalemia.

Causes for hypokalemia

1. High milk yield in early lactation: The average potassium retention for early lactation cows (less than 75 days in milk) was 66 g/d. It seems that potassium intake and excretion are closely correlated. Early lactation cows were in a negative potassium balance because of higher potassium secretion in milk.
2. Heat stress:  With an increase in ambient temperature dairy cows rely on adaptive mechanisms to dissipate heat and these include, moving to shade if available, decreasing DMI, increasing water intake, and increasing evaporative loss via respiration and sweating. during hot weather, they can lose significant amounts of potassium through sweat.
3. Medications: Certain corticosteroids with a mineralocorticoid action can increase potassium excretion in the kidneys. Hypokalemic states can also result after the combination of glucose plus certain diuretics, such as furosemide, when administered in the urinary obstruction. Lastly, multiple treatments of dextrose and insulin are also responsible for Hypokalemic condition.
4. Other diseases: Furthermore, certain diseases and conditions can also contribute to hypokalemia in cattle. For instance, cows with milk fever or ketosis have an increased risk of developing low potassium levels due to the high calcium and glucose demand in their bodies. Other conditions such as kidney disease, liver disease, or acid-base imbalances can also lead to hypokalemia in cattle.

Symptoms of hypokalemia

The signs and symptoms of hypokalemia in cow may vary depending on the severity of the condition. In mild cases, an animal may not show any noticeable symptoms, but as the potassium levels continue to drop, the following signs may become apparent:

1. Decreased Appetite: Cow with hypokalemia may show a decreased appetite and may not be interested in eating their regular feed.
2. Weight Loss: As a result of decreased appetite, the animal may also experience weight loss.
3. Weakness and Lethargy: Low potassium levels can cause weakness and lethargy in cattle, making them less active and alert.
4. S-shaped Neck curvature/Muscle Tremors: Potassium is essential for proper muscle function, and a deficiency can led to muscle tremors or twitching in cattle. Typical S-Shape position can be observed in low body potassium in case of dairy cow. 
5. Recumbency/Downers Cow: In severe cases, an animal may have difficulty standing or walking due to muscle weakness and impaired coordination.
6. Abnormal Heart Rhythms: Potassium is crucial for proper heart function, and any disruption in its levels can lead to abnormal heart rhythms in cattle.
7. Increased Urination and Thirst: Cow with hypokalemia may have an increased need to urinate and drink water due to the excessive loss of fluids from the body.

Potassium supplements in lactating cows

There are several supplemental sources of potassium that can be used, namely, potassium carbonate, potassium bicarbonate, or potassium chloride. The preferred choice for treating hypokalemia in lactating dairy cow is oral potassium supplementation. Oral potassium supplementation is better than intravenous as it is less expensive, convenient to administer, and allows for higher doses with fewer risk of side effects. One method that has gained popularity in recent years is the use of potassium chloride supplements. While potassium is needed in cow with whole-body potassium depletion, chloride is needed in cow with alkalaemia and pH-induced compartmental shift of potassium to the intracellular space. Hence, potassium chloride administration appears to be suitable formulation in addressing hypokalemia in cows.

Potassium chloride supplements come in different forms, including powders and liquids, and are designed to provide a concentrated dose of potassium to support the overall health of the animal. Inappetant lactating dairy cow should be given with 60–120 g of potassium chloride twice at a 12-hour interval.  Adult cow with severe hypokalemia (< 2.5 mmol/L) should initially be treated with 120 g of KCl PO, followed by a second 120- g dose of KCl 12 hours later, for a total 24-hour treatment of 240 g KCl. It is also important to note that high potassium rations may interfere magnesium (Mg) absorption; therefore, 4:1 ratio of K to Mg need to be maintained to avoid magnesium deficiency.

Conclusion

Potassium is transported across intra- and extracellular spaces, absorbed with food, and eliminated through urine, faeces, sweat and milk. Since milk contains around 1.4 g of potassium per liter, it plays a significant role in the body’s excretion and loss, particularly in dairy cows with large yields. Potassium is absorbed in the small intestine and its availability in digestion is nearly 100 percent. The dairy cow’s minimum requirement for K is 0.90% to 1.0% of the ration dry matter (NRC 2001). However, 1.0 % potassium is too low in the lactation diet. This mild deficiency of potassium may become marginally deficient in high yielding cows, especially during their first 10 weeks of lactation. Prevention is always better than cure, and the same applies to hypokalemia in cattle. To prevent this condition from occurring, it is essential to ensure that the animal’s diet is properly balanced and contains adequate amounts of potassium. Potassium chloride supplements have the potential to offer many benefits, such as electrolyte balance, improved muscle function, and increased milk production. Effective use of potassium chloride involves understanding the appropriate dosage and monitoring strategies. With careful management, potassium chloride supplements can be a valuable tool in maintaining the health and productivity of lactating cows.