Expert’s corner: Electrolytes for calves

Posted on April 13, 2022 in Starting Strong - Calf Care
By Dr. Megan Weisenbeck, Northern Valley Livestock Services


Calf diarrhea is not a new problem on beef or dairy operations.  Common causes of calf diarrhea include cryptosporidium, coronavirus, rotavirus, coccidia, and E. coli as well as bacteria-contaminated milk or colostrum, very high or variable total solids of milk fed, temperature variation at feeding time, and inconsistent feeding times.  Some of these feeding-related causes can also cause clostridial abomasitis and bloat.

Regardless of the cause of diarrhea, replacement of water – ideally by electrolyte solutions – is a main part of the treatment plan.  Electrolyte products are typically a combination of minerals, carbohydrates (sugars) and amino acids.   However, note the phrase “replacement of water.”  The most critical part of offering electrolytes is water!

Why do we feed electrolytes?
Dehydration can be a serious problem that needs to be corrected with fluid therapy.  Acid-base balance also needs to be corrected.  Therefore, it is important to find a fluid therapy method that replaces water along with electrolytes that are out of balance.  Typically, I recommend beginning with oral fluid therapy followed by intravenous or subcutaneous fluids as needed based on the severity of dehydration.

How to feed electrolytes?
Recently, I have come across a few situations where electrolytes were being mixed into milk.  It is not a good idea to mix electrolytes into milk or milk replacer.  This practice defeats the hydration purpose of electrolytes and can have negative side effects on the calf.

The most important component of electrolyte preparations is the water added to the product. Dehydrated calves require additional water, so additional feedings are necessary.  If electrolytes are used in milk, we do not provide the extra water the calf needs.  In addition, some electrolyte formulations contain ingredients that can inhibit the formation of the casein clot and normal digestion of milk.

Furthermore, there is another important reason to not add electrolytes to milk or milk replacer.  Every solution we mix or feed has a certain osmolality.  Osmolality refers to the concentration of dissolved solutes (chemicals, minerals, electrolytes) in a liquid solution and is measured in mOsm/L.  This measurement can be applied to feeding solutions and even blood.

Whole milk is approximately 300 mOsm/L and milk replacer tends to run higher (between 300 and 500 mOsm/L).  If we feed something with a high osmolality, the body will try to dilute the solution until it is closer to the same osmolality of the body (about 300 mOsm/L).  As a result, when we add electrolytes to milk or milk replacer, we do not hydrate the calf, but worsen diarrhea and dehydration.  It also increases the risk of abomasal bloat/abomasitis because high osmolality (probably greater than 500 mOsm/L) can slow the emptying rate of the abomasum.  Most electrolyte products run between 300 and 700 mOsm/L, so adding them to a 300 mOsm/L milk product dramatically increases the osmolality of feed.

Timing of electrolyte feeding
We typically recommend that electrolytes are fed at least one hour after milk.  Electrolytes can affect the formation of the casein clot and digestion of milk.  This can reduce the digestibility of milk and calories obtained from milk feeding and slow the emptying rate of the abomasum. If calves are normally fed milk or milk replacer in the morning and afternoon, an optimal time to feed electrolyte would be around 11 a.m. or noon. A second electrolyte feeding (if needed) can be offered one to two hours after the evening feeding.

Milk or milk replacer feeding should continue when calves scour. Calves need the liquid and nutrients provided by the normal liquid diet. Remember, very few electrolyte formulations contain sufficient calories to support maintenance and gain. Calories derived from milk or milk replacer are important to allow the calf to defeat the pathogen.

What electrolyte product?
Choose an electrolyte that is advertised as a treatment and not as a supplement.  Those advertised as supplements are not typically formulated to have adequate amounts of carbohydrates/electrolytes for thorough treatment of scouring calves.  To keep it simple, I recommend paying close attention to the alkalinizing agent and osmolality of product.  I did not discuss alkalinizing agents, but their basic premise is to correct blood pH (calves with diarrhea can be acidotic, which means they have a low blood pH).

Also look for electrolytes that are easy to mix.  Sometimes this is a trial-and-error process.  I have found that some electrolyte products, particularly those in powder form, can leave residue in the bottle or tube feeder no matter how hard or long you mix.  Aim to feed the electrolyte solution at the same temperature as milk (100 to 105 degrees F).

To summarize, electrolyte products should be fed in at least 2 quarts of warm water and separately from milk or milk replacer to provide hydration to calves.

Category: Animal health
Calf and heifer nutrition
Starting Strong - Calf Care