Electrolytes can save lives

by Geof W. Smith, D.V.M. 
College of Veterinary Medicine, North Carolina State University, Raleigh. 

When used correctly, electrolytes help calves overcome diarrhea, the number one cause of death in our youngest herdmates.

ONE of the keys to success when using oral electrolytes is to rec­ognize diarrhea early and begin treatment right away. If the first sign of diarrhea is that the calf "won't drink its milk," you are too late. If the calf is down and can't get up, you are way too late.

Seeing the actual manure when calves are housed on straw is often difficult, so it is impor­tant to watch calves closely when feeding. Calves should be "excited" to be fed and usu­ally drink milk aggressively. Drinking slowly might be an early sign of a calf not feeling well.

Look at the calves' eyes as well. If they are starting to sink (where you can see a space between the eyelid and the eyeball), that's an early sign of dehydration. If you can get calves started on electrolytes at the first sign of diarrhea, we can usually prevent them from becoming severely dehydrated or having their blood pH drop to dangerously low levels.

Mix It well 
Beginning at the first sign of diarrhea, oral electrolytes should be fed to calves at least once per day. My preference is to always mix oral electrolytes with water and feed separately from milk. If a farm feeds milk twice a day, electro­lytes can be offered in the middle of the day.

I often get asked whether or not you can feed oral electrolytes mixed with milk. This is a somewhat complicated question and depends on what electrolyte product you are using as well as what "milk" you are feeding.

The two concerns associated with feeding electrolytes and milk together are that: 1) bicarbonate might interfere with milk diges­tion in the abomasum and 2) high osmolality meals will slow the emptying of the stomach (abomasum) and promote bloat.

It is well established that concentrated (high osmolality) solutions will sit in the calrs stomach and are a major risk factor for bloat. This is why most experts recommend using a Brix refractometer to check the total solids of milk or milk replacer before feeding it.

When you add electrolytes directly to milk, the osmolality of the milk rises significantly. Whole milk has a relatively low osmolality (about 275 to 300 mOsm/L) as would most conventional (20:20) milk replacers. In con­trast, higher protein (25 to 28 percent) milk replacers can have much higher osmolalities (sometimes well over 600 mOsm/L). If you are feeding a high protein (accelerated growth) milk replacer, adding an electrolyte directly to the milk may push osmolality over 1,000 mOsm/L. This is a bad idea.

Osmolality of oral electrolytes can vary con­siderably. Some are in the 350 to 400 range, while others are well above 700 mOsm/L (because they contain higher levels of sugar). Don't mix these "high energy" electrolytes with any type of milk.

For farms that want to combine milk and electrolyte feeding, I suggest the following:

a. Use an oral electrolyte product that con­tains acetate or has bicarbonate concentrations less than 40 cubic millimeters per liter (mM/L).

b. Make sure the oral electrolyte has an osmolality less than 400 to 450 mOsm/L.

c. Use whole milk if possible or a conven­tional (20 percent protein) milk replacer that is nonmedicated (since antibiotics or other additives will also raise osmolality).

Calves should receive electrolytes at least once a day (or twice a day for the first day or two if the diarrhea is severe) and continue daily until diarrhea resolves. Although there isn't a lot of data on how long diarrhea actually asts in calves, most studies would suggest at least seven to eight days.

A frequently asked question is whether calves need a second feeding of electrolytes the following day. The reality is that they need electrolytes daily until the diarrhea has completely stopped. Since most electrolytes are about $2 per dose, think of this as a cheap insurance policy to make sure the calf doesn't go down and require IV fluids.

Don't skip the milk 
You will occasionally see recommendations to stop feeding milk while the calf has diar­rhea. The logic is that calves need to "rest their gut," and the thought is that continuing milk feeding will worsen the diarrhea. This concept is based on the principle that milk will supply nutrients in the intestines that the bacteria could use as an energy source.

Other arguments for withholding milk include a faster healing of the intestines, less opportunity for overgrowth of the intestines with harmful bacteria, and impaired digestion and utilization of milk and/or milk replacer. Despite these ideas, research has shown milk feeding does not prolong or worsen diarrhea.

A very good field study published several years ago demonstrated that calves with diar­rhea that were fed both milk and oral electro­lyte gained more weight than did calves from which milk was withheld for one to two days. In addition, there was no difference in the severity or duration of diarrhea.

A more recent study done on a dairy in Colo­rado enrolled 360 calves with naturally occur­ring diarrhea. One group of calves received two feedings of electrolytes only twice a day for two days and then 1 liter of milk mixed with 1 liter of electrolytes through Day 4 or until diarrhea resolved. The other group received another prod­uct mixed with half a gallon of milk twice daily for two days and longer if diarrhea persisted.

The calves in the group where milk feeding was continued gained more weight during the diarrhea period, had higher weaning weights, and a faster resolution of diarrhea. These stud­ies indicate that even high energy oral electro­lyte products with very high glucose concentra­tions do not provide enough energy to meet the maintenance and growth requirements of a calf.

Maintain calves on their full milk diet plus oral electrolytes when possible. If calves are depressed and refuse to suckle, milk can be withheld for one feeding and an oral electrolyte product substituted. However, milk feeding should always be resumed within 12 hours.

Follow the label 
The goals of oral fluid therapy are to replace fluids and electrolytes, correct acid base prob­lems, and provide nutritional support. Electro­lytes can be used in any diarrheic calf that has at least a partially functional gastrointestinal tract. If electrolytes are administered to a calf with ileus (no stomach or intestinal motility), the fluid pools in the rumen or abomasum resulting in bloat and acidosis.

In general, a calf with any sort of suckle reflex or that demonstrates any "chewing" action can tolerate oral fluids. Usually, when calves are "down" and can't stand, they need aggressive IV fluid therapy if they are going to survive.

Oral electrolyte solutions will continue to serve as the backbone of treatment protocols for diarrhea in calves because they are cheap and easy to administer. However, the producer should understand how to choose a product that will work optimally and use it correctly .