Managing infectious diarrhea in calves.

Talking about infectious calf scours, Escherichia coli, rotavirus, and Cryptosporidium parvum are frequently incriminated as causative agents in diarrheas among neonatal food animals. 

These organisms can be considered a major cause of economic loss to the producer because of costs associated with therapy, reduced performance, and high morbidity and mortality rates.  Moreover, diarrheic animals may harbor, incubate and act as a source to healthy animals and humans of some of these agents. It is obvious scouring calves need to be treated as fast as possible whereby it is proven, providing tannins from sweet chestnut or pyrolised charcoal can help in shortening the number of scouring days.

Calf scours causes more financial losses to cow-calf producers than any other health problem in their herds. Not being a single disease, calf scours is a clinical sign associated with several diseases characterized by diarrhea. It is important to recognize these calves quickly as regardless of the cause, the scouring calves lose fluids resulting in  dehydration and suffer from electrolyte loss and acidosis.

Infectious calf scours can be grouped into:

• Bacterial cause: E. coli, Salmonella spp., Cl. Perfringens
• Viral causes: rotavirus, coronavirus, BVD and IBR virus
• Protozoan parasites: Cryptosporidium, Coccidia
• Yeast and moulds

Some pathogens may be more predominant than others in a given area. Single infectious are common, but mixed infections are often reported.

Prevention of scours
Because calf scours result from a combination of non-infectious factors and infectious microorganisms, it is essential to use more than shots and pills in any effort to control scours successfully. There are managerial as well as medical requirements which must be met. They must complement each other. Furthermore, calf scours prevention is a year-round effort, not a set of activities centred only around the calving season.

Management aspects
All facets of management are important. Particular attention should be paid to nutrition, environment, sanitation, and care of the new-born calf.

Nutrition of the dam
The ration of the pregnant female should be balanced in energy, protein, minerals and vitamins. Care should be given to adjust the nutritional requirements during cold, inclement weather and to keep in mind that pregnant replacement heifers have not reached their mature size.  Particular care must be taken to provide them with sufficient feed energy for maintenance and growth. Failure to meet energy needs will not only result in a weak calf at birth but also contributes to delays in return to oestrus and lowered conception rates. Special attention should be given to energy deficiencies and/or vitamin A and E shortages.

Environment and sanitation
The new-born calf needs a dry/clean place if we expect it to survive free of scours. Geographic and climatic conditions dictate the type of management needed to assure decent shelter. Sanitation is just as important as a dry/clean environment. Ideally, provide a special area used only for calving. After the calf is born and has nursed, it should be moved with its dam to a nursing area before being turned to pasture.

Attention to the new-born
Ensure that all new-born calves receive colostrum in early life. The calf must nurse or be given 2 litres of colostrum during the first 2-4 hours after being born and a total of 4 litre within 12 hours.  If the delivery was difficult, the dam may be tired or painful, and the calf may be weakened as well; this may result in a failure of the calf to nurse colostrum. In such cases, it is prudent to milk the colostrum from the dam and feed it to the calf via an oesophageal feeder. Make sure it is from cows vaccinated against infections predominant in your area and attempt to get it from older cows in the dairy herd. Older, vaccinated cows are more likely to have greater antibody levels than young, unvaccinated heifers.
It is often a good plan to obtain fresh colostrum from a local dairy and freeze it or purchase a colostrum replacer for occasions when the dam does not have colostrum. When needed, frozen colostrum should be thawed out slowly; boiling will destroy most of the antibodies. Colostrum may be kept frozen almost indefinitely. Many calves will also benefit from a vitamin A injection. Vitamin A deficiency is associated with scours. The calf should be given 500,000 I.U. (usually 1 cc) of vitamin A early in life.

Vaccination programs
Farms which have experienced severe cases of scour in the past – or where there is a history of scour – should consider vaccinating the pregnant cow or heifer before calving in a bid to tackle the problem.  Be sure to consult your local veterinarian about vaccine products and time of administration. Timing is critical as colostral antibodies need to be in adequate concentrations in colostrum to provide ample passive immunity to the calf.

Treatment
The highest priority in treating scours is to give back to the calf the water and electrolytes that it has lost in scours. This corrects dehydration, restores normal acid-base balance, and replaces salts in the calf’s bodily fluids.

The use of antibiotics in diarrhoeic calves has been shown to be contraindicated in many studies, due to the further disruption of gut flora, the establishment of carrier states of salmonella-infection and the development of antimicrobial resistance factors in the enteric flora.

As calves can still digest and get benefit from milk,  you can feed them milk or replacer even if they have scours. Calves need enough energy to maintain their weight as well as their immune system, especially when they are sick. Oral rehydration solutions cannot provide enough energy because they are limited in the amount of glucose that can be added in order to keep the osmolarity of the solution low.
Because the electrolytes can interfere with the digestion of milk (the bicarbonate and citrate used as alkalinizing agent), it is recommended to alternate milk feedings with electrolyte feedings.

Administration of an oral rehydration solution (ORS)
This option is most appropriate for scouring calves that are still able to stand and who are alert enough to follow their dams and move away when approached. You can administer electrolytes by having the calf suck from a nipple bottle or drink from a pail. If they won't drink or suck, you should be prepared to give electrolytes by passing a tube. The easiest way for most producers to pass a tube is to use an oesophageal feeder.
ORS-powders that have been prepared by veterinary pharmaceutical manufacturers are carefully balanced to provide the correct proportions of salts relative to water for optimal benefit to the calf. This makes these are recommended over home-prepared recipes.

Depending on the size of the calf and the severity of the scours, 2 - 6 litres of electrolytes may need to be administered each day. Typically, the total volume of fluid is divided into two or more feedings per day.

What should an ORS solution contain?

• Water, the most important component of an ORS solutions
• Electrolytes like sodium , potassium and chloride.
  Sodium should be included in the solution at 70 to 145 mmol/L. Sodium is tightly regulated by the body; both low (from diarrhea, for example) and high levels of sodium in the body can cause problems. Excess sodium means calves will need to drink more water to dilute the sodium; extra water may not be available or the calf may be too weak to reach it. Sodium should be at an average ratio of one to one with glucose to be absorbed efficiently.
  Potassium and chloride are needed to maintain pH of the blood and for muscle contractions, especially in the heart. Although little research has been done  on amounts needed to replenish electrolytes in scouring calves, the range of potassium and chloride found in most solutions is respectively 20 to 30 mmol/L and 50 to 100 mmol/L.
• Alkalinizing agents are included to decrease metabolic acidosis and may also provide some energy. They are usually attached to sodium and include bicarbonate, citrate, lactate, acetate or propionate. Acetate is the most easily metabolized. Alkalinizing agents should be included at 50 to 80 mmol/L.
• Glucose serves as an energy source. It is transported into the intestine on a one to one ratio with sodium, helping sodium absorption. However, no more than 200 mmol/L should be included because this may change the osmolarity of the solution.
• Glycine is a non-essential amino acid that is commonly included to enhance absorption of glucose. To calculate the amount that should be included, the levels of glycine and sodium should be added and the total should not exceed 145 mmol/L. The total of glycine and sodium should also equal the glucose level.

Where the inclusion of electrolytes , glucose and alkalinizing agents is to rehydrate the calf and to restore the electrolyte balance, the inclusion of sweet chestnut tannins and powdered charcoal can shorten the duration of the diarrheic episode (DDE).

• Sweet chestnut tannins
  The administration of tannins (5g per litre of ORS) in calves with diarrhea seemed to shorten the DDE, suggesting an effective astringent action of chestnut tannins in the calf, as already reported in humans. The use of chestnut tannins in calves could represent an effective, low-impact treatment for neonatal diarrhea.
• Pyrolysed charcoal
  2 Handful of powdered pyrolysed charcoal powder added per litre of rehydration fluid will make the charcoal absorbs and locks in the enterotoxins  secreted by pathogenic bacteria inhabiting the animal's digestive system.
  The use of carbon gained from pyrolysis for feeding purposes has been known for a long time. Already in 1936, Mangold presented a comprehensive study on the effects of charcoal in feeding animals, concluding that "the prophylactic and therapeutic effect of charcoal against diarrheal symptoms attributable to infections or the type of feeding is known.

Author:
Bart De Meue - freelance marketing
Commissioned by Sanluc International nv

References

1. Treatment of calf diarrhea: Oral Fluid Therapy
G. Smith, North Carolina State University, Veterinary Clinics of N. America Food Animal Practice 25(1) : 55-72, April 2009.

2. Electrolytes for dairy calves
J. Heinricks, Prof. of Dairy Science, Penn State University and S. Kehoe, Associate Prof., University of Wisconsin-River Falls. 

3. “Calf scours: causes, prevention and treatment” article by G. Henderson, for “The great plains beef cattle” handbook by G. White, DVM, University of Nebraska-Lincoln and K. Wohlgemuth, DVM, North Dakota State University-Fargo.

4. “The use of biochar in cattle farming" 
Achim Gerlach & Hans-Peter Schmidt, The biochar journal, 2014.

5. Oral administration of chestnut tannins to reduce the duration of neonatal calf diarrhea
F. Borelli, L. Turini, G. Sarri, A. Serra, A. Buccioni and M. Mele. BMC Veterinary Research, 2018 14:227.