Diarrhoea and pneumonia are the two most prominent diseases among calves. Calf diarrhoea results in additional expenses and unnecessary losses in the form of mortalities, the cost of medication, labour, substandard growth and a decrease in milk production during a heifer’s first lactation.

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“Anyone with calf-rearing experience will agree with this,” says Dr Louis Hoek, a veterinarian at CapeCross Veterinary Services in Tsitsikamma. Dr Hoek notes that calf diarrhoea is also one of the most frustrating conditions to treat, especially since it takes up a considerable amount of time and requires a great deal of patience and dedication.

“It is generally believed that the colour of the manure will lead you to the cause of calf diarrhoea. In my opinion, however, a diagnosis cannot be based solely on this aspect. The colour and composition of the manure is a function of the rate at which it travels through the intestinal tract; it is not a direct consequence of the organism. Although a producer may at times guess the cause, I recommend dealing with the problem properly once a specific diagnosis has been made,” he says.

Main causes

According to Dr Hoek, calf diarrhoea can be attributed to several significant causes.

In calves younger than three weeks

  • Rotavirus: It is the most common cause of diarrhoea. The manure can at times contain blood. If calves are treated properly, there ought to be no mortalities.
  • Cryptosporidium: This is currently a huge problem in South Africa and generally presents itself along with a virus. It can spread very quickly, but calves that are treated properly can survive.
  • Coronavirus: It is similar to the rotavirus but is not as common.
  • E. coli: It usually occurs in very young calves and often causes acute mortalities even before the calves can be treated. According to Dr Hoek, it is probably over-diagnosed as many non-pathogenic strains are a common occurrence in calf manure from which E. coli is then cultivated. A commercial vaccine is available for the most common strain, but not for others.
  • Clostridium perfringens: The diarrhoea is usually bloody, and acute mortalities occur. However, it does not affect as many animals as the aforementioned diseases.
  • Nutrition-related diarrhoea: This type of diarrhoea is very common and does not usually lead to mortalities. As a rule, animals recover fairly quickly.

Calves older than three weeks:

  • Coccidiosis: This disease is common. Symptoms include bloody manure. It does not usually cause mortalities, but calves tend to become emaciated. Recovery is good following treatment.
  • Salmonella: Acute mortalities occur. Carrier animals are usually present in the herd.
  • Worms: It causes emaciation coupled with diarrhoea. Calves normally respond well to treatment.
  • Clostridium perfringens: Bloody diarrhoea is common and acute mortalities occur.
  • Nutrition-related diarrhoea: It is very common, and mortalities are typically low. Calves usually recover quickly.

Preventive measures

According to Dr Hoek, few problems in life can be solved by using quick fixes, but he firmly believes that adequate colostrum plays a major role in controlling calf diarrhoea. “Of course the quality of the colostrum has to be top notch and can be measured with a colostrometer.”

He says if dry cows are given the correct vaccines at the right time, it will ensure that the colostrum contains the correct antibodies. “Colostrum needs to be ingested in the first six hours after birth. The reason is that the ability to absorb colostrum drops to 50% after twelve hours and to 10% after 24 hours. A calf must therefore receive 2,5 to 3ℓ of colostrum within the first six hours of its life, depending on its size.”

Dr Hoek believes the biggest challenge facing a producer who buys and rears bull calves, is purchasing calves that have ingested sufficient, good-quality colostrum. “Make sure the calves come from a reliable source. Avoid calves that had to travel far, as well as those sold at auctions or by hawkers, or calves from different farms in a combined group.”

Various guidelines can be followed for the control of calf diarrhoea.

Biosecurity and hygiene

He believes that biosecurity is a crucial factor, although it is often neglected. “Dairy farmers need to make sure their bull calves are kept and loaded separately. They must be kept away from heifer calves. A good vaccination programme forms the backbone of a biosecurity plan.”

Good hygiene practices should be obvious but are unfortunately also often neglected. Dr Hoek believes that producers who pay attention to good hygiene, will reap the rewards.

“Have a critical look at your feeding process and housing, as this will give you a good indication of weaknesses that might assist disease transmission. Make sure that the younger calves are fed first and sick calves last. Also ensure that the calf pens have good drainage and that there is no run-off water between the pens that can transmit diseases,” he explains.

According to him, it is also important to keep flies at bay in places where calves are reared, as they can easily transmit diseases and are a source of irritation.

There are differing opinions as to the number of calves that can be housed together. Dr Hoek says calves are social animals and housing them together reduces their stress. “It should be noted, though, that calves that are not housed separately can easily transmit diseases to each other. Housing four to five calves together seems to work for many producers.”

Guidelines for sick calves

Dr Hoek provides the following guidelines for producers with sick calves:

  • Make sure a veterinarian makes a diagnosis and that you know how to prevent a similar incident from recurring.
  • Do everything in your power to stop the disease from spreading.
  • Make sure that sick calves are not dehydrated, as this can cause mortalities. Do not remove the milk (as was believed in the past). Depending on the product, mix electrolytes with milk or water. Keep in mind that a calf’s stomach can only hold a certain amount of fluid. Giving too much at a time causes it to end up in the rumen, where the pH is higher. The milk can then become rancid and make the calf even sicker. The best method is to provide milk in the morning and afternoon, with electrolytes in the middle of the day.
  • Your veterinarian will advise you on other specific treatments based to his or her diagnosis.

He emphasises that a producer does not have to be satisfied with a mortality rate of more than 5%. “Instead, use an expert, such as your local veterinarian, who possesses the knowledge needed to diagnose calf diarrhoea correctly and who can make a significant difference to your herd.” – Carin Venter, Stockfarm

For more information, phone Dr Louis Hoek on 079 561 5597 or send an email to louishoek@gmail.com.