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Diarrhoea or scouring, which can lead to poor growth and mortality in calves, remain a major challenge for producers. According to Dr Johan van Rooyen of the Steynsburg Animal Hospital, animals kept in large groups is one of the reasons why diarrhoea is common in calves.

This is especially the case in dairy herds where calves are kept in smaller camps. As a rule, beef cattle herds that graze veld do not suffer from calf diarrhoea, he says.

E. coli infections

According to Dr Van Rooyen, the causes of diarrhoea include contagious (bacteria and infections that are transmitted) as well as physical causes related to milk and its quality.

Escherichia coli (E. coli) bacterial infection is one of the leading causes of diarrhoea in young dairy calves. It is especially prevalent in unhygienic environments characterised by stagnant water, wet conditions, animals that congregate in large groups and dirty calf pens.

“These infections typically occur in calves younger than ten days. If it ends up in the bloodstream it can cause septicaemia, after which coli septicaemia develops, which is fatal. In some cases, E. coli can even cause meningitis in calves.”

His advice is to vaccinate cows so that when calves ingest colostrum, they will also ingest the antibodies against E. coli.

However, he warns, E. coli remains an issue because the bacterium changes its antigenicity. This means the vaccine becomes less effective with subsequent administrations. A few very effective vaccines do, however, still exist. Combining an effective vaccine with strict hygiene protocols and a good biosecurity programme can help in keeping E. coli at bay.

Cryptosporidiosis

Another cause of calf diarrhoea is cryptosporidiosis. Dr Van Rooyen says this unicellular organism, which is related to coccidiosis, is highly contagious and can lead to mortalities. Cryptosporidiosis usually develops in calves younger than three days, mainly due to poor biosecurity measures. This is because cryptosporidium parasites occur in sewage systems near human settlements.

“Treatment is expensive and there is no vaccine against cryptosporidiosis. Other viruses and bacteria that cause calf diarrhoea include clostridium, salmonella, and the corona- and rotaviruses. However, there are vaccines for these.”

Physical causes

The quality of colostrum is important for the prevention of calf diarrhoea. According to Dr Van Rooyen, a calf must receive a good dose of colostrum in the first six hours after birth. Therefore, its dam needs to be immunised in order to develop antibodies.

The lack of the right type of antibodies in the colostrum can increase the calf’s susceptibility to disease (and diarrhoea), but if cows were sufficiently vaccinated prior to calving the colostrum will contain enough antibodies to protect the calf. There are also products that protect a calf via the colostrum.

Other causes of diarrhoea include milk replacers that were not prepared correctly, poor water quality or calves that did not get enough to drink. These calves will often consume leaves, sticks and other material in the pens, which only aggravates matters.

If calves start consuming solid feed before their rumens have developed sufficiently, a process of rotting rather than fermentation takes place in the rumen. It can poison the calf and cause severe diarrhoea.

Managing calf diarrhoea

Nutrition management plays a key role. In addition, clean water should be given when calves are dehydrated.

Dr Van Rooyen says calf diarrhoea can be managed quite well by positioning and elevating individual calf pens some distance off the ground. Workers who operate in these pens must also follow the necessary biosecurity measures. This includes wearing clean shoes and overalls. Access control must be strictly monitored, and flies and mosquitoes must be controlled.

The administration of probiotics is another preventative measure. ‘Good’ bacteria can be distributed by spraying a certain area or via feeding. These good bacteria will dominate the negative bacteria and will stop them from multiplying.

“It is a natural process and there are a lot of these organisms available on the market,” he says. “These mixtures are available in liquid or powder form and are given to the calves via milk. It can be bought from suppliers, or producers can cultivate it on their farms or spray it in a certain area.”

For more information, contact Dr Johan van Rooyen on 048 884 0899 or email veearts.sdh@nokwi.co.za.

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