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Calf scours

When calves are raised as a mob it is highly likely that more than one infectious agent will be present in the mob. Whether the calves succumb to one or more of these infectious agents will depend largely on the passive immunity they have derived from their mother's colostrum, the level of challenge (hygiene) and their ability to combat the infection themselves (energy intake).

The two most commonly encountered agents are rotavirus and the protozoa cryptosporidium which can infect people. The importance of these infections arises because of the damage they do to the intestinal lining which leads to poor absorption of fluids and electrolytes.

The loss of fluids and electrolytes over this period can be corrected with Oral Re-hydration Solutions (ORS). The length of treatment with ORS is governed by the infectious agent. Generally a cryptosporidium infection will last a few days longer than a rotavirus infection. However, both agents may infect the same calf at the same time.

The first goal for recovery is rehydration

Select an ORS that is formulated to promote early calf recovery.  Strong intervention based on volume and frequency needs to be made in the first 12-24 hours. For many calves this requires in excess of 6 litres per day and up to 10 litres for older and heavier calves. A highly palatable ORS aids the process of calves self-feeding these volumes of electrolytes.

Withholding milk feeds

If we're relying on the calf to drink these volumes of fluids and electrolytes, it is essential to withhold milk feeds for this early period. A milk-fed calf has less desire to self-hydrate on electrolytes, defeating the goal of calves being prepared to self-administrate. Most of the electrolytes fed contain buffers which can actually prevent milk from clotting.

Re-introduction of feeding

Once the calf is rehydrated, ORS fluids may be reduced but still continued between feeds. Timing and management of the re-introduction of milk at 24 - 36 hours need to be individually assessed for each calf.  Milk may need to be restricted if a nutritional scour from carbohydrate overload is to be prevented.

The second goal for recovery is to promote the healing of the lining of the small intestine. This lining is made up of millions of microscopic finger like structures. These can become flattened by infections with especially rotavirus and cryptosporidium and it is this that can cause a scour to continue for some days after an infection has been cleared. The use of good quality electrolytes during the initial stages of ORS therapy can aid in this process.

The first and most important point at which calves become infected is when they are in contact with their mothers as they start seeking the udder for milk. Calving on a clean dry paddock with earlier removal of calved cows from this area will reduce the risk of infection transfer.

Electrolyte Dose recommendations:

                        Morning               Midday                 Afternoon

Day 1:              2L ORS               2L ORS               2L ORS

Day 2:              2L ORS               2L colostrum     2L ORS

Day 3:              2L colostrum     2L ORS               2L colostrum

Day 4:              Back to normal milk feeding protocol

These recommendations are of a general nature and individual calves may respond more rapidly or require an extension of this treatment. The duration of treatment is largely dependent on the causative agent.

Notes:

Some calves may still produce loose faeces for a few days after treatment. This is an indication the intestinal villi are still recovering.

All ORS should be prepared fresh as directed by the manufacturer.

Milk should not be diluted with electrolyte because, as suggested above, the buffers in the ORS can actually prevent milk clotting thus making the scour worse.

Most calf scours do not require treatment with antibiotics. There are exceptions to the rule such as scours caused by Salmonella, E. coli and Campylobacter. For this reason we often recommend taking a scour sample from two or three affected calves to identify the cause of the scour and thus use the most appropriate therapy.

Remember... try to ensure the calves you are buying have received colostrum in the first few hours of life and if possible source it directly from a farm father than through sale yards. It is also a good idea to give calves a feed of electrolytes when they first arrive rather than placing them straight onto milk. By following these few simple guidelines you can go a long way to reducing the likelihood of calf scours on your property.  For more advice on how to prevent and treat calf scours, please contact Totally Vets.