Supporting recovery from calf diarrhoea

Diarrhoea in the young calf is a commonly occurring challenge on many farms. Recent research by MSD Animal Health, completed as part of their Youngstock Survey in 2020, indicated that 90% of dairy farms had experienced scour in calves in the previous 12 months and that over 65% had experienced mortality due to scour. Diarrhoea is reported as a major cause of morbidity and mortality in early life, which can result in significant economic losses and potential welfare challenges.

It is important to note that it is often not the diarrhoea itself but the consequence of dehydration and associated metabolic acidosis which can lead to calf mortality. For this reason, successful recovery from diarrhoea relies on the proactive implementation of proven nutritional strategies that effectively target these consequences. Having a clear protocol, alongside a proven product, should be considered a key part of an on-farm calf rearing programme.

Regardless of the cause, calves suffering from diarrhoea undergo extensive electrolyte and water losses. Calves are at a higher risk of dehydration, compared to adult cattle, due to a number of factors. These include body size to surface area ratio as well as differences in metabolic rate and body composition. The key factor is that the majority of the calf’s fluid is stored outside cells in extracellular fluid pools, as opposed to the adult cow where the majority of the fluid is within the cells in intracellular fluid pools. Extracellular fluid is lost quickly and easily when a calf is affected by diarrhoea.

The main goal of diarrhoea treatment should involve the application of oral rehydration solutions (ORS), also termed oral electrolyte solution (OES). ORS were originally developed in the 1960s for the rehydration of human patients suffering from cholera infections. Although much research has been completed on oral rehydration therapy considerable variability exists in the composition, and therefore effectiveness, of commercially available ORS for calves.

A common practice to manage digestive disturbances is to withdraw milk until the diarrhoea has stopped. However, several research studies show that withholding milk can increase weight loss and dehydration, and prolong the calf’s recovery from diarrhoea. New research shows that offering ORS alongside the usual milk allowance maximises recovery from diarrhoea. It is important to remember that a calf’s energy intake primarily relies on whole milk or calf milk replacer, so a better nutritional choice is to reduce meal size and increase feeding frequency if required

In addition to this, it is best to proactively provide ORS early when calves start exhibiting signs of dehydration and have a depressed appetite. A practical approach is then to feed ORS in between milk meals through a teat bucket or a bottle. See Table 1 for an example feeding scheme.

Table 1: Example of feeding scheme for calves with diarrhoea

Previously it was common practice for ORS to be fed in whole milk or milk replacer as it reduces the labour associated with the treatment of calves. However, this practice needs to be revaluated. Most ORS products contain high concentrations of sugar and salts. Whole milk, and especially milk replacers, already contain high concentrations of lactose and sodium.
When mixing ORS into milk, the osmolality of the solution can rise above 600 mOsm/kg, with sodium concentrations above 100 mmol/L.

Osmolality measures the concentration of particles in a solution and is calculated by adding the concentrations of sugars and minerals. As a reference, normal osmolality for blood and whole milk is close to 300 mOsm/kg. Above this level a solution is called hypertonic. Feeding very hypertonic solutions to calves may result in increased diarrhoea severity as water will be pulled into the gut. Additionally, very concentrated milk meals slow down abomasal emptying rates, which may increase the incidence of gastrointestinal disorders such as abomasal bloat. Therefore, best practice is to feed ORS separately to ensure it can effectively rehydrate the calf. It is also essential that clean fresh water is always available.

LifeStart Science is providing guidance on best nutritional practice for feeding and management of calves with diarrhoea and dehydration. This has shown that due to formulation differences, all ORS are not equally effective at rehydration. It is important to use a scientifically proven product that has been carefully formulated with a low osmolality to stabilise water and electrolyte balance and therefore effectively rehydrate calves.

OsmoFit is the next generation of oral rehydration solutions for calves which is the result of extensive in calf research. Based on a patent-pending formula OsmoFit provides a precisely balanced nutrient supply to support effective rehydration in calves.