Osmolality is key to increasing calf intakes

13 December 2019

Maximising calves intakes can be vital to herd growth rates and measuring the osmolality of calf milk replacers can be a key step in achieving this, according to calf specialist, Katie Tiernan of Trouw Nutrition Ireland.


Osmolality is the measure of the concentration of particles in a solution. It is calculated by adding the concentration of the sugars, such as lactose, and minerals such as sodium, magnesium and chloride. The osmolality of cow’s milk is 330mOsm/L which is optimal for the absorption and digestion of nutrients by calves, but many milk replacers when mixed have osmolality close to 400-600mOsm/L. Greatly increasing or decreasing the osmolality from the target level can affect digestibility and increase the risk of gastrointestinal problems including nutritional scours.

The gastrointestinal tract plays two crucial roles. First, it absorbs nutrients from the diet to fuel growth and secondly it prevents unwanted compounds and pathogens from entering the blood stream. This intestinal barrier plays an essential role in calf health. Anything that alters the permeability of the gut wall can facilitate the onset of disease. Increasing osmolality affects the gut barrier function and integrity which can have detrimental effect. Where osmolality in milk replacer is too high it is also likely there will be an increased incidence of abomasal bloat. Finally, high osmolality levels can exacerbate the severity of scouring in sick calves.

New research by Trouw Nutrition has taken innovative steps to limit the risk of osmolality causing problems in calves by developing a new calf milk replacer, Energized Calf Milk. ECM has a high fat content (25%) and reduced lactose content which closely resembles the fatty acid profile found in cow’s milk, thus increasing the overall digestibility of energy.