Osmolarity relates to the process of osmosis. A calf’s blood has an osmolarity of approx. 300 and cow’s milk 300-320 so the two are therefore well balanced and little transfer of water from blood to gut would occur. The main factors affecting osmolarity are Lactose levels i.e. sugar molecules and salt (Sodium and chloride ions). Whey based milk replacers will generally have a higher lactose and salt level and therefore higher osmolarity. Though in better quality whey products one can use whey powder low in lactose in order to lower osmolarity.
Calf milks with high skim content for example; Calf Defender (transition milk powder), Calf Distinction, Enterprise Once-a-Day, Sure Start, Calf Gold, Calf Supreme also Calf Prime and Calf Delight have always had a low osmolarity. The effects and influences of the osmolarity of milk powders is well known and we have always been aware of the difference between high quality skim products in comparison to some poorer quality whey products in terms of looser dung occurring when poorer whey products are fed.
To clarify the process of homogenisation – this is when liquid fats/oils are mixed with liquid skim or whey and homogenised to create fat molecules of less than 2 microns in diameter which are then encapsulated in milk solids and spray dried at low temperature. This process results in less free fat in calf milk and leads to greater digestibility.
The move to higher fat/lower protein milk powders with similar ratios to cow’s milk (Fat 3.8-4.0% and Protein 3.1-3.3%) has a lot of merit. This is particularly so with many large herds where larger calf sheds can be very cold with calves needing additional energy during the critical first 4-week period of its life.
We now have 3 products, Calf Defender (transition milk powder), Calf Distinction and Enterprise Once- a-Day with this reverse ration of higher fat and less protein, both with a high skim content and with 100% all milk protein.