Rétentat de lait/Rétentat de lait en poudre

What it is. By-product retained on the membrane after ultrafiltration, nanofiltration or microfiltration of milk. It is marketed in liquid or powder form, with a composition dominated by milk proteins, variable lactose content and mineral ash. The powder results from drying the liquid retentate.

What it is for. Used as a protein source in feed, mainly for young animals requiring highly digestible milk proteins. It is generally used in milk replacers and starter feeds, where its protein/lactose ratio can be adjusted depending on the membrane filtration process used. Formulation should take into account the declared crude protein, ash and lactose contents, which vary with the filtration technique applied.

Points to watch. Crude protein, crude ash and lactose content must be declared, as well as moisture content above 8%. Composition varies according to the filtration process (ultra-, nano- or microfiltration) and the milk source, requiring a check of the supplier's specification sheet for each batch. As a milk-derived product, it is hygroscopic and sensitive to storage conditions, particularly in powder form.