[Quality Assessment of Bovine and Equine Colostrum - An Overview].

Introduction: Good quality colostrum intake is essential for passive immunity in neonatal calf and foals. The quality of colostrum depends on its IgG content. Since in practice the possibilities for a direct determination of these parameter are limited, an estimation of colostrum quality is often based on its biophysical properties. The simple methodology allows to perform measurements directly on site and immediately after birth. The biophysical properties included in the current review are density, refractive index, relative density, viscosity, pH, and color. The determination of the density of bovine colostrum is a common method for the evaluation of the IgG content in practice since it correlates with IgG. Density of bovine colostrum should be 1047 g/l. Different colostrometers are available for the measurement. This method is also used in the horses. Density of equine colostrum should be 1060 g/l. Refractive index or the relative density by refractometer has been proven to correlate with the IgG and is an established method in cattle and horses. Good bovine colostrum should have an index of 22% brix and equine colostrum 23% brix. Although not yet established in practice an additional methodology would be the determination viscosity of bovine colostrum. Viscosity could be measured with an outlet cup. A relationship between viscosity and IgG has demonstrated. Sufficient data for this method is missing for equine colostrum. Color and pH are not suitable for estimating the IgG content.