[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.

Effects of myostatin on the mechanical properties of muscles during repeated active lengthening in the mouse

The aim of the present study was to investigate how myostatin dysfunction affects fast and slow muscle stiffness and viscosity during severe repeated loading. Isolated extensor digitorum longus (EDL) and soleus muscles of young adult female mice of the BEH (dysfunctional myostatin) and BEH+/+ (functional myostatin) strains were subjected to 100 contraction-stretching loading cycles during which contractile and mechanical properties were assessed. BEH mice exhibited greater exercise-induced muscle damage, although the effect was muscle- and age-dependent and limited to the early phases of simulated exercise. The relative reduction of the EDL muscle isometric force recorded during the initial 10-30 loading cycles was greater in BEH mice than in BEH+/+ mice and exceeded that of the soleus muscle of either strain. The induced damage was associated with lower muscle stiffness. The effects of myostatin on the mechanical properties of muscles depend on muscle type and maturity.