Abstract :
The small size of goat milk fat globules (MFGs) is one of the factors contributing to the higher
digestibility of goat milk compared to other milks. In this study, size, protein composition
and lipid distribution of MFGs were evaluated comparatively in a popular dairy breed, Saanen,
and in a minor breed, Sarda. MFGs were found to be significantly smaller in Sarda
compared to Saanen goats, with average diameters of 2.73 ± 0.15 m and 3.63 ± 0.27 m,
respectively. Raman spectroscopy revealed differences in the lipid profiles of differently
sized MFGs within each breed, with MFGs of the same size class having comparable profiles
between breeds. Proteomic characterization by SDS-PAGE followed by tandem mass
spectrometry (GeLC–MS/MS) and label-free differential quantification highlighted significant
differences in expression levels of MFG proteins from the two breeds, with a higher
abundance of cytoplasmic proteins in Sarda MFGs and of membrane proteins in Saanen
MFGs. Moreover, differences in the relative abundance of several major MFG proteins were
observed for the two breeds. In conclusion, this study demonstrates the existence of breeddependent
differences in the lipid and protein makeup of goat MFGs, likely related to their
different size distribution. This highlights once again the importance of investigating biodiversity
in autochthonous and neglected breeds, which often possess valuable attributes
that might be lost as a consequence of the widespread diffusion of highly productive, but
more homogeneous, dairy breeds.
