The last few years have seen a number of advances in the understanding of genetic polymorphisms of caprine caseins, and especially in molecular characterization of the allelic variants and analysis of their frequencies in Spanish and other breeds (Grosclaude et al. 1994; Jordana et al. 1996). Although more is being discovered about the influence of these polymorphisms on the yield and characteristics of cheeses (Remeuf, 1993; Pirisi et al. 1994), little work has been done on the quantitation of different casein fractions of goats' milk throughout lactation. Measurements have been made using SDS-PAGE (Quiles et al. 1990) and cation- exchange FPLC (Brown et al. 1995), and Recio et al. (1997a) have demonstrated the potential of capillary electrophoresis (CE) for the analysis and quantitation of milk proteins. Use of CE has resulted in the development of rapid automated analysis with very high resolution, requiring very small sample and buffer volumes and with a significantly reduced amount of solvent waste.

The aim of the present study was to determine the influence of herd and milking period on the contents of the various nitrogen and casein fractions, the latter being determined by CE, in milk from goats of the Murciana-Granadina breed.