Protein Components of Goat’s Milk

Milk is a complex biological fluid produced by the mammary gland which has three main functions: (i) nutritional; (ii) immunological; and (iii) physiological. Recently, the physiological role of milk has been emphasized in research, and consumer demand for high-quality products has increased. Consequently, the transformation industry has started to market ‘high-quality milk’ with particular nutritional/dietary characteristics. In industrialized countries, milk proteins represent 30% of total dietary protein intake and 75% of Ca intake (Meisel, 1993a,b, 1997; Morand-Fehr, 1996; Reinert and Fabre, 1996; Spuergin et al., 1997; Restani et al., 1999). Several epidemiological studies have focused on the influence of cow’s milk consumption on health, especially on cancer development. However, available data are contradictory, due to the complex interactions among milk components. Nevertheless, a positive linear relationship between cancer and energy intake or fat-rich milk consumption has been suggested (Attaie and Richter, 2000). Milk contains lipid components which are well-known anticarcinogenic agents (Parodi, 1997). According to the World Cancer Research Fund, the lipid components of milk and derived products increase the risk of two types of cancer only (kidney and prostate) (WCRF, 1997). In an early study on the use of goat’s and ass’s milk, high infant mortality occurred due to the bad microbiological characteristics of the goat’s milk employed (Michel, 1910). As a consequence, for more than half a century goat’s milk was not recommended for human diets. However, since the 1980s several other studies and epidemiological research have highlighted the nutritional properties and the presence of minor components of pharmacological interest in goat’s milk, thus recommending its usage in human feeding (Domeniconi and Balzola, 1980; Birkbeck, 1984; Parry, 1984; Darnton Hill et al., 1987; Awiatlo et al., 1990; Park, 1991; Houdebine, 1995; MacDonald, 1995; Albertini et al., 1999).