Volume 1(1)/2011 (December, 30)

Suteu M., 2011 Porcine milk protein polymorphisms. Porcine Research 1(1):1-112.

Abstract. Biochemical polymorphism of proteins is a widely spread phenomenon in all animal species, meaning that in individuals belonging to the same species a certain protein may be present in more than one molecular form. Biochemical polymorphism of milk proteins in dairy species has been intensely studied. The first polymorphism of a milk protein was highlighted in 1955 in cattle, when using paper electrophoresis, two polymorphic variants of β-lactoglobulin were discovered and named A and B, respectively. Milk proteins are divided in two major groups: the casein fraction and the whey proteins. The first group, characterized by a limited mobility at 4.6 pH (they precipitate), comprises the four caseins: αS1-, aS2-, β- and κ-casein. Whey proteins remain soluble in an acid pH; they are represented, in most species, by α-lactalbumin and β-lactoglobulin. In porcine milk a third major whey protein was first identified in 1987, called at the time novel whey protein. Relatively recently (1998), this third major porcine whey protein was characterized, namely WAP (whey acidic protein), a protein also encountered in mouse, rat, rabbit and camel milk. The present paper underlines the polymorphisms that appear within major milk proteins in highly improved porcine breeds, such as: Large White, Landrace, Pietrain and Duroc and local Romanian unimproved breeds: Mangalita and Bazna. Having in mind that genes encoding major milk proteins are used worldwide in marker assisted selection in other species (αS1-casein in goats – associated with milk protein content and flavour; κ-casein and β-lactoglobulin in cattle – associated with milk quantity and quality, bovine β-casein – associated with human health etc.) it is probable that highly polymorphic genes such as porcine β-casein will be the next selection markers in pig breeding.

Key words: porcine milk, proteins, αS1-casein, aS2-casein, β-casein, κ-casein, α-lactalbumin, β-lactoglobulin, whey acidic protein, WAP, Large White, Landrace, Pietrain, Duroc, Mangalita, Bazna.

29.12.2011. 13:32