Bovine milk has been described as an almost perfect food because it is a rich source of vitamins, calcium, and essential amino acids (Karatzas and Turner 1997). Some of the vitamins found in milk include vitamins A, B, C, and D. Milk has greater calcium content than any other food source, and daily consumption of two servings of milk or other dairy products supplies all the calcium requirements of an adult person (Rinzler et al. 1999).
Caseins represent about 80% of the total milk protein and have high nutritional value and functional properties (Brophy et al. 2003). The caseins have a strong affinity for cations such as calcium, magnesium, iron, and zinc. There are four types of naturally occurring caseins in milk: S1, S2, , and (Brophy et al. 2003).
They are clumped in large micelles, which determine the physicochemical properties of milk. Even small variations in the ratio of the different caseins influence micelle structure, which in turn can change the milk’s functional properties.
The amount of caseins in milk is an important factor for cheese manufacturing, since greater casein content results in greater cheese yield and improved nutritional quality (McMahon and Brown 1984). It has been estimated that enhancing the casein content in milk by 20% would result in an increase in cheese production, generating an additional $190 million/year for the dairy industry (Wall et al. 1997)
Dairy cattle have only one copy of the genes that encode (s1/s2), , and -casein proteins, and out of the four caseins, and are the most important (Bawden et al. 1994). Increased milk -casein content reduces.