Genetic polymorphism of Casein cluster in Sudan Nubian dairy goats

Abstract

Milk samples from eighty seven lactating Nubian does were analysed to study the genetic 
polymorphism of casein protein. The genetic variants in milk samples were detected using 
polyacrylamide gel electrophoresis focusing (PAGE-IEF) method. The electrophoretic 
pattern revealed that milk samples of the Nubian goat contained the four major casein 
variants: as1-casein (CSN1S1), as2 –casein (CSN1S2), b-casein (CSN2) and k-casein 
(CSN3). Five CSN1S1 alleles viz. CSN1S1, CSN1S1, CSN1S1, CSN1S1, andCSN1S1 
were identified .The predominant allele was CSN1S1, with a frequency of 0.662 followed 
by CSN1S1 (0.125), and CSN1S1 (0.112). A very low frequency, the allele CSN1S1 
occurred. The null frequency - (i.e. absence of this particular allele in the sampled 
population).-for this locus (CSN1S1) was 0.050. The CSN1S1 locus had undergone Hardy
Weinberg Equilibrium.  The CSN1S2 locus showed the variants namely, A, C and X and 
the variant frequencies were 0.775, 0.212, and 0.013, respectively. Two genetic variants 
(A and B) were also observed in the CSN3 locus having the frequencies of 0.950 and 0.050, 
respectively.  In this study, polymorphism of CSN2 locus was observed, represented by A 
and X variants, with 0.988 and 0.012 frequencies.