Effect of β-lactoglobulin (LGB) and k-casein (CSN3) alleles on some characteristics of milk produced by Cinisara cows

Abstract

It is well known that β-lactoglobulin (LGB) and k-casein (CSN3) alleles affect milk cheese making properties. The purpose of this study was to analyse the A and B allele distribution at the LGB and CSN3 loci in Cinisara breed and their influence on milk and cheese making production traits. The Cinisara is a Sicilian breed which, according to DAD-IS database (FAO), consists of about 5,000 individuals and is reared mainly for milk production which is usually transformed into Caciocavallo Palermitano, a typical stretched-curd cheese. We typed 314 lactating cows at the LGB and CSN3 loci by means of RFLP-PCR analyses. The frequencies of LGB A and B alleles were 0.22 and 0.78, respectively; the frequencies of CSN3 A and B alleles were 0.46 and 0.54, respectively. Individual milk samples were analysed for total nitrogen (TN) and non-casein nitrogen (NCN) according to FIL-IDF standard procedure. The coagulation properties were measured using the Formagraph. Data were analysed using ANOVA procedure in which the fixed effect of CSN3 genotype or the fixed effect of LGB genotype was evaluate. The results of this study show that also in Cinisara the LGB A and B alleles are associated with significantly different effects on NCN (lower for BB genotype, P<0.001), and casein index (higher value for BB genotype, P<0.0001). As a consequence, the LGB alleles are associated also with significantly different effects on coagulation properties such as coagulation time (r) and curd firming time (k20) (lower value for BB genotype, P<0.011, P<0.050, respectively); while they are not associated with different effects on curd firmness (a30 and a2r). CSN3 A and B alleles are not associated with different effects on NCN, and casein index. On the contrary, they are associated with significantly different effects on coagulation properties: BB genotype shows lower value for coagulation time (r) (P<0.0001) and curd firming time (k20) (P<0.0001); higher value for curd firmness (a30) (P<0.0001) and curd firmness (a2r) (P<0.0001) than AA genotype. Our results confirm again that LGB and CSN3 genotypes affect cheese making properties and show that Cinisara cows, due to higher frequencies of alleles with positive effect on cheese making properties, produce a high quality milk for cheese processing.