Exploring the Genotype at CSN3 Gene, Milk Composition, Coagulation and Cheese-Yield Traits of the Sardo-Modicana, an Autochthonous Cattle Breed from the Sardinia Region, Italy

Effect of CSN3 Gene Polymorphism on the Formation of Milk Gels Induced by Physical, Chemical, and Biotechnological Factors

During the last decade, research into genetic markers in the casein gene cluster has been actively introduced in cattle breeding programs. A special interest has been paid to the polymorphism of the CSN3 gene, responsible for the expression of the k-casein, playing a key role in protein coagulation, interaction with whey proteins, stabilization, and aggregation of casein micelles. This paper aimed to determine the effect of CSN3 genetic polymorphism on acid; rennet; acid-rennet; heat- and acid-induced as well as heat- and calcium-induced coagulation in skimmed milk; and protein-standardized milk systems (UF, NF, RO, VE). The influence of polymorphic variants of the CSN3 gene on the coagulation ability of milk proteins was assessed by the particle size of casein micelles, protein retention factor in the clot, and coagulation ability (duration of induction period, mass coagulation period, dynamic viscosity in gel point). The correlation between CSN3 gene polymorphism and protein coagulation was revealed. Milk systems obtained from CSN3 BB milk were found to have the shortest duration of coagulation, formation of better gel strength values, and increased yield compared to CSN3 AA. This study will improve the efficiency of milk processing and optimize the technology of dairy product production.

Mitochondrial DNA diversity of the Sardinian local cattle stock

The aim of this research was to characterize the genetic diversity of the Sarda (Sa, n = 131), Sardo Bruna (SB, n = 44) and Sardo Modicana (SM, n = 26) cattle breeds, reared in the island of Sardinia (Italy). A portion of the mitochondrial DNA hypervariable region was sequenced, in order to identify a potential signature of African introgression. The F_ST coefficients among populations ranged between 0.056 for Sa vs SB and 0.167 for SB vs SM. AMOVA analysis indicated there was a significant differentiation of the three breeds, although most of diversity was gathered at the within-breed level. The Median Joining Network of the Sardinian sequences showed a potential founder effect signature. A MJ network including Sardinian cattle plus African, Italian, Iberian and Asian sequences, revealed the presence of haplogroup T3, already detected in Sa cattle, and the presence of Hg T1 and Hg T1′2′3, in Sa and SB. The presence of a private haplotype belonging to haplogroup T1, which is characteristic of African taurine breeds, may be due to the introgression of Sardinian breeds with African cattle, either directly (most probable source: North African cattle) or indirectly (through a Mediterranean intermediary already introgressed with African blood).

Characteristics of kappa-casein gene polymorphism in cows of Swiss breed and their productive qualities at a large dairy

Kappa-casein is a fraction of the main milk protein, which determines the technological properties of milk and the quality of dairy products, especially cheese and fermented milk products. The study tested the distribution of kappa-casein gene genotype polymorphism (CSN3) in mothers and daughters of the Swiss breed cows, taking into account their milk productivity qualities. The study was performed on 111 cows of the Swiss breed on a large dairy. The observation group I included 51 cow-mothers of the Swiss breed; group II – 60 cow-daughters of the Swiss breed. In a study of the polymorphism of the kappa-casein gene in cow-mothers and cow-daughters of the Swiss breed, the dominance of allele B (0.73 and 0.70) was found, which was registered more than two times more often than allele A. The incidence of genotypes AA – AB – BB in cow-mothers of the Swiss breed was as follows: 5.9% – 43.1% – 51.0% with indicators of observed heterozygosity 0.43 and expected heterozygosity 0.40. In cow-daughters of the Swiss breed the frequency of the BB genotype was the same, but, genotype АА was registered almost twice as often, with lower indicators of observed heterozygosity and smaller increases of indicators of expected heterozygosity than in cow-mothers. Cow-mothers of the Swiss breed with the AA genotype, in comparison with the AB genotypes, had higher milk yields during lactation (by 43%), fat production (by 86.9%), ratio of fat to protein (by 40.5%). Also note, the cow-mothers of the Swiss breed with the AA genotype, in comparison with the BB genotypes, had reliably high rates of fat to protein (by 35.8%) and only a trend to higher fat production; fat and protein. The production of fat in dairy cows-daughters with the BB genotype was higher than with the AA genotype, but only at the level of tendency. The correlation analysis showed that the AA genotype of the kappa-casein gene in cow-mothers of the Swiss breed was associated with the duration of lactation, indicators of milk yield during lactation, fat production, fat content and protein in milk with registration of reliable and positive coefficients of correlation. The genotypes in cow-daughters did not have a reliable correlation with the duration of lactation and fat or protein content in milk. The results of the kappa-casein gene polymorphism study indicated that the AA genotype of cow-mothers of the Swiss breed was associated with higher productive milk qualities which should be taken into account when forming a highly productive herd of cattle of the Swiss breed under intensiveoperative technology at a large-scale dairy unit.