Short communication: Carora cattle show high variability in alpha(s1)-casein

Area of Science:

• Animal Genetics and Breeding
• Dairy Science
• Molecular Biology

Background:

• The Carora cattle breed, a Bos taurus shorthorn breed from Venezuela, is primarily utilized for milk production.
• Understanding the genetic variability of milk proteins is crucial for optimizing dairy production and cheese-making traits.
• Previous studies have not extensively detailed the genetic polymorphism of key milk protein genes in the Carora breed.

Purpose of the Study:

• To analyze the genetic variability of milk protein genes (alpha(s1)-casein (CSN1S1), beta-casein (CSN2), kappa-casein (CSN3), and beta-lactoglobulin (LGB)) in the Carora cattle breed.
• To identify and quantify genetic variants within these milk protein loci.
• To assess the implications of identified variants, particularly CSN1S1*G, for milk production and cheese-making properties.

Main Methods:

• Milk protein typing was performed at the protein level using isoelectrofocusing on 184 samples from 5 Carora herds in Venezuela.
• The alpha(s1)-casein (CSN1S1) gene was further analyzed at the DNA level using a PCR-based method to differentiate CSN1S1*G from CSN1S1*B.
• Haplotype frequencies for the CSN1S1-CSN2-CSN3 gene complex were estimated, considering genetic associations.

Main Results:

• Significant genetic variation was observed, especially in the CSN1S1 gene, with four identified variants: CSN1S1*B (frequency = 0.8), CSN1S1*G (0.101), CSN1S1*C (0.082), and a potential novel variant, CSN1S1*I.
• Predominant alleles for other loci included CSN2*A2 (0.764), CSN3*B (0.609), and LGB*B (0.592).
• The CSN1S1*G variant, found at a relatively high frequency, is associated with improved milk-clotting parameters but negatively impacts cheese ripening, suggesting potential selection considerations.

Conclusions:

• The study highlights substantial genetic diversity in milk proteins within the Carora breed, with CSN1S1 showing the highest variability.
• The CSN1S1*G allele, likely inherited from Brown Swiss cattle, warrants attention for its dual effects on milk processing traits.
• Routine milk protein typing, incorporating DNA analysis for CSN1S1 variants, is recommended for effective breeding programs and enhanced cheese production in the Carora breed.