Beta-lactoglobulin is one of the proteins found in cow’s milk. It belongs to the group of whey proteins, constituting, together with caseins, the basic protein composition of milk. The gene responsible for the production of β-LG shows polymorphisms, affecting the amount of protein produced. Two most common β-LG variants, A and B, have been identified. Variant A is characterized by increased milk yield and whey protein content – thus higher levels of beta-lactoglobulin. Variant B, on the other hand, shows higher casein and fat content – lower levels of beta-lactoglobulin.
Βeta-lactoglobulin is encoded by the BLG gene located on bovine chromosome 11. The β-LG gene polymorphism is determined by single nucleotide substitutions within the protein structure and amino acid swaps. The A variant is characterized by the presence of the amino acid glycine. AA genotypes show an increase in whey proteins, including beta-lactoglobulin, and a decrease in casein proteins and milk fat content. Variant B is distinguished by the amino acid alanine. The occurrence of BB genotypes is associated with higher casein and fat content, favorably affecting the production of cheese products.
The occurrence of beta-lactoglobulin polymorphism has been demonstrated in individual cattle breeds: Lineback, Devon, Ankole-Watusi, Ayrshire, Beefmaster, Belgian Blue, Brown Swiss, Dexter, Dutch Belted, Gir, Guernsey, Holstein-Friesian, Jersey, Kerry, Maine-Anjou, Montbeliarde, Normande, Norwegian Red, Piedmontese, Pinzgauer, Red & White, Salers, Shorthorn, Simmental.
| Result | Interpretation |
| AA | HIGH AMOUNT OF BETA-LACTOGLOBULIN |
| AB | INTERMEDIATE AMOUNT OF BETA-LACTOGLOBULIN |
| BB | LOW AMOUNT OF BETA-LACTOGLOBULIN |
REFERENCES #
- Ganai NA, Bovenhuis H, van Arendonk JA, Visker MH. Novel polymorphisms in the bovine beta-lactoglobulin gene and their effects on beta-lactoglobulin protein concentration in milk. (2009). Anim Genet. 40(2):127-33.
- Rachagani S, Gupta ID, Gupta N, Gupta SC. Genotyping of beta-lactoglobulin gene by PCR-RFLP in Sahiwal and Tharparkar cattle breeds. (2006). BMC Genet. 25;7:31.
- Wolanciuk A. The association of genetic variants of β-lactoglobulin and κ-casein with yield and chemical composition of milk obtained from four breeds of cow. (2015). Scientific Annals of Polish Society of Animal Production – Vol. 11 (2015), No 1, 21-32.