Genes encoding equine β-lactoglobulin (LGB1 and LGB2): Polymorphism, expression, and impact on milk composition.
Authors: Wodas Lukasz, Mackowski Mariusz, Borowska Alicja, Puppel Kamila, Kuczynska Beata, Cieslak Jakub
Journal: PloS one
Summary
# Editorial Summary: β-lactoglobulin Polymorphism and Equine Milk Composition β-lactoglobulin represents a substantial proportion of equine milk whey protein, yet limited knowledge exists regarding genetic variation at the LGB1 and LGB2 loci and its influence on milk quality traits—information potentially valuable for breeding programmes and lactation management. Researchers screened twelve horse breeds using direct DNA sequencing across both genes' full coding regions, introns, and regulatory sequences, identifying 83 polymorphic sites (47 in LGB1, 36 in LGB2), of which eight were novel variants. Two linked LGB1 single nucleotide polymorphisms demonstrated statistically significant association with total milk protein content (p < 0.01), whilst breed exerted substantial influence on both gene expression levels and milk β-lactoglobulin concentration (p < 0.01 and p < 0.05 respectively), though lactation stage only affected mRNA transcript abundance. These findings suggest that genetic screening for specific LGB variants could inform breeding selection for improved milk protein yields, and that breed-specific differences warrant consideration when evaluating milk composition across different equine populations—particularly relevant for stud records and performance assessment in breeding mares.
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Practical Takeaways
- •Genetic selection for specific β-lactoglobulin variants may allow breeders to optimize milk protein content in mares, particularly relevant for foal feeding and mare milk products
- •Breed differences in milk composition are partially driven by genetic variation in these whey protein genes, supporting targeted breeding decisions
- •Understanding these genetic markers could inform selection protocols for mares used in milk production or breeding programs
Key Findings
- •Identified 83 polymorphic sites in equine LGB1 and LGB2 genes across 12 breeds, including 8 previously unknown variants
- •Two linked LGB1 SNPs (rs1143515669 and rs1144647991) were significantly associated with total milk protein content (p < 0.01)
- •Horse breed significantly influenced both gene transcript levels (p < 0.01) and milk β-lactoglobulin content (p < 0.05)
- •Lactation period affected gene expression levels but not milk composition traits