Polymorphisms of α-lactoalbumin, β-lactoglobulin and prolactin genes are highly associated with milk composition traits in Spanish Merino sheep

Effect and Interaction of β-Lactoglobulin, Kappa Casein, and Prolactin Genes on Milk Production and Composition of Awassi Sheep

“…This study reports the association between β-LG , PRL , and CSN3 genes and milk production and composition of Awassi sheep. These genes were chosen because of their direct involvement in the growth and development of the mammary gland, maintenance of milk secretion, and synthesis of milk [2,12,14,15,22,31]. The genes are also located in the region of QTL influencing milk quantity and quality [12,14,15,22,23].…”

“…Milk protein polymorphisms are of great importance in the dairy industry and animal-breeding programs due to its association with quantitative and qualitative milk traits and its potential use in genetic selection programs of dairy sheep breeds [11]. Many studies with diverse breeds of dairy sheep have indicated Beta-lactoglobulin ( β-LG ), Prolactin ( PRL ) and Kappa casein ( CSN3 ) as promising candidate genes for milk production and composition [2,12,13,14,15,16].…”

“…The most common genetic variants detected in all studied sheep breeds are A and B, while the variant C is regarded as rare, and only found with low frequencies in Carranzana, Black Merino and White Merino breeds [15]. Subsequent studies have demonstrated the β-LG gene’s polymorphic effect on milk components including yield, protein, fat, and lactose content [14,19,20] as well as the impact of protein genetic variants on the properties of milk [2].…”

“…The PRL gene plays a key role in the development of the mammary gland and milk secretion; its depletion in sheep provokes a severe reduction in milk production [21], suggesting that PRL is a functional candidate gene contributing to variations in milk production. Many researchers suggested the association of PRL gene polymorphisms with milk yield and composition traits in different dairy sheep breeds [13,14,16,22]. The PRL gene is in a region of the ovine chromosome 20 with putative quantitative trait locus (QTL) for milk yield and composition [23].…”

Analysis of Whole Genome Resequencing Datasets from a Worldwide Sample of Sheep Breeds to Identify Potential Causal Mutations Influencing Milk Composition Traits

“…Other studies have also focused on the genetic variants of the genes coding for the sheep milk whey proteins, α-Lactalbumin and β-Lactoglobulin, which account for 17-22% of the total milk proteins in sheep milk [13]. These whey proteins are encoded by two genes located on OAR3, the LALBA gene and the LGB gene (annotated as PAEP in the sheep reference genome Oar_v3.1), both located on regions that have been associated with milk performance traits in dairy sheep [14,15]. In this sense, it is worth mentioning that a missense variant in the coding region of the LALBA gene (p.Val27Ala) was identified through a GWAS study as the causal mutation of a previously identified QTL effect influencing milk protein and milk fat content in Spanish Churra sheep [16].…”