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

Abstract

A participatory animal-breeding program was applied to 9 commercial Awassi sheep flocks in Jordan. This study aimed to assess the influence of Beta-lactoglobulin (β-LG), Prolactin (PRL), and Kappa casein (CSN3) genes, genotypes and their interaction on milk production and composition traits of 167 genotyped Awassi ewes via Polymerase Chain Reaction (PCR) followed by sequencing. Allele frequencies for the two variants were 0.42 and 0.58 for β-LG, 0.82 and 0.18 for PRL, and 0.92 and 0.08 for CSN3. No association was found among β-LG and CSN3 polymorphic genotypes with milk production traits. However, ewes with PRL AA genotype showed higher milk production, β-LG AB was associated with lowest fat%, high solid not fat (SNF)%, protein%, and lactose%. β-LG BB was associated with highest milk density. PRL, β-LG, and CSN3 polymorphic genotypes were differentially associated with milk production and component traits. Furthermore, β-LG × PRL interaction showed the highest milk production and fat%; β-LG × PRL recorded the highest SNF%, protein%, lactose%, and milk density, while the PRL × CSN3 had the highest fat% and SNF%. The enhancing effects of these gene interactions can be incorporated in Awassi breeding programs to improve milk production and composition.

Relationships between Hha1 Calpastatin Gene Polymorphism, Growth Performance, and Meat Characteristics of Awassi Sheep

“…Polymerase Chain Reaction- Restricted Fragment Length Polymorphism (PCR-RFLP) genotyping was used as previously described [7,8] to find new possible polymorphisms in the region between exons 61 bp 1C, 88 bp 1D, and 473 bp of the CAST gene previously studied [8]. A 622 bp amplicon was amplified using forward 5′-TGGGGCCCAATGACGCCATCGATG-3′ and reverse 5′- GGTGGAGCAGCACTTCTGATCACC-3′ primers on the Life Pro Thermal Cycler (Hangzhou Bioer Technology Co., Hangzhou, China).…”

“…A 622 bp amplicon was amplified using forward 5′-TGGGGCCCAATGACGCCATCGATG-3′ and reverse 5′- GGTGGAGCAGCACTTCTGATCACC-3′ primers on the Life Pro Thermal Cycler (Hangzhou Bioer Technology Co., Hangzhou, China). The optimum annealing temperature for PCR was determined empirically using gradient PCR, using reaction mix and conditions as described previously [7,8]. Briefly, initial denaturation was conducted at 95 °C for 3 min, followed by 35 cycles of annealing at 63 °C for 50 s, polymerization at 72 °C for 60 s, and a final extension at 72 °C for 10 min.…”

“…Briefly, initial denaturation was conducted at 95 °C for 3 min, followed by 35 cycles of annealing at 63 °C for 50 s, polymerization at 72 °C for 60 s, and a final extension at 72 °C for 10 min. Then 10 μL of the PCR product was digested with Hha1 restriction enzyme at 37 °C for 12 h, and resolved on 2% agarose gel, as described [7]. One PCR product from each different genotype of the CAST gene was purified and sequenced in both directions to confirm the detected genotypes, using 3730 × l DNA Analyzer and Big Dye Terminator v3.1 Cycle Sequencing Kit (Thermo Fisher Scientific, United States).…”

A Comparative Review of the Extrinsic and Intrinsic Factors Regulating Lactose Synthesis

“…In many cases, not surprisingly, these variants can be implicated in pathways underlying the synthesis of other major milk components including -lactoglobulin [138][139][140][141][142], milk fat (1-acylglycerol-3-phosphate O-acyltransferase 6 and diacylglycerol O-acyltransferase 1) [143][144][145], lactotransferrin [146] and the caseins [146]. In other cases, polymorphisms are more directly implicated in the hormonal regulation of the synthesis of lactose or other milk components, as is the case for the leptin receptor [143,147,148], growth hormone [146], growth hormone receptor, PRL, and suppressor of cytokine signaling 3 [138][139][140][141][142], or glucocorticoid receptor DNA-binding factor-1 [146] genes. While associative, these types of analyses can inform genetic selection strategies in livestock, where similar data accompanied by lactation performance measures will undoubtedly reveal a better understanding of the genetic regulation of lactose synthesis in humans.…”

Genes encoding equine β-lactoglobulin (LGB1 and LGB2): Polymorphism, expression, and impact on milk composition

“…It seems that selected equine LGB gene variants can be considered potential markers for these particular traits; however, further studies with larger animal groups of different horse breeds are necessary. Associations between β-lactoglobulin polymorphisms and total milk protein and/or fat concentration have previously been described for cattle [12,42,43] and sheep [44,45]. We have also recorded a relationship between genotypes in rs1151091548 (LGB1) and rs1147750066 (LGB2) SNPs and the milk lactose level of PPH and PCH mares, respectively.…”