Cytochrome P450, family 2, subfamily A, polypeptide 6 (CYP2A6) and kinesin-like protein KIF12 (KIF12) genes are predicted as candidate genes which play important roles in lamb flavour and odour. The aim of this study was to analyse the genotype polymorphism of CYP2A6 and KIF12 genes, to study association and expression of these genes with lamb flavour and odour. Identification of genes polymorphism and associations of CYP2A6 and KIF12 genes were performed using PCR-RFLP method and GLM analysis. The PCR-RFLP products of CYP2A6 and KIF12 were digested by restriction enzyme BsmAI and BfaI, respectively. The expression of CYP2A6 gene was performed using qRT-PCR. The results showed that the CYP2A6 and KIF12 genes were polymorphics. The CYP2A6 gene found to have two genotypes (TT and GT), whereas the KIF12 gene found to have three genotypes (CC, CT, and TT). The CYP2A6 and KIF12 genes were in Hardy Weinberg Equilibrium (HWE). Association analysis showed that CYP2A6 (g.49170107 G>T) was significantly (PT) was not significantly associated with lamb flavour and odour. The GT genotype exhibited a greater 3-methylindole (MI) or skatole than the TT genotype (P<0.05). The mRNA expression analysis showed that CYP2A6 mRNA expression was higher (P<0.01) in animals with the TT genotype. These results will improve the understanding of the functions of the CYP2A6 in lamb flavour and odour, especially in term of 3-methylindole (MI) or skatole compound within the liver and will shed light on CYP2A6 as a candidate in the selection of sheep with low lamb flavour and odour.

This study was aimed to identify single nucleotide polymorphism (SNP) and pathway analysis of APOA5 with fatty acids traits in sheep. A total of 47 rams consisted of 20 heads of Javanese Fat Tailed (JFT), 17 heads of Javanese Thin Tailed (JTT), and 10 heads of Garut Composite Sheep (GCS) were used in this study. Fatty acids traits were measured at the age of 12 months with the average body weight of 25-30 kg. Identification of polymorphism of APOA5 (g.26929941 C>T) gene were analyzed using Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP). The pathway analysis of APOA5 gene was performed using Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis. The SNP of APOA5 gene were found polymorphic with three genotypes (CC, CT, and TT). The gene frequency of CC, CT, and TT were 0.83, 0.11, and 0.06, respectively. The chi square test revealed that the locus of APOA5 (g.26929941 C>T) was in Hardy-Weinberg equilibrium, except in thin tailed sheep. The chi-square values of JFT, JTT, and GCS were 0.05, 0.03, and 0.04, respectively. A SNP of APOA5 was associated (P<0.05) with polyunsaturated fatty acids including eicosapentanoic acid (C20:5n3) and docosahexanoic (C22:6n3) and saturated fatty acid lauric acid (C12:0) in combined population (JFT, JTT, and GCS). Furthermore, pathway analysis showed that APOA5 belonged to phagosome and peroxisome proliferator-activated receptors (PPAR) signaling pathway. In conclusion, this analysis has identified APOA5 and related pathway crucial for fatty acid composition and metabolism in sheep, as well as this gene provide molecular marker to select sheepmeat with high unsaturated fatty acid.

Tenderness is a key meat quality trait that determines the public acceptance of lamb consumption, so genetic improvement toward lamb with higher tenderness is pivotal for a sustainable sheep industry. However, unravelling the genomics controlling the tenderness is the first step. Therefore, this study aimed to identify the transcriptome signatures and polymorphisms related to divergent lamb tenderness using RNA deep sequencing. Since the molecules and enzymes that control muscle growth and tenderness are metabolized and synthesized in the liver, hepatic tissues of ten sheep with divergent phenotypes: five high- and five low-lamb tenderness samples were applied for deep sequencing. Sequence analysis identified the number of reads ranged from 21.37 to 25.37 million bases with a mean value of 22.90 million bases. In total, 328 genes are detected as differentially expressed (DEGs) including 110 and 218 genes that were up- and down-regulated, respectively. Pathway analysis showed steroid hormone biosynthesis as the dominant pathway behind the lamb tenderness. Gene expression analysis identified the top high (such as TP53INP1, CYP2E1, HSD17B13, ADH1C, and LPIN1) and low (such as ANGPTL2, IGFBP7, FABP5, OLFML3, and THOC5) expressed candidate genes. Polymorphism and association analysis revealed that mutation in OLFML3, ANGPTL2, and THOC5 genes could be potential candidate markers for tenderness in sheep. The genes and pathways identified in this study cause variation in tenderness, thus could be potential genetic markers to improve meat quality in sheep. However, further validation is needed to confirm the effect of these markers in different sheep populations so that these could be used in a selection program for lamb with high tenderness.

Objective: The objective of this study was to identify polymorphism in olfactomedin like 3 (OLFML3) gene, and association analysis with meat quality, carcass characteristics, retail meat cut, and fatty acid composition in sheep, and expression quantification of OLFML3 gene in phenotypically divergent sheep.Methods: A total of 328 rams at the age of 10 to 12 months with an average body weight of 26.13 kg were used. A novel polymorphism was identified using high-throughput sequencing in sheep and genotyping of OLFML3 polymorphism was performed using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Among 328 rams, 100 rams representing various sheep genotypes were used for association study and proc general linear model was used to analyse association between genotypes and phenotypic traits. Quantitative real-time polymerase chain reaction (qRT-PCR) was used for the expression analysis of OLFML3 mRNA in phenotypically divergent sheep population.Results: The findings revealed a novel polymorphism in the OLFML3 gene (g.90317673 C>T). The OLFML3 gene revealed three genotypes: CC, CT, and TT. The single nucleotide polymorphism (SNP) was found to be significantly (p<0.05) associated with meat quality traits such as tenderness and cooking loss; carcass characteristics such as carcass length; retail meat cut such as pelvic fat in leg, intramuscular fat in loin and tenderloin, muscle in flank and shank; fatty acids composition such as tridecanoic acid (C13:0), palmitoleic acid (C16:1), heptadecanoic acid (C17:0), ginkgolic acid (C17:1), linolenic acid (C18:3n3), arachidic acid (C20:0), eicosenoic acid (C20:1), arachidonic acid (C20:4n6), heneicosylic acid (C21:0), and nervonic acid (C24:1). The TT genotype was associated with higher level of meat quality, carcass characteristics, retail meat cut, and some fatty acids composition. However, the mRNA expression analysis was not different among genotypes.Conclusion: The OLFML3 gene could be a potential putative candidate for selecting higher quality sheep meat, carcass characteristics, retail meat cuts, and fatty acid composition in sheep.

The aim of this study was to investigate the association and expression of LEPR with fat quality, flavour and odour in sheep. A total of 47 rams were used in this study. Fatty acids composition, BCFA (Branch Chanin Fatty Acids; MNA, MP, MOA, and EOA) and skatole (MI) representing fat quality, flavour and odour in sheep were measured at ages of 10-12 months old. Identification of novel variant and expression analysis of LEPR gene with different fat quality, odour and flavour were performed by PCR RFLP and qRT-PCR, respectively. A SNP in genomic region g.40854778 A>C of the LEPR gene was associated (P<0.05) with fat quality of saturated fatty acids (SFA) including [tricosanoic acid (C23:0) and tetracosanoic acid (C24:0)] and poly unsaturated fatty acid (PUFA) [docosahexaenoic acid (C22:6n3)]. However, the novel variant of LEPR was not significantly associated (P<0.05) with fat content, odour and flavour (MNA, MP, MOA, EOA, and MI). The mRNA expression analysis showed that LEPR mRNA expression was higher (P<0.01) in sheep found at the AA genotype. It could be concluded that variant SNP in the LEPR may contribute to fatty acid composition without influencing odour and flavour traits in sheep.