Genetic and Ageing Effects on Beef Quality

The overall aim of this thesis was to investigate genetic and ageing effects on beef quality. To study the genetic effects, association analyses were carried out between single nucleotide polymorphisms (SNPs) at DGAT1, LEP, SCD1, CAPN1 and CAST genes with colour, marbling, water holding capacity (WHC) and tenderness in meat from young bulls of the beef cattle population in Sweden. In total 243 young bulls from five beef breeds were included in the analysis. The results confirmed previously reported associations of the K232A polymorphism in the DGAT1 gene with marbling and polymorphisms in CAPN1 and CAST genes with meat tenderness. The LEP, SCD1 and CAPN1 genes showed association with meat colour traits. Our results confirm that part of the variation in these beef quality traits is under genetic control. Although our analyses revealed only minor breed differences, the lack of consistent gene effects between studies with different breeds indicate that association between markers and traits may not be consistent over breeds, possibly due to different genomic background. This may have implications on the applicability across populations of SNP chips developed in only one or a few breeds. To assess the ageing effects, three ageing methods, dry ageing bag, vacuum ageing and traditional dry ageing were compared. The beef muscles longissimus thoracis et lumborum and gluteus medius were used for the ageing process. The results showed that the dry ageing bag, as an alternative to traditional unpackaged dry ageing, made it possible to decrease meat ageing loss and microbial growth compared with traditional dry ageing. Meat aged in dry ageing bags has similar sensory characteristics as traditional dry ageing for most of the sensory attributes. Compared with vacuum ageing, the total product yield was lower after ageing meat in dry ageing bags. However, the dry ageing bags produced meat with enhanced tenderness and juiciness, characteristics that are valued by consumers. Thus, by using dry ageing bags it is possible to produce dry-aged meat under more controlled conditions without negative effects on sensory or other quality attributes.