Identification of genes controlling marbling in cattle
Investigate the genes controlling the deposition of the intramuscular fat (that is, marbling) in beef cattle to better understand fat metabolism and to provide genetic markers for selection to improve beef quality.
Marbling or intramuscular fat in beef is highly prized in some export markets, such as Japan and Korea. Since a premium is paid for intensely marbled meat in these markets, producers seek to control intramuscular fat deposition in cattle through nutrition.
Long term grain feeding on diets low in beta-carotene will increase marbling in some cattle breeds. However, in other cattle breeds long term grain feeding merely increases the amount of subcutaneous fat. Thus, it is clear that there is both a nutritional and a genetic component to intramuscular fat deposition.
However, the genetics underlying intramuscular fat deposition have not been determined. One of the issues is that the process of marbling is not well understood.
It is not clear if the process involves increasing the amount of lipid filling in mature adipocyte fat cells (hypertrophy) OR whether the process involves increasing the actual number of mature adipocyte fat cells (hyperplasia). It is also not known whether the process may involve other factors, such as vascularisation, which may affect lipid deposition in specific locations.
Previous work in our group suggests that other factors such as vascularisation may be fundamental to the ability of specific breeds and animals to deposit intramuscular fat in muscle. To explore this possibility, the project will examine the correlation between vascularity and marbling.
In addition, specific genes related to vascularity will be analysed to determine if they also affect marbling.
Images of marbling in different breeds will be analysed in relation to their fat deposition in muscles and the vascularisation of the muscle.
In addition, new regions of the cattle genome controlling intramuscular fat deposition have been identified.
Based on the results, new candidate genes will be selected for sequencing and genotyping to determine if they control marbling by affecting the vascular system.
Co-supervisor: Professor Wayne Pitchford
Research area: Animal and veterinary bioscience: Molecular genetics of livestock, particularly beef cattle, with an emphasis on fat and energy metabolism; use of biotechnologies to improve livestock production.
Recommended honours enrolment: Honours in Animal Science