Cellular conditions for intramuscular fat deposition in Japanese Black and Holstein steers

• Published in: Meat science Vol. 89; no. 1; pp. 13 - 20
• Main Authors: Albrecht, E., Gotoh, T., Ebara, F., Xu, J.X., Viergutz, T., Nürnberg, G., Maak, S., Wegner, J.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.09.2011; Elsevier
• Subjects: Adipocyte; adipocytes; Adipocytes - cytology; Adipocytes - metabolism; Animals; Beef; Biological and medical sciences; biopsy; Body Fat Distribution; breed differences; Breeding; Cattle; cell growth; energy; Fatty acid binding protein 4; Fatty Acid Synthases - genetics; Fatty Acid Synthases - metabolism; Fatty Acid-Binding Proteins - genetics; Fatty Acid-Binding Proteins - metabolism; Food industries; Fundamental and applied biological sciences. Psychology; genes; Holstein; intramuscular fat; lipids; longissimus muscle; Male; Marbling; Meat and meat product industries; meat carcasses; muscle fibers; Muscle Fibers, Skeletal - cytology; Muscle Fibers, Skeletal - metabolism; Muscle structure; Peroxisome proliferator-activated receptor γ; Phenotype; PPAR gamma - genetics; PPAR gamma - metabolism; RNA, Messenger - metabolism; steers; subcutaneous fat; Subcutaneous Fat - cytology; Up-Regulation; Wagyu; Adipocyte; Peroxisome proliferator-activated receptor γ; Beef; Fatty acid binding protein 4; Marbling; Muscle structure; Bovine; Meat product; Lipids; Fatty acids; Protein; Vertebrata; Mammalia; Fat; Muscle; Artiodactyla; Ungulata
• ISSN: 0309-1740; 1873-4138
• DOI: 10.1016/j.meatsci.2011.03.012

The experiment was conducted to study the development of intramuscular fat in Japanese Black (JB) compared to Holstein (HS) steers and to find breed differences for fat depot development and distribution in the carcass under equal feeding conditions. Additional to slaughter samples, biopsy samples of longissimus muscle (LM) and subcutaneous fat, taken at 10, 14, 18, and 22 months of age, were used for histological and molecular investigations. Japanese Black steers stored about 14% more fat in the LM (P = 0.001), resulting in larger marbling flecks (P < 0.001). Muscle fibers and intramuscular adipocytes in both breeds responded to the high energy feeding with significant enlargement, which was faster in JB. Histograms of intramuscular adipocytes size showed a shift toward larger cells during growth, but also the abundance of small, developing adipocytes. This development was accompanied by a correlated up-regulation of adipogenic genes until 22 months of age.