Interaction among GH polymorphism, somatotropic axis and productivity in Japanese Black cattle

2006 Fiscal Year Final Research Report Summary

• Project/Area Number: 17380159
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Zootechnical science/Grassland science
• Research Institution: Tohoku University
• Principal Investigator: KATOH Kazuo Tohoku University, Graduate School of Agricultural Science, Associate Professor, 大学院農学研究科, 助教授 (60091831)
• Co-Investigator(Kenkyū-buntansha): SUZUKI Keiichi Tohoku University, Graduate School of Agricultural Science, Professor, 大学院農学研究科, 教授 (10344706)
• Project Period (FY): 2005 – 2006
• Keywords: Japanese Black cattle / GH gene / gene morphism / Somatotropic axis / meat quality

Research Abstract

In order to investigate the relationship between GH polymorphism and productivity in Japanese Black cattle, we analyzed GH genotypes and measured meat quality in Miyagi Prefecture.
1. The genotypes for AA, AB, BB, AC, BC and CC in 149 animals were 45.6, 15.4, 20.8, 5.4, 11.4 and 1.3%, respectively. The percentages for A, B and C allele were 56.0, 34.2and 9.7%, respectively. This finding indicates that A allele was dominant in Miyagi Prefecture. This result was also reported in Tottori Prefecture, but was quite different from that in Hyogo, Okayama and Shimane Prefectures where C allele was dominat.
2. There was a significant relationship between A allele and Rib thickness, but not Carcass weight, Dairy carcass gain, Rib eye area or back fat thickness. This finding indicates that A allele is profitable for Rib thickness.
3. Analysis of the relationship between GH genotypes and fatty acid compositions in Rib eye muscle demonstrated that C allele was profitable for accumulation of unsaturate d fatty acids such as oleic acid, but not for saturated fatty acids such as stearic acid in Rib eye intramuscular fats, compared with those for non-C allele. In practice, the percentage of oleic acid for C allele was 56.5% (54.9% for non-C allele), while that for stearic acid for C allele was 12.3% (vs 13.5% for non-C allele). The percentage of unsaturated fatty acids for C allele was 62.7%, while that for non-C allele was 60.8%. These findings suggest that C allele is profitable for meat quality, especially for unsaturated fatty acid accumulation in spite of disadvantage for body weight gain. It is generally accepted by consumers that unsaturated fatty acids are healthy and advantageous for meat taste.
In conclusion, these findings suggest that A allele was dominant in Miyagi Prefecture, and that there was a significant relationship between GH genotypes and meat quality: especially C allele was preferable for unsaturated fatty acid percentage in Rib eye intramuscular fat and meat quality. In the near future, we should investigate the mechanisms by which GH genotypes affect the meat quality, especially actions on the key enzymes (FASN and SCD) that are involved in the production of unsaturated fatty acids, and the somatotropic axis that is essential for animal growth.