The mechanism of intramyocellular lipids accumulation of Japanese Shorthorn cattle on the completed grass-fed beef production system

2020 Fiscal Year Final Research Report

• Project/Area Number: 18K05952
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 42010:Animal production science-related
• Research Institution: Kitasato University
• Principal Investigator: OGASAWARA Hideki 北里大学, 獣医学部, 講師 (30535472)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: 放牧 / 有機畜産 / 日本短角種 / Double muscled / 脂肪滴含有筋線維 / CD36 / 筋線維型

Outline of Final Research Achievements

The aim of this study is to investigate the mechanism of intramyocellular lipids accumulation in the biceps femoris (BF: proximal and middle parts) of normal and double muscled (DM)Japanese Shorthorn cattle on the completed grass-fed beef production system. We analyzed distribution of myofiber types and intramyocellular lipid from birth to fattening period, identification of DGAT2 immunoreactivity myofiber, expression of myogenic and lipogenic genes in BF. All myofiber types (Ⅰ、ⅠD、ⅡA、ⅡB) and intramyocellular lipids expressed 6 month (weaning period). Proximal part of BF higher expressed intramyocellular lipids than middle part. DGAT2 immunoreactivity myofiber were found in about 20% of BF, had been co-expressed intramyocellular lipids. DM had a high proportion of ⅡB, but grazing increased intramyocellular lipids. We found that myostatin, CD36, LPL and FABP3 are strongly involved in intramyocellular lipids accumulation by grazing.

Free Research Field

家畜飼養学・組織学

Academic Significance and Societal Importance of the Research Achievements

近年、SDGsなど持続可能な畜産方式として有機畜産が注目されており、国内でも放牧による赤身肉生産が普及している。本研究では脂肪交雑が少ないため不良遺伝として淘汰されてきたDM日本短角種を放牧と自給粗飼料のみでの生産方式で活用可能かを検討し、放牧牛肉の特徴である筋線維内の目に見えない脂肪（脂肪滴含有筋線維）の出生期から肥育期までの推移とその蓄積機構の一部を解明した。本研究成果は放牧牛肉研究において、消費者への放牧牛肉の新たな知見を提供するだけでなく、新たな形質を用いた放牧・自給粗飼料の肥育方式の確立・普及ならびにわが国の牛肉自給率の向上に貢献するものである。