Preliminary Study: How Does Maternal Nutrition Affect Intramuscular Adipocyte Development in Longissimus Thoracis and Biceps Femoris Muscles of Wagyu Fetuses?.

Abstract The aim of this study was to determine the effects maternal nutrition on Wagyu (Japanese Black) fetal intramuscular fat. Multiparous Wagyu cattle (N=12) were randomly allocated to two nutrition groups: high-nutrition group (HN: 120% of nutritional requirement, n=6) and low nutrition group (LN: 60%, n=6) from conception to d 8.5 months of gestation. Fetuses were harvested and fetal longissimus thoracis (LT) and biceps femoris (BF) morphometrics analyses were performed to focus on the intramuscular adipose precursor cells and adipocytes in the connective tissue (Table 1). Delta like 1 Homolog (DLK1) is expressed on the cell membrane, so its immunopositive area on the connective tissue was measured, and CCAAT Enhancer Binding Protein Beta (C/EBPB) and Peroxisome Proliferator-Activated Receptor γ (PPARG) are expressed in the cell nucleus, so those immunopositive number on the connective tissue was counted (Table 1). The cross-sectional area (CSA) of adipocytes in LT was greater (P < 0.05) for HN than for LN, but there was no difference in the BF. In both HN and LN, the number of adipocytes per unit area of connective tissue tended to be higher in LT than in BF (P=0.08, and P=0.09, respectively). The DLK-1 positive area of the connective tissue area was smaller (P=0.03) for HN than for LN. Conversely, the number of PPARG-positive cells in the connective tissue area was 2.96-fold greater (P< 0.01) for HN than for LN, however, the difference was not found in the number of C/EBPB-positive cells (P= 0.57). From these results, maternal nutrition particularly affects the development of intramuscular adipocytes in LT and promotes the increase in adipocyte CSA, and differentiation from adipose progenitor cells to adipocytes.