Department of Animal Sciences, The Ohio State University, Columbus, OH 43210, USA.
Michigan State University Extension - Sanilac County, Sandusky, MI 48471, USA.
J Anim Sci. 2023 Jan 3;101. doi: 10.1093/jas/skac371.
This study investigates intramuscular (IM) adipocyte development in the Longissimus muscle (LM) between Wagyu- and Angus-sired steers compared at a similar age and days on feed (D) endpoint or similar body weight (B) endpoint by measuring IM adipocyte cell area and lipid metabolism mRNA expression. Angus-sired steers (AN, n = 6) were compared with steers from two different Wagyu sires (WA), selected for either growth (G) or marbling (M), to be compared at a similar days on feed (DOF; 258 ± 26.7 d; WA-GD, n = 5 and WA-MD, n = 5) in Exp. 1 or body weight (BW; 613 ± 18.0 kg; WA-GB, n = 4 and WA-MB, n = 5) in Exp. 2, respectively. In Exp. 1, WA-MD steers had a greater (P ≤ 0.01) percentage of IM fat in the LM compared with AN and WA-GD steers. In Exp. 2, WA-MB steers had a greater (P ≤ 0.01) percentage of IM fat in the LM compared with AN and WA-GB steers. The distribution of IM adipocyte area was unimodal at all biopsy collections, with IM adipocyte area becoming progressively larger as cattle age (P ≤ 0.01) and BW increased (P ≤ 0.01). Peroxisome proliferator activated receptor delta (PPARd) was upregulated earlier for WA-MD and WA-MB cattle compared with other steers at a similar DOF and BW (P ≤ 0.02; treatment × biopsy interaction). Peroxisome proliferator activated receptor gamma was upregulated (PPARg) at a lesser BW for WA-MB steers (P = 0.09; treatment × biopsy interaction), while WA-MD steers had a greater (P ≤ 0.04) overall mean PPARg mRNA expression compared with other steers. Glycerol-3-phosphate acyltransferase, lipin 1, and hormone sensitive lipase demonstrated mRNA expression patterns similar to PPARg and PPARd or CCAAT enhancer binding protein beta, which emphasizes their importance in marbling development and growth. Additionally, WA-MD and WA-MB steers often had a greater early mRNA expression of fatty acid transporters (fatty acid transport protein 1; P < 0.02; treatment × biopsy interaction) and binding proteins (fatty acid binding protein 4) compared with other steers. Cattle with a greater marbling propensity appear to upregulate adipogenesis at a younger chronological and physiological maturity through PPARd, PPARg, and possibly adipogenic regulating compounds, lysophosphatidic acid, and diacylglycerol. These genes and compounds could be used as potential markers for marbling propensity of cattle in the future.
本研究通过测量肌内脂肪细胞面积和脂质代谢 mRNA 表达，比较了在相似的年龄和天数（D）终点或相似体重（B）终点下，来自和牛和安格斯种公牛的牛背最长肌（LM）中的肌内脂肪细胞发育。安格斯种公牛（AN，n = 6）与来自两个不同和牛种公牛的公牛（WA）进行比较，选择生长（G）或大理石花纹（M），以便在 Exp.1 中在相似的天数（DOF；258 ± 26.7 d；WA-GD，n = 5 和 WA-MD，n = 5）或体重（BW；613 ± 18.0 kg；WA-GB，n = 4 和 WA-MB，n = 5）上进行比较。在 Exp.1 中，WA-MD 牛的 LM 中肌内脂肪百分比高于 AN 和 WA-GD 牛（P ≤ 0.01）。在 Exp.2 中，WA-MB 牛的 LM 中肌内脂肪百分比高于 AN 和 WA-GB 牛（P ≤ 0.01）。在所有活检采集时，肌内脂肪细胞面积的分布呈单峰分布，随着牛的年龄（P ≤ 0.01）和体重（P ≤ 0.01）的增加，肌内脂肪细胞面积逐渐增大。过氧化物酶体增殖物激活受体 delta（PPARd）在 WA-MD 和 WA-MB 牛中的表达早于其他牛在相似的 DOF 和 BW 时上调（P ≤ 0.02；处理×活检相互作用）。在较小的 BW 时，过氧化物酶体增殖物激活受体γ（PPARg）上调（P = 0.09；处理×活检相互作用），而 WA-MD 牛的整体平均 PPARg mRNA 表达高于其他牛（P ≤ 0.04）。甘油-3-磷酸酰基转移酶、脂联素 1 和激素敏感脂肪酶的 mRNA 表达模式与 PPARg 和 PPARd 或 CCAAT 增强子结合蛋白β相似，这强调了它们在大理石花纹发育和生长中的重要性。此外，WA-MD 和 WA-MB 牛的脂肪酸转运蛋白（脂肪酸转运蛋白 1；P < 0.02；处理×活检相互作用）和结合蛋白（脂肪酸结合蛋白 4）的早期 mRNA 表达通常高于其他牛。具有更高大理石花纹倾向的牛似乎通过 PPARd、PPARg 和可能的脂肪生成调节化合物溶血磷脂酸和二酰基甘油在更年轻的生理和生理成熟度上调脂肪生成。这些基因和化合物将来可能被用作牛大理石花纹倾向的潜在标记。
