Department of Animal Science, Texas A&M University, College Station, TX 77843, USA.
Department of Agricultural Sciences, West Texas A&M University, Canyon, TX 79016, USA.
Meat Sci. 2020 Dec;170:108238. doi: 10.1016/j.meatsci.2020.108238. Epub 2020 Jul 9.
We hypothesized that zilpaterol hydrochloride (ZH) depresses marbling scores in beef cattle by dilution of the intramuscular (i.m.) adipose tissue in the longissimus thoracis (LT) by increased muscle cross-sectional area. Crossbred steers were treated with ractopamine hydrochloride (RH; 28 d) or ZH (20 d) or no β-adrenergic agonist (CON). ZH increased LT cross-sectional area (P < .001) and depressed rib fat depth (P < .001), USDA marbling score (P < .05), percent LT lipid (P < .02), total lipid in a 2.54 cm-thick LM steak (P < .05) and most LT lipid fatty acids (P ≤ .05),but had no effect on mean i.m. adipocyte volume (P = .15). ZH increased the relative volume proportion of smaller i.m. adipocytes (250 to 500 pL) and decreased the proportion of larger i.m. adipocytes (2000 and 3000 pL) (P < .05). We conclude that ZH reduces marbling score both by dilution of the marbling and a depression of i.m. adipocyte relative volumes.
我们假设盐酸齐帕特罗（ZH）通过增加肌肉横截面积来稀释胸最长肌（LT）中的肌内（i.m.）脂肪组织，从而降低牛肉大理石花纹评分。杂交阉牛接受盐酸莱克多巴胺（RH；28d）或 ZH（20d）或无β-肾上腺素能激动剂（CON）处理。ZH 增加了 LT 横截面积（P<.001），降低了肋部脂肪深度（P<.001）、美国农业部大理石花纹评分（P<.05）、LT 脂质百分比（P<.02）、2.54cm 厚 LM 牛排中的总脂质（P<.05）和大多数 LT 脂质脂肪酸（P≤.05），但对平均 i.m.脂肪细胞体积无影响（P=.15）。ZH 增加了较小 i.m.脂肪细胞（250 至 500pL）的相对体积比例，降低了较大 i.m.脂肪细胞（2000 和 3000pL）的比例（P<.05）。我们得出结论，ZH 降低大理石花纹评分既是通过大理石花纹的稀释，也是通过降低 i.m.脂肪细胞的相对体积来实现的。
