Department of Animal Sciences, Purdue University, West Lafayette, IN 47907, United States of America.
Department of Animal and Poultry Sciences (0306), Virginia Tech, 3480 Litton-Reaves Hall, Blacksburg, VA 24061, United States of America.
Meat Sci. 2021 Apr;174:108418. doi: 10.1016/j.meatsci.2020.108418. Epub 2020 Dec 28.
Pork quality is a product of the rate and extent of muscle pH decline paced by carbohydrate metabolism postmortem. The beta-adrenergic agonist ractopamine (RAC) alters muscle metabolism but has little impact on pork quality. The objective of this study was to determine how feeding RAC alters postmortem carbohydrate metabolism in muscle. Muscle pH was higher early postmortem in pigs fed RAC for 2 wks compared to control, while other time points and temperatures were largely unaffected. Early postmortem, muscle lactate levels were reduced (P < 0.05) after feeding RAC for 1 and 2 wks. Similarly, pigs fed RAC for 4 wks had reduced (P < 0.05) glycogen levels early postmortem compared to control pigs, but unexpectedly, L* values (lightness) increased (P < 0.05) after inclusion of RAC in the diet for 4 wk. These data show RAC feeding reduces glycogen content and changes lactate accumulation postmortem, but raise questions about the role glycolytic flux has in driving pork quality development.
猪肉品质是由肌肉死后碳水化合物代谢所决定的 pH 值下降速度和幅度决定的。β-肾上腺素激动剂莱克多巴胺（RAC）改变肌肉代谢，但对猪肉品质影响不大。本研究旨在确定 RAC 如何改变肌肉的死后碳水化合物代谢。与对照组相比，连续 2 周饲喂 RAC 的猪在宰后早期的 pH 值更高，而其他时间点和温度的影响则不大。宰后早期，饲喂 RAC 1 周和 2 周后，肌肉中的乳酸水平降低（P<0.05）。同样，连续 4 周饲喂 RAC 的猪宰后早期的糖原水平也低于对照组（P<0.05），但出人意料的是，在饲料中添加 RAC 4 周后，L*值（亮度）增加（P<0.05）。这些数据表明，RAC 喂养会降低糖原含量并改变死后乳酸的积累，但对糖酵解通量在驱动猪肉品质发展中的作用提出了疑问。
