In the livestock industry, intramuscular fat content is a key factor affecting meat quality. Many studies have shown that dietary calcium supplementation is closely related to lipid metabolism. However, few studies have examined the relationship between dietary calcium supplementation and intramuscular fat accumulation. Here, we used C2C12 cells, C57BL/6 mice (n = 8) and three-way cross-breeding pigs (Duroc×Landrace×Large white) (n = 10) to study the effect of calcium addition on intramuscular fat accumulation. In vitro, we used calcium chloride to adjust the calcium levels in the medium (2 mmol/L or 3 mmol/L). Then we measured various indicators. In vivo, calcium carbonate was used to regulate calcium levels in feeds (Mice: 0.5% calcium or 1.2% calcium) (Pigs: 0.9% calcium or 1.5% calcium). Then we tested the mice gastrocnemius muscle triglyceride content, pig longissimus dorsi muscle meat quality and lipidomics. In vitro, calcium addition (3 mmol/L) had no significant effect on cell proliferation, but promoted the differentiation of C2C12 cells into slow-twitch fibers. Calcium supplementation increased triglyceride accumulation in C2C12 cells. Calcium addition increased the number of mitochondria and also increased the calcium level in the mitochondria and reduced the of key enzymes activity involved in β-oxidation such as acyl-coenzyme A dehydrogenase. Decreasing mitochondrial calcium level can alleviate lipid accumulation induced by calcium addition. In addition, calcium addition also reduced the glycolytic capacity and glycolytic conversion rate of C2C12 cells. In vivo, dietary calcium supplementation (1.2%) promoted the accumulation of triglycerides in the gastrocnemius muscle of mice. Dietary calcium supplementation (1.5%) had no effect on pig weight, but significantly improved the flesh color of the longissimus dorsi muscle, reduced the backfat thickness and increased intramuscular fat content in pigs. Besides, calcium addition had no effect on longissimus dorsi pH, electrical conductivity and shear force. These results suggest that calcium addition promotes intramuscular fat accumulation by inhibiting the oxidation of fatty acids. These findings provide a new tool for increasing intramuscular fat content and an economical strategy for improving meat quality.

中文翻译：

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膳食补钙促进肌内脂肪堆积

在畜牧业中，肌内脂肪含量是影响肉质的关键因素。许多研究表明，膳食补钙与脂质代谢密切相关。然而，很少有研究检查膳食钙补充剂与肌肉内脂肪积累之间的关系。在这里，我们使用 C2C12 细胞、C57BL/6 小鼠（n = 8）和三向杂交猪（Duroc×Landrace×Large white）（n = 10）来研究钙添加对肌肉内脂肪积累的影响。在体外，我们使用氯化钙来调整培养基中的钙水平（2 mmol/L 或 3 mmol/L）。然后我们测量了各种指标。在体内，碳酸钙用于调节饲料中的钙含量（小鼠：0.5% 钙或 1.2% 钙）（猪：0.9% 钙或 1.5% 钙）。然后我们测试了小鼠腓肠肌甘油三酯含量、猪背最长肌肌肉质量和脂质组学。在体外，钙添加（3 mmol/L）对细胞增殖没有显着影响，但促进了 C2C12 细胞向慢肌纤维的分化。钙补充剂增加了 C2C12 细胞中甘油三酯的积累。钙的添加增加了线粒体的数量，也增加了线粒体中的钙水平，并降低了参与 β-氧化的关键酶如酰基辅酶 A 脱氢酶的活性。降低线粒体钙水平可以减轻由钙添加引起的脂质积累。此外，钙的添加还降低了C2C12细胞的糖酵解能力和糖酵解转化率。在体内，膳食钙补充剂 (1. 2%) 促进了小鼠腓肠肌中甘油三酯的积累。日粮补钙（1.5%）对猪体重没有影响，但显着改善了背最长肌的肉色，降低了背膘厚度，增加了猪的肌内脂肪含量。此外，钙的添加对背最长肌的 pH 值、电导率和剪切力没有影响。这些结果表明，钙的添加通过抑制脂肪酸的氧化来促进肌肉内脂肪的积累。这些发现为增加肌内脂肪含量提供了一种新工具，并为改善肉质提供了一种经济策略。但显着改善了背最长肌的肉色，降低了背膘厚度，增加了猪的肌内脂肪含量。此外，钙的添加对背最长肌的 pH 值、电导率和剪切力没有影响。这些结果表明，钙的添加通过抑制脂肪酸的氧化来促进肌肉内脂肪的积累。这些发现为增加肌内脂肪含量提供了一种新工具，并为改善肉质提供了一种经济策略。但显着改善了背最长肌的肉色，降低了背膘厚度，增加了猪的肌内脂肪含量。此外，钙的添加对背最长肌的 pH 值、电导率和剪切力没有影响。这些结果表明，钙的添加通过抑制脂肪酸的氧化来促进肌肉内脂肪的积累。这些发现为增加肌内脂肪含量提供了一种新工具，并为改善肉质提供了一种经济策略。