Lowering dietary cation-anion differences (DCAD) can enhance responsiveness to Ca-homeostatic hormones and increase Ca availability, which might have potential to activate a Ca-dependent protease, calpain, and to enhance postmortem myofibrillar proteolysis. In this study, we investigated the effects of DCAD manipulation on calpain activity and beef tenderness in Japanese Black cattle which are characterized by their high marbling. Thirty-six Japanese Black steers were allotted to one of two treatments: (i) control (CON; DCAD +6.09 mEq/100 g of dry matter (DM)) or (ii) negative DCAD (NEGD; DCAD -8.27 mEq/100 g DM) for 70 days before slaughter. Lowering DCAD decreased DM and energy intake (P < 0.01) even though it did not negatively affect the growth performance or carcass characteristics. In NEGD, urine pH was decreased by acidification caused by the negative DCAD (P < 0.01). Calpain activities tended to be improved in NEGD (P = 0.09), but Warner-Bratzler shear force values were not affected by treatment. Although calpain activities tended to improve, lowering DCAD to -8.27 for 70 days before slaughter was insufficient to enhance beef tenderness in Japanese Black steers.

中文翻译：

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饮食中阳离子负离子差异对日本黑公牛car体特性和牛肉嫩度的影响。

降低饮食中阳离子负离子差异（DCAD）可以增强对Ca稳态激素的反应能力，并增加Ca的利用率，这可能具有激活Ca依赖性蛋白酶，钙蛋白酶和增强死后肌原纤维蛋白水解的潜力。在这项研究中，我们调查了DCAD操作对以黑大理石为特征的日本黑牛的钙蛋白酶活性和牛肉嫩度的影响。将三十六只日本黑ste牛皮分配给以下两种处理之一：（i）对照（CON； DCAD +6.09 mEq / 100 g干物质（DM））或（ii）阴性DCAD（NEGD； DCAD -8.27 mEq / 100 （g DM）屠宰前70天。降低DCAD会降低DM和能量摄入（P <0.01），即使这并没有负面影响生长性能或car体特性。在NEGD中，DCAD阴性导致的酸化降低了尿液的pH（P <0.01）。在NEGD中钙蛋白酶的活性趋于改善（P = 0.09），但Warner-Bratzler的剪切力值不受治疗的影响。尽管钙蛋白酶活性趋于改善，但在宰杀前的70天中将DCAD降低至-8.27不足以增强日本黑公牛的牛肉嫩度。