Finishing late-maturing bulls on grass may alter the antioxidant/prooxidant balance leading to beef with higher susceptibility to lipid oxidation and a lower colour stability compared to bulls finished on cereal concentrates. In this context, lipid oxidation and colour stability of beef from late-maturing bulls finished on pasture, with or without concentrate supplements, or indoors on concentrate was assessed. Charolais or Limousin sired bulls (n = 48) were assigned to four production systems: (1) pasture only (P), (2) pasture plus 25% dietary DM intake as barley-based concentrate (PC25), (3) pasture plus 50% dietary DM intake as barley-based concentrate (PC50) or (4) a barley-based concentrate ration (C). Following slaughter and postmortem ageing, M. Longissimus thoracis et lumborum was subjected to simulated retail display (4°C, 1000 lux for 12 h out of 24 h) for 3, 7, 10 and 14 days in modified atmosphere packs (O2 : CO2; 80 : 20). Lipid oxidation was determined using the 2-thiobarbituric acid-reactive substances assay; α-tocopherol was determined by HPLC; fatty acid methyl esters were determined using Gas Chromatography. Using a randomised complete block design, treatment means were compared by either ANOVA or repeated measures ANOVA using the MIXED procedure of SAS. Total polyunsaturated fatty acid (PUFA) concentrations were not affected by treatment, n-3 PUFAs were higher (P < 0.001) and the ratio of n-6 to n-3 PUFAs was lower (P < 0.001) in muscle from P, PC25 and PC50 compared to C. α-Tocopherol concentration was higher in muscle from P compared to PC50 and C bulls (P = 0.001) and decreased (P < 0.001) in all samples by day 14. Lipid oxidation was higher in muscle from C compared to P bulls on day 10 and day 14 of storage (P < 0.01). Finishing on pasture without supplementation did not affect beef colour stability and led to lower lipid oxidation, possibly due to the higher α-tocopherol concentration compared to concentrate finished beef.

中文翻译：

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分批添加浓缩物水平对牧场成熟的后期公牛牛肉的颜色和脂质稳定性的影响。

与在谷物浓缩物中精制的公牛相比，在草上精加工的晚熟公牛可能会改变抗氧化剂/促氧化剂的平衡，从而导致牛肉对脂质氧化的敏感性更高，并且颜色稳定性较低。在这种情况下，评估了在有或没有浓缩饲料补充剂的情况下或在室内浓缩饲料的牧场上完成的后期成熟公牛牛肉的脂质氧化和颜色稳定性。夏洛来牛或利穆赞种公牛（n = 48）被分配到四个生产系统：（1）仅牧场（P），（2）牧场加25％膳食DM摄入的大麦浓缩汁（PC25），（3）牧场加以大麦类浓缩物（PC50）或（4）大麦类浓缩物日粮（C）的形式摄入50％的膳食DM。宰杀和尸体老化后，将M. Longissimus thoracis et lumborum进行模拟零售展示（4°C，在改良的空气包装（O2：CO2; 80:20）中，在24小时中的1000 lux中持续12小时，持续3、7、10和14天。使用2-硫代巴比妥酸反应性物质测定法测定脂质氧化；用HPLC测定α-生育酚；使用气相色谱法测定脂肪酸甲酯。使用随机完整区组设计，使用SAS的MIXED程序通过ANOVA或重复测量ANOVA比较治疗手段。P，PC25肌肉中总多不饱和脂肪酸（PUFA）浓度不受治疗影响，n-3 PUFAs较高（P <0.001），n-6与n-3 PUFAs的比例较低（P <0.001）。与PC50相比，C.α。生育酚浓度在公牛中要高于PC50和C公牛（P = 0.001），并且在第14天时所有样品中的α-生育酚浓度均下降（P <0.001）。与在储存的第10天和第14天的公牛相比，来自C的肌肉的脂质氧化更高（P <0.01）。在牧场上不添加补充剂不会影响牛肉的颜色稳定性，并导致脂质氧化降低，这可能是由于与浓缩牛肉相比，α-生育酚浓度更高。