年龄对舍饲育肥牦牛肉营养价值和抗氧化活性的影响

本实验旨在研究年龄对舍饲育肥牦牛肉营养价值和抗氧化活性的影响，为优质牦牛肉的生产提供指导。选取18 头健康麦洼公牦牛，根据年龄分为1.5、2.5 岁组和4.5 岁组，每组6 个重复，预饲期15 d，正式实验期180 d。结果表明：1）年龄对牦牛肉中粗蛋白质和粗灰分有显著影响（P＜0.05），其中4.5 岁组牦牛肉中粗蛋白质量分数为23.50%，2.5 岁组粗灰分质量分数为1.36%，均在3 组中最高；2）不同年龄牦牛肉中必需氨基酸占总氨基酸比例（the ratio of essential amino acids to total amino acids，EAA/TAA）和EAA占非必需氨基酸比例差异显著（P＜0.05），其中2.5 岁组最高，4.5 岁组其次，1.5 岁组最低，但2.5 岁组鲜味氨基酸占TAA比例仅为42.88%，显著低于1.5 岁组的43.49%和4.5 岁组的43.43%（P＜0.05）；3）年龄对脂肪酸质量分数影响较小，仅2.5 岁组二十一烷酸（C21:0）质量分数显著高于1.5 岁组和4.5 岁组（P＜0.05），而其他脂肪酸质量分数和比例差异不显著（P＞0.05），另外山嵛酸（C22:0）和11,14-二十碳烯酸（C20:2）仅在1.5 岁组中检出，在2.5 岁组和4.5 岁组均未检出；4）随着年龄的增长，牦牛肉中丙二醛含量不断升高，4.5 岁组比1.5 岁组升高了53.80%，但不同年龄牦牛肉中过氧化氢酶、总超氧化物歧化酶、谷胱甘肽过氧化物酶活力和总抗氧化能力无显著差异（P＞0.05）。综上所述，年龄能够影响牦牛肉的营养成分，但对其抗氧化活性无明显影响。

Effect of Age on Nutritional Value and Antioxidant Activity of House-feeding Yak Meat

This study was conducted to investigate the effect of age on nutritional value and antioxidant activity of house-feeding yak meat, and to provide the guidance for the production of high-quality yak meat. The healthy Maiwa male yaks (n = 18) were allocated to three groups (1.5-year-old = ‘AGE1.5’, 2.5-year-old = ‘AGE2.5’ and 4.5-year-old = ‘AGE4.5’) by age, with 6 yaks in each group. Pre-experimental period was 15 days, and the trial period was 180 days. The results showed that: 1) the age had a significant effect on crude protein and crude ash of yak meat (P < 0.05). The content of crude protein in yak meat of AGE4.5 group was 23.50%, and the content of crude ash in yak meat of AGE2.5 group was 1.36%, which was the highest in three groups. 2) The ratio of essential amino acids to total amino acids (EAA/TAA) and essential amino acids to non-essential amino acids (EAA/NEAA) in different age groups were significantly different (P < 0.05), as followed by an order: AGE2.5 > AGE4.5 > AGE1.5. The ratio of flavor amino acids to total amino acids (FAA/TAA) in the AGE2.5 group was 42.88%, which was significantly lower than 43.49% in the AGE1.5 group and 43.43% in the AGE4.5 group (P < 0.05). 3) The effect of age on fatty acids in yak meat was relatively weak. The content of C21:0 in the AGE2.5 group was significantly higher than that of the AGE1.5 and AGE4.5 groups (P < 0.05), while the contents of other fatty acids were not significantly different (P > 0.05). The C22:0 and C20:2 were detected in the AGE1.5 group, but did not detected in the AGE2.5 and AGE4.5 groups. 4) As the extension of age, the content of malondialdehyde (MDA) gradually increased, with increase by 53.80% in the AGE4.5 group when compared with the AGE1.5 group. However, the contents of catalase (CAT), total superoxide dismutase (T-SOD), total antioxidant capacity (T-AOC) and glutathione peroxidase (GSH-Px) in yak meat from different age groups were not significant (P > 0.05). In conclusion, age can modify nutritional components of yak meat, but has no significant effect on its antioxidant property.