中文摘要：

【目的】探究在放牧、舍饲条件下幼龄山羊肌肉品质及抗氧化能力的发育性变化。【方法】选择体况良好、体重相近的经产湘东黑山羊母羊25头,进行同期发情处理,怀孕后产羔,获得36头羔羊,不记公母。出生后20 d内所有羔羊均仅喂以母乳。在0、7、14 d,每个时间点分别随机选取4头屠宰;21 d时,将剩余的24头羔羊随机分为放牧组和舍饲组,每组12头,除母乳外,放牧组以牧草为食,舍饲组补给精料及与放牧组相同的牧草,40 d断奶;在42、56、70 d时,两组每个时间点分别随机选取4头进行屠宰。称量宰前活重、胴体重,采集背最长肌,测定肌肉中粗蛋白（CP）、肌内脂肪（IMF）、氨基酸（AA）、脂肪酸（FA）的组成和含量及主要抗氧化酶活性,包括过氧化氢酶（CAT）、超氧化物歧化酶（SOD）、谷胱甘肽过氧化物酶（GSH-Px）、还原型谷胱甘肽（GSH）和总抗氧化能力（T-AOC）。【结果】（1）羔羊宰前活重、胴体重随日龄显著增加（P〈0.05）,相较于舍饲羊,放牧羊宰前活重较低（P〉0.05）,但胴体重较高（P〉0.05）。（2）无论是放牧还是舍饲,肌肉干物质中CP水平随日龄呈线性增加趋势（P〈0.05）,IMF含量呈升高趋势（P〉0.05）;相较于舍饲羊,放牧羊CP水平较低（P〉0.05）,IMF含量明显较高（P〈0.05）。（3）肌肉中氨基酸总量（TAA）、成人必需氨基酸（AEAA）、婴儿必需氨基酸（BEAA）在不同日龄间没有显著差异（P〉0.05）,但TAA随日龄有升高趋势（P〉0.05）,鲜味氨基酸（FAA）随日龄呈显著增加趋势（P〈0.05）;相较于舍饲羊,放牧羊TAA、AEAA、FAA含量较低,BEAA则较高,但均差异不显著（P〉0.05）。（4）肌肉中饱和脂肪酸（SFA）在放牧条件下随日龄变化不显著（P〉0.05）,舍饲时呈二次曲线变化（P〈0.05）,单不饱和脂肪酸（MUFA）显著降低（P〈0.05）,多不饱和脂肪酸（PUFA）、必需脂肪酸?

英文摘要：

【Objective】The objective of this experiment is to explore developmental changes of meat quality and antioxidant capacity of grazing and house-feeding goats. 【Method】Thirty-six kid goats were collected from 25 Xiangdong black female goats with estrus synchronization. All postnatal goats were fed on goat milk in 20 days. At 0, 7, and 14 d, 4 kid goats were slaughtered, respectively. And then the rest of these kids were assigned into two groups of 12 per group based on different feeding systems-grazing and house-feeding. At 21 d, the grazing group started to feed goat milk and forage, and the house-feeding group was fed on goat milk and a diet of forage supplemented with concentrate starter. All kids were weaned at 40 days. At 42, 56, and 70 d, 4 kids were slaughtered, respectively, in each group. The longissimus dorsi muscle from all 36 kids were collected and crude protein, intramuscular fat, amino acids, fatty acids contents and antioxidant enzymes（catalase, superoxide dismutase, glutathione peroxidase, reduced glutathione and total antioxidant capacity） activities were determined.【Result】The live weight and carcass weight of kids increased significantly with age（P〈0.05）. When compared with house-feeding kids, grazing kids had lower（P〉0.05） live weight, but higher（P〉0.05） carcass weight. The content of crude protein in dry matter showed a linear increasing trend in two groups（P〈0.05）, while intramuscular fat（IMF） showed an increasing trend（P〉0.05）.Grazing kids presented lower contents of crude protein（P〉0.05） and higher IMF than house-feeding kids. The level of total amino acids（TAA）, adult essential amino acids（AEAA） and baby amino acids（BEAA） were not affected significantly by age, whereas both TAA（P〉0.05） and flavor amino acids（FAA）（P〈0.05） showed an increasing trend. Likewise, TAA, AEAA and BEAA were not affected remarkably by feeding system; grazing kids had lower TAA, AEAA and FAA, but higher BEAA than house-feeding kids（P