饲粮甜菜碱水平对雪山草鸡腿肌肉品质、糖酵解水平和抗氧化能力的影响

Effects of dietary betaine levels on meat quality,glycolysis level,antioxidant ability of Xueshan chicken

[目的]本试验旨在研究饲粮甜菜碱水平对雪山草鸡肌肉品质、糖酵解水平和抗氧化能力的影响。[方法]400只1日龄雌性雪山草鸡随机均分为5组。分别饲喂5种日粮:基础日粮分别加0(对照组)、125、250、500和1000 mg·kg^(-1)无水甜菜碱。试验期为102 d。[结果]饲粮中甜菜碱添加水平线性增加雪山草鸡屠宰率(P<0.05),线性降低腹脂率(P<0.05)。随着饲粮中甜菜碱添加水平的升高,腿肌的蒸煮损失呈线性降低(P<0.05),24和48 h滴水损失和剪切力呈线性和二次降低(P<0.05),pH_(24h)值呈线性和二次增加(P<0.05),弹性和不易流动水峰面积比(P_(21))呈线性增加(P<0.05),自由水峰面积(A_(22))和峰面积比(P_(22))呈线性降低(P<0.05)。此外,腿肌中乳酸含量和糖酵解潜力(GP)随饲粮中甜菜碱添加水平的升高呈二次降低(P<0.05)。随着饲粮中甜菜碱添加水平的升高,腿肌中过氧化氢酶(CAT)活性与总抗氧化能力(T-AOC)及GSH/GSSG呈线性增加(P<0.05),还原型谷胱甘肽(GSH)含量呈线性和二次增加(P<0.05),GSH/GSSG值呈线性提高(P<0.05),氧化型谷胱甘肽(GSSG)含量呈线性降低(P<0.05)。甜菜碱线性上调了腿肌中核因子E2相关因子2(Nrf2)、CAT、谷胱甘肽过氧化物酶基因(GPx)、γ-谷氨酸-半胱氨酸连接酶催化亚基基因(γ-GCLc)mRNA表达量。[结论]甜菜碱可以改善腿肌肌肉水分分布,降低糖酵解潜力,并通过Nrf2介导下游基因表达来调节酶与非酶抗氧化系统,以此提高肌肉抗氧化能力,最终改善雪山草鸡肉品质。

[Objectives]This study investigated the effects of dietary betaine levels on meat quality,glycolysis level and antioxidant ability of Xueshan chicken.[Methods]A total of 400 one-day-old female Xueshan chickens were randomly divided into five groups with eight replicates of ten chickens for a 102-day feeding trial.Broilers were fed a basal diet supplemented with 0(control),125,250,500 and 1000 mg·kg^(-1) anhydrous betaine,respectively.[Results]Betaine supplementation linearly improved dressed percentage and reduced the percentage of abdominal fat(P<0.05).Dietary betaine linearly decreased cooking loss(P<0.05),linearly and quadratically decreased drip loss(24 and 48 h postmortem)and shear force(P<0.05),and increased pH_(24h) value in thigh muscle.Betaine supplementation linearly enhanced the thigh muscle springiness and the ratio of the immobilized water peaks area(P_(21))(P<0.05),and linearly reduced free water peaks area(A_(22))and their ratio(P_(22))(P<0.05).Additionally,the lactate content and glycolytic potential(GP)of thigh muscle were quadratically decreased by betaine supplementation.With increasing betaine levels,the activity of catalase(CAT),total antioxidant capacity(T-AOC)and the ratio of reduced glutathione/oxidized glutathione(GSH/GSSG)linearly increased(P<0.05),and the content of oxidized glutathione(GSSG)linearly decreased(P<0.05),the content of glutathione(GSH)linearly and quadratically increased(P<0.05).Besides,dietary betaine linearly upregulated thigh muscle mRNA expressions of nuclear factor erythroid 2-related factor 2(Nrf2),CAT,glutathione peroxidase gene(GPx)andγ-glutamate-cysteine ligase catalytic subunit gene(γ-GCLc).[Conclusions]Betaine could improve meat quality by reducing lactate content to increase ultimate pH,altering moisture distribution to enhance muscle springiness,water-holding capacity and tenderness,and regulating enzymatic and non-enzymatic antioxidant systems activated by Nrf2 to improve muscle antioxidant capacity.