补饲和放养牦牛肉品质及肌肉微观结构差异

Differences in Meat Quality and Muscle Microstructure of Yak: A Comparison between Supplementary Feeding and Grazing

为研究补饲和放养牦牛肉品质及肌肉微观结构的差异,选取青海省海北州天然放养的12头牦牛,随机分为补饲组和放养组,屠宰后分别取2组牦牛的冈上肌、背阔肌和半腱肌,并对其食用品质、营养品质及肌肉微观结构进行测定分析。结果表明:补饲牦牛背阔肌和半腱肌的亮度(L*值)分别较放养牦牛高1.09和2.99,3个部位肉的p H值、持水力和剪切力均低于放养牦牛,每个部位肉的脂肪含量较放养牦牛高42%以上,且肌纤维横截面积、肌纤维直径、肌纤维膜厚度、Ⅰ带和A带均极显著低于放养牦牛(P<0.01),但肌纤维密度极显著高于放养牦牛?(P<0.01)。提示,补饲牦牛肉的肉色较好,肌纤维较细,嫩度好,但是持水力较差,脂肪含量高。

The aim of this study was to examine differences in meat quality and muscle microstructure between yaks receiving supplementary feeding and grazed yaks. Twelve pasture-grazed yaks from Haibei prefecture, Qinghai province were selected and randomized into supplementary feeding and grazing groups. The yaks in both groups were slaughtered and supraspinatus, latissimus dorsi and semitendinosus muscles were excised for the evaluation of eating quality and nutritional quality and microstructure observation. Results showed supplementary feeding resulted in an increase the brightness （L＊） of latissimus dorsi andsemitendinosus muscles by 1.09 and 2.99, respectively, and a reduction in pH, water-holding capacity and shear force for the three muscles of yaks as compared to grazing. Additionally, the fat contents of these three muscles were increased by over 42% by supplementary feeding, accompanied with an extremely significant decrease in muscle cross-sectional area, fiber diameter, membrane thickness, band A width and bandⅠ width （P 〈 0.01） and an extremely significant increase in fiber density （P〈 0.01）. These results showed that meat color of supplementary feeding yak was better, with smaller muscle fibers and good tenderness but poorer water holding capacity and higher intramuscular fat content.