J Anim Sci. 2017 Dec;95(12):5397-5406. doi: 10.2527/jas2017.2022.
The objective of this study was to examine the effect of percent Brahman genetics on Warner-Bratzler shear force (WBSF), desmin and troponin-T (TnT) degradation, hydroxylysyl pyridinoline (HP) crosslink content, and perimysial collagen melting temperature. Steers ( = 131) produced in 2012 and 2013 were harvested at 1.27 cm of visual s.c. back fat thickness. Steers were divided into 4 genetic categories consisting of steers that contained 6/32 or less Brahman genetics, 12/32 Brahman genetics, 14/32 to 18/32 Brahman genetics, and 23/32 to 32/32 Brahman genetics. Twenty-four hours after harvest, a 7.62-cm piece of the longissimus lumborum beginning at the 13th rib was collected and aged for 14 d. Following aging, three 2.54-cm steaks were cut for WBSF, trained sensory panel, and laboratory analyses. Laboratory analyses steaks were used to determine protein degradation, HP crosslink analysis, and perimysial collagen melting temperature. Data were analyzed using a polynomial regression for unequally spaced treatments. As the percent Brahman genetics increased, WBSF increased (linear, = 0.01). As percent Brahman genetics increased, tenderness score decreased (less tender) and connective tissue score increased (more connective tissue; linear, = 0.01). As the percentage of Brahman genetics increased, the amount of degraded desmin (38 kDa) and TnT (34 and 30 kDa) decreased (linear, < 0.03) whereas the amount of immunoreactive 36 kDa TnT increased (linear, = 0.04). Percent Brahman genetics had no effect ( = 0.14) on HP crosslink content but did tend to increase ( = 0.07) perimysial collagen melting temperature as the percent Brahman increased. The percentage of Brahman genetic influence was positively correlated to WBSF ( = 0.25), 36 kDa immunoreactive TnT ( = 0.26), and perimysial collagen melting temperature ( = 0.25, = 0.01). Sensory panel tenderness ( = -0.44), juiciness ( = -0.26), and connective tissue scores ( = -0.63); 38 kDa degraded desmin ( = -0.34), 34 ( = -0.36) and 30 kDa degraded TnT ( = -0.29); and HP collagen crosslinks ( = -0.20) were negatively correlated to percent Brahman genetic influence ( < 0.03). Increasing Brahman genetic influence in steers negatively affects tenderness, partially through a reduction in degradation of desmin and TnT. Although HP collagen crosslinks are unaffected by Brahman genetics, a tendency for increased perimysium melting temperature indicates that other collagen-stabilizing crosslinks may be affected.
本研究的目的是检验 Brahman 遗传百分比对 Warner-Bratzler 剪切力（WBSF）、结蛋白和肌钙蛋白-T（TnT）降解、羟赖氨酸吡啶啉（HP）交联含量以及肌间结缔组织胶原熔融温度的影响。2012 年和 2013 年生产的阉牛在可视皮下背膘厚 1.27cm 时进行屠宰。将阉牛分为 4 个遗传类别：Brahman 遗传基因含量为 6/32 或更低、12/32 Brahman 遗传基因、14/32 至 18/32 Brahman 遗传基因和 23/32 至 32/32 Brahman 遗传基因的牛。屠宰后 24 小时，从第 13 根肋骨处采集长肌背最长肌的 7.62cm 长的一段进行 14d 的成熟。成熟后，取 3 块 2.54cm 的牛排进行 WBSF、训练感官小组和实验室分析。用于实验室分析的牛排用于确定蛋白质降解、HP 交联分析和肌间结缔组织胶原熔融温度。使用不等间距处理的多项式回归来分析数据。随着 Brahman 遗传百分比的增加，WBSF 增加（线性，=0.01）。随着 Brahman 遗传百分比的增加，嫩度评分降低（更不嫩），结缔组织评分增加（更多结缔组织；线性，=0.01）。随着 Brahman 遗传百分比的增加，降解的结蛋白（38kDa）和 TnT（34 和 30kDa）的量减少（线性，<0.03），而免疫反应性 36kDa TnT 的量增加（线性，=0.04）。Brahman 遗传百分比（=0.14）对 HP 交联含量没有影响，但随着 Brahman 遗传百分比的增加，肌间结缔组织胶原熔融温度有升高的趋势（=0.07）。Brahman 遗传影响的百分比与 WBSF（=0.25）、36kDa 免疫反应性 TnT（=0.26）和肌间结缔组织胶原熔融温度（=0.25，=0.01）呈正相关。感官小组嫩度（= -0.44）、多汁性（= -0.26）和结缔组织评分（= -0.63）；38kDa 降解的结蛋白（= -0.34）、34（= -0.36）和 30kDa 降解的 TnT（= -0.29）；以及 HP 胶原蛋白交联（= -0.20）与 Brahman 遗传百分比的影响呈负相关（<0.03）。Brahman 遗传对牛的影响增加会降低嫩度，部分原因是结蛋白和 TnT 的降解减少。尽管 HP 胶原蛋白交联不受 Brahman 遗传的影响，但肌间结缔组织熔融温度升高的趋势表明，其他胶原稳定交联可能受到影响。
