Department of Animal and Veterinary Sciences, Clemson University, Clemson, SC 29634, USA.
J Anim Sci. 2013 Mar;91(3):1454-67. doi: 10.2527/jas.2012-5914. Epub 2013 Jan 23.
Angus-cross steers (n = 128; initial BW = 270 ± 3.8 kg) were used in a 3-yr study to assess effects of forage species grazed before slaughter versus concentrate finishing on carcass and meat quality. At the completion of the stockering phase, steers were randomly allotted to mixed pasture (MP; n = 36/yr) or corn-silage concentrate (CON; n = 12/yr) finishing treatments. At 40 d before harvest, MP steers were randomly divided into 3 forage species treatments: alfalfa (AL), pearl millet (PM), or mixed pasture (MP). Average daily BW gain was greater (P = 0.001) for CON than for forage-finished (FOR) steers during the early and overall finishing phase. During the late finishing phase when FOR steers were grazing difference forage species, ADG was greater (P = 0.03) for PM than MP or AL. Harvest weight and HCW were greater (P < 0.001) for CON than FOR due to the differences in animal performance. Total fat percentage of the 9th to 11th rib section was 46% less(P = 0.028) for FOR than CON due to reductions (P < 0.001) in the percentage of subcutaneous fat. Warner-Bratzler shear force (WBS) values at 14 d and 28 d of aging did not differ (P > 0.78) between CON and FOR and were not altered (P > 0.40) by forage species. Trained sensory panel juiciness, initial tenderness, and overall tenderness scores did not differ (P > 0.17) by finishing treatment or forage species. Beef flavor intensity was greater (P < 0.001) for CON than FOR. Beef flavor intensity was greater (P < 0.02) for AL and PM than MP. Off-flavor intensity was greater (P < 0.001) for all forage-fed steaks, regardless of forage species, than CON. Finishing on forages reduced (P = 0.003) total lipid content by 61% for the LM compared with CON finished cattle. Forage species grazed before harvest did not alter (P > 0.05) total lipid content of the LM. Oleic acid concentration and total MUFA of the LM were 21% and 22% less (P = 0.001) for FOR than CON. Concentrations of all individual [linolenic acid, eicosapentaenoic (EPA), docosapentaenoic (DPA), and docosadexaenoic (DHA) acids] and total n-3 fatty acids were greater (P < 0.001) for FOR than CON. Finishing on AL increased (P = 0.017) the concentration of linolenic acid compared with MP or PM. The ratio of n-6 to n-3 fatty acids was greater (P = 0.001) for CON than FOR and did not differ (P = 0.88) by forage species. Concentrate finishing increases carcass weight with same time endpoints and accelerates deposition of MUFA in comparison with FOR, which reduces carcass weight and fat deposition but maintains high concentrations of n-3 and CLA fatty acids. Finishing system or forage species grazed 40 d before slaughter did not alter beef tenderness but FOR had greater off-flavors according to both trained and descriptive sensory panelists.
Angus-cross 阉牛（n = 128；初始 BW = 270 ± 3.8 kg）用于一项 3 年的研究中，以评估在屠宰前放牧的饲草种类与浓缩饲料育肥对胴体和肉质的影响。在放养阶段结束时，阉牛被随机分配到混合牧场（MP；n = 36/yr）或玉米青贮浓缩物（CON；n = 12/yr）育肥处理。在收获前 40 天，MP 阉牛被随机分为 3 种饲草种类处理：紫花苜蓿（AL）、珍珠粟（PM）或混合牧场（MP）。在早期和整个育肥阶段，CON 阉牛的平均日增重（ADG）高于牧草育肥（FOR）阉牛（P = 0.001）。在晚期育肥阶段，当 FOR 阉牛放牧不同的饲草种类时，PM 的 ADG 高于 MP 或 AL（P = 0.03）。由于动物性能的差异，CON 阉牛的收获体重和 HCW 高于 FOR 阉牛。9 至 11 肋段的总脂肪百分比由于皮下脂肪百分比降低（P < 0.001），FOR 阉牛比 CON 阉牛低 46%（P = 0.028）。14 天和 28 天老化的 Warner-Bratzler 剪切力（WBS）值在 CON 和 FOR 之间没有差异（P > 0.78），并且不受饲草种类的影响（P > 0.40）。经过训练的感官小组多汁性、初始嫩度和总体嫩度评分不因育肥处理或饲草种类而不同（P > 0.17）。牛肉风味强度 CON 高于 FOR（P < 0.001）。AL 和 PM 比 MP 具有更高的牛肉风味强度（P < 0.02）。无论饲草种类如何，所有饲草育肥的牛排的异味强度都高于 CON（P < 0.001）。与 CON 育肥的牛相比，育肥前放牧减少了（P = 0.003）LM 中的总脂质含量 61%。在收获前放牧的饲草种类不会改变（P > 0.05）LM 中的总脂质含量。与 CON 相比，LM 中的油酸浓度和总 MUFA 分别降低了 21%和 22%（P = 0.001）。所有个体[亚麻酸、二十碳五烯酸（EPA）、二十二碳六烯酸（DPA）和二十二碳六烯酸（DHA）酸]和总 n-3 脂肪酸的浓度在 FOR 中比 CON 更高（P < 0.001）。与 MP 或 PM 相比，AL 育肥增加了亚麻酸的浓度（P = 0.017）。n-6 与 n-3 脂肪酸的比例在 CON 中比 FOR 更高（P = 0.001），并且不受饲草种类的影响（P = 0.88）。与 FOR 相比，浓缩饲料育肥增加了胴体重，并在相同的时间终点加速 MUFA 的沉积，这降低了胴体重和脂肪沉积，但保持了高浓度的 n-3 和 CLA 脂肪酸。育肥系统或在屠宰前 40 天放牧的饲草种类不会改变牛肉嫩度，但根据经过训练和描述性感官小组的评估，FOR 具有更高的异味。
