Dikeman M E, Reddy G B, Arthaud V H, Tuma H J, Koch R M, Mandigo R W, Axe J B
J Anim Sci. 1986 Jul;63(1):92-101. doi: 10.2527/jas1986.63192x.
One hundred forty-four Angus male calves were assigned to one of five slaughter-age groups: 9, 12, 15, 18 and 24 mo of age. After weaning, one-half of the calves within slaughter age were castrated. One-half of the 12-, 15-, 18- and 24-mo age groups of each sex were further randomly allotted to a high-energy (HE) or low-energy (LE) finishing diet. Eight bulls and eight steers assigned to the 9-mo slaughter group were fed the HE diet only. Samples from the longissimus muscle (LM) were taken at the 12th rib for histological evaluations of fat deposits. Thin sections from the LM at the 11th rib were stained for lipid, collagen and elastin. Steaks from the LM were cooked and evaluated by a sensory panel and sheared by a Warner-Bratzler shear (WBS) device. The 9-10-11th rib sections were separated into muscle, fat and bone. Collagen, elastin and collagen solubility were determined chemically. Bulls had heavier carcasses, less fat and lower sensory scores for tenderness and juiciness than steers. Steers fed the HE diet had lower WBS values than bulls on either diet. Cooking losses were higher for bulls at 12, 18 and 24 mo than for steers. Histological evaluation showed that collagen content was higher for bulls than for steers and higher for cattle fed the LE diet than those fed the HE diet. Among cattle on the HE diet, the 9-mo cattle had more collagen than all older groups. Neither sex nor diet had an effect on elastin content shown by histological evaluation, but 12-mo cattle had the most elastin and the 15- and 18-mo cattle had the least elastin. Collagen content determined by chemical analysis was not affected by sex, diet or slaughter age. Correlation coefficients among histologically and chemically evaluated collagen and elastin and meat traits were too low to be of practical importance. The time-intensive histological techniques used in our study provided little additional information over that obtained from visually evaluated or chemically measured meat traits.
144头安格斯雄性犊牛被分配到五个屠宰年龄组之一：9、12、15、18和24月龄。断奶后，屠宰年龄组内的一半犊牛被阉割。每个性别12、15、18和24月龄组的一半犊牛进一步随机分配到高能（HE）或低能（LE）育肥日粮组。分配到9月龄屠宰组的8头公牛和8头阉牛只饲喂高能日粮。在第12肋处采集背最长肌（LM）样本用于脂肪沉积的组织学评估。第11肋处背最长肌的薄片进行脂质、胶原蛋白和弹性蛋白染色。背最长肌牛排经烹饪后由感官评定小组进行评估，并使用沃纳-布拉茨勒剪切（WBS）装置进行剪切。第9 - 10 - 11肋部分被分离为肌肉、脂肪和骨骼。通过化学方法测定胶原蛋白、弹性蛋白和胶原蛋白溶解度。公牛的胴体比阉牛重，脂肪少，嫩度和多汁性的感官评分较低。饲喂高能日粮的阉牛的WBS值低于两种日粮下的公牛。12、18和24月龄公牛的烹饪损失高于阉牛。组织学评估表明，公牛的胶原蛋白含量高于阉牛，饲喂低能日粮的牛的胶原蛋白含量高于饲喂高能日粮的牛。在高能日粮的牛中，9月龄的牛比所有年龄较大的组含有更多的胶原蛋白。组织学评估显示，性别和日粮对弹性蛋白含量均无影响，但12月龄的牛弹性蛋白含量最高，15和18月龄的牛弹性蛋白含量最低。化学分析测定的胶原蛋白含量不受性别、日粮或屠宰年龄的影响。组织学和化学评估的胶原蛋白、弹性蛋白与肉品质性状之间的相关系数过低，不具有实际意义。我们研究中使用的耗时的组织学技术相比从肉眼评估或化学测量的肉品质性状所获得的信息，几乎没有提供更多信息。
