Apple J K, Dikeman M E, Simms D D, Kuhl G
Anim. Sci. and Ind. Dept., Kansas State University, Manhattan 66506.
J Anim Sci. 1991 Nov;69(11):4437-48. doi: 10.2527/1991.69114437x.
Seventy-two Holstein steers averaging 182 kg were assigned randomly to one of six treatment groups: 1) nonimplanted controls (C); 2) implanted with 36 mg of zeranol (Z); 3) implanted with 20 mg of estradiol benzoate and 200 mg of progesterone (EP); 4) implanted with 140 mg of trenbolone acetate (TBA); 5) implanted with 140 mg of trenbolone acetate plus 20 mg of estradiol benzoate and 200 mg of progesterone (TBA + EP); and 6) implanted with 140 mg of trenbolone acetate plus 36 mg of zeranol (TBA + Z). Each treatment group consisted of three replications of four animals per pen, which were implanted on d 0, 56, 112, and 168. Masculinity and muscling scores were assigned at 24 h preslaughter. Hide removal difficulty was scored by a plant supervisor. Quality and yield grade data were obtained at 24 h postmortem. Longissimus muscle (LM) steaks were removed and cooked for Warner-Bratzler shear (WBS) determinations and sensory panel (SP) evaluations. Over the entire feeding period (249 d), TBA + EP steers had higher (P less than .05) ADG than TBA + Z, TBA, and C steers. All treatments had higher (P less than .05) ADG than C, with the exception of TBA. The only feed efficiency differences were those following the 168-d implant time, when TBA steers were more (P less than .05) efficient than TBA + Z or C steers. The TBA + EP and TBA + Z steers were more (P less than .05) masculine and their hides were more (P less than .05) difficult to remove than those of EP and C steers. Carcass weights of TBA + EP steers were heavier (P less than .05) than those of TBA or C steers. The TBA + EP steers had larger (P less than .05) LM areas than Z, TBA, and C steers. Also, TBA + EP steers tended (P = .07) to have lower numerical yield grades than EP, Z, or C steers. Even though mean marbling scores and quality grades were similar (P greater than .05) among treatment groups, only 50% of TBA + EP carcasses graded low Choice or higher, compared with 100, 75, 82, 90, and 83% for C, TBA, Z, EP, and TBA + Z carcasses, respectively. The only meat palatability differences were that myofibrillar and overall tenderness scores tended to be lower (P = .07) for steaks from EP and TBA + Z than for steaks from Z and C groups.
72头平均体重182千克的荷斯坦公牛被随机分配到六个处理组之一：1）未植入对照组（C）；2）植入36毫克玉米赤霉醇（Z）；3）植入20毫克苯甲酸雌二醇和200毫克孕酮（EP）；4）植入140毫克醋酸群勃龙（TBA）；5）植入140毫克醋酸群勃龙加20毫克苯甲酸雌二醇和200毫克孕酮（TBA + EP）；6）植入140毫克醋酸群勃龙加36毫克玉米赤霉醇（TBA + Z）。每个处理组由每栏4头动物的三个重复组成，分别在第0、56、112和168天进行植入。在屠宰前24小时进行雄性特征和肌肉评分。由工厂主管对去皮难度进行评分。在宰后24小时获取胴体质量和产量等级数据。取出背最长肌（LM）牛排并进行烹饪，以测定沃纳 - 布拉茨勒剪切力（WBS）和进行感官评定小组（SP）评估。在整个饲养期（249天），TBA + EP组公牛的平均日增重（ADG）高于TBA + Z、TBA和C组公牛（P < 0.05）。除TBA组外，所有处理组的ADG均高于C组（P < 0.05）。唯一的饲料效率差异出现在168天植入时间之后，此时TBA组公牛比TBA + Z或C组公牛更高效（P < 0.05）。TBA + EP和TBA + Z组公牛比EP和C组公牛更具雄性特征（P < 0.05），且它们的皮更难去除（P < 0.05）。TBA + EP组公牛的胴体重比TBA或C组公牛更重（P < 0.05）。TBA + EP组公牛的LM面积比Z、TBA和C组公牛更大（P < 0.05）。此外，TBA + EP组公牛的产量等级数值往往低于EP、Z或C组公牛（P = 0.07）。尽管各处理组之间的大理石花纹评分均值和质量等级相似（P > 0.05），但TBA + EP组胴体中只有50%被评为低精选级或更高等级，而C、TBA、Z、EP和TBA + Z组胴体的这一比例分别为100%、75%、82%、90%和83%。唯一的肉适口性差异是，EP和TBA + Z组牛排的肌原纤维和总体嫩度评分往往低于Z和C组牛排（P = 0.07）。
