Vanderwert W, Berger L L, McKeith F K, Baker A M, Gonyou H W, Bechtel P J
J Anim Sci. 1985 Aug;61(2):310-9. doi: 10.2527/jas1985.612310x.
A 2(3) factorial arrangement of treatments was utilized to determine effects of postweaning zeranol implantation, breed (Angus vs Limousin) and castration (bull vs steer) on growth, behavior and carcass traits. An initial slaughter group was used to account for breed differences in composition and to determine fat and lean growth in the 9-10-11th rib section (NTE). The remaining cattle were fed a finishing diet to a fat end point of .76 cm, as determined by a backfat probe. Control bulls outgained (P less than .01) control steers both to the first kill date and over the entire test and did not require significantly more time to reach the fat end point. The implant did not influence gain in bulls but did increase gain in steers. Angus and Limousins were similar in growth rate for the first 126 d before the first slaughter date. Limousins required more (P less than .01) time to reach the fat end point. Bulls and Limousins produced heavier (P less than .01) carcasses and larger rib eyes (P less than .05; bulls; P less than .01; Limousins). Steers and Angus had higher (P less than .01) marbling scores and lower bone maturity. Implanting decreased (P less than .05) marbling and increased carcass maturity. Small but significant shifts in carcass wholesale cut weight distribution were found between breed and sex condition groups. Bulls and Limousins had greater lean growth in the NTE. Bulls and steers were similar in fat growth, but Angus exceeded Limousin in this trait. Zeranol reduced scrotal circumference (P less than .01) and testicle weight at slaughter (P less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)
采用2（3）析因处理安排来确定断奶后玉米赤霉醇植入、品种（安格斯牛与利木赞牛）和去势（公牛与阉牛）对生长、行为和胴体性状的影响。最初的屠宰组用于说明品种在组成上的差异，并确定第9 - 10 - 11肋骨部位（NTE）的脂肪和瘦肉生长情况。其余牛只饲喂育肥日粮，直至背膘探针测定背膘厚度达到0.76厘米的育肥终点。对照公牛在首次屠宰日期前和整个试验期间的增重均超过（P < 0.01）对照阉牛，且达到育肥终点所需时间无显著差异。植入物对公牛的增重无影响，但增加了阉牛的增重。在首次屠宰日期前的前126天，安格斯牛和利木赞牛的生长速度相似。利木赞牛达到育肥终点所需时间更长（P < 0.01）。公牛和利木赞牛的胴体更重（P < 0.01），眼肌面积更大（公牛，P < 0.05；利木赞牛，P < 0.01）。阉牛和安格斯牛的大理石花纹评分更高（P < 0.01），骨骼成熟度更低。植入物降低了（P < 0.05）大理石花纹评分，提高了胴体成熟度。在品种和性别条件组之间发现胴体批发切块重量分布有微小但显著的变化。公牛和利木赞牛在NTE部位的瘦肉生长更多。公牛和阉牛的脂肪生长相似，但在这一性状上安格斯牛超过利木赞牛。玉米赤霉醇降低了屠宰时的阴囊周长（P < 0.01）和睾丸重量（P < 0.05）。（摘要截取自250字）
