Smith Zachary K, Renter David G, Holland Ben P, Word Alyssa B, Crawford Grant I, Nichols Wade T, Nuttelman Brandon L, Streeter Marshall N, Walter Lee-Anne J, Hutcheson John P, Dicke Bill, Brandt Robert T, Szasz Josh I, Bryant Tony C, Pringle Lois F G, Carlson Zac E, Erickson Galen E, Johnson Bradley J
Department of Animal Science, South Dakota State University, Brookings, SD.
Center for Outcomes Research and Epidemiology, Kansas State University, Manhattan, KS.
Transl Anim Sci. 2020 Jul 2;4(3):txaa109. doi: 10.1093/tas/txaa109. eCollection 2020 Jul.
Randomized complete block design experiments ( = 6 experiments) evaluating steroidal implants (all from Merck Animal Health, Madison, NJ) were conducted in large-pen feedlot research facilities between 2015 and 2018 comparing an 80 mg trenbolone acetate (TBA) and 8 mg estradiol-17β (E) initial implant (Revalor-IH) and reimplanted with 200 mg TBA and 20 mg E (Revalor-200; REPEATED) to a single 80 mg TBA and 8 mg E uncoated; 120 mg TBA and 12 mg E coated implant (Revalor-XH) at arrival (SINGLE) on growth and carcass responses in finishing heifers. Experiments occurred in Nebraska, Oklahoma, Washington, and Texas. Similar arrival processing was used across experiments where 17,675 heifers [initial body weight = 333 kg SEM (4.1)] were enrolled into 180 pens (90 pens per treatment with 65-240 heifers per pen) and fed for 145-222 d. Only REPEATED heifers were removed from their pen at reimplant. Diets contained monensin and tylosin, consisted of ingredients common to each region, and contained greater than 90% concentrate. Ractopamine hydrochloride was fed for a minimum of 28 d prior to harvest. Linear mixed models were used for all analyses; model-adjusted means for each implant group and the corresponding SEM were generated. Distributions of U.S. Department of Agriculture (USDA) quality grade (QG) and yield grade (YG) were analyzed as ordinal outcomes. No differences ( ≥ 0.11) were detected for any performance parameters except dry matter intake (DMI), where SINGLE had greater ( = 0.02) DMI (9.48 vs. 9.38 ± 0.127 kg) compared with REPEATED. Heifers implanted with REPEATED had greater ( ≤ 0.02) hot carcass weight (HCW; 384 vs. 382 ± 2.8 kg), dressing percentage (64.54 vs. 64.22 ± 0.120%), and ribeye area (91.87 vs. 89.55 ± 0.839 cm) but less ( ≤ 0.01) rib fat (1.78 vs. 1.83 ± 0.025 cm) and calculated YG (2.82 vs. 2.97 ± 0.040) and similar ( = 0.74) marbling scores (503 vs. 505 ± 5.2) compared with SINGLE heifers. Distributions of USDA YG and QG were impacted ( ≤ 0.03) by treatment such that REPEATED had fewer USDA Prime and YG 4 and 5 carcasses. Heifer growth performance did not differ between implant regimens, but HCW and muscling did, perhaps indicating that REPEATED may be suited for grid-based marketing, and SINGLE might be suited for heifers sold on a live basis depending upon market conditions and value-based grid premiums and discounts. However, these decisions are operational dependent and also may be influenced by factors including animal and employee safety, stress on animals, processing facilities, time of year, labor availability, and marketing strategies.
2015年至2018年期间，在大型围栏饲养场研究设施中进行了随机完全区组设计实验（共6个实验），评估类固醇植入物（均来自新泽西州麦迪逊市的默克动物保健公司），比较初始植入80毫克醋酸群勃龙（TBA）和8毫克雌二醇-17β（E）（Revalor-IH），并在重新植入时使用200毫克TBA和20毫克E（Revalor-200；重复植入），与到达时单次植入80毫克TBA和8毫克E的未包衣植入物；120毫克TBA和12毫克E的包衣植入物（Revalor-XH）（单次植入）对育成小母牛生长和胴体反应的影响。实验在内布拉斯加州、俄克拉荷马州、华盛顿州和得克萨斯州进行。各实验采用相似的到达处理方式，共17675头小母牛[初始体重 = 333千克，标准误（4.1）]被放入180个围栏（每个处理90个围栏，每个围栏65 - 240头小母牛），饲养145 - 222天。只有重复植入的小母牛在重新植入时被移出围栏。日粮中含有莫能菌素和泰乐菌素，由各地区常见的成分组成，且浓缩料含量大于90%。在屠宰前至少28天饲喂盐酸莱克多巴胺。所有分析均使用线性混合模型；生成每个植入组的模型调整均值及相应的标准误。将美国农业部（USDA）质量等级（QG）和产量等级（YG）的分布作为有序结果进行分析。除干物质采食量（DMI）外，未检测到任何性能参数存在差异（P≥0.11），其中单次植入组的DMI较高（P = 0.02）（9.48千克对9.38±0.127千克），高于重复植入组。与单次植入的小母牛相比，重复植入的小母牛具有更高（P≤0.02）的热胴体重（HCW；384千克对382±2.8千克）、屠宰率（64.54%对64.22±0.120%）和眼肌面积（91.87平方厘米对89.55±0.8
