Pfizer Animal Health, 5 Giralda Farms, Madison, NJ 07940, USA.
J Anim Sci. 2012 Dec;90(13):5056-66. doi: 10.2527/jas.2012-5091. Epub 2012 Oct 16.
Synovex Plus (SP) is a product that delivers 28 mg of estradiol benzoate (EB) and 200 mg of trenbolone acetate (TBA). We studied the impact of a polymeric, porous coating on SP implants (CSP) to prolong release of EB and TBA, and stimulate feedlot performance of feedlot cattle for an extended period. In an explant study, 30 steers were implanted with SP in one ear and CSP in the contralateral ear. Cattle (n = 6/d) were necropsied 40, 81, 120, 160, and 200 d after treatment, and remaining EB and TBA were quantified. Linear regression of EB and TBA remaining as a function of time for each treatment were computed. Rates of EB and TBA depletion from SP were -0.1980 (r(2) = 0.9994) and -1.7073 mg/d (r(2) = 0.9644), respectively, and for CSP rates of EB and TBA depletion were -0.1049 (r(2) = 0.9123) and -0.9466 mg/d (r(2) = 0.9297), respectively. The effect of treatment on depletion rates of each analyte were significant (P < 0.05). Data also showed EB and TBA were delivered from CSP at least 200 d but were delivered from SP about 120 d. Multisite trials with beef-type steers (4 sites) and heifers (4 sites) evaluated feedlot performance and carcass characteristics in response to a CSP implant or when sham implanted (SC). A randomized complete block design with 9 blocks and 2 treatments was used per site within animal gender. Across sites, steers (n = 342, BW = 297 kg) were fed finishing rations for 190 to 202 d (mean 198 d) and heifers (n = 342, BW = 289 kg) were fed finishing rations for 191 to 201 d (mean 198 d). Cattle were harvested and carcasses evaluated. Data were pooled across sites within gender for statistical analysis. Steers and heifers treated with CSP yielded greater (P ≤ 0.003) ADG, DMI, and G:F than SC steers and heifers. Mean BW differences between CSP and SC continued to increase throughout the study, indicating CSP stimulated growth of steers and heifers for 198 d. Mean carcass weights of CSP steers (P = 0.005) and heifers (P = 0.004) were greater than those of SP steers and heifers by 26.2 and 20.6 kg, respectively. The LM area was larger (P < 0.001) in CSP steers and heifers than SC cattle. Marbling decreased with CSP treatment (P ≤ 0.031), which caused reductions (P ≤ 0.006) in proportions of carcasses grading Prime or Choice. Evidence from these studies showed that a single administration of CSP increased feedlot cattle performance for at least 198 d, compared with SC, and may reduce the need to reimplant cattle.
Synovex Plus (SP) 是一种含有 28 毫克苯甲酸雌二醇 (EB) 和 200 毫克醋酸去甲雄三烯醇酮 (TBA) 的产品。我们研究了一种聚合物多孔涂层对 SP 植入物（CSP）的影响，以延长 EB 和 TBA 的释放时间，并在更长时间内刺激育肥牛的生长性能。在一项组织外研究中，30 头公牛的一侧耳朵植入 SP，另一侧耳朵植入 CSP。处理后 40、81、120、160 和 200 d 对牛进行屠宰，并定量剩余的 EB 和 TBA。分别计算每个处理中剩余 EB 和 TBA 随时间变化的线性回归。SP 中 EB 和 TBA 的消耗速率分别为 -0.1980（r(2) = 0.9994）和 -1.7073 mg/d（r(2) = 0.9644），而 CSP 中 EB 和 TBA 的消耗速率分别为 -0.1049（r(2) = 0.9123）和 -0.9466 mg/d（r(2) = 0.9297）。处理对每种分析物消耗速率的影响均具有统计学意义（P < 0.05）。数据还表明，EB 和 TBA 至少可以从 CSP 中释放 200 d，但从 SP 中释放约 120 d。在 4 个育肥场（4 个育肥场）和 4 个育肥场（4 个育肥场）中进行了多点试验，评估了 CSP 植入物或假植入（SC）对育肥牛的生长性能和胴体特性的影响。每个动物性别内的 9 个区块和 2 种处理均采用随机完全区块设计。在所有地点，公牛（n = 342，BW = 297 kg）饲喂育肥日粮 190 至 202 d（平均 198 d），小母牛（n = 342，BW = 289 kg）饲喂育肥日粮 191 至 201 d（平均 198 d）。对牛进行屠宰和胴体评估。在性别内，对所有地点的数据进行了汇总，以便进行统计分析。用 CSP 处理的公牛和小母牛的 ADG、DMI 和 G:F 均高于 SC 公牛和小母牛（P ≤ 0.003）。整个研究过程中，CSP 和 SC 之间的平均 BW 差异持续增加，表明 CSP 刺激了公牛和小母牛的生长，持续了 198 d。CSP 公牛（P = 0.005）和小母牛（P = 0.004）的胴体重均大于 SP 公牛和小母牛的胴体重，分别高出 26.2 和 20.6 kg。CSP 公牛和小母牛的 LM 面积大于 SC 牛（P < 0.001）。大理石花纹随 CSP 处理而减少（P ≤ 0.031），这导致了 Prime 或 Choice 等级胴体比例的降低（P ≤ 0.006）。这些研究的证据表明，与 SC 相比，单次施用 CSP 可至少提高 198 d 的育肥牛的生长性能，并且可能减少对牛重新植入的需求。
