Henricks D M, Brandt R T, Titgemeyer E C, Milton C T
Department of Animal and Veterinary Sciences, Clemson University, SC 29634, USA.
J Anim Sci. 1997 Oct;75(10):2627-33. doi: 10.2527/1997.75102627x.
The effects of the growth-promoting steroids estradiol-17 beta (E2), trenbolone acetate (TBA), and melengestrol acetate (MGA) in heifers on serum concentrations of E2 and trenbolone-17 beta (TBOH) were examined. Feed intake and growth performance were also measured. Serum concentrations of E2 and TBOH were measured on d 0, 1, 3, 5, 7, 13, 21, 28, 42, 56, 84, 112, and 140 in finishing heifers administered the following treatments: 1) control; 2) MGA, .5 mg per heifer daily; 3) Revalor-H (140 mg TBA + 14 mg E2); 4) Revalor-H + MGA; 5) Finaplix-H (200 mg TBA); and 6) Finaplix-H + MGA. Revalor-H implantation (Treatments 3 and 4) increased (P < .05) serum E2 concentrations; peak concentrations (67.5 pg/mL) occurred between d 21 and 56. Feeding MGA (Treatment 4) had no effect (P > .05) on this increase in serum E2 concentrations (63.3 pg/mL). From d 84 until d 140, serum E2 was greater (P < .05) for the Revalor-H treatment (average of 19 pg/mL) than for the control (7 pg/mL) or Finaplix-H treatments (6.5 pg/mL). Serum E2 concentrations increased numerically two- to threefold from d 56 to 140 in controls fed MGA, compared with controls not fed MGA. There was the expected increase in serum TBOH concentrations after TBA implantation in the Revalor-H and Finaplix-H treatments; concentrations were similar (P > .05) for Revalor-H (221 pg/mL) and Finaplix-H (280 pg/mL). After d 56, serum TBOH concentrations decreased in both treatments to 10 and 20% of these concentrations, respectively. Feeding MGA increased serum TBOH (P < .05). Dry matter intake by heifers did not differ among treatments. Feeding of MGA improved gains (P = .12) and efficiencies (P < .01) in nonimplanted heifers and had no effect (P > .4) on gains or efficiencies in Finaplix-implanted heifers.
研究了促生长类固醇17β-雌二醇（E2）、醋酸群勃龙（TBA）和醋酸美仑孕酮（MGA）对小母牛血清中E2和17β-群勃龙（TBOH）浓度的影响。同时还测定了采食量和生长性能。在接受以下处理的育成小母牛中，于第0、1、3、5、7、13、21、28、42、56、84、112和140天测定血清E2和TBOH浓度：1）对照；2）MGA，每头小母牛每日0.5毫克；3）Revalor-H（140毫克TBA + 14毫克E2）；4）Revalor-H + MGA；5）Finaplix-H（200毫克TBA）；6）Finaplix-H + MGA。植入Revalor-H（处理3和4）使血清E2浓度升高（P < 0.05）；峰值浓度（67.5皮克/毫升）出现在第21至56天之间。饲喂MGA（处理4）对血清E2浓度的这种升高没有影响（P > 0.05）（63.3皮克/毫升）。从第84天到第140天，Revalor-H处理组的血清E2浓度（平均19皮克/毫升）高于对照组（7皮克/毫升）或Finaplix-H处理组（6.5皮克/毫升）（P < 0.05）。与未饲喂MGA的对照组相比，饲喂MGA的对照组从第56天到140天血清E2浓度在数值上增加了两到三倍。在Revalor-H和Finaplix-H处理中植入TBA后，血清TBOH浓度出现预期升高；Revalor-H组（221皮克/毫升）和Finaplix-H组（280皮克/毫升）的浓度相似（P > 0.05）。第56天后，两种处理的血清TBOH浓度分别降至这些浓度的10%和20%。饲喂MGA可使血清TBOH升高（P < 0.05）。各处理间小母牛的干物质采食量没有差异。饲喂MGA可提高未植入小母牛的增重（P = 0.12）和效率（P < 0.01），对植入Finaplix的小母牛的增重或效率没有影响（P > 0.4）。
