Muir L A, Wien S
J Anim Sci. 1983 Jul;57(1):139-45. doi: 10.2527/jas1983.571139x.
An 8-wk growth trial was conducted to assess the effects of continuous infusion of thyrotropin-releasing hormone (TRH) and an active TRH analog less than Aad-His-Pro-NH2 (the less than Aad is L-pyro-alpha-aminoadipic acid) on growth trial performance, carcass composition and hormone profiles of growing lambs. Both drugs were infused at 600 micrograms X lamb -1 X d -1 with 16 lambs/treatment. Both TRH and less than Aad-His-Pro-NH2 decreased average daily gain (ADG; P less than .01) and increased feed conversion (FC; P less than .01) compared with saline infused controls. Average daily feed intake was not altered. Carcasses of lambs given TRH or less than Aad-His-Pro-NH2 contained fewer kilograms of moisture (P less than .05) and appeared to contain fewer kilograms of protein. Thyrotropin-releasing hormone and less than Aad-His-Pro-NH2 increased thyroid gland weights (P less than .05), but pituitary gland weights were not different. Plasma thyrotropin (TSH) concentrations were increased by both drugs compared with control lambs, peaking at 4 to 7 d after initiating infusion. However, by 14 d, TSH concentrations returned to control levels. Triiodothyronine (T3) and thyroxine (T4) were elevated by both drugs over the entire 8-wk trial, with peak levels reached at 10 d and maintained for the duration of the study. Both TRH and less than Aad-His-Pro-NH2 increased prolactin over the entire period. Growth hormone levels were not altered by either drug. The effects of less than Aad-His-Pro-NH2 infusion on growth trial performance, carcass composition and hormone profiles of growing lambs were very similar to TRH. The negative effects of TRH and less than Aad-His-Pro-NH2 infusion on ADG, FC and carcass protein appear to be the result of elevated T3 and T4 levels.
进行了一项为期8周的生长试验，以评估持续输注促甲状腺激素释放激素（TRH）和一种活性TRH类似物（小于Aad-His-Pro-NH2，其中小于Aad为L-焦-α-氨基己二酸）对生长羔羊生长性能、胴体组成和激素水平的影响。两种药物均以600微克/只羔羊 -1/天 -1的剂量输注，每个处理组有16只羔羊。与输注生理盐水的对照组相比，TRH和小于Aad-His-Pro-NH2均降低了平均日增重（ADG；P＜0.01）并提高了饲料转化率（FC；P＜0.01）。平均日采食量未改变。给予TRH或小于Aad-His-Pro-NH2的羔羊胴体中水分含量较少（P＜0.05），且蛋白质含量似乎也较少。促甲状腺激素释放激素和小于Aad-His-Pro-NH2增加了甲状腺重量（P＜0.05），但垂体重量无差异。与对照羔羊相比，两种药物均使血浆促甲状腺激素（TSH）浓度升高，在开始输注后4至7天达到峰值。然而，到14天时，TSH浓度恢复到对照水平。在整个8周的试验中，两种药物均使三碘甲状腺原氨酸（T3）和甲状腺素（T4）升高，在第10天达到峰值并在研究期间保持。在整个期间，TRH和小于Aad-His-Pro-NH2均使催乳素增加。两种药物均未改变生长激素水平。小于Aad-His-Pro-NH2输注对生长羔羊生长性能、胴体组成和激素水平的影响与TRH非常相似。TRH和小于Aad-His-Pro-NH2输注对ADG、FC和胴体蛋白质的负面影响似乎是T3和T4水平升高的结果。
