Rosebrough R W, McMurtry J P, Vasilatos-Younken R
Growth Biology Laboratory, United States Department of Agriculture-Agricultural Research Service, Beltsville Agricultural Research Center, MD 20705, USA.
Br J Nutr. 1998 Jan;79(1):89-95. doi: 10.1079/bjn19980012.
Indian River male broiler chickens growing from 7 to 28 d of age were fed on diets containing either 120 or 210 g crude protein and 0 or 1 mg triiodothyronine (T3)/kg diet to study in vitro lipogenesis (IVL). In addition, a carry-over period (180 g crude protein/kg diet from 28 to 40 d of age) was used to test the persistence of prior treatment effects. The higher protein level increased, but T3 decreased (P < 0.01) growth and feed consumption at 28 d of age. The lower protein level increased (P < 0.05) and T3 decreased IVL in 28-d-old chickens. These effects were only sustained for 6 d following the switch to a common diet at 28 d. IVL at 40 d of age was not affected by either crude protein or T3 fed during the 7-28 d period. The higher protein level increased plasma insulin-like growth factor-1 during the period from 7 to 28 d; however, this effect lasted for only 6 d following the switch to a common diet. Plasma growth hormone (GH) at 28 d of age was inversely related to dietary protein level. Changing to a common level of crude protein did not change plasma GH values at 12 d, indicating that the nutritional state of the young chicken may affect GH at a later period of life. Metabolic changes noted in this study were rapid and maintained for a short period of time following the feeding of a common diet.
对7至28日龄的印第安河雄性肉鸡饲喂含有120或210克粗蛋白以及0或1毫克三碘甲状腺原氨酸（T3）/千克日粮的饲料，以研究体外脂肪生成（IVL）。此外，采用一个延续期（28至40日龄时为180克粗蛋白/千克日粮）来测试先前处理效果的持续性。较高的蛋白质水平增加了28日龄时的生长和采食量，但T3降低了生长和采食量（P<0.01）。较低的蛋白质水平增加了28日龄鸡的IVL（P<0.05），而T3降低了IVL。这些影响在28日龄换成普通日粮后仅持续了6天。40日龄时的IVL不受7至28日龄期间饲喂的粗蛋白或T3的影响。较高的蛋白质水平在7至28日龄期间增加了血浆胰岛素样生长因子-1；然而，换成普通日粮后这种影响仅持续了6天。28日龄时的血浆生长激素（GH）与日粮蛋白质水平呈负相关。换成普通粗蛋白水平后，12日龄时的血浆GH值没有变化，这表明雏鸡的营养状态可能会在其后期生活中影响GH。本研究中观察到的代谢变化迅速，在饲喂普通日粮后短时间内维持。
