Rosebrough R W, Mitchell A D, McMurtry J P
United States Department of Agriculture-Agricultural Research Service, Beltsville, MD 20705, USA.
Br J Nutr. 1996 Apr;75(4):573-81. doi: 10.1079/bjn19960160.
Indian River male broiler chickens growing from 7 to 30 d of age were fed on diets containing crude protein levels ranging from 120 to 300 g/kg plus 0 or 1 mg triiodothyronine (T3)/kg diet. The purpose of this study was to examine the effects of these treatments on lipogenesis after a common diet was fed (180 g crude protein/kg diet from 30 to 56 d of age). Dietary treatment groups were sampled at 30 and 56 d. In vitro lipogenesis was determined by incubating liver explants for 2 h at 37 degrees in Hanks' salts containing 25 mM-HEPES and 10 mM-[2-14C]acetate and then measuring acetate incorporation into total lipid. Growth and feed consumption from 7 to 30 d increased (P < 0.01) as dietary protein increased from 120 to 210 g/kg diet. Both measurements decreased as crude protein increased from 210 to 300 g/kg diet. T3 decreased (P < 0.01) growth and feed intake during this period. Low-protein (< 180 g/kg) diets increased (P < 0.05) and T3 decreased lipogenesis in 30-d-old chickens. Although birds given T3 from 7 to 30 d grew at the greatest rate from 30 to 56 d of age, the final body weight was still less than controls. In vitro lipogenesis at 56 d of age was not affected by either of the two dietary treatments. In contrast, the relative size of the abdominal fat pad (g/kg body weight) at 56 d was decreased by feeding T3 from 7 to 30 d. Any changes in metabolism elicited by either dietary protein levels or hormone treatments may be specific to the particular dosing interval and are not sustained when a common diet is fed during a repletion period.
对7至30日龄的印第安河雄性肉鸡饲喂粗蛋白水平为120至300 g/kg且添加0或1 mg三碘甲状腺原氨酸（T3）/kg日粮的日粮。本研究的目的是检验这些处理对饲喂普通日粮（30至56日龄时粗蛋白为180 g/kg日粮）后脂肪生成的影响。在30和56日龄时对日粮处理组进行采样。通过将肝脏外植体在含有25 mM - HEPES和10 mM - [2 - 14C]乙酸盐的汉克斯盐溶液中于37℃孵育2小时，然后测量乙酸盐掺入总脂质中的量来测定体外脂肪生成。随着日粮蛋白质从120 g/kg增加到210 g/kg，7至30日龄的生长和采食量增加（P < 0.01）。随着粗蛋白从210 g/kg增加到300 g/kg，这两项指标均下降。在此期间，T3降低了生长和采食量（P < 0.01）。低蛋白（< 180 g/kg）日粮增加了30日龄鸡的脂肪生成（P < 0.05），而T3降低了脂肪生成。尽管从7至30日龄给予T3的鸡在30至56日龄时生长速度最快，但最终体重仍低于对照组。56日龄时的体外脂肪生成不受两种日粮处理中任何一种的影响。相反，从7至30日龄饲喂T3可降低56日龄时腹部脂肪垫的相对大小（g/kg体重）。日粮蛋白质水平或激素处理引起的任何代谢变化可能特定于特定的给药间隔，并且在恢复期饲喂普通日粮时不会持续。
