Lauterio T J, Scanes C G
J Nutr. 1987 Apr;117(4):758-63. doi: 10.1093/jn/117.4.758.
The hormonal response to protein restriction was studied in breeds of chickens with different rates of growth and body size. Fast-growing (broiler) chicks and lighter-weight (White Leghorn) birds were fed isoenergetic 5% (low) and 20% (control) protein diets ad libitum starting at 2 wk of age. At 4 wk of age, one-half of each group continued receiving the initial diet, while the other half was fed the alternate diet for two additional weeks. Growth was decreased in birds fed the low protein diet due to restriction of protein, sustained low feed intake and hence possibly insufficient energy for growth. Birds fed low protein diets had higher plasma growth hormone (GH) concentrations (325% in Leghorns and 233% in broilers) compared with controls. Plasma concentrations of somatomedin-C in protein-restricted Leghorn and broiler chicks were only 50 and 34% of those of controls, respectively. Similarly plasma concentrations of thyroxine (T4) and triiodothyronine (T3) were reduced in protein-deprived birds compared with those fed adequate protein. Plasma T3 concentrations of restricted birds were 48 (Leghorns) and 47% (broilers) of those of controls, whereas plasma T4 concentrations were 44 (Leghorns) and 41% (broilers) of those of controls.
对不同生长速度和体型的鸡品种进行了蛋白质限制的激素反应研究。从2周龄开始，给快速生长（肉鸡）雏鸡和体重较轻（白来航鸡）的鸡自由采食等能量的5%（低）和20%（对照）蛋白质日粮。在4周龄时，每组的一半继续接受初始日粮，而另一半再额外饲喂两周交替日粮。由于蛋白质限制、持续低采食量以及因此可能生长能量不足，饲喂低蛋白日粮的鸡生长减缓。与对照组相比，饲喂低蛋白日粮的鸡血浆生长激素（GH）浓度更高（白来航鸡中高325%，肉鸡中高233%）。蛋白质限制的白来航鸡和肉鸡雏鸡中胰岛素样生长因子-C的血浆浓度分别仅为对照组的50%和34%。同样，与饲喂充足蛋白质的鸡相比，蛋白质缺乏的鸡血浆甲状腺素（T4）和三碘甲状腺原氨酸（T3）浓度降低。限制组鸡的血浆T3浓度分别为对照组的48%（白来航鸡）和47%（肉鸡），而血浆T4浓度分别为对照组的44%（白来航鸡）和41%（肉鸡）。
