Hocking P M, Saunderson C L
Institute of Animal Physiology and Genetics Research, Edinburgh Research Station, Roslin, Midlothian.
Br J Nutr. 1992 May;67(3):391-9. doi: 10.1079/bjn19920044.
Protein degradation rates were assessed by the excretion of Nt-methylhistidine (NtMH) in four strains of mature chickens, two White Leghorns and two broilers (dwarf and normal), fed on diets containing two levels of dietary protein. Over 0.9 of labelled NtMH was recovered within 7 d of injection from three White Leghorn, three dwarf and three normal broiler males. Protein degradation, measured by NtMH output, was related to adult body-weight by the power 0.71 and strain intercepts were significantly different. Strain differences disappeared when the rate of output of NtMH per unit lean was evaluated. The rate of output of NtMH per unit muscle was higher in birds fed on a low-protein diet of 100 g crude protein (nitrogen x 6.25; CP)/kg compared with males fed on 150 g CP/kg. It was concluded that the lower rate of protein degradation in broiler compared with layer strains at young ages is related to increased adult body-weight in agreement with well-established biological principles.
通过测定四种成年鸡（两种白来航鸡和两种肉鸡，包括矮小型和正常型）在两种蛋白质水平日粮条件下的N-甲基组氨酸（NtMH）排泄量来评估蛋白质降解率。从三只白来航公鸡、三只矮小型公鸡和三只正常型肉鸡公鸡注射后7天内，回收了超过90%的标记NtMH。以NtMH输出量衡量的蛋白质降解与成年体重的关系为幂指数0.71，且品系截距显著不同。当评估每单位瘦肉的NtMH输出率时，品系差异消失。与饲喂150 g粗蛋白（CP）/kg的公鸡相比，饲喂100 g CP/kg低蛋白日粮的鸡每单位肌肉的NtMH输出率更高。得出的结论是，与蛋鸡品系相比，肉鸡在幼龄时较低的蛋白质降解率与成年体重增加有关，这与公认的生物学原理一致。
