Graduate School of Science and Technology, Niigata University, Niigata 950-2181, Japan; National Agriculture and Food Research Organization for Institute of Livestock and Grassland Science, Ibaraki 305-0901, Japan.
Graduate School of Science and Technology, Niigata University, Niigata 950-2181, Japan.
Poult Sci. 2020 Jun;99(6):3102-3110. doi: 10.1016/j.psj.2019.11.025. Epub 2020 May 8.
Taste is crucial to meat quality, and free Glu is an important taste-active component in meat. Our recent study showed that the short-term feeding of a low-Lys diet increases the concentration of free Glu and other free amino acids in chicken muscle and improves its taste. Here, we investigated the mechanisms by which the feeding of a low-Lys diet increases free Glu in chicken muscle. Two groups (n = 10 per group) of 28-day-old female Ross strain broiler chickens were fed diets with a graded Lys content of 90% or 100% of the recommended Lys requirement (according to National Research Council [1994] guidelines) for 10 D. Free amino acid concentrations and the mRNA abundance of protein metabolism-related genes were measured in breast muscle, and breast muscle metabolome analysis was conducted. Free Glu in muscle was increased by 51.8% in the Lys 90% group compared with the Lys 100% group (P < 0.01). Free threonine, glutamine, glycine, valine, isoleucine, leucine, tyrosine, phenylalanine, histidine, and 3-methyl-histidine concentrations in breast muscle were also increased in the Lys 90% group (P < 0.05). Metabolome analysis also showed that free amino acids were increased in the Lys 90% group. The mRNA abundance of μ-calpain, caspase-3, and 20S proteasome C2 subunit were increased in the Lys 90% group (P < 0.05). Moreover, the free Glu concentration in muscle was correlated with mRNA abundance of μ-calpain (r = 0.74, P < 0.01), caspase 3 (r = 0.69, P < 0.01), 20S proteasome C2 subunit (r = 0.65, P < 0.01), and cathepsin B (r = 0.52, P < 0.05). Our study suggests that the feeding of a low-Lys diet to chickens increased the free Glu content of breast muscle by promoting protein degradation.
味道对肉质至关重要，游离谷氨酸（Glu）是肉质的重要呈味成分。我们最近的研究表明，短期饲喂低赖氨酸（Lys）日粮会增加鸡肉中游离 Glu 和其他游离氨基酸的浓度，从而改善其口感。在此，我们研究了低 Lys 日粮增加鸡肉中游离 Glu 的机制。将两组（每组 10 只）28 日龄雌性罗斯肉鸡分别饲喂赖氨酸含量为 90%或 100%推荐需要量（根据美国国家研究委员会 [1994] 指南）的日粮 10 d。测量胸肌中的游离氨基酸浓度和与蛋白质代谢相关基因的 mRNA 丰度，并进行胸肌代谢组学分析。与 Lys 100%组相比，Lys 90%组肌肉中的游离 Glu 增加了 51.8%（P < 0.01）。Lys 90%组胸肌中的游离苏氨酸、谷氨酰胺、甘氨酸、缬氨酸、异亮氨酸、亮氨酸、酪氨酸、苯丙氨酸、组氨酸和 3-甲基组氨酸浓度也增加（P < 0.05）。代谢组学分析还表明，Lys 90%组的游离氨基酸增加。Lys 90%组的 μ-钙蛋白酶、半胱天冬酶-3 和 20S 蛋白酶体 C2 亚基的 mRNA 丰度增加（P < 0.05）。此外，肌肉中的游离 Glu 浓度与 μ-钙蛋白酶（r = 0.74，P < 0.01）、半胱天冬酶-3（r = 0.69，P < 0.01）、20S 蛋白酶体 C2 亚基（r = 0.65，P < 0.01）和组织蛋白酶 B（r = 0.52，P < 0.05）的 mRNA 丰度呈正相关。本研究表明，饲喂低 Lys 日粮可通过促进蛋白质降解来增加鸡肉中游离 Glu 的含量。
