日粮蛋白质水平通过作用于亚成年草鱼（Ctenopharyngodon idella）的肌纤维生长和胶原蛋白代谢来改变肌肉硬度。

Dietary protein levels changed the hardness of muscle by acting on muscle fiber growth and the metabolism of collagen in sub-adult grass carp (Ctenopharyngodon idella).

作者信息

Dong Min, Zhang Lu, Wu Pei, Feng Lin, Jiang Weidan, Liu Yang, Kuang Shengyao, Li Shuwei, Mi Haifeng, Tang Ling, Zhou Xiaoqiu

机构信息

Animal Nutrition Institute, Sichuan Agricultural University, Chengdu, 611130, China.

Fish Nutrition and Safety Production University Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu, 611130, China.

出版信息

J Anim Sci Biotechnol. 2022 Aug 25;13(1):109. doi: 10.1186/s40104-022-00747-7.

DOI:10.1186/s40104-022-00747-7

PMID:36002862

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC9404606/

Abstract

BACKGROUND

Nutrient regulation has been proven to be an effective way to improve the flesh quality in fish. As a necessary nutrient for fish growth, protein accounts for the highest proportion in the fish diet and is expensive. Although our team found that the effect of protein on the muscle hardness of grass carp was probably related to an increased collagen content, the mechanism for this effect has not been deeply explored. Moreover, few studies have explored the protein requirements of sub-adult grass crap (Ctenopharyngodon idella). Therefore, the effects of different dietary protein levels on the growth performance, nutritional value, muscle hardness, muscle fiber growth, collagen metabolism and related molecule expression in grass carp were investigated.

METHODS

A total of 450 healthy grass carp (721.16 ± 1.98 g) were selected and assigned randomly to six experimental groups with three replicates each (n = 25/replicate), and were fed six diets with 15.91%, 19.39%, 22.10%, 25.59%, 28.53% and 31.42% protein for 60 d.

RESULTS

Appropriate levels of dietary protein increased the feed intake, percentage weight gain, specific growth rate, body composition, unsaturated fatty acid content in muscle, partial free amino acid content in muscle, and muscle hardness of grass carp. These protein levels also increased the muscle fiber density, the frequency of new muscle fibers, the contents of collagen and IGF-1, and the enzyme activities of prolyl 4-hydroxylases and lysyloxidase, and decreased the activity of matrix metalloproteinase-2. At the molecular level, the optimal dietary protein increased collagen type I α1 (Colα1), Colα2, PI3K, Akt, S6K1, La ribonucleoprotein domain family member 6a (LARP6a), TGF-β1, Smad2, Smad4, Smad3, tissue inhibitor of metalloproteinase-2, MyoD, Myf5, MyoG and MyHC relative mRNA levels. The levels of the myostatin-1 and myostatin-2 genes were downregulated, and the protein expression levels of p-Smad2, Smad2, Smad4, p-Akt, Akt, LARP6 and Smad3 were increased.

CONCLUSIONS

The appropriate levels of dietary protein promoted the growth of sub-adult grass carp and improved muscle hardness by promoting the growth of muscle fibers, improving collagen synthesis and depressing collagen degradation. In addition, the dietary protein requirements of sub-adult grass carp were 26.21% and 24.85% according to the quadratic regression analysis of growth performance (SGR) and the muscle hardness (collagen content), respectively.

摘要

背景

营养调控已被证明是改善鱼类肉质的有效方法。蛋白质作为鱼类生长必需的营养物质，在鱼类日粮中所占比例最高且成本昂贵。尽管我们的研究团队发现蛋白质对草鱼肌肉硬度的影响可能与胶原蛋白含量增加有关，但这种影响的机制尚未深入探究。此外，很少有研究探讨亚成年草鱼（Ctenopharyngodon idella）的蛋白质需求。因此，本研究调查了不同日粮蛋白质水平对草鱼生长性能、营养价值、肌肉硬度、肌纤维生长、胶原蛋白代谢及相关分子表达的影响。

方法

选取450尾健康草鱼（721.16 ± 1.98 g），随机分为6个实验组，每组3个重复（n = 25/重复），分别投喂蛋白质含量为15.91%、19.39%、22.10%、25.59%、28.53%和31.42%的6种日粮，为期60天。

结果

适宜水平的日粮蛋白质增加了草鱼的采食量、增重百分比、特定生长率、鱼体组成、肌肉中不饱和脂肪酸含量、肌肉中部分游离氨基酸含量以及肌肉硬度。这些蛋白质水平还提高了肌纤维密度、新肌纤维出现频率、胶原蛋白和IGF-1含量、脯氨酰4-羟化酶和赖氨氧化酶的酶活性，并降低了基质金属蛋白酶-2的活性。在分子水平上，适宜的日粮蛋白质提高了I型胶原蛋白α1（Colα1）、Colα2、PI3K、Akt、S6K1、La核糖核蛋白结构域家族成员6a（LARP6a）、TGF-β1、Smad2、Smad4、Smad3、金属蛋白酶组织抑制剂-2、MyoD、Myf5、MyoG和MyHC的相对mRNA水平。肌肉生长抑制素-1和肌肉生长抑制素-2基因的水平下调，p-Smad2、Smad2、Smad4、p-Akt、Akt、LARP6和Smad3的蛋白表达水平升高。