This study aimed to evaluate the effects of dietary guanidine acetic acid (GAA) supplementation on growth performance, carcass traits and the expression of muscle growth‐related genes in finishing pigs. A total of 128 (81.03 ± 1.09 kg body weight) crossbred pigs (Duroc × Landrace ×Yorkshire) were blocked by body weight and allotted to 16 pens (eight pigs per pen), and pens were randomly assigned within blocks to one of five dietary treatments, with a basal diet (control group) or a basal diet supplemented with 0.03%, 0.06% and 0.09% GAA respectively. During the 60‐day trial, GAA increased the average dairy gain (ADG) and average daily feed intake (ADFI) (p < .05). The back fat thickness of pigs fed 0.06% GAA was lower than other groups (p < .05). Pigs fed 0.06% GAA had improved lean meat percentage, loin muscle area, shear force and cross‐sectional area of muscle fibre in comparison with control group (p < .05). The drop loss and the muscle fibre density in pigs fed 0.06% GAA were lower than control (p < .05). In addition, dietary GAA enhanced the expression of myosin heavy chain gene (MYH4), myogenic determination (Myod) and myogenic factor 5 (Myf5) in longissimus dorsi and carnitine palmitoyltransferase‐1(CPT‐1) in liver (p < .05). Meanwhile, GAA decreased the expression of Myostatin in longissimus dorsi and fatty acid synthase (FAS) in liver (p < .05). In conclusion, our results showed that appropriate dietary GAA supplementation (0.06%) promotes skeletal muscle development through changing myogenic gene expression and myofibre characteristics.

中文翻译：

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日粮胍基乙酸通过改变生肌基因表达和肌纤维特性改善育肥猪的生长性能和骨骼肌发育

本研究旨在评估日粮中添加胍乙酸 (GAA) 对育肥猪生长性能、胴体性状和肌肉生长相关基因表达的影响。将总共​​ 128 头（ 81.03 ± 1.09 kg 体重）杂交猪（Duroc × Landrace ×Yorkshire）按体重分组并分配到 16 个围栏（每围栏 8 头猪），围栏内随机分配到五个日粮中的一个治疗，基础饮食（对照组）或基础饮食分别补充 0.03%、0.06% 和 0.09% GAA。在 60 天的试验中，GAA 增加了平均乳增重 (ADG) 和平均每日采食量 (ADFI) ( p  < .05)。饲喂0.06% GAA的猪背膘厚度低于其他组（p < .05）。与对照组相比，饲喂 0.06% GAA 的猪的瘦肉百分比、腰肌面积、剪切力和肌肉纤维横截面积均有所改善 ( p  < .05)。饲喂 0.06% GAA 的猪的下降损失和肌肉纤维密度低于对照 ( p  < .05)。此外，膳食 GAA 增强了背最长肌中肌球蛋白重链基因 (MYH4)、肌源性测定 (Myod) 和肌源性因子 5 (Myf5) 以及肝脏中肉碱棕榈酰转移酶-1(CPT-1) 的表达 ( p  < .05) . 同时，GAA降低背最长肌Myostatin和肝脏脂肪酸合成酶（FAS）的表达（p < .05）。总之，我们的结果表明，适当的膳食 GAA 补充剂 (0.06%) 通过改变生肌基因表达和肌纤维特征促进骨骼肌发育。