Effects of different dietary ratio lysine and arginine on growth, muscle fiber development and meat quality of Megalobrama amblycephala

Abstract

The purpose of this experiment was to explore the effects of different dietary lysine to arginine ratio (L:A) on the growth performance, muscle fiber development and muscle quality of Megalobrama amblycephala. 300 healthy M. amblycephala with an average initial weight of 41.49 ± 0.78 g were randomly divided into 5 groups with 4 replicates in each group. The 8-week breeding experiment was carried out with 5 levels of L:A (2.00, 1.50, 1.00, 0.67 and 0.50). The results showed that final body weight (FBW) and weight gain rate (WGR) increased significantly in the group with dietary L:A= 1.00 (P < 0.05) and 1.50. Feed conversion rate (FCR) increased significantly in the L:A= 0.50 group (P < 0.05), although there was no significant difference in feed intake (FI) between groups. Subsequent tests showed that the muscle resilience of experimental fish was improved significantly (P < 0.05) when the ratio of dietary lysine to arginine was 2.00. The cooking loss of L:A= 1.00 and 1.50 group increased significantly (P < 0.05) and obtained a higher MFI index in the meanwhile. The sarcomere length of the experimental fish showed a downward trend first and then rose (P < 0.05) with the gradual reduction of lysine in diets, and the minimum value appeared in the L:A= 1.00 group. In addition, when the ratio of lysine to arginine was 1.00, the mRNA expression of myod and mrf4 genes increased significantly (P < 0.05), ampkα2 was significantly lower than that of L:A= 2.00 group (P < 0.05). Camk and can, which are related to Ca2+-dependent signaling pathways, were not significantly affected by the ratio of lysine to arginine in diets. These results showed that when the ratio of lysine to arginine was 1.00, the growth performance, muscle tenderness and water-holding capacity of M. amblycephala were improved. In summary, different dietary lysine to arginine ratios has a significant impact on the growth performance and meat quality of M. amblycephala, and this effect on muscle fiber development and meat quality may be achieved through the AMPK/Sirt1 energy-sensing pathway.