A comparative study of dietary amino acid patterns: unveiling growth, composition, and molecular signatures in juvenile Onychostoma macrolepis

The wild Onychostoma macrolepis, a species under national class II protection in China, lacks a specific compound feed for captive rearing. Understanding the dietary amino acid pattern is crucial for optimal feed formulation. This study aimed to investigate the effects of the four different dietary amino acid patterns, i.e., anchovy fishmeal protein (FMP, control group) and muscle protein (MP), whole-body protein (WBP), fish egg protein (FEP) of juvenile Onychostoma macrolepis, on the growth performance, body composition, intestinal morphology, enzyme activities, and the expression levels of gh, igf, mtor genes in juveniles. In a 12-week feeding trial with 240 juveniles (3.46±0.04g), the MP group demonstrated superior outcomes in growth performance (FBW, WGR, SGR), feed utilization efficiency (PER, PRE, FCR). Notably, it exhibited higher crude protein content in whole-body fish, enhanced amino acid composition in the liver, and favorable fatty acid health indices (AI, TI, h/H) in muscle compared to other groups (P < 0.05). Morphologically, the MP and FMP groups exhibited healthy features. Additionally, the MP group displayed significantly higher activities of TPS, ALP, and SOD, along with elevated expression levels of gh, igf, mtor genes, distinguishing it from the other groups (P < 0.05). This study illustrated that the amino acid pattern of MP emerged as a suitable dietary amino acid pattern for juvenile Onychostoma macrolepis. Furthermore, the findings provide valuable insights for formulating effective feeds in conserving and sustainably farming protected species, enhancing the research's broader ecological and aquacultural significance.