White muscle proteome analysis showing insights into the protein expression in orange-spotted grouper (Epinephelus coioides) muscle

Replacing the fishmeal in fish feed with alternatives that have lower protein has become desirable to reduce production costs in aquaculture enterprises. Two diets were fed to orange-spotted grouper (Epinephelus coioides) to analyze the effects on the blood biochemical parameters and white muscle proteome. A low protein diet (LP diet) replaced 30% fishmeal proteins with carbohydrates while a plant protein diet (PP diet) replaced 60% of the fishmeal proteins with plant-base proteins (type of plants, e.g., wheat, corn, soy). Results showed that the LP diet significantly down-regulates the expression of creatine kinase and muscle structural proteins such as alpha myosin heavy chain, tropomyosin and actin. Fish fed with the LP diet also showed impaired weight gain and lower feeding efficiency. These results suggested the negative effects of a LP diet on fish growth and metabolism. On the other hand, the PP diet showed significant up-regulation of tropomyosin and similar expression of other muscle structural proteins compared to the control group. Over expressions of soluble adenylyl cyclase and a chromosomal SCAF7390 were also observed in the PP diet fish, indicating the positive effects of the PP diet on pH homeostasis and protein divergence. These results have shown that the proteomic changes induced by plant - based protein diets are similar to the fishmeal diet, indicating PP may be a potential partial replacement of fishmeal protein in fish feed.