Abstract
This study was conducted to investigate the effects of substitution of dietary fishmeal (FM) by compound plant protein supplemented with essential amino acids on growth performance, plasma physiology, and muscle growth-related genes of gibel carp (Carassius auratus gibelio). Four diets with equal digestible protein were prepared, where 30FM (control feed) contained 30% FM and land animal protein as a protein source, 10FM contained 10% FM, PMAa contained full plant meal (PM) supplemented with crystalline amino acid, and PM contained full PM feed. There was no significant difference in the specific growth rate (SGR) with 30FM, 10FM, and PMAa diets (p > 0.05); however, the SGR of PM group was the lowest with significant difference (p < 0.05). Feed efficiency of the PM group was the lowest with significant difference (p < 0.05). The whole-body crude protein content of fish in PMAa group was significantly higher than that in each group with additional FM (p < 0.05). There were no significant differences in plasma total cholesterol (TC), triglyceride (TG), high-density lipoprotein cholesterol (HDL-C) or low-density lipoprotein cholesterol (LDL-C), and free amino acid profile of 30FM, 10FM, and PMAa groups (p > 0.05); however, they were significantly higher than that in PM group (p < 0.05). The expression of key genes in the TOR signaling pathway (tor, s6k1, 4e-bp2, and eif4e), autophagy (ulk1 and atg13), and ubiquitin–proteasome (trim63 and znrf2) system of the PMAa group was similar to that of the FM group (p > 0.05), indicating that the muscle growth-related biomarker genes were positively regulated by the appropriate dietary amino acid composition at the transcriptional level. These results suggest that FM in gibel carp diet can be totally replaced by PM without negative impact on growth performance and muscle growth-related biomarkers at the transcriptional level, which provided the requirement of digestible protein and balanced amino acid profile is satisfied.
Highlights
Over the past decades, aquaculture has been growing rapidly (Verhoeven et al, 2016) and has been a large contributor of animal protein for humans
Studies shown that FM was still the most optimal protein source in the diet and leads to the best growth performance for omnivorous species, such as tilapia (Oreochromis niloticus, Ahmad et al, 2020; Ismail et al, 2020) and carp (Cyprinus carpio, Wang et al, 2020), even herbivorous species, such as grass carp (Ctenopharyngodon idella, Jiang et al, 2016)
Protein apparent digestibility coefficient of the ingredients of gibel carp was measured in our laboratory, previously, according to the method
Summary
Aquaculture has been growing rapidly (Verhoeven et al, 2016) and has been a large contributor of animal protein for humans. It has been confirmed that the content of dietary FM could be reduced using plant ingredients in many cultured species. The addition of FM is low in the commercial feed formulation for omnivorous species. Studies shown that FM was still the most optimal protein source in the diet and leads to the best growth performance for omnivorous species, such as tilapia (Oreochromis niloticus, Ahmad et al, 2020; Ismail et al, 2020) and carp (Cyprinus carpio, Wang et al, 2020), even herbivorous species, such as grass carp (Ctenopharyngodon idella, Jiang et al, 2016). Few reports are available to guide the total replacement of FM by plant ingredients in Cyprinidae species, which are widely cultured in China. There are several factors restricting the usage of plant materials in aquatic feeds, such as amino acid imbalances, antinutritional factors (Tibbetts et al, 2017), and low mineral and high cellulose content (Hansen et al, 2007)
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