Evaluation of chicken liver meal as fish meal alternative in large yellow croaker Larimichthys crocea diet: Effects of growth performance, antioxidant capacity, intestinal health and microflora, and protein metabolism

An 8-week feeding trial was performed on Larimichthys crocea (initial body weight: 19.28 ± 1.85 g) to investigate the impact of replacing fish meal (FM) by chicken liver meal (CLM) on various aspects including growth performance, intestinal health and microflora, antioxidant capacity as well as protein metabolism. Five diets were formulated with different levels of FM replacement by CLM: 0 % (CLM0), 25 % (CLM25), 50 % (CLM50), 75 % (CLM75), and 100 % (CLM100). Results indicated that substituting 50 % of the dietary FM with CLM did not significantly affect growth performance and feed utilization. Analysis of intestinal structure revealed a considerable decrease in villus width (VW) and villus height (VH) in CLM75 and CLM100 groups. The CLM75 and CLM100 diets led to a significant decrease in the activity of amylase (AMS), lipase (LPS), catalase (CAT) as well as total antioxidant capacity (T-AOC) for liver of Larimichthys crocea, while remarkably increasing malondialdehyde (MDA) content. 16S rRNA sequencing revealed that CLM75 and CLM100 diets resulted in increased relative abundances of Proteobacteria phylum and decreased relative abundances of Firmicutes phylum. Moreover, immunoblotting analysis demonstrated that CLM75 and CLM100 diets also caused a significant decrease in the phosphorylation level of 4E-binding protein 1 (4E-BP1) in muscle of Larimichthys crocea. Based on these findings, without negatively altering Larimichthys crocea growth and gut health, CLM can substitute up to 50 % dietary FM.