Effects of dietary collagen cofactors and hydroxyproline on the growth performance, textural properties and collagen deposition in swim bladder of Nibea coibor based on orthogonal array analysis

Abstract

The global demand for collagen is continuously growing over years. Nutritional regulation of quality and collagen deposition in the swim bladder, an ideal collagen source of marine product, is a promising method for improving the economic value of fish. In this study, to enhance growth efficiency and collagen deposition in swim bladder of an important economic marine fish, the chu’s croaker (Nibea coibor), a L9(34) orthogonal array was designed with three levels for each factor, which are hydroxyproline (Hyp) and the key cofactors for proline hydroxylation during collagen post-translation modification, such as A1-A3 (Hyp): 0, 10 and 20 g/kg; B1-B3 (vitamin C, VC): 0, 0.20 and 0.40 g/kg; C1-C3 (Fe2+): 0, 0.20 and 0.40 g/kg; D1-D3 (α-ketoglutarate, AKG): 0, 10 and 20 g/kg, to formulate the trial feeds. An 8-week feed trial was carried out on 405 fish (initial weight 269.04 ± 3.18 g) which were randomly distributed into the nine treatment groups with three replicates of 15 fish per cage. Results indicated that appropriate increase of dietary Hyp and VC level is more beneficial to collagen deposition and textural properties in swim bladder, while Hyp and AKG exerted more significant effects on the growth performance. Gene expression analysis of collagen metabolism indicated that Hyp mainly improved the synthesis of type I collagen and inhibited collagen degradation, while VC and AKG mainly play an important role in hydroxylation of proline residues on collagen. The best combination for growth performance and collagen deposition in swim bladder were suggested to be A2B2C1D3 and A2B2C1D1, respectively. The results demonstrated that appropriate dietary supplementation of Hyp and cofactors can improve growth and collagen production of swim bladder. Our result would provide reference data for nutritional regulation of the species and optimization of the commercial feed to provide fish products with high quality.