Replacement of Fishmeal by Fermented Animal Protein Blend in the Feed of Mystus vittatus: Analysis of Optimality By Programming and Modeling

Optimum replacement of fishmeal (FM) is a challenge for scientists to develop low-cost feed for fish. In this study five experimental feeds were formulated by replacing 0 (control), 25, 50, 75 and 100% of FM by fermented animal protein blend (FAPB). Fingerlings of Mystus vittatus (average wt. 3.27 g) reared on these feeds for 12 weeks showed a significant reduction in growth and deposition of nutrients and amino acids in muscles in 100% replacement level, but exhibited an anomalous pattern of these parameters in other replacement levels. Multi-Objective Programming based on four growth parameters (weight gain, specific growth rate, feed conversion ratio, and protein efficiency ratio) produced optimum fishmeal replacement level (OFRL) as 38.43%, while it changed to 39.67% based on the growth parameters and crude protein (CP) and 51.22% based on the growth parameters, CP and crude lipid together. OFRL for maximum deposition of essential and non-essential amino acids (EAA & NAA) was found 31.54% and 51.32% respectively. Applying structural equation modeling we found that the histidine, lysine (EAA), aspartic acid and glycine (NAA) would produce negative effects on weight gain when FAPB was used as a FM replacer. While histidine was deficient, lysine, aspartic acid and glycine deposited in excess in muscle. It is concluded from this study that FM replacement level by FAPB in the diet of M. vittatus needs to be determined by considering the influence of CP, EAA and NAA to avoid excessive deposition of some amino acids and to obtain a compromise FM based on decision-makers goal.