Aquaculture for all

Soy shown as suitable replacement for fishmeal in largemouth bass diets

Feed ingredients Freshwater fish

Fermented soybean meal (FSM) could be used to replace up to 30 percent of fishmeal used in diets for farmed largemouth bass diets.

So suggest the authors of a new study, who have published the results of an eight week investigation into the effects on growth performance, intestinal histology and microbiota of largemouth bass (Micropterus salmoides) when replacing fish meal with FSM and soybean meal (SM).

China is one of the largest producers of farmed largemouth bass

© Jim Tidwell

The researchers, from Shanghai Ocean University, compared the effects of a basal diet that contained 350 g/kg FM with those in which the FM was replaced with SM and FSM at the ratios of 30 percent and 60 percent (SM‐30, SM‐60, FSM‐30 and FSM‐60), respectively.

Groups of largemouth bass, which began the trial at an average of 4.43g, were fed the diets for eight weeks.

The results showed that weight gain of fish fed with FSM‐60 and SM‐60 diets was significantly lower, and feed conversion ratio of SM‐30, SM‐60 and FSM‐60 groups was significantly higher than the CON group (p < .05). The intestinal villus height of SM‐60 group and the villus width of SM‐60 and FSM‐60 group were significantly lower than the CON group (p < .05). The 30% FM replacement by SM and FSM significantly increased the abundance of Cetobacterium and Mycoplasma, respectively (p < .05).

The researchers conclude that fermented soybean meal could replace 30 percent of the fishmeal in standard largemouth bass diets without negative impacts on their growth performance, while the soybean meal should be controlled below 30 percent.

Further information

The study was published under the title “Effects of fish meal replaced by fermented soybean meal on growth performance, intestinal histology and microbiota of largemouth bass (Micropterus salmoides)” in Aquaculture Nutrition.