Aquaculture Reports (Jul 2020)
Effect of soybean antigenic protein on feed palatability of fishmeal replaced diets for obscure puffer (Takifugu fasciatus) and the alternation of diet preference by domestication
Abstract
Ingredient Y-maze choice test, feed intake test and rare earth elements trace test were conducted in obscure puffer (Takifugu fasciatus) to study whether soybean antigenic protein would affect diet palatability when fishmeal was partially replaced by soybean products. Another eight-week domestication trial was conducted to research the possible alternation of such diet preference. In Y-maze test, both aqueous and ethanol solutions of five ingredients (fishmeal, soybean meal, fermented soybean meal, casein, and antigenic protein) were used to study the ingredient preference. Four practical diets (FMH-diet with high fishmeal, FML-diet with low fishmeal, FMLF-diet with 18.56% fishmeal replaced by fermented soybean meal, FMLS-diet with 18.56% fishmeal replaced by soybean meal) and four semi-purified diets (AP0, AP5, AP8, AP12.5) containing corresponding levels of soybean antigenic protein) were all or partially used in feed intake test and rare earth elements trace test. The results showed that the ingredient preference differed with aqueous solutions and ethanol solutions. Feed intake ratio of FMLF was significantly higher than FMH and least in FMLS, AP0 was significantly higher than AP12.5 for undomesticated fish. In rare earth element trace test, before domestication, puffer showed higher preferences of FML than FMLF and FMH and least in FMLS; after 8-week-domestication, all groups showed higher preferences to FMLS than FML and FMLF, least in FMH. In semi-purified diet groups, before domestication, the preference decreased as dietary antigenic protein increase; after domestication, all groups showed higher preferences to AP8 and least in AP12.5. These indicated that undomesticated obscure puffer had higher preference to fermented soybean meal than soybean meal. Antigenic protein might be contributed to such preference, and domestication increased the preference of puffer to diet containing 8% soybean antigenic protein. Thus, domestication can be a potential method to improve the acceptance of puffer to diet with fishmeal replaced by soybean products.
