Inducing Subacute Enteritis in Yellowtail Kingfish Seriola lalandi: the Effect of Dietary Inclusion of Soybean Meal and Grape Seed Extract on Hindgut Morphology and Inflammation

In this 42-d trial, grape seed extract (GSE) was evaluated as a potential treatment for subacute enteritis in Yellowtail Kingfish Seriola lalandi induced by soybean meal (SBM) at winter water temperatures (12-15 degrees C). Four diets were investigated: a fish meal control diet (46% fish meal, 0% SBM), a SBM diet (30% SBM with 0 mg/kg GSE), and two 30% SBM diets containing either 20 mg/kg or 40 mg/kg GSE. Yellowtail Kingfish growth performance was significantly reduced when fed 30% SBM. Fish fed 30% SBM exhibited a significant enlargement of the lamina propria, a sign of subacute enteritis, and a significant decrease in myeloperoxidase (MPO) activity, compared with those fish fed the control diet. Dietary inclusions of GSE did not affect growth performance, intestinal morphology, or MPO activity. We recommend that SBM be excluded from Yellowtail Kingfish diets. We also recommend future studies investigate higher dietary GSE inclusions, other potential dietary additives, or more refined soy products, to alleviate subacute enteritis in Yellowtail Kingfish.