Title: Lysine supplementation of commercial fishmeal-free diet in hybrid striped bass affect growth expression genes Authors
|Gaylord, Gibson -|
Submitted to: Book of Abstracts Aquaculture America
Publication Type: Abstract Only
Publication Acceptance Date: January 15, 2014
Publication Date: N/A
Technical Abstract: Substitution of fishmeal with alternate proteins in aquafeeds often results in dietary imbalances of first-limiting essential amino acids (EAA) and poorer fish performance. Previously, we conducted a growth trial to test the hypothesis that ideal protein theory accurately predicts first-limiting amino acids and optimum lysine level for a fishmeal-free, commercial-grade diet formulated for hybrid striped bass (HSB). Results concluded that while lysine was not first limiting, appropriate levels (between 2.7 and 4.1 g/100g of diet) are needed for improved fish performance. Our goal in the present study was to elucidate how dietary lysine supplementation influences myogenesis, specifically the expression of two genes (myostatin or myogenin). In fish, myostatin has a role in inhibiting proliferation of myoblast cells, while myogenin is required for the differentiation of myoblasts and fusion of myogenic precursor cells to create new fibers or to existing fibers. Real time q-PCR results suggest that the levels of lysine added (basal 1.93, 1.78, 3.51, 5.10 g/100 g of diet) has an impact on myogenin and myostatin expression in HSB (Figure 1). The diet with the optimum or predicted level (3.51 g/100 g) of dietary lysine has the greatest amount of myogenin expression and overall less myostatin expression while maintaining acceptable protein accretion, hepatosomatic index (HSI), and muscle ratio. The 5.10 g/100 g of dietary lysine expression suggests this is the upper limit, as the amount of myogenin expression decreases, myostatin expression increases, and the ratio of myostatin/myogenin increases markedly (predicted muscle fiber development would be inhibited) which is both metabolically and financially wasteful for lean muscle growth.