Thesis (Ph.D., Animal and Veterinary Science) -- University of Idaho, 2016 | An in vivo experiment was conducted to determine the effects of dietary intake of purple corn extract (PCE) supplementation (5%), an ingredient rich in anthocyanins, on growth performance, plasma antioxidant status and n-3 PUFA levels in muscle and plasma of rainbow trout. Results suggest dietary intake of PCE may protect against lipid peroxidation by increasing the antioxidant capacity in plasma as well as by up-regulating the expression of the antioxidant enzyme gpx1 in erythrocytes in fish. A significantly lower total fat content in fish body implying reduced fat substrate prone to lipid peroxidation was observed. In agreement with this statement we detected a trend toward significantly lower levels of lipid-peroxidation marker (MDA) in plasma of fish fed the PCE supplemented diet. We observed no differences in n-3 PUFA levels in muscle, however, significantly higher levels of n-3 PUFA in plasma of fish fed the PCE supplemented diet were detected. In addition, an in vitro experiment was conducted to determine the effects of three doses (treatments A, B and C; 1x, 2.5x and 10x, respectively) of a mixture of three types of anthocyanidins (peonidin, cyanidin and pelargonidin chloride) on the expression of genes involved in myogenic program, the Notch signaling and antioxidant enzymes in primary myogenic cells from skeletal muscle of juvenile rainbow trout after 24 hours treatment. Anthocyanidins enhance gpx1 expression in myogenic cells, thereby boosting the skeletal muscle tissue antioxidant defense in fish. For its part, anthocyanidins appears to delay myogenic differentiation in myocytes by up-regulating the expression of pax7 and decreasing pax7/myoD ratio. This effect seems to be mediated by Notch signaling since we observed an up-regulation of two Notch signaling target genes (her6 and hey2), similarly to what has been observed in mammalian C2C12 myoblasts. A second in vitro experiment was conducted to determine the effects of same anthocyanidin mixture doses on myogenic program after 24 and 36 hours treatment in early-induced and non-induced myogenic cells from rainbow trout. The effect of anthocyanidins on myogenic program appears to differ between time of exposition to anthocyanidin doses in early-induced myogenic cells by boosting myogenic differentiation signaling after 24 hours treatment while pausing differentiation after 36 hours treatment. These findings demonstrate that anthocyanidins modulate myogenic program in fish myogenic primary cells, thereby potentially affecting somatic growth in fish fed plant-derived extracts rich in this type of polyphenols. Further research related to in vivo protection against lipid peroxidation and modulation of lipid metabolism related to decreasing adiposity in fish fed diets supplemented with additives rich in plant-derived biocompounds is warranted.