Feasibility of Partial Replacement of Fishmeal with Proteins from Different Sources in Diets of Korean Rockfish(Sebastes schlegeli)

An 8-week feeding experiment was conducted in an indoor recirculation seawater system to investigate the effects of partial replacement of dietary fishmeal with proteins from five sources on the growth performance and feed utilization of Sebastes schlegeli. Six isonitrogenous and isoenergetic diets were formulated using fishmeal(FM, the control) as sole protein source, or proteins from five sources including poultry by-product meal(PBM), meat and bone meal(MBM), soybean meal(SBM), cottonseed meal(CSM) and canola meal(CNM). Fifteen percent of the crude protein provided by fish meal was replaced, respectively. The results showed that the differences in specific growth rate(SGR) and survival rate(SR) among fish fed PBM, MBM, SBM, CSM and whole FM diets were not significant. However, SGR and SR of fish fed CNM diet was significantly lower than that of other treatments. Feeding rate, feed conversion, nutrient retention showed similar patterns to that of growth. Fish fed CSM and CNM showed significantly lower apparent digestibility coefficient(ADC) of dry matter and gross energy than those fed others while fish fed CNM showed lower ADC of crude protein than those fed others(P<0.05). These results suggested that it was feasible to substitute 15% dietary protein provided by fishmeal with PBM, MBM, SBM and CSM, respectively, but not with CNM as the replacement with CNM reduced fish growth and feed utilization.

Partial replacement of soybean meal by yellow mealworm(Tenebrio molitor)meal influences the flesh quality of Nile tilapia(Oreochromis niloticus)

This study investigated the effects of yellow mealworm meal(YM)replacing soybean meal(SBM)at different proportions(0%,15%,30%and 45%,referred as YM0,YM15,YM30 and YM45,respectively)on the flesh quality of Nile tilapia.A total of 360 fish(70.0±0.12 g)were randomly divided into 4 groups(3 tanks per group).Fish were fed the experimental diet twice daily for 10 wk.The results showed that muscle protein content significantly decreased in YM30 and YM45,while the lipid content significantly decreased in YM45(P<0.05).The essential amino acids and flavor amino acids of the muscle were not affected by the YM substitution,while saturated fatty acid content decreased in YM30 and YM45 compared with YM0(P<0.05).Fillets in YM45 had higher hardness,gumminess,and a higher proportion of thin myofibers(≤100μm,P<0.05)than those in other groups.Further analysis revealed that apoptosis and atrophy related genes were up-regulated,while the muscle antioxidant capacity decreased significantly in YM45(P<0.05),which may be related to the high acid value in YM45 diet.Our findings indicated that YM could replace up to 30%SBM without substantially altering the flesh quality.When the replacement ratio increased to 45%,the flesh quality would change.Special attention should be paid to avoid feed rancidity which may affect the flesh quality of fish.