| Exp 1 Comparison of flesh quality of large yellow croaker(Pseudosciaena crocea) cultured in different modesThe present study was conducted to compare the flesh quality of large yellow croaker(Pseudosciaena crocea) cultured in different modes in Ning De, Fujian which was traditional cage culture with feeding trash fish(TF), traditional cage culture with feeding formula feed(FF) and deep-water cage(DWC). The physical indicators, skin color, electroconductivity, p H, water loss ratio, trimethylamine, inosinic acid, amino acid, fatty acid, collagen and muscle composition of the three groups were measured. The result showed that the a* and b* of ventral skin, the contents of crude protein, crude lipid, inosinic acid, total unsaturated fatty acids and total fatty acid of flesh showed no significant differences between FF and DWC(P>0.05), and both of the two groups had significantly higher values than those of TF group(P<0.05). The content of total essential amino acids and total amino acids in muscle of DWC were significantly higher than that of TF(P<0.05), and the two values of FF showed no significant difference when compared to the other two groups(P>0.05). DWC and FF groups had higher contents of inosine acid(IMP) and collagen, and lower drip loss at 2h, 4h than TF group(P<0.05). FF group had higher levels of delecious amino acids and free amino acids in flesh than DWC and TF groups, but the frozen seepage loss of FF group was significantly lower than that of the other two groups(P<0.05). The above results showed that the flesh quality of large yellow croaker fed formula feed is similar to that of fish cultured in deep-water cage, and both have better flesh quality than that of fish fed trash fish.Exp 2 Replacement of Fish Meal with Peanut Meal and Fermented Peanut Meal in Diets for Tilapia(Oreochramis miloticas × O.aureus)The present study was conducted to investigate the influences of replacing fish meal by peanut meal and fermented peanut meal in diets on the growth performance, muscle composition(including amino acids composition) and protease activity of tilapia(Oreochromis niloticus × O.aureus). Seven isonitrogenous diets were designed as control diet containing 6% fish meal, fish meal substituted diets with 1/3, 2/3, 3/3 fish meal replaced by peanut meal and fermented peanut meal, respectively, and fed to tilapia with body weight of(68.0 ±0.4)g for 8 weeks. The result showed that the replacement of 1/3 fish meal by peanut meal, or 2/3 fish meal by fermented fish meal did not significantly affect the weight gain(WG) and feed conversion ratio(FCR)(P>0.05). The contents of muscle moisture, crude protein, crude fat, crude ash and the amount of muscle essential amino acid, non-essential amino acid showed no significant difference among groups(P>0.05). The gastric protease activity of fish fed diet with 2/3 fish meal replaced by peanut meal was significantly lower than that of control fish(P<0.05), but the replacement of fish meal by fermented peanut meal did not significantly affect the gastric protease activity(P>0.05).The intestinal protease activity showed no significant difference among groups(P>0.05).In conclusion, peanut meal can replace 1/3 fish meal, and fermented peanut meal can replace 2/3 fish meal in tilapia diet with a inclusion of 6% fish meal.Exp 3 Effects of dietary geniposidic acid on the growth, serum biochemical indices and flesh quality of tilapia(Oreochromis niloticus × O.aureus)The present study was conducted to investigate the influences of adding geniposidic acid in diets on the growth performance, serum biochemical indices and flesh quality of tilapia(Oreochromis niloticus × O.aureus). Seven isonitrogenous diets were designed as control diet without the addition of geniposidic acid(0mg/kg) or with the addition of geniposidic acid at levels of 50mg/kg, 100mg/k, 200mg/kg, 400mg/kg and 600mg/kg, respectively, and then fed to tilapia with body weight of(15.0±0.1)g for 60 days.The result showed that the weight gain(WG) of each group was 765.9%,747.4%,753.4%,763.7%,737.8%, 754.8%, and feed coefficient ratio(FCR) was 1.20,1.23,1.22,1.20,1.22 and 1.21, respectively. The WG and FCR showed no significant difference among groups(P>0.05).The serum SOD, ALP, AST and ALT activities, and the moisture, crude protein, crude lipid, ash, collagen and water loss ratio of flesh showed no significant difference among groups(P>0.05). It is concluded that the geniposidic acid cannot improve the growth performance, serum biochemicalindices and flesh quality of tilapia. |
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