category: feed additives
authors: yirong le,yuping sun, jesús matas, sofia morais, mingzheng jiang, tiejun huang
book/journal:conference: international symposium on fish nutrition and feeding (isfnf2018), las palmas de gran canaria, spain
a feeding trial was conducted to test the application of a functional palatability enhancer (fpe) containing umami compounds in improving the feed palatability and performance of snakehead fish fed low-fishmeal diets. seven isonitrogenous (43% crude protein) and isolipidic (7% total lipid) test diets were formulated, where diet 1 was a high-fishmeal diet (positive control - pc) containing 25% fishmeal, and diets 2 to 7 were prepared by replacing 10% fishmeal contents with soybean protein concentrate, and supplementing with 0 (negative control – nc), 0.05, 0.08, 0.11, 0.14 or 0.2% of the umami fpe. triplicate groups of fish (average initial weight 93.5 ± 0.01 g) were randomly stocked in twenty-one 300-l tanks at a stocking density of 30 fish per tank. the fish were fed to satiation by hand twice daily, 7 days per week, for a period of 56 days. results showed that weight gain (%) and specific growth rate (sgr) of fish were significantly reduced in fish fed the low-fishmeal diet (nc), and increased in a dose-responsive manner with the supplementation of the fpe, being significantly higher than the nc and non-significantly different from the pc at the 0.2% inclusion level. the improved growth was mostly attributable to an enhanced feed intake, which was significantly reduced in the nc but recovered to levels identical to the high fishmeal pc when the fpe was added to the diet at 0.14 and 0.2%. feed conversion ratio (fcr) was not significantly different between treatments but results showed a trend for a reduced feeding efficiency (increased fcr) when dietary fishmeal level was reduced, while the supplementation with 0.2% fpe reduced the fcr to the same level as the pc. survival rate was high and not influenced by the dietary treatments. therefore, based on the overall performance of fish in this study, it can be concluded that functional palatability enhancers containing umami compounds can act as attractants in low-fishmeal diets, and supplementation with this type of products can be an effective strategy for reducing the inclusion levels of marine-based ingredients in fish diets, while maintaining normal feeding behavior and growth in juvenile snakehead fish.