Objective

: To evaluate the addition of sulfuric (98 %) and formic acids on the silage of fishery byproducts and its effect on productive and economic indicators of Clarias gariepinus.

Materials and Methods

: Two hundred seventy fingerlings, of 10,4 ± 0,06 g of average weight, were used, distributed in a complete randomized design with three treatments and three repetitions. The treatments were: concentrate feed for catfish fattening (control), fish silage prepared with sulfuric acid (98 %) and silage elaborated with formic acid. All the animals were individually weighed for calculating the indicators final average weight, feed conversion, protein efficiency and survival. In addition, the costs of the diets were calculated from the international prices of the raw materials. Simple classification variance analysis was carried out through the statistical package INFOSTAT.

Results

: No statistical differences were found in final weight (66,3 and 70,7 g), feed conversion (1,18 and 1,15) and protein efficiency (3,09 and 3,18) between the diets with fish silage. These values were higher (p < 0,05) than the ones reached with the control (final weight of 56,4 g; feed conversion of 1,5 and protein efficiency of 2,3). The survival was high in all the treatments (94,4; 100 and 96,7 %). The economic analysis showed that the highest profits were obtained with the silages ($ 2 618,8 and 2 428,5 US/t) compared with the control ($ 2 061,15 US /t).

Conclusion

: The utilization of silages from fishery byproducts in extruded diets, elaborated with sulfuric (98 %) and formic acids, improved the productive indicators of C. gariepinus, with a positive economic effect by decreasing the import of fish meal.

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