Alternative substitutes to fishmeal in aquafeeds should be investigated, with a focus on feeding carnivorous species. Fermented fish silage meal produced by processing waste of the main aquaculture species farmed in the Amazon could constitute a palliative alternative with a circular economy approach. The present research aimed to characterize the proximate composition and amino acid content of a fermented fish silage meal produced by processing waste of pirarucu, tambaqui and pirapitinga, as a potential ingredient for the formulation of aquafeeds.
Fermented fish silage (FFS) was produced with waste from the primary processing of Amazonian fishes from aquaculture [a mixture composed of pirarucu (30%), tambaqui (56%) and pirapitinga (14%)] collected at an aquaculture center in the city of Pucallpa, Ucayali, Peru. The ingredients chosen for the preparation of the silage correspond to local experiences. Fish waste (70%) was ground in a meat grinder and natural yogurt was added (15%) as a source of microorganisms for the production of lactic acid, ground papaya (3.75%) and ground pineapple (3.75%) were used as the source of the proteolytic enzyme papain, and molasses (7.50%) were used as the main source of carbohydrates. All ingredients were well mixed to ensure adequate acidification and protein hydrolysis of the silage. The silage was produced in a plastic container and then hermetically sealed to guarantee anaerobic fermentation for nine days. The fermentation period was determined as nine days in order to guarantee the hydrolysis of more than 70% of the silage proteins without affecting the protein quality. Finally, the temperature and pH of the silage (Portable pHmeter, PH-013) were registered. To produce FFS meal, a traditional drying process was carried out at 135°C for 9 days in an oven. After this time, it was taken to a grinder to obtain a fine, nutritious powder. Samples (n=3) of the FFS meal were taken in order to analyze the proximate composition and the amino acid content.
The initial temperature and pH recorded for the silage were 29.10 °C and 6.70, respectively. At the end of the fermentation period, a temperature of 28.30 °C was recorded, while the pH was 4.21. The FFS meal presented the following characteristics of proximate composition: dry matter (84.94%), ash (7.71%), crude protein (22.66%), lipids (11.97%), carbohydrates (57.66%). The FFS meal presented the following characteristics of amino acid content (% of the protein): 6.60, Arg; 1.90, His; 2.60, Ile; 2.30, Leu; 3.90, Lys; 1.30, Met; 4.10, Phe; 2.30, Thr; 0.40, Trp; 2.30, Val.
The FFS meal could be an interesting palliative ingredient for aquafeeds, as an energy source. Due to the use of available and inexpensive raw materials and artisanal processing, the FFS meal is an ingredient that can generate positive impacts in reducing feeding costs in aquaculture.