Produção e caracterização de silagem de vísceras de peixe como ingrediente em rações para tambaqui

Abstract

Aquaculture is on the rise, and the demand for aquaculture products is expected to increase over the coming decades. Along with the increase in fish farming, there is the generation of a large volume of fish waste. Fish waste present a high biological value, and can be processed into new products, with potential for use in aquafeed and petfood. The main aim of this thesis was to use tambaqui viscera in the silage production as a new feed ingredient that adds value to its production chain. In chapter I, a literature review was carried out on the world panorama of fishery and aquaculture production, we presented a contextualization of the use of fish waste in silage form and its applications as an ingredient in animal feed. In chapter II, the aim was to produce acidic and fermented silages from fish viscera to determine its nutritional value and the apparent digestibility coefficient of nutrients and energy for juvenile tambaqui Colossoma macropomum. The silages presented an average of 55% of dry matter, 62.9% of lipids and 12% of crude protein. Leucine and lysine predominated as essential amino acids. Fish viscera silages showed levels between 5.4 to 17.8 mg of eicosapentaenoic acid per gram of lipids and 1.7 to 8.9 mg of docosahexaenoic acid per gram of lipids. The apparent digestibility coefficient (ADC) was highest than 82% for gross energy for all silage formulations. The ADCs for protein were similar among fermented silages, with a maximum level of 92% for wheat middlings silage. The bioconversion of fish viscera into silage makes it an energetic ingredient for aquafeeds, which is well digested by tambaqui juveniles. The fermented silage of viscera with molasses was chosen to evaluate the growth performance of tambaqui because it has physical characteristics (pasty) that facilitate its inclusion in mixtures of omnivorous fish diets, prior to extrusion. Chapter III evaluated the inclusion of different levels of silage fermented of tambaqui viscera with molasses (VS) in diets for juvenile tambaqui. Pellets with higher silage inclusions showed lower expansion and buoyancy rates. The fish presented similar growth between the experimental groups, reaching 500% in relation to the final weight. The average apparent feed conversion was 1.43, the protein efficiency rate was 2.28% and a relative growth rate was 1.79%/day. Fish fed with 20% SV showed an increase in plasmatic cholesterol level, however within the range suitable for healthy tambaqui. The inclusion of viscera silage in diets for tambaqui juveniles reduced the activity of the alanine aminotransferase enzyme, confirming its normal liver function. The experimental diets presented production costs ranging from R$ 4.65 to R$ 4.68, however the difference did not influence the economic efficiency indicators. It is possible to include 20% of viscera silage fermented with molasses in tambaqui juvenile diets without impairing their growth and health.