ABSTRACT Cost and environmental restrictions limit the use of fishmeal (FM) in aquafeeds and plant protein (PP) sources. Soybean by-products are important alternative; however, their antinutritional factors may reduce fish growth. This study evaluates the effect of FM substitution for PP (soybean meal and soy protein concentrate) in diets of dourado (Salminus brasiliensis), a promising species for fish farming and empirically considered highly tolerant to PP-based diets. A control diet was formulated to contain 20 % of fishmeal and 61 % of plant protein (SBM) and other five diets with decreasing FM graded levels (16 %, 12 %, 8 %, 4 %, 0 %), which were replaced by soybean protein concentrate (SPC), comprising six treatments and four replicates. Fifteen dourados (6.73 ± 0.2 g) were stocked into 200 L tanks in a recirculating system, fed with experimental diets three times a day to apparent satiation for 90 days. Growth performance, food conversion ratio, protein efficiency ratio and protein retention efficiency of fish were impaired when FM substitution exceeded 13.05 % (the broken line analysis method). Histological analysis of intestinal mucosa showed a decrease in villus height when fishmeal was totally replaced by PP, which probably impaired digestive functions of fish and reflected in a severe loss on growth performance.

Determinou-se o valor nutricional e avaliou-se o desempenho de leitões alimentados com rações contendo glicerinas semipurificadas de origem vegetal (GSPV) e mista (GSPM). Na digestibilidade foram utilizados 32 leitões, machos castrados, distribuídos em delineamento em blocos ao acaso. Foram estudadas duas glicerinas (GSPV e GSPM) e três níveis de inclusão na dieta-teste (4, 8 e 12%). A unidade experimental consistiu de um leitão. A energia metabolizável (EM) das glicerinas foi estimada pela análise de regressão do consumo de EM (kcal kg-1) associada à glicerina vs. o consumo de glicerina (kg). Os valores de EM (kcal kg-1), na matéria natural, obtidos foram 3.373 para GSPV e 2.932 para GSPM, indicando que as duas glicerinas são fontes de alta energia disponível para a alimentação de leitões. No desempenho, foram utilizados 90 leitões, distribuídos em blocos ao acaso, em esquema fatorial 2 x 4 + 1, sendo duas glicerinas, quatro níveis de inclusão (3, 6, 9 e 12%), cinco repetições e dois leitões por unidade experimental. Adicionalmente foi formulada uma ração-testemunha sem glicerina (0%). Não houve efeito do nível de inclusão de glicerina sobre o desempenho, sugerindo que é viável a utilização em até 12% de ambas as glicerinas na alimentação de leitões.

The nutritional value and the performance of piglets fed on diets with semipurified glycerin (SPGV) and mixed (SPGM) vegetable oil was determined and evaluated. Thirty-two crossbred piglets, allotted in a completely randomized block design, were used in the digestibility trial. Two types of glycerin (SPGV and SPGM) and three levels of diet (4, 8 and 12%) were studied. The experimental unit consisted of one piglet. Glycerins' metabolizable energy (ME) was estimated by regression of ME (kcal kg-1) intake associated with glycerin vs. glycerin intake (kg). ME as-feed-basis rates were 3,373 for SPGV and 2,932 for SPGM, or rather, the glycerins are highly available energy source for piglets. In the performance trial, 90 piglets were allotted in a completely randomized blocks design in a 2 x 4 + 1 factorial scheme, two glycerins, four levels (3, 6, 9 and 12%), five replicates (pens) and two piglets per pen. A control diet with no glycerin (0%) was additionally formulated. Since no effect of glycerin inclusion on pig performance occurred, it was feasible to use up to 12% of both types of glycerin on piglets feeding.