Farelo de linhaça in natura e demucilada como fonte proteica na dieta de juvenis de jundiá (Rhamdia quelen)

Abstract

This study aimed to evaluate the performance profile, digestive enzymes and metabolic effects of silver catfishes (Rhamdia quelen) in response to the partial substitution of protein source for animal protein (PB) of linseed meal in nature (FL) and demucilaged (FLD). Two hundred and forty juvenile catfish (average initial weight of 14.49 ± 1.85 g and length averaging 11.74 ± 0.61 cm) were randomly assigned to 12 cases of propylene with a working volume of 280 liters (20 fish / box) in a water recirculation system for a period of 51 days supply. During the experimental period, the water quality parameters remained within the optimum for this species. The treatments were: control diet; 17% FL (17% replacement of animal PB by PB of FL); 17%FLD (17% replacement of animal PB by PB of FLD) and 35% FLD (35 % substitution of animal PB by PB of FLD), each treatment consisted of three repetitions. The animals were fed three times daily to apparent satiation. Every 28 days samples were collected to monitor the growth. During the experimental period, growth variables (weight, total and standard length, total biomass, daily weight gain, condition factor, specific growth rate, feed conversion) and parameters of carcass (carcass yield, digestivossomático index, hepatosomatic, quotient intestinal and deposition of protein and fat) were evaluated. In addition, we determined: chemical composition (moisture, ash, fat and protein) in whole fish, blood parameters (glucose, total triglycerides, total cholesterol and total protein) in liver tissue ( glycogen, glucose, protein, free amino acids, ammonia and lactate). Activities of enzymes acid protease, amylase, trypsin and quymotripsin were also measured. The fish fed the control diet had lower levels of feed conversion (p <0.05). However, the rest of the growth parameters were not altered by the inclusion of FL and FLD. Diet 35%FLD had lower QI, moisture content, higher content of carcass fat and total fat deposited and activity of the enzyme trypsin. The blood level of triglycerides, albumin and total protein did not differ among treatments, but higher cholesterol levels (178,72 ± 10,71) and plasma glucose (62,71 ± 5,16) were found in 35%FLD treatment. The liver parameters were not affected by treatments. The composition of linseed meal after the process of demucilagen concentrated PB content and decreases to half the content of soluble fiber. Therefore, it is suggested that the FLD and FL can be used to compose part of silver catfish feed as an alternative source and cost.