Eficácia da suplementação de atrativos alimentares em dieta prática do camarão Litopenaeus vannamei

Abstract

This study evaluated the effects of dietary supplementation of krill meal (KRL), Euphausia superba, high in protein, and the giant squid meal (SQD), Dosidicus gigas, in practical diets over the growth performance, immune response, proximate body composition and feed preference of juvenile shrimp, Litopenaeus vannamei. A basal diet was formulated with 38.00% soybean meal, 7.00% poultry by-product meal, 3.00% fish meal and 2.41% wheat gluten. To act as a control (CTL), the basal diet was supplemented with 3.00% soy protein concentrate (SPC). Six other diets were supplemented with KRL and SQD at 1.00, 2.00 and 3.00% in combination with 2.00, 1.00 and 0.00% of SPC, respectively. To evaluate the growth performance, shrimp of 1.58 ± 0.18 g were stocked in 37 tanks of 0.5 m3 under 123 animals/m2

and farmed for 70 days. Shrimp immune response was carried out was determined by the total hemocyte count (THC) using a Neubauer camera and an optical microscope. Feed preference was determined through apparent feed intake when simultaneously delivering two different diets, for 21 days, in 44 rectangular tanks of 61 L with 11.24 ± 4.64 g (n = 440) shrimp. At harvest, shrimp survival, gain in yield, weekly growth, apparent feed intake and feed conversion ratio did not differ statistically with means (± standard deviation) of 96.37 ± 2.62%, 1,121 ± 84 g/m2

, 0.97 ± 0.07 g, 12.0 ± 0.4 g/shrimp and 1.42 ± 0.09, respectively. Supplementation of chemoattractants positively influenced shrimp final body weight compared to animals fed the CTL diet (10.82 ± 0.86 g). Shrimp fed SQD reached the highest body weight, followed by KRL. Dietary supplementation of 3.00% KRL or SQD resulted in a significant increase in shrimp body weight compared to 1.00 or 2.00%. The highest THC was observed in treatments fed 1.00% KRL (28.10 ± 14.50x106

cells/mL) or 1.00% SQD (28.21 ±

16.03 x 106

cells/mL) compared to the CTL group (22.43 ± 10.66 x 106

cells/mL; n = 15). On the other hand, the krill-containing diet had a higher feed preference than the CTL diet, at 1.00 and 3.00%, but the 1.00% SQ diet did not differ from the CTL, and at 2.00 and 3.00% were less preferred than the CTL. When analyzing diets supplemented with KRL alone, 1.0% was less effective than 2.0%, but both had an equal preference at 3.00%. On the other hand, 1.00% SQD supplementation resulted in a higher preference than at 2.00 and 3.00%. There was a higher feed preference with 3.00% KRL compared to 2.00 or 3.0% SQD. The supplementation of practical diets for juvenile Litopenaeus vannamei with squid meal and a high protein krill meal promote a higher shrimp body weight at 3.00%, a greater immune response at only 1.00 % and a higher feed preference at 1.00 and 3.00% dietary inclusion, respectively.