Dietary supplementation of astaxanthin krill oil enhances the growth performance of juvenile Litopenaeus vannamei raised intensively in enclosed and exposed tank systems under salinity stress

ABSTRACT

This work evaluated if dietary supplementation of astaxanthin krill oil with or without soybean oil to a grower shrimp feed enhances the growth performance of L. vannamei farmed under salinity stress. Shrimp of 1.08 ± 0.11 g body weight (BW) were reared for 74 days under 135 animals/m² in 50 1-m³outdoor tanks. Half of the tanks were operated enclosed by a milky-colored sheet and the remaining ones were fully exposed to sunlight and rain. Shrimp were fed a 38% crude protein feed top-coated with astaxanthin krill oil (K) and/or soybean oil (S) at ratios of 0K-3S, 1K-2S, 2K-1S, and 3K-0S% of the diet, as fed basis, respectively. In air-exposed tanks, mean salinity reached 31 ± 6 g/L compared to 36 ± 4 g/L in enclosed tanks. Shrimp survival was similarly high in both rearing systems (90.6 ± 3.8 and 89.2 ± 5.3% in air-exposed and enclosed tanks, respectively) and was unaffected by oil supplementation (P > .05). Shrimp raised in the air-exposed tanks achieved a significantly higher final BW, weekly growth, gained yield, apparent feed intake (AFI) and a lower FCR (feed conversion ratio) compared to animals in the enclosed tanks. As a result of top-coating feed for the air-exposed tanks with the 1K-2S oil mix, the highest shrimp final BW (14.03 ± 0.52 g) and yield (1,515 ± 40 g/m²) could be achieved when compared to the enclosed rearing system and all the other diets. Under longer exposure periods to hypersalinity in enclosed tanks, a minimum of 2K-1S was required to maximize BW (10.80 ± 0.63 g) when compared to the other enclosed diet groups.

KEYWORDS:

• Hypersalinity
• shrimp
• astaxanthin
• krill oil

Acknowledgments

The last author acknowledges the support from a research productivity fellowship (CNPq/MCT, PQ# 303678/2017-8).

Compliance with ethical standards

All applicable international, national, and/or institutional guidelines for the care and use of animals were followed by the authors.

Disclosure statement

The authors declare that they have no conflict of interest.