Two shrimp genetic lines (LGR: faster growth and LWR: higher white spot syndrome virus resistance) were evaluated with six dietary treatments containing different sources (animal and plant), and three protein levels (low, medium and high). A five-week bioassay was conducted using Litopenaeus vannamei with an average initial weight of 2.08 ± 0.06 g to determine the influence of the genetic line, protein source, and protein level on the weight gained per week, survival, and expression of immune-related genes. The overall mean of weight gain was 1.02 g/week for LGR and 0.71 g/week for LWR. Survival was 71.7% for LGR and 78.9% for LWR. The genetic line influenced weekly weight gain and survival while a significant interaction between genetic line, protein source, and protein level, influenced the expression of immune-related genes of shrimp. The data suggested that a diet containing plant-based protein (30-35%) at medium level was sufficient to obtain adequate values of weekly weight gain and survival without affecting
Shrimp farming is supported by fast-growth and high-resistance genotypes. Protein requirement is important for shrimp perfomance. Fishmeal is the main source, but their limited production increase feed formulation costs for aquaculture. This study evaluated the effect of genotype and protein source on performance of two shrimp genotypes. Shrimps with fast-growth (FG) and high-resistance (HR) were randomly assigned to two dietary treatments (animal and vegetal protein) in a 2 Â 2 factorial design. A 36-day bioassay was realised in clear-water hyper-intensive system to compare FG and HR performance using three replicate tanks for each genotype and dietary treatment. Each tank was seeded with 10 shrimp with average initial weight of 2.03 ± 0.10 g for FG genotype and 2.07 ± 0.02 g for HR genotype, at a density of 250 shrimp/m 3. A weekly biometry was realised to monitor the shrimp performance. We observed a significant interaction (p < .05) between genotype and diet for shrimp growth performance. Compared with HR shrimp, FG shrimp showed higher growth and better feed efficiency. The maximum weight gain was recorded, FG shrimp was significantly higher than HR shrimp independently of protein source. Diet with different protein source significantly influence the performance of FG shrimp, while in HR shrimp there is no significant difference between dietary treatment. The comparison showed that genotype, diet and their interactions influenced the performance of Litopenaeus vannamei. This research may be useful for improving genetic selection programmes, reducing feed costs for shrimp industry and design-feeding strategies for shrimp genotypes. HIGHLIGHTS Litopenaeus vannamei genotypes respond differently to diet. Fishmeal reduction on diet is posible in shrimps with high resistance. Genotype and diet interaction influence shrimp performance.
This short-term study evaluated the effect of non-lethal high CO 2 concentration on the transcriptional response of immune-related genes of Pacific white shrimp (Litopenaeus vannamei) cultured in recirculating aquaculture systems (RAS). Two experimental groups were created: high CO 2 (47.67±2.04 mg L −1 ) and low CO 2 (2.0±1.93 mg L −1 ). Shrimp of 8.85±1.20 g were placed randomly at a density equivalent to 100 individuals m −3 and were monitored at 6, 12, 18, and 24 h. The transcriptional response of immune-related genes was analyzed by qPCR. Gene expression of hemocyanin, prophenoloxidase, and heat shock protein 60 was downregulated at 24 h, suggesting affectations on oxygen transportation, melanization, and protein functioning of L. vannamei under high CO 2 concentrations. Also, gene up-regulation of lipopolysaccharide-and β-glucan-binding protein and cytosolic manganese superoxide dismutase can impair the bacterial recognition and antioxidant defense of shrimp exposed to high CO 2 concentrations. These results suggest that concentration at about 47 mg L −1 of CO 2 can significantly influence the transcriptional response modulation of immune-related genes.
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