The Effect of UVA Supplementation Time on the Main Nutrients of the Muscle of Penaeus vannamei

UVA is an important component of natural light and has certain ecological functions. However, it remains unclear whether UVA affects the nutrient composition of Penaeus vannamei. We built a supplementary light culture system for P. vannamei and used classic nutrient composition analysis techniques to analyze the nutrient, fatty acid, and amino acid composition of the shrimp muscle tissue after different supplementary UVA light durations. Our results provide a theoretical reference for the technological improvement of P. vannamei culture. A total of 450 shrimps [weighing (9.56±0.10) g] were included in a 28-day culture experiment with background lighting of 12L: 12D photoperiod with full spectrum LED light [light intensity (1.00±0.02) W/m2]. The experimental design randomly included different UVA [light intensity (1.00±0.02) W/m2] supplementation (0 h, T0 h; 2 h, T2 h; 4 h, T4 h; 8 h, T8 h; 12 h, T12 h). The results revealed no significant variation in the water and crude ash content of the shrimp muscles after different UVA light durations. The crude fat content increased significantly in the T2 h and T4h groups (P 0.05). Seventeen common amino acids (excluding tryptophan, which was not detected) were detected in the muscle of P. vannamei. These included seven essential amino acids (EAA), two semi-essential amino acids (HEAA) and eight non-essential amino acids (NEAA). The results showed significant variation between the fraction of the 17 amino acids at different UVA light supplementation durations, with three essential amino acids (methionine, leucine, and lysine), one semi-essential amino acid (arginine), three non-essential amino acids (aspartic acid, glutamic acid, and glycine) and total, essential, semi-essential and non-essential amino acids in the T2 h and T4 h groups. The content of the three essential amino acids (threonine, isoleucine, and phenylalanine) did not differ significantly (P > 0.05) with the different UVA light supplementation durations. The amino acid composition in the shrimp muscles showed that among the 17 amino acids at different UVA supplementation durations, the highest levels were glutamic acid with 2.02%, 2.72%, 2.71%, 1.95% and 1.93% in the T0 h, T2 h, T4 h, T8 h, and T12 h groups respectively, followed by glycine, aspartic acid, arginine, leucine, and lysine. The cystine content was the lowest, at 0.02%, 0.03%, 0.04%, 0.03% and 0.04% in the T0 h, T2 h, T4 h, T8 h, and T12 h groups, respectively. The EAA/TAA of shrimp muscle at different UVA supplementation durations ranged from 0.36 to 0.38 and EAA/NEAA from 0.68 to 0.73, with no components varying significantly between the treatments (P > 0.05). The evaluation of the nutritional composition of the muscle of P. vannamei under different UVA light supplementation durations identified the muscle composition of shrimp in the T2 h and T4 h groups was high in protein and fat, while other nutritional components did not vary significantly from the other three groups. The EAA, HEAA, NEAA, and TAA contents, as well as the C16:0 and polyunsaturated fatty acids were higher in the T2 h and T4 h groups than those in the other groups. Therefore, shrimp in the T2 h and T4 h groups were more nutritious with a better nutritional status. In terms of the nutritional composition of the muscles of P. vannamei, 2–4 h of UVA supplementation can improve their nutritional quality and increase their nutritional value to a certain extent. In conclusion, the aquaculture light environment for P. vannamei requires further optimization