No abstract

HIGHLIGHTSArtificial sunlight with the main components of UVB, UVA, and visible light was used to investigate the influence of photoperiod on large-scale farming of juvenile Chinese soft-shelled turtles in a greenhouse.The effects of photoperiod on digestive enzyme activity, stress, and oxidative status of juvenile Chinese soft-shelled turtles were revealed.The optimal photoperiod for juvenile Chinese soft-shelled turtles reared in a greenhouse was 0 h light:24 h dark.Abstract. To improve light conditions for soft-shelled turtles in a greenhouse, the effects of photoperiod on growth, digestive enzyme activity, stress, and oxidative status of juvenile Chinese soft-shelled turtles were investigated. In this study, juvenile Chinese soft-shelled turtles were reared under three photoperiods (hours light:hours dark), i.e., 0L:24D, 6L:18D, and 12L:12D) for four months. Results demonstrated that differences in growth were insignificant during the experiment, but the growth parameters of final weight, weight gain rate (WGR), and feed conversation ratio (FCR) were better at 0L:24D, and the survival rate was significantly higher at 0L:24D than at 12L:12D. Regarding digestive function, serum trypsin activity was significantly higher at 0L:24D than at 6L:18D, while lipase activity was significantly higher at 0L:24D than at 12L:12D. For the stress response parameters, serum cortisol level was significantly lower in turtles exposed to 0L:24D compared to the other treatments. With regard to antioxidant enzyme activities, the total antioxidant capacity (T-AOC) was significantly lower at 0L:24D compared to the other treatments, while superoxide dismutase (SOD) activity was significantly higher in turtles exposed to 0L:24D. The activity of glutathione peroxidase (GSH-PX) was significantly lower at 0L:24D than at 12L:12D. The malonaldehyde (MDA) activity was a little lower at 0L:24D than at 6L:18D; however, it significantly decreased in turtles exposed to 12L:12D. On the whole, the results indicated that the photoperiod treatments had no significant effects on the growth of juvenile Chinese soft-shelled turtles, while extended light exposure may cause physiological stress in turtles. Considering the survival rate, digestive function, cortisol level, and oxidative status, it is suggested that juvenile soft-shelled turtles should be reared under a 0L:24D photoperiod. Keywords: Chinese soft-shelled turtle, Digestive enzyme activity, Growth, Oxidative status, Photoperiod, Stress.

HighlightsSunlamps with UV and visible light were used in large-scale farming of Chinese soft-shelled turtles in a greenhouse.The effects of lighting mode on the growth performance, survival rate, stress response, and oxidative stress of juvenile Chinese soft-shelled turtles were studied.Lighting mode had significant impacts on survival rate, stress, and oxidative stress of Chinese soft-shelled turtles.Lighting the basking area only was the optimal lighting mode and caused less stress for Chinese soft-shelled turtles.Abstract. To investigate the effects of sunlamp-based lighting mode on the growth performance, survival rate, stress response, and oxidative stress of juvenile soft-shelled turtles in a greenhouse, four lighting modes with three replicates were used in this study: lighting the basking area and water simultaneously (LBW), lighting the water only (LW), lighting the basking area only (LB), and no light (NL). Results showed that the final weight, weight gain rate, and specific growth rate had no significant differences among treatments. The survival rate was significantly lower in LBW than in NL, while no significant differences were observed among NL, LB, and LW. On the physiological level, serum cortisol level was significantly lower in LB compared to the other two treatments with light, and glucose level was significantly lower in LB than in LW and NL. With regard to oxidative stress, indexes indicated that the turtles suffered less oxidative stress in LB. Glutathione peroxidase (GSH-PX) was significantly lower in LB compared to the other three treatments. Total antioxidant capacity (T-AOC) was significantly lower in LB, as well as in LW and NL, than in LBW, and no significant differences were found among LB, LW, and NL. Additionally, complement 3 (C3) was significantly higher in LB than in NL, which indicated that the turtles had higher immune-related protein in LB. On the whole, the results demonstrated that lighting mode had significant impacts on survival rate, stress response, and oxidative stress. It can be concluded that lighting the basking area only is the optimal lighting mode for soft-shelled turtles in a greenhouse. From the perspective of breeding welfare, soft-shelled turtles are suggested to be provided with a separate area for basking when cultured in a greenhouse. Keywords: Chinese soft-shelled turtle, Lighting mode, Oxidative stress, Stress response, Survival rate.

Feed has the greatest impact on the carbon footprint of the aquaculture, and also determines the water quality in aquaculture to a great extent. Making appropriate feeding control strategies is one of the most effective ways to promote cleaner production as well as fish welfare in aquaculture. Reliable and accurate fish appetite grading especially based on time-limited data is a prerequisite for achieving high-precision and reasonable feeding control in practical production. To date, however, few efforts have been done on this challenge. For these, regarding Micropterus salmoides as the experimental fish, a novel and practical method, based on a modified kinetic energy feature-based graph convolutional network (GCN), was developed in this study. First, graphs were constructed based on the extracted modified kinetic energy features and their temporal correlation. Then, with the help of a series of the convolution and global pooling operations, a GCN model was customized based on the constructed graphs. Following this, the customized GCN model was enriched by the self-attention pooling mechanism and customized network structure. Results show that the proposed GCN-based approach outperforms other typical state-of-the-art methods in fish appetite grading, and the grading accuracy obtained here could be 98.60% using only the first 4.2 seconds as well as the first 8.3 seconds of input data, which is not much different from that (98.89%) using full-length (25 second-long) input data. What’s more, compared to the recurrent neural network (RNN)-based method which performance is closest to our method, the space complexity of the proposed approach here can better satisfy the requirements of real aquaculture, in which the quantity of the trainable parameters here is only 6.4% ~ 31.8% of the RNN-based method. In summary, the proposed modified kinetic energy feature-based GCN approach is favorable for the appetite grading of fish like Micropterus salmoides with time-limited data, which is a promising approach in dealing with feeding control tasks and alleviating the water environmental burden in aquaculture.