Dietary antioxidant supplementation, especially astaxanthin, has shown great results on reproductive aspects, egg quality, growth, survival, immunity, stress tolerance, and disease resistance in aquatic animals. However, the effects of dietary astaxanthin supplementation from different sources are still unknown. A comprehensive comparison of survival, growth, immune response, antioxidant activity, thermal resistance, disease resistance, and intestinal microbial structure was conducted in dietary antioxidant supplementation from the sources of Gracilaria lemaneiformis (GL), industrial synthetic astaxanthin (80 mg/kg astaxanthin actual weight, named as group ‘SA80’), Phaffia rhodozyma (80 mg/kg astaxanthin actual weight, named as group ‘PR80’) and Haematococcus pluvialis (120 mg/kg astaxanthin actual weight, named as group ‘HP120’) at their optimal supplementation amounts. Furthermore, the SA80, PR80, and HP120 groups performed better in all aspects, including survival, growth, immune response, antioxidant activity, thermal resistance, and disease resistance, compared with the GL group. The PR80 and HP120 group also had a better growth performance than the SA80 group. In terms of heat stress and bacterial challenge, abalone in the PR80 group showed the strongest resistance. Overall, 80 mg/kg astaxanthin supplementation from Phaffia rhodozyma was recommended to obtain a more effective and comprehensive outcome. This study contributes to the discovery of the optimum dietary astaxanthin supplementation source for abalone, which is helpful to improve the production efficiency and economic benefits of abalone. Future research can further explore the action mechanism and the method of application of astaxanthin to better exploit its antioxidant role.

As living standards have improved, consumer demand for high-quality dried abalone has increased. Traditional abalone grading is achieved through slice analysis (sampling analysis) combined with human experience. However, this method has several issues, including non-uniform grading standards, low detection accuracy, inconsistency between internal and external quality, and high loss rate. Therefore, we propose a deep-learning-aided approach leveraging X-ray images that can achieve efficient and non-destructive internal quality grading of dried abalone. To the best of our knowledge, this is the first work to use X-ray to image the internal structure of dried abalone. The work was divided into three phases. First, a database of X-ray images of dried abalone was constructed, containing 644 samples, and the relationship between the X-ray images and the internal quality of the dried abalone was analyzed. Second, the database was augmented by image rotation, image mirroring, and noise superposition. Subsequently, a model selection evaluation process was carried out. The evaluation results showed that, in a comparison with models such as VGG-16, MobileNet (Version 1.0), AlexNet, and Xception, VGG-19 demonstrated the best performance in the quality grading of dried abalone. Finally, a modified VGG-19 network based on the CBAM was proposed to classify the quality of dried abalone. The results show that the proposed quality grading method for dried abalone was effective, achieving a score of 95.14%, and outperformed the competitors, i.e., VGG-19 alone and VGG-19 with the squeeze-and-excitation block (SE) attention mechanism.

Dietary lipid sources influence growth, tissue nutrient composition, and physiological responses in aquatic animals, but their effects on female broodstock abalone remain insufficiently understood. This study evaluated the effects of five dietary lipid sources, including fish oil, perilla seed oil, safflower oil, olive oil, and lard, on growth performance, foot muscle nutritional quality, digestive-gland antioxidant status, and survival following Vibrio harveyi AP37 challenge in female broodstock Haliotis discus hannai. A total of 500 female abalone were randomly assigned to five dietary treatments, with four replicates per treatment, and fed isonitrogenous and isolipidic diets for 90 days. Results showed that the dietary lipid source significantly affected growth, foot muscle crude protein and lipid contents, amino acid and fatty acid compositions, and digestive-gland antioxidant status. The fish oil group showed the highest measured total amino acid and taurine contents and docosahexaenoic acid (DHA) proportion in foot muscle, together with the highest observed final survival after V. harveyi challenge. Perilla seed oil and olive oil warrant further evaluation as alternative supplemental lipid sources under the present experimental conditions. These findings provide useful information for lipid source selection in formulated diets for female broodstock abalone.