Quansen Xie

To understand the basic nutritional composition and enhance the application of largemouth bass ( Micropterus salmoides ), the nutritional quality of muscle and skin of largemouth bass with body weight of 450.10±1.11g, 650.31±1.20 g, and 850.10±1.13 g was analyzed. Results showed that the skin and muscle of fish with a body weight of 650.31±1.20 g were most suitable for processing and comprehensive utilization. Glycine had the lowest percentage, while glutamic acid was the most prevalent amino acid connected to umami. Total amino acid (TAA), essential amino acid (EAA), and D-aspartic acid (DAA) levels first increased and then decreased as the body weight increased. Largemouth bass of an intermediate size exhibited the highest levels of TAA and DAA, and superior amino acid balance and had the highest nutritional value among the three groups. The most common necessary minerals were Na, Mg, and K. The skin had higher concentrations of these elements than muscle, and their amounts rose and reduced in proportion to body weight. Our results demonstrated that the male largemouth bass with a body weight of 650.31±1.20 g had the muscle with the highest nutritional quality and the greatest application potential.

In this study, we added Bacillus licheniformis to the diet of hybrid sturgeon (Acipenser baerii ♀ Acipenser schrenkii ♂) to determine its effects on growth performance, blood physical and chemical indices and intestinal microflora composition. One hundred and sixty adult hybrid sturgeon were selected and fed with four types of diets (equal nitrogen and fat levels) that were respectively supplemented with 0.00% (control group), 0.10% (Group B), 0.20% (Group C) and 0.40% (Group D) B. licheniformis for 120 days. Results showed that the fish in group C had the highest final body weight, weight gain rate and specific growth rate (p < 0.05). The feed coefficients, crude protein and crude fat of group B, group C and group D were significantly lower than that of group A (p < 0.05). And the crude protein (CP) and crude fat (EE) in groups B, C and D were significantly higher than the control group (p < 0.05). The serum TC and TG, ALP, ALT, AST and GLU contents in the B. licheniformis-added groups were also significantly higher than those of the control group (p < 0.05). In addition, Cetobacterium was the dominant bacterial taxon in each group. With increasing the content of B. licheniformis in the diet, the Cetobacterium content decreased and the Plesiomonas content increased correspondingly. Adding B. licheniformis to the diet greatly decreased the abundance of Streptococcus, Candidatus Competibacter and Lactococcus. Our results indicated that appropriately adding (0.20%) B. licheniformis could increase growth, reduce the feed coefficient and increase the diversity of the intestinal microbiota of hybrid sturgeon.

The meat yield, nutrient composition, and quality of the skin and muscle of eels with different body weights, 124.10 ± 0.12, 253.42 ± 0.31, and 385.10 ± 0.44 g, was systematically studied, were determined to provide the basic data for the processing and efficient use of rice field eel, Monopterus albus. The results showed that muscle and skin accounted for a more significant proportion of eels with body weight of 253.42 ± 0.31 g, compared with other eels ( and ). As increasing offish mass, the collagen protein, essential amino acids, umami amino acids, and total amino acids in muscle and skin increased and then decreased. The eels with body weight of 253.42 ± 0.31 g had the highest contents of these compounds. In the skin and muscle of all test eels, the natrium, magnesium, and kalium were the main essential mineral elements. Similarly, with the increasing of body weight of eel, an increasing and then decreasing trend was observed for all essential mineral elements measured. Our results demonstrated that the nutrient composition of the skin and muscle of Monopterus albus could be significantly affected by body weight, and the eels with body weight of 253.42 ± 0.31 g had the most favorable nutrient composition.

We investigated the effect of the feeding regimen (group 1: fed twice daily at 8:00 and 18:00 for 28 days followed by 5 days of fasting; group 2: fed twice daily at 8:00 and 18:00 for 28 days and then fed once daily at 8:00 for 5 days; and group 3: fed twice daily at 8:00 and 18:00 for 33 days) on the circadian rhythms of the RNA/DNA ratio in the liver and muscle of the loach Misgurnus anguillicaudatus. The experiment was carried out with a photoperiod of 14 hr (light):10 hr (dark), with light from 07:30 to 21:30, followed by sampling. Cosine rhythm analysis and parametric analysis revealed obvious diurnal variation regularity in all three groups. The amplitude and phase of diurnal regularity in the RNA/DNA ratios increased after feeding. The highest value in group 2 was higher than that in group 3. Correlation analysis showed a correlation coefficient between the RNA/DNA ratios of the two tissues of 0.85. The coefficients of variation in the maximum RNA/DNA ratio and two cycles of chi‐square values in liver tissue were lower than those in muscle tissue, but the stability of the ratio was more reliable and representative in liver than in muscle. These results suggest the occurrence of some altered circadian rhythms of the RNA/DNA ratios in the liver and muscle of the loach M. anguillicaudatus and that the best sampling time was after 4 hr of daily feeding.