Growth performance, physiological parameters, and transcript levels of lipid metabolism-related genes in hybrid yellow catfish (Tachysurus fulvidraco ♀ × Pseudobagrus vachellii ♂) fed diets containing Siberian ginseng.

In high-density aquaculture, fish health can suffer because of excessive feeding, which causes fatty liver disease. Siberian ginseng (Acanthopanax senticosus) has been used as a feed additive to promote animal growth, immunity, and lipid metabolism. In this study, we explored the effects of A. senticosus on the physiology of hybrid yellow catfish (Tachysurus fulvidraco ♀ × Pseudobagrus vachellii ♂). A control group and five groups fed diets containing A. senticosus (0.5, 1, 2, 4, and 8 g A. senticosus/kg feed) were established and maintained for 8 weeks. Dietary supplementation with A. senticosus at 4 g/kg promoted growth of the hybrid yellow catfish. Serum total cholesterol (TC) and triacylglycerol (TG) levels at 2 g/kg A. senticosus (TC: 1.31 mmol/L; TG: 1.08 mmol/L) were significantly lower than in the control group (TC: 1.51 mmol/L; TG: 1.41 mmol/L), and 4 g/kg A. senticosus (17.20 µmol/g tissue) reduced the liver TG level compared with the control group (21.36 µmol/g tissue) (P <0.05). Comparative transcriptomic analysis of liver tissue between the control group and the group showing optimum growth (4 g/kg A. senticosus) revealed 820 differentially expressed genes and 44 significantly enriched pathways, especially lipid metabolism pathways such as unsaturated fatty acid and fatty acid metabolism. The transcript levels of five lipid metabolism-related genes were determined by quantitative real-time PCR. The results showed that 2-4 g/kg A. senticosus supplementation reduced the FADS2, ELOVL2, CYP24a, and PLPP3 transcript levels and 4 g/kg A. senticosus increased the DIO2 transcript level (P <0.05), leading to altered synthesis of TG and thyroxine and reduced fat deposition in the liver. Our results show that dietary A. senticosus affects the regulation of fat metabolism and promotes the growth of hybrid yellow catfish. A. senticosus is a healthy feed additive, and the appropriate dietary supplementation rate is 2-4 g/kg.

[Study on ecological stereoscopic cultivation mode of Amomum villosum-Dimocarpus longan].

In order to set up a technical standard for planting Amomum villosum in wood forest in the future, we analyzed the relationship between the ecological factors and the yield of A. villosum planted in five Dimocarpus imocarpus longan wood forests and five miscellaneous wood forests in Yangchun city, to find out the dominant factors that affect the yield of A. villosum. The results showed that agricultural measures of fertilization, artificial irrigation and removing the old plants were positively correlated with the yield of A. villosum, the pesticide spraying and soil pH value were negatively correlated with the yield of A. villosum. But the effects of ecological factors on the yield were not significantly. High yield regions are generally located in the ravine, two sides of mountain stream and other places where water is more adequate. The slope of cultivated field with high yield is generally less than 30°, lighting and ventilation are more appropriate; soil type is generally sandy or loam, shade density is generally about 50%, and pollinators are many in quantity and variety. And we found that there was a large difference in mineral nutrient contents of soils among ten plantations. Results indicate that the yield of A. villosum is determined by the combination of each ecological factor. Suitable light intensity, moisture, ventilation and reasonable fertilization are conductive to increase the yield of A. villosum, but the use of pesticides and soil alkalization hinder the increase of A. villosum production. Too high shade density and the abuse of pesticides may be the main reason for limiting the yield of A. villosum planted in D. longan wood forests. This study has obtained key techniques of the ecological stereoscopic cultivation mode of A. villosum-D. longan, which lays a theoretical foundation for the guidance of farmers in planting A. villosum in the D. Longan forest in the future.

[Phosphate transform of composting with pre-mixing insoluble phosphate using high temperature dissolved phosphorus microbes inoculation].

In order to enhance the available phosphorus (P) of compost production, the experimental design of composting included three treatments was conducted. The treatments were: Control (CK) with no dissolved phosphate microbes inoculation, no rock phosphate mixing; CP with no dissolved phosphate microbes inoculation, rock phosphate mixing; CMP with dissolved phosphate microbes inoculation, rock phosphate mixing. At different composting phases, the samples were taken for the determination of phosphorus forms. Compared to CK, organic P, dissolved P and rapidly available P of CP increase by 2 049.8, 264.2, 954.0 mg/kg at final stage of composting, respectively; while that of CMP increase by 4 188.6, 648.7, 3 576.4 mg/kg, respectively. The increase of organic P, dissolved P and rapidly available P in CMP is 2.04, 2.46, 3.75 times as that of CP, respectively. The results indicated dissolved phosphate microbes inoculation composting with pre-mixing rock phosphate would accelerate transform efficiency of insoluble phosphate, increase the available P of compost production.