|Other Abstract||In this dissertation, the Jerusalem artichoke powder（JAP） was used as feed additive in the artificial cultivation of Litopenaeus vannamei to investigate the effects of Jerusalem artichoke powder on the growth, immunity and intestinal flora of Litopenaeus vannamei. Meanwhile, the synergistic effects of Jerusalem artichoke powder and Bacillus licheniformis on Litopenaeus vannamei were studied. The main research contents and conclusions of the dissertation are as follows:
1. The effects of Jerusalem artichoke powder on Litopenaeus vannamei
The Jerusalem artichoke powder was added into the basic diet, the nutrient analysis results showed that the nutrients include 42% crude protein, 4% crude fat and 16% ash respectively, which could meet the growth needs of prawns. The experimental groups were as follows: Control group A (basic diet), Experimental group B (0.5% JAP), Experimental group C (1.0% JAP), and Experimental group D (1.5% JAP). After four weeks of feeding experiment, the composition and abundance of intestinal microbial, immunity and growth performance of Litopenaeus vannamei were analyzed. The results
showed that: (1) JAP supplement did not change the intestinal microflora diversity of prawns, but the intestinal microorganisms of the experimental group in all JAP group were more homologous. 0.5% JAP significantly increased the relative abundance of bacillus (P<0.05). 1.0% and 1.5% JAP can significantly reduce the number of Vibrio in the intestines of prawns and increased the relative abundance of beneficial bacteria such as Erythrobacter and Flavobacterium. Which could promote the host growth immunity. (2) 0.5% JAP could significantly improve the total antioxidant capacity of prawns
(P<0.05). 1.0% JAP of dietary can significantly improve the phagocytic activity, total antioxidant capacity, lysozyme activity and related immune indexes, as well as the feed utilization rate of prawns. 1.5% JAP could improve the blood cell number, total antioxidant capacity and lysozyme activity of the prawns, while the final average weight, special growth rate and weight gain rate of the prawns were also significantly increased (P<0.05).
2. The effects of JAP and Bacillus licheniformis on Litopenaeus vannamei
The JAP and Bacillus licheniformis were add to the basic diet to prepare feed. The experimental groups were as follows: Control group A2 (basic diet), Experimental group B2 (1.0% JAP), Experimental group C2 (108CFU/g Bacillus licheniformis), and
Experimental group D2 (1.0% JAP+108CFU/g Bacillus licheniformis). After four weeks of feeding experiment, the composition and relative abundance of intestinal microbial, immunity and growth performance of Litopenaeus vannamei were measured. The experimental results indicated that: (1) The experimental groups had no significant effect on the diversity of intestinal microbes (P> 0.05). The intestinal flora homology between the experimental groups was stronger, and the difference were greater than the control A2 group. Compared with the experiment B2 group, although the experiment D2 group promotion effect on some beneficial bacteria such as Erythrobacter and Flavobacterium were reduced, but the relative abundance of harmful bacteria such as Vibrio and Alternomonas were reduced too, which proved that the synergistic effect between JAP and Bacillus licheniformis. (2) The experimental group D2 showed a more significant promotion effect on immune indicators such as the number of blood cells and respiratory bursts. Performance has no synergistic effect (P> 0.05).
The results show that within a certain range, JAP could reduce the relative abundance of Vibrio intestinal tract of Litopenaeus vannamei and promote the growth performance of prawns. Adding 1.0% or 1.5% JAP in the feed could significantly improve the growth performance, immunity and regulate intestinal flora balance of prawns. Meanwhile, the combination uses of 1.0% JAP and Bacillus licheniformis showed better synergistic effects. This study provides a theoretical basis for the application of JAP in prawns cultivation.|