Zhou HongQi

Effects of feeding modes of chitosan on prevention of starvation of Ctenopharyngodon idellus.

Grass carp(mean body weight 19.46±0.04 g) were first fed for 60 days by three modes(mode A,grass carp were fed basal diet without chitosan; mode B,grass carp were fed experimental diet,supplemented with 0.5% chitosan in basal diet; mode C,grass carp were first fed experimental diet and then basal diet at an interval of 15 days) and then starved for 15 days. Growth index,nitrogen oxide(NO) content and lysozyme(LSZ) activity in head-kidney(HK),spleen,hepatopancreas and serum were measured to investigate effects of feeding modes of chitosan on prevention of starvation of grass carp. The results showed that length gain and weight gain of grass carp at the end of 60 days feeding were significantly higher in modes B and C than those of the control(P0.05) and were the similar variation(P0.05) after 15 days starvation,regardless of feeding or starvation. NO content,in HK and hepatopancreas,and LSZ activity,in HK and serum,were significantly higher in starvation treat in mode A. On the contrary,NO content ,except in HK,and LSZ activity or NO content,except in spleen,and LSZ activity,except in hepatopancreas,were significantly lower(P0.05) in starvation treat or had no statistical significance(P0.05) between starvation and feeding treats in modes B and C.Obviously,starvation caused various influence in different tissues and effects caused by different oral administration treats were dissimilar on prevention of starvation of grass carp. Comparatively,modes B and C had an effective resistance to starvation stress,but there was no statistical significance in both of them. Given economical efficiency and practicability,chitosan by incontinuous feeding will be suggested to promote growth and lighten the stress caused by starvation.

Effects of chitosan and probiotics on non-specific immune function and the levels of serum thyroid hormone and cortisol in allogynogenetic silver crucian carp (Carassius auratus gibelio).

In order to probe that chitosan and probiotics may regulate immune function of allogynogenetic silver crucian carp (Carassius auratus gibelio) by the pathway of triiodothyroxine (T3 ),tetraiodothyroxine (T4) and cortisol in fish,allogynogenetic silver crucian carp(initial weight of 78. 31 ±2. 15 g) were fed with control and tested diets which were control diet with 0. 50% chitosan A,0. 50% chitosan B,0. 20% probiotics,the complex of 0. 50% chitosan A and 0. 05% probiotics respectively. The number,differential count and phagocytic activity of peripheral blood leucocyte,lysozyme activities in spleen,lymphocyte proliferation in spleen were measured after 64 d feeding period. The T3,T4,cortisol levels in serum were assessed by means of radio-immunoassay. Results showed that the supplement with chitosan,probiotics,or the complex of chitosan and probiotics had no notable influence on the number of peripheral blood leucocyte (P 0. 05),but it could enhance the lymphocyte count,phagocytic percentage,phagocytic index and lysozyme activity in spleen (P 0. 05),and decrease the polymorphocyte count remarkably (P 0. 05). The supplement with chitosan,probiotics,or the complex of chitosan and probiotics had no notable influence on transformation of lymphocyte in spleen (P 0. 05) but the supplement with 0. 5% chitosan A could increase transformation of B lymphocyte in spleen ( P 0. 05). The supplement with chitosan,probiotics,or the complex of chitosan and probiotics could increase the serum T3 level (P 0. 05) and decrease the serum cortisol and the serum T4 remarkably (P 0. 05) except that the supplement with 0. 50% chitosan B had no notable influence on the amount of T4 (P 0. 05). Thus it can be seen that chitosan and probiotics might regulate immune function of allogynogenetic silver crucian carp by the pathway of increase in serum T3 and decrease in serum cortisol.

Effects of bubbling on growth, use of N and P and biochemical composition of the microalgae Dunaliella salina.

In order to assay the effects of different bubbling modes on microalgae during cultivation,the growth,biochemical composition and utilization on N and P from medium for Dunaliella salina treated with three bubbling modes(shaking flask manually,continuous aeration and CO2 bubbling) respectively were investigated in this paper.The results showed that the biomass(1.62×107 ind/mL) of D.salina treated with continuous aeration was significantly higher than those of the other groups after 5 days.D.salina mainly used the nitrogen stored in cell for growth and reproduction in the first 3 days.Then N in the culture medium was dramatically absorbed by D.salina cell.While the cell of D.salina could rapidly absorb P from the culture medium after inoculation and store P in the cell for the following growth and reproduction.After first three cultured days,N content in the culture medium treated with continuous aeration was significantly lower than those of the other groups.The bubbling mode did not affect the cell of D.salina to absorb P from the culture medium significantly.The contents of total lipid,crude protein and amino acid of D.salina treated with continuous aeration were significantly lower than those of the other groups.The content of PUFAs(poly-unsaturated fatty acids) of the cell treated with continuous aeration was significantly higher than the other groups.It is therefore suggested that the bubbling modes affect growth as well as cell composition of the microalgae D.salina.The growth performance and fatty acid nutritional value of the cell treated with continuous aeration improve while the amino acid nutritional value of the same cell decreases.