فهرست مطالب x. ouyang

Four feeding levels (40%, 60%, 80% and 100% of satiation) were designed as the different treatment groups to assess its effects on water quality and plankton community structure in the yellow catfish rearing enclosure ecosystem. The results showed that the weight gain and specific growth rate decreased significantly as the feeding level decreased. The soluble nutrients (except for NO2-N) concentrations were significantly affected by the feeding level with the prolonging of rear time. A significant increase in phytoplankton biomass before 9 days was observed in all the treatments, and then decreased significantly until 21 days, while the zooplankton biomass was significantly increased during the entire experiment. Both the phytoplankton and zooplankton biomass were significantly affected by the feeding level. Our results suggested that the increment of nitrogen compounds before 9 or 12 days could be explained by the input of compound diets, while the decrement of nitrogen compounds afterward and phosphorous compounds could be explained by the changes of zooplankton biomass. Based on water quality and plankton structure, moderate nutrient restriction (60%-80% of satiation) is a feasible feeding strategy for better growth performance as well as better water quality and balanced plankton structure. On the other hand, input of moderate phosphorus by dietary supplementation and/or fertilization is necessary in yellow catfish culture both for the better plankton structure and the health of fish. In addition, the polyculture of the minority members of zooplankton filter feeders might be a feasible strategy to control the excessive zooplankton.

This study explored the effects of GnRH agonist (GnRHa) immunity on expression of FSHR mRNA in pituitary and FSHR protein in uteri, and also confirmed its efficacy on uterine development. 42 prepuberty and non cyclic ewes were assigned to 6 experimental groups (EG) during anestrus season. Animals in EG-I, EG-II and EG-III were subcutaneously injected with 200, 300 and 400 μg alarelin antigens (day 0 and 14). Animals in EG-IV and EG-V were subcutaneously injected with 200 and 300 μg alarelin antigen (day 0, 7, 14 and 21). Uterine FSHR protein expression was detected using Western-blotting. RT-PCR was implemented to measure expression of pituitary FSHR mRNA on day 70 after the immunity. Compared to the CG, pituitary FSHR mRNA levels reduced by 58%, 88% and 91% (P<0.01) in EG-I, EG-II and EG-III. FSHR mRNA in EG-IV and EG-V reduced by 64.29% (P<0.05) and 10.11% compared to EG-I and EG-II. Expression levels of uterine FSHR protein in EG-III and EG-V were higher than that in CG. The uterine glands, mitochondria and mitochondrial crista decreased, and the glandular cavity reduced, also the microvilli shortened. Uterine horn weights in EG-I, EG-II and EG-III reduced by 4.66%, 10.20% and 16.63%, respectively. Uterine wall thickness (UWT) in EG-I, EG-II and EG-III reduced by 1.41%, 5.84% and 8.75% (P 0.05). The endometrial epithelium thickness (EET) in EG-I, EG-II and EG-III decreased 2.70%, 8.87% and 19.15%. The positive correlations between uterine horn weights and UWT, EET and FSHR were calculated.