| The experiment studied the effects of starvation and different dietary protein levels on the ovary development ofcarassius auratus gibelio (Bloch), the purpose of which was to research the effects of nutritional condition on gonad development of fish and the mechanism of broodstock nutrition and consequently provide theory foundation for larvae breeding.Five isocaloric diets containing 0%, 16%, 24%, 32% and 40% crude protein were formulated using fish meal, corn starch, CM-cellulose, rape oid, Ca (H2PO4) 2, vitamin and mineral mixture, concomitantly a starvation group was set. All carassius auratus gibelio (Bloch) used in this study were from the same broodstock (body weight 30.0±5.0g, length 10.0±2.3cm) . The fish were kept in indoor circulating aquaria under a 12h/12h( light/dark )regime, and the feeding rate is 1% of the body weight. Samples taken in the middle of each month were used to determine the serum vitellogeriin phosphorus content, RNA/DNA ratio of hepatopancreas and gonad, gonad somatic index and the proportion of oocytes belong to each stage. At the last sampling, the protein, lipid, and water content of gonad and muscle, and the diameter of maturing oocytes were measured, the fecundities of each group were calculated also. The results were listed as follow: (1) The RNA/DNA ratio of hepatopancreas and gonadHepatopancreas RNA/DNA ratio of all groups ascended in December and February, and descended in January and March. The RNA/DNA ratio of the starvation group was the lowest all the time. From December to February the RNA/DNA ratio of group 0% was higher than the starvation group but lower than other groups. But there were no significant differences among the groups with dietary levels from 16% to 40%. And no evident relationship was found between dietary protein level and hepatopancreas RNA/DNA ratio in March.The changing manner of gonad RNA/DNA ratio was similar to hepatopancreas, also ascended in December, descended in January, ascended again in February and descended again in March. The difference was that the RNA/DNA ratios of the starvation group, group 0% and 16% didn't decrease but increased. RNA/DNA ratio of the starvation group was the lowest from December to February. Along with the process of time the effect of dietary protein level on gonad RNA/DNA ratio became more and more evident. The difference among the groups was most significant in February, the gonad RNA/DNA ratio increased when the dietary protein level rising. On the contrary, the gonad RNA/DNA ratio decreased when raising the dietary protein level in March. (2 ) The content of serum vitellogeninAlong with the process of time serum vitellogenin content of the starvation group decreased invariably. But the changing mode of other groups was not so similar. The contents of group 0%, 16% and 24% all had peak value in December and February respectively. But the contents of group 32% and 40% didn't decrease but kept increasing in January. From November to February the result was that the higher the dietary protein level the higher the serum vitellogenin content which indicated that higher dietary protein level was propitious to the vitellogenin synthesizing. The gonads of most experimental fish matured in March so the serum vitellogenin contents of all groups decreased sharply.(3) Oocyte developmentThere was no significant difference among groups at the proportion of the oocyte belonging to stage I. The dietary protein level hadn't engendered evident effects on oocyte development in December. From January to March the ratios of oocyte belong to stage IV in group starvation and 0% were the lowest, and mat of group 32% and 40% were the highest. The result indicated that higher dietary protein level was propitious to oocyte development. From December to January, in all groups the ratios of stage II oocyte declined and the ratios of stage III oocyte increased. From January to March, except for group starvation and 0%, the ratios of stage II oocyte kept relatively stable in other groups, stage III oocyte declined and stage IV oocyte increased. It was indicated that the time span between November and January was the main phase of oocyte developing from stage II to HI, and the time between January and March was the main phase of oocyte developing from stage III to IV.(4) The gonad somatic indexExcept for the starvation group, the GSI of other groups got marked increase, and which rised relatively rapid in the time between November and February, but kept stable between February and March. There was no significant difference among all the groups from November to January. In February and March the result was that the higher the dietary protein level the higher the GSI. In the experiment the GSI of the starvation group was the lowest all the time, but from November to January it increased also and hadn't significant difference when compared to other groups, however begin from January the GSI of the starvation group displayed a descending trend.(5) The biochemical composition of muscle and gonadThe muscle protein contents of the groups were 13.34%, 15.09%, 15.36%, 15.83%, 16.28% and 16.02% respectively, lipid contents were 0.59%, 0.59%, 0.69%, 0.82%, 0.81% and 0.83% respectively, moisture contents were 81.80%, 80.21%, 80.18%, 79.47%, 79.16% and 79.26% respectively. The gonad protein contents of the groups were 20.72%, 23.11%, 24.49%, 24.83%, 24.87% and 26.63% respectively, lipid contents were 1.17%, 1.53%, 1.54%, 1.81%, 1.78% and...
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