| In order to study the optimum protein level of Onychostoma macrolepis yearling and reserve broodstock,Two kinds of fat samples with different protein levels were designed,and two feeding experiments were carried out.Broodstock protein needs test is divided into five treatments,dietary protein level of 30%,33%,36%,39% and 42%,And yearling tests were also divided into five treatments with feed protein levels of 28%,32%,36%,40% and 44%.Each dealing with 3 replicates,and each repeating 30 fish.The initial specifications were 26.53 ± 0.37 g and 12.35 ± 0.07 g,respectively,for 67 days and 68 days of feeding test.After the trial,Through the growth performance,biological traits,feed utilization,body composition,tissue fatty acid composition and digestive enzyme activity,Comprehensive evaluation of the optimum protein levels for yearling and broodstock.As shown below:The results of the broodstock test showed that was no significant difference in the growth of between the groups(P>0.05).The abdominal fat index and gonadal index of females increased with the increase of feed protein level,and gonadal index in the CP39 group reached the highest level.Abdominal fat index in the CP36-CP42 groups reached the highest level,but there were no significant differences between the other biological characters and the biological traits of males(P>0.05).With the increase of protein levels,whole body and muscle crude protein content is not affected.With the increase of protein level,the correlation coefficient of adipose tissue and gonadal body with feed fatty acid increased.With the increase in feed protein levels,the greater the number of female oocytes,the higher the developmental maturity,but when the protein level is too high(39% to 42%),female oocytes show a certain over-cooked state.The results of the the yearling fish test showed that the Significantly affected of different protein levels on the weight gain rate(WGR)and specific growth rate(SGR).WGR and SGR increased with the increase of protein level,and reached the maximum in CP37.43 group,then decreased slowly.WGR and SGR as the evaluation index,Quadratic polynomial regression fitting,known the optimal protein level was 36.84%-37.30%.In contrast,feed coefficient(FCR)first decreased,after increased,and in CP37.43 group was the lowest,significantly lower than CP28.83 group and CP43.87 group(P<0.05).Shape index was not affected by feed protein levels(P>0.05).Muscle crude protein content increased with the increase of protein levels,and CP28.8 group,CP32.76 group and CP43.8 group were significantly different(P<0.05).The crude protein of whole body was significantly higher than that of CP28.83%(P<0.05).when the protein level was more than 32.76%.HepatoPancreasand intestinal trypsin activity increased with the increase of feed protein level,more than 40.6% protein levels decreased,but the difference of lipase was not significant(P>0.05).In conclusion,The difference of protein level was not affect the growth of broodstock,but had a significant effect on gonadal development.It is recommended that the level of protein requirement of broodstock should be 39%.For the yearling fish,Suitable protein levels promote growth,reduce feed utilization,increase liver and intestinal trypsin activity,and promote better deposition of crude protein in body.It is suggested that the protein level should be added to 36.84%-37.43%. |
