不同投饵率对施氏鲟幼鱼生长及体成分的影响

Effects of feeding rate on growth of Amur sturgeon Acipencer schrenckii

采用同一种饵料 5个投喂率水平 (1.5 %、2 .0 %、2 .5 %、3.0 %、3.5 % ) ,室外流水养殖系统 ,在水温 (16 .5± 1.8)℃的条件下对施氏鲟 (Acipenserschrenckii)幼鱼 (4 2 .6± 9.2 )g进行 4 2d生长实验。结果表明 ,相对增重率、饵料利用率、鱼体蛋白质及水分含量受投饵率影响显著 (P <0 .0 5 )。随着投饵率的增加 ,相对增重率呈先升高、后降低的趋势 ,饵料利用率随着投饵率的升高而下降。根据最大相对增重率和最大饵料利用率 ,确定施氏鲟幼鱼适宜投喂率在水温 15～ 18℃时为体重的 2 .0 %。

Amur sturgeon (Acipenser schrenckii) is a specific economical fish only in Amur River, which possesses an important place in fisheries of Amur River. It was conducted to artificial reproduction successfully in China in 1957. Rearing Amur sturgeon with formulated feed in lab was not succeeded until 1992, and the prelude to raise this kind of fish under artificially controlled condition was opened. Feeding rate is an important factor affecting the growth of fish, and ascertainment of the optimal feeding rate is the key to success of any aquaculture operation. Several studies have been reported on Amur sturgeon culture. The study of effects of different feeding rate and the optimum feeding rate on growth performance of juvenile Amur sturgeon (Acipenser schrenckii) has not been studied yet. A growth experiment was conducted to determine the optimum feeding rate and the effects of different feeding rate on the growth performance of juvenile Amur sturgeon (Acipenser schrenckii) were studied. Five feeding rates from 1.5 to 3.5% (at 0.5% increments) body weight per day (BW/day) were used in this test. A commercial diet was given to Amur sturgeon with an average individual body weight (42.6±9.2 ) g for 42 d. Its proximate composition was 10.1% moisture, 40.2% crude protein, 10.6% crude lipid, and (3.2%) ash respectively. The fish individually weighed were distributed randomly into 15 pools with 60 fish each pool, and a few fish were redistributed among the pools until there were not significantly different (P>(0.05)) among the total body weight in each pool. Every three pools were allocated to each feeding rate group. Daily feed intakes at different feeding rates were divided into four meals for half an hour each meal. i.e. one third of the total daily intake was fed at 07∶00 am, one sixth at 11∶00 am, one sixth at 15∶00 am, and one third at 19∶00 pm. The fish were inspected daily for abnormal behavior and mortality. The pools were cleaned and flushed daily by pulling the external overflow pipes to drain the waste water out. The fish were weighed individually every two weeks and the amount of diet was adjusted according to the total body weight of fish in each pool for the subsequent two weeks. At the end of the experiment, three fish were sampled randomly from each pool. The three fish were pooled together for each replicate (three replicates per feeding rate) and for the whole body composition determination. All results were analyzed using SPSS statistical software program. After 42 d growth experiment, the results showed that percent body weight increase (BWI %), feed efficiency(FE), and whole body moisture and protein content were significantly (P<(0.05)) affected by feeding rate. The BWI % increased with feeding rate from 1.5% to a maximum at 3.0%. There was no significant difference (P>0.05) among 2.0% and 3.5% groups, but the BWI% of 1.5% group was significantly lower (P<0.05) than the other groups. The FE was markedly higher in 1.5% group than others, but was not significantly different (P>0.05) from that of 2.0% group. The whole body moisture content in 1.5% group was significantly (P<0.05) higher than that of the other groups, but the whole body protein content was significantly (P<0.05) lower than that of other groups. Based on the maximum BWI%, the maximum FE and the analysis of approximate body nutrients, the optimal feeding rate for hatchery-produced juvenile Amur sturgeon (42.6±9.2) g at water temperature 15-18 ℃ was 2.0%.