饲料蛋白质水平对台湾泥鳅生长性能、形体指标和体成分的影响

本试验旨在探索饲料蛋白质水平对台湾泥鳅生长性能、形体指标及体成分的影响。选用初始体重为(8.57±0.35)g的台湾泥鳅720尾,随机分成4组,每组3个重复,每个重复60尾。4组台湾泥鳅投喂蛋白质水平分别为25%、30%、35%和40%的试验饲料,养殖时间为60d。结果表明:随着饲料蛋白质水平的增加,台湾泥鳅末重和增重率均呈先升高后趋于稳定的变化趋势,且均在饲料蛋白质水平为35%时达到最大。饲料系数随着饲料蛋白质水平的升高呈先降低后趋于稳定的变化趋势,且在饲料蛋白质水平为40%时最低。饲料蛋白质水平从35%增加到40%,末重、增重率和饲料系数无显著变化(P0.05)。基于增重率和饲料系数的折线模拟结果表明,台湾泥鳅达到最大增重率的饲料蛋白质水平为34.57%,饲料系数最低的饲料蛋白质水平为35.47%。随着饲料蛋白质水平的升高,蛋白质效率、蛋白质沉积率和成活率均呈先升高后降低的变化趋势。通过二次多项式回归分析可知,台湾泥鳅蛋白质效率和蛋白质沉积率最高时的饲料蛋白质水平分别为33.61%和34.68%。随着饲料蛋白质水平的升高,台湾泥鳅脏体比和肝体比均呈先降低后趋于稳定的变化趋势,鱼体粗蛋白质含量呈先升高后趋于稳定的变化趋势,鱼体粗脂肪含量呈先降低后趋于稳定的变化趋势。结果提示,适量增加饲料蛋白质水平可提高鱼体生长速度,增加鱼体可食用部分比例,提高蛋白质效率和蛋白质沉积率,但饲料蛋白质水平过高,会降低蛋白质沉积率和蛋白质效率。在本试验条件下,综合考虑生长性能指标和蛋白质利用情况,台湾泥鳅适宜饲料蛋白质水平为33.61%~35.47%。

Effects of Dietary Protein Level on Growth Performance,Physical Indices and Body Composition of Taiwan Loach

This experiment was aimed to investigate the effects of dietary protein level on growth performance,physical indices and body composition of Taiwan loach.A total of 720 Taiwan loach with an initial body weight of (8.57±0.35) g were divided into 4 groups with 3 replicates per group and 60 fish per replicate.Four experimental diets were formulated with the protein levels of 25%,30%,35% and 40%,respectively.Each diet was fed to one group for 60 d.The results showed as follows: the final weight (FW) and weight gain rate (WGR) of Taiwan loach were initially increased and then tended to stabilize with the increase of dietary protein level.Both of FW and WGR reached the highest values when dietary protein level was 35%.The feed conversion ratio (FCR) was initially decreased and then tended to stabilize with the increase of dietary protein level,and the minimum value was obtained when dietary protein level was 40%.When dietary protein level raised from 35% to 40%,FW,WGR and FCR were not significantly changed (P>0.05).The broken line simulation results of WGR and FCR showed that the Taiwan loach had the highest growth rate when dietary protein level was 34.57%,and had lowest FCR when dietary protein level was 35.47%.With the increase of dietary protein level,all of protein efficiency ratio (PER),protein retention efficiency (PRE) and survival rate (SR) increased at first and then decreased.By quadratic polynomial regression analysis,dietary protein level was 33.6% and 34.68%,respectively,when the Taiwan loach had the highest PER and PRE.With the increase of dietary protein level,both of viscerasomatic index (VSI) and hepaticsomatic index (HSI) were initially decreased and then tended to stabilize.Crude protein content of whole body was initially increased and then tended to stabilize with the increase of dietary protein level,while crude lipid content of whole body was initially decreased and then tended to stabilize.The results indicate that appropriately increase of dietary protein level can improve fish growth rate,and increase edible part content of fish,improve the PRE and PER.But it can decrease PER and PRE when dietary protein level is too high.Under the conditions in the present experiment,the suitable dietary protein level is 34.57% to 35.47 based on comprehensive analysis of growth performance and protein utilization.