零鱼粉饲料与高鱼粉饲料饲喂下凡纳对虾饲料利用效率相关性状的遗传评估

Genetic Evaluation of Feed Efficiency Traits of Pacific White Shrimp(Penaeus vannamei)Fed Zero-and High Fishmeal Diets

为探讨选育零鱼粉需求凡纳对虾(Penaeus vannamei)品种的可能性,解决目前鱼粉短缺、饲料成本居高不下的问题,本研究在零鱼粉饲料(蛋白含量占38%)和高鱼粉饲料(鱼粉含量占25%,蛋白含量占42%)饲喂条件下进行凡纳对虾饲料利用效率相关性状的遗传评估。选择30个家系进行40 d的单尾饲养实验,结果显示,饲喂高鱼粉饲料对虾的平均增重率(62.00%)和平均饲料效率比(124.00%)明显高于饲喂零鱼粉饲料(23.50%和49.40%)。对虾摄食量和增重率在零鱼粉饲料和高鱼粉饲料饲喂下的遗传力在0.458±0.140到0.699±0.155之间,饲料效率比在零鱼粉饲料和高鱼粉饲料饲喂下的遗传力分别为0.186±0.098和0.341±0.110。由于没有剖分出共同环境效应,遗传力都存在一定程度高估,因此,零鱼粉饲料饲喂下的饲料效率比的遗传变异并不高。摄食量和增重率在2种饲料间的遗传相关分别为0.580±0.171和0.676±0.155,表示这2个性状存在中等的基因型与饲料互作效应。饲料效率比在2种饲料间的遗传相关仅为0.299±0.304,表示该性状存在严重的基因型与饲料互作效应。综上结果来看,使用零鱼粉饲料不利于凡纳对虾的养殖及选育工作的开展。

Pacific white shrimp Penaeus vannamei,as one of the most productive and economically valuable shrimp species in the world,have many favorable characteristics,such as a short growth cycle,strong adaptability and disease resistance,and a low nutritional demand.They are omnivorous animals whose diet mainly consists of animal-derived food.Conventional feed used in their culture contains fishmeal as the main protein source.Feed costs account for 40%~60%of their production costs.Therefore,breeding P.vannamei strains without demand for fishmeal would be an effective way to address the issues of fishmeal shortage and high feed costs.Improving utilization efficiency for diets without fishmeal is key to breeding such P.vannamei strains.In this study,genetic parameters for feed efficiency traits(feed efficiency ratio,feed intake,and weight gain)and genotype by environment interaction were evaluated using two diets,one without fishmeal(38%protein)and one with 25%fishmeal(42%protein).Thirty families of P.vannamei were selected for a 40-day feeding experiment.A total of 900 shrimp(30 animals per family)were selected.Fifteen animals per family were fed a zero-fishmeal diet,and the other 15 animals were fed a high fishmeal diet.The feed intake and body weight of all animals were measured for calculating the feed efficiency ratio and weight gain.The variance components for these traits were estimated using a univariate model and an average information restricted maximum likelihood algorithm,and genetic(phenotypic)correlations between traits were estimated using bivariate analysis.The results showed that shrimp fed a high fishmeal diet exhibited a significantly higher mean weight gain(62.00%)and feed efficiency ratio(124.00%)than those fed a zero-fishmeal diet,which had a mean weight gain of 23.50%and feed efficiency ratio of 49.40%.There was a small difference in the mean feed intake between shrimp fed a high fishmeal diet(7.09 g)and those fed a zero-fishmeal diet(7.28 g).The heritability estimates for feed intake of shrimp fed zero-and high fishmeal diets were 0.699±0.155 and 0.556±0.139,respectively.For weight gain,the heritability estimates of shrimp fed zero-and high fishmeal diets were 0.458±0.140 and 0.667±0.146,respectively,which were high.However,the differences between diets and between traits were not statistically significant(P>0.05).The heritability estimates for feed efficiency ratio of shrimp fed zero-and high fishmeal diets were 0.186±0.098 and 0.341±0.110,respectively,which were low to medium.The differences in feed efficiency ratio between diets was not statistically significant(P>0.05).All the above heritability estimates were overestimated,to some extent,because common environmental effects were not estimated.Therefore,there was not much genetic variation in feed efficiency ratio in shrimp fed a zero-fishmeal diet,suggesting limited potential in selection breeding of this trait.Regardless of diet,genetic correlations among feed intake,weight gain,and feed efficiency ratio were moderate to high(0.580±0.188 to 0.945±0.040).Genetic correlations between diets were 0.580±0.171 and 0.676±0.155 for feed intake and weight gain,respectively,indicating that these two traits had moderate genotype by diet interactions.The genetic correlation between diets was only 0.299±0.304 for feed efficiency ratio,which indicates a serious genotype by diet interaction.According to the above results,use of a zero-fishmeal diet is not good for the culture and breeding of P.vannamei.In the future,fishmeal content in the diet may be appropriately increased,and genetic parameters and potential feed efficiency traits should be evaluated in low fishmeal diets.