不同饲料料型及投喂频率对斑点叉尾鮰幼鱼生长及肌肉品质的影响

本研究旨在探究不同饲料料型及投喂频率对斑点叉尾鮰(Ictalurus punctatus)生长及肌肉品质的影响。研究采用双因素试验设计,以饲料料型(膨化饲料,EF;颗粒饲料,PF)和投喂频率(2次/日,F2;3次/日,F3)为影响因素,共4个组,分别命名为EFF2、PFF2、EFF3和PFF3,每组3个平行,投喂8周,每天定时投喂两次(7:30和16:30)或3次(7:30, 12:00, 16:30)。结果显示,斑点叉尾鮰的末重和增重率受到投喂频率的影响,F2组显著高于F3组(P0.05);而饲料料型则对斑点叉尾鮰的生长无显著影响(P0.05)。颗粒饲料组的肌肉粗脂肪含量和内聚性、回复性显著低于膨化饲料组(P0.05),而硬度显著高于膨化饲料组(P0.05)。F3组的肌肉硬度、胶着性和咀嚼性则显著高于F2组(P0.05)。颗粒饲料组生肌调节因子5 (myogenic factor 5, Myf5)和肌肉生长抑制素(myostatin,MSTN)基因的相对表达量显著低于膨化饲料组(P0.05)。F3组肌肉中MSTN基因相对表达量显著高于F2组,而肌细胞生成素(myogenin,MyoG)基因相对表达量则呈现相反趋势。综上,投喂同种配方的膨化饲料和颗粒饲料对斑点叉尾鮰的生长效果相似,但是投喂颗粒饲料的斑点叉尾鮰硬度更大,而投喂膨化饲料则肌肉脂肪含量更高;斑点叉尾鮰的最佳投喂频率是每天2次。

Effects of different feed types and feeding frequencies on growth and muscle quality of juvenile channel catfish (Ictalurus punctatus)

This study aimed to investigate different feed type and feeding frequency on growth and muscle quality of juvenile channel catfish (Ictalurus punctatus). A 2×2 design with three replicates was performed in this trial, which included feed type (extruded feed, EF; pellet feed, PF) and feeding frequency (twice daily, F2; three times daily, F3). In an 8-week trial, regular feeding twice (7:30 and 16:30) or three times (7:30, 12:00, 16:30) daily occurred, and the amount of feed was adjusted to keep all cages consistent. The results showed that the final weight and weight gain rate of channel catfish were influenced by the feeding frequency, the results from the F2 group were significantly higher than that of the F3 group (P<0.05); meanwhile, feed type did not affect the growth of channel catfish (P>0.05). The crude fat content, cohesiveness, and resilience of the pelleted feed group were significantly lower than that of the extruded feed group (P<0.05), whereas the hardness was significantly higher than the extruded feed group (P<0.05). The hardness, adhesiveness, and chewiness of the F3 group were significantly higher than that of the F2 group (P<0.05). The relative expression of myogenic factor 5 (Myf5) and myostatin (MSTN) genes in the pelleted feed group was significantly lower than that in the extruded feed group (P<0.05). The relative expression of the MSTN gene in muscle of the F3 group was significantly higher than that of the F2 group, but the relative expression of the myogenin (MyoG) gene showed the opposite trend. The present study indicated that the growth of channel catfish fed extruded feed was similar to those fed pelleted feed with the same formula. Fish fed pellet feed had higher hardness, whereas fish fed extruded feed had higher muscle fat content. The optimum feeding frequency of channel catfish was twice daily in this study.