饲料中不同碳水化合物水平对刺参幼参生长和能量收支的影响

Effects of dietary carbohydrate intake on the growth and energy budget of juvenile Apostichopus japonicus(Selenka) sea cucumbers

通过设置不同碳水化合物水平（25.61%,34.55%,45.31%,55.82%,66.09%）,探讨对刺参幼参[体重（1.67±0.06） g]生长、饲料利用、体组成和能量收支的影响。实验周期为60 d,每组设3个重复,每个重复40头幼参。结果表明：（1）随着摄食碳水化合物水平的升高,特定生长率和饲料转化率均呈现先上升后下降的趋势。基于 SGR和 FCE 的二次回归模型估算幼参碳水化合物的最适需求量为50.15%～53.95%；（2）蛋白质效率和摄食能在45.31%～66.09%碳水化合物水平组均显著高于25.61%～34.55%组,说明碳水化合物为幼参获得蛋白质节约效应提供了能量；（3）饲料中碳水化合物水平对幼参摄食率、排粪率和表观消化率均有显著性影响,适宜的碳水化合物水平会提高机体对营养物质的利用效率；（4）全参、体壁及消化道中粗脂肪含量均随摄食碳水化合物水平的升高而有所增加,表明摄食过量碳水化合物会造成幼参体组织脂肪的沉积；（5）在66.09%碳水化合物水平下,幼参生长能占摄食能的比例显著降低,粪能、排泄能及呼吸能占摄食能的比例有所升高,说明过高的碳水化合物水平会造成机体能量利用效率的降低。综上,适宜的碳水化合物水平可以促进幼参生长,提高饲料利用效率,而摄食过量碳水化合物会造成其体组织脂肪的沉积,并影响机体能量代谢水平。

Carbohydrates are widely included in aquafeed as the major non-protein energy source owing to their wide availability and low cost. This study evaluated the effects of the quantity of dietary carbohydrates （25.61%, 34.55%, 45.31%, 55.82%, 66.09%） on growth performance, feed utilization, body composition, and the energy budget of juvenile Apostichopus japonicus （Selenka） sea cucumbers. Sea cucumbers were given feed with the dif-ferent percentages of carbohydrates for 60 days, with 3-replicates per treatment and 40 sea cucumbers per replicate [ x ±SE： （1.67±0.06） g, body weight]. During the experiment, the specific growth rate and feed conversion effi-ciency initially increased then decreased with higher levels of dietary carbohydrates. Based on second-order polynomial regression models of these variables, optimal carbohydrate levels for the sea cucumber were estimated to be 50.15%–53.95%. The protein efficiency ratios and energy consumed were significantly higher in diets with 45.31%–55.09% carbohydrates than in those with 25.61%–34.55%, demonstrating that carbohydrates provided energy for protein sparing. Dietary carbohydrate intake had significant effects on sea cucumber feed intake, feces production, and apparent digestibility coefficient. Optimal carbohydrate intake enhanced the efficiency of nutrient utilization. Whole body, body wall, and intestinal crude lipid content all increased with higher levels of dietary carbohydrates, where excess carbohydrates resulted in tissue lipid deposition. In diets with 66.09% carbohydrates, the percentage of energy intake used for growth significantly decreased, while energy accounted for by feces, ex-cretion, and respiration increased, indicating that excess dietary carbohydrates reduced energy utilization effi-ciency. In conclusion, optimal levels of dietary carbohydrate intake promoted growth and feed utilization in thesea cucumber, while lipid deposition and energy metabolism variability resulted from excess dietary carbohydrates.