低磷饲料添加山梨酸对松浦镜鲤生长、肠道健康及磷吸收的影响

Effects of sorbic acid supplementation in low phosphorus diety on growth, intestinal health and phosphorus metabolism of Songpu mirror carp (Cyprinus carpio Songpu)

  • 摘要:
    目的 研究低磷饲料中添加山梨酸对松浦镜鲤幼鱼生长、肠道健康及磷吸收的影响。
    方法 选用初始体重(5.07±0.02) g的松浦镜鲤,进行养殖实验,为期8周。共制备5组饲料,以磷酸二氢钠为磷源,对照组(C)磷添加水平为2%;试验组磷添加水平为1.5%,分别添加不同水平的山梨酸,0%(S0)、0.5%(S0.5)、1%(S1)、2%(S2)。
    结果 ①与S0组相比,S1组终末体重、增重率(WGR)、全鱼粗蛋白与粗灰分含量显著升高,饲料系数(FCR)与全鱼粗脂肪含量显著降低,均与C组无显著性差异。②S1组血清磷(P)含量显著高于C组与S0组;添加山梨酸组的血清尿素氮(BUN)含量显著低于C组与S0组。③S1、S2组前肠与山梨酸各添加组中肠和后肠的胰蛋白酶活性显著高于S0组,与C组无显著性差异。④S1组各肠段总抗氧化能力(T-AOC)、中肠超氧化物歧化酶(SOD)、还原性谷胱甘肽(GSH)显著高于C组与S0组;S1组前、中肠过氧化氢酶(CAT)显著高于S0组,且与C组无显著性差异。⑤与S0组相比,山梨酸各添加组的前肠及S1、S2组后肠的皱襞高度显著升高,且与C组无显著性差异。S1组后肠绒毛宽度显著高于其他低磷组,且与C组无显著性差异。S1组基层厚度显著高于S0组且与C组无显著性差异。⑥山梨酸各添加组前肠IIb型钠依赖性磷酸盐转运体(NaPi-b)的表达量显著低于S0组,S0.5与S1组后肠NaPi-b的表达量显著低于S0组;各山梨酸添加组前肠钠钾依赖型ATP酶(Na+-K+-ATP)的表达量与C组无显著性差异;S2组AKP表达量显著高于其他各组。
    结论 在低磷饲料中添加1%的山梨酸能够调节消化酶活性,改善肠道健康,促进磷吸收,最终提高松浦镜鲤的生长性能。为研究山梨酸对松浦镜鲤幼鱼的磷吸收影响提供理论依据,同时为水产养殖水环境的绿色发展提供支持。

     

    Abstract: This study aimed to explore how sorbic acid supplementation in low-phosphorus feed affects the growth, intestinal health, and phosphorus absorption of juvenile Songpu mirror carp (Cyprinus carpio Songpu). Juvenile C. carpio Songpu with an initial body weight of (5.07±0.02) g were fed for 8 weeks. Five experimental diets were formulated: monosodium dihydrogen phosphate was used as the phosphorus source, the phosphorus supplementation level was set at 2% for the control group (C); for the experimental groups, the phosphorus supplementation level was fixed at 1.5%, namely 0% (S0), 0.5% (S0.5), 1% (S1) and 2% (S2). The results showed that: Compared with the S0 group, the final body weight, weight gain rate (WGR), crude protein and crude ash contents in the whole fish of the S1 group were significantly increased, while the feed conversion ratio (FCR) and crude lipid content in the whole fish were significantly decreased. Moreover, all these indices showed no significant difference from those of the C group. The S1 group showed a marked increase in serum phosphorus concentration relative to the C and S0 groups. In contrast, serum urea nitrogen (BUN) concentrations were significantly reduced in the S0.5, S1, and S2 groups compared to the C and S0 groups. After sorbic acid supplementation, the trypsin activities in the foregut of the S1 and S2 group, as well as in the midgut and hindgut of all sorbic acid-supplemented groups, were significantly higher than those in the S0 group, with no significant differences from the C group. In the S1 group, the total antioxidant capacity (T-AOC) in all intestinal segments, as well as superoxide dismutase (SOD) and reduced glutathione (GSH) in the midgut, were significantly higher than those in the C and S0 group. Additionally, catalase (CAT) activities in the foregut and midgut of the S1 group were significantly higher than those in the S0 group and showed no significant difference from the C group. Compared with the S0 group, the fold heights of the foregut in all sorbic acid supplemented groups, as well as those of the hindgut in the S1 and S2 groups, were significantly increased and did not differ from those of the C group. The villus width in the hindgut of the S1 group was not significantly different from that of the C group but was significantly higher than that of other low-phosphorus groups. The muscular thickness in the S1 group was significantly higher than that in the S0 group but showed no significant difference compared to the C group. The expression levels of type IIb sodium-dependent phosphate transporter (NaPi-b) in the foregut of all sorbic acid-supplemented groups were significantly lower than those in the S0 group.; the expression level of NaPi-Ⅱb in the hindgut of the S0.5 and S1 groups was significantly lower than that in the S0 group. The expression level of sodium-potassium-dependent ATPase (Na+-K+-ATP) in the foregut of sorbic acid-supplemented groups showed no significant difference from that in the C group. The expression level of AKP in the S2 group was significantly higher than that in all other group. In conclusion, dietary supplementation of 1% sorbic acid in low-phosphorus diets can regulate digestive enzyme activities, improve intestinal health, promote phosphorus absorption, and ultimately enhance the growth performance of C. carpio Songpu .

     

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