1 材料与方法
1.1 试验设计及饲料配制
1.2 饲养管理
1.3 样品采集
1.4 试验试剂和仪器
1.5 指标测定
1.5.1 生长性能和形体指标
1.5.2 肌肉纤维指标
1.5.3 肌肉质构指标
1.5.4 饲料及鱼肉营养成分含量
1.5.5 肌肉中土腥味物质含量
1.5.6 肠道消化酶活性
1.5.7 肠道组织切片形态学
1.5.8 前肠短链脂肪酸含量
1.5.9 DNA提取及16S rRNA基因测序
表1 基础饲料组成及营养水平(风干基础)Table 1 Composition and nutrient levels of the basal diet (air-dry basis) |
| 项目 Items | 含量 Content |
|---|---|
| 原料 Ingredients/(g/kg) | |
| 鱼粉 Fish meal | 360.0 |
| 豆粕 Soybean meal | 216.0 |
| 谷朊粉 Wheat gluten | 70.0 |
| 鱼油 Fish oil | 30.0 |
| 大豆油 Soybean oil | 20.0 |
| 小麦粉 Wheat meal | 212.0 |
| 酵母粉 Yeast meal | 20.0 |
| 卵磷脂 Lecithin | 25.0 |
| 矿物质预混料 Mineral premix1) | 20.0 |
| 维生素预混料 Vitamin premix2) | 20.0 |
| 抗氧化剂 Antioxidant | 0.5 |
| 诱食剂 Attractant | 3.0 |
| 防霉剂 Mold inhibitor | 1.0 |
| 氯化胆碱 Choline chloride | 2.5 |
| 合计 Total | 1 000.0 |
| 营养水平 Nutrient levels/%3) | |
| 粗蛋白质 Crude protein | 49.00 |
| 粗脂肪 Crude lipid | 9.00 |
| 粗灰分 Ash | 15.00 |
| 水分 Moisture | 8.00 |
1)矿物质预混料为每千克饲料提供 Mineral premix provided the following per kg of the diet:NaF2 2 mg,KI 1 mg,CoCl2 (1%) 50 mg,CuSO4 10 mg,Fe2(SO4)3 80 mg,ZnSO4 50 mg,CuSO4 60 mg,MgSO4 1 200 mg,Ca(H2PO4)2 8 000 mg,NaCl 100 mg,沸石粉 zeolite powder 10.447 g。 2)维生素预混料为每千克饲料提供 Vitamin premix provided the following per kg of the diet:VB1 21 mg,VB2 40 mg,VB6 20 mg,VB12 0.5 mg,VK3 10 mg,肌醇 inositol 800 mg,VB5 60 mg,烟酸 niacin 200 mg,叶酸 folic acid 20 mg,VH 1.5 mg,VA 32 mg,VD3 5 mg,VE 120 mg,VC 2 000 mg,胆碱 choline 2 000 mg,乙氧基喹啉 ethoxyquin 150 mg,微晶纤维素 microcrystalline cellulose 14.52 g。 3)营养水平为实测值。Nutrient levels were measured values. |
1.6 数据统计与分析
2 结果与分析
2.1 混合益生菌对大口黑鲈生长性能和形体指标的影响
表2 混合益生菌对大口黑鲈生长性能和形体指标的影响Table 2 Effects of mixed probiotics on growth performance and shape indexes of largemouth bass |
| 指标 Items | 组别 groups | ||
|---|---|---|---|
| CON | MP-0.1% | MP-1.0% | |
| 存活率 SR/% | 88.19±9.35 | 96.66±6.39 | 98.38±2.64 |
| 增重率 WGR/% | 360.37±60.44 | 367.10±81.37 | 420.81±30.81 |
| 饲料效率 FCR | 0.86±0.10 | 0.92±0.09 | 0.96±0.01 |
| 特定生长率 SGR/(%/d) | 1.17±0.10 | 1.18±0.14 | 1.27±0.05 |
| 肥满度 CF/(g/cm3) | 3.07±0.20 | 3.11±0.15 | 2.99±0.04 |
| 肝体比 HI/% | 2.01±0.15 | 2.16±0.57 | 2.03±0.25 |
| 脏体比 VI/% | 7.26±1.34 | 8.01±1.09 | 7.41±1.19 |
同行数据肩标不同小写字母表示差异显著(P<0.05),相同或无字母表示差异不显著(P>0.05)。下表同。 | |
In the same row, values with different small letter superscripts mean significant difference (P<0.05), while with the same or no letter superscripts mean no significant difference (P>0.05). The same as below. |
2.2 混合益生菌对大口黑鲈肉品质的影响
2.2.1 肌肉纤维形态分析
图1 混合益生菌对大口黑鲈肌肉纤维形态的影响a~c:横切面肌肉纤维结构,放大100倍;a:CON组,b:MP-0.1%组,c:MP-1.0%组。d~e:肌肉纤维直径和肌肉纤维密度。MF:肌肉纤维。 Fig.1 Effects of mixed probiotics on myofiber morphology of largemouth bass a to c: myofiber structure of cross sections, magnification is 100; a: CON group, b: MP-0.1% group, c: MP-1.0% group. d and e: myofiber diameter and myofiber density. MF: myofiber. |
2.2.2 肌肉质构特性分析
2.2.3 肌肉营养成分分析
图3 混合益生菌对大口黑鲈肌肉营养成分含量的影响Asp:天冬氨酸;Thr:苏氨酸;Ser:丝氨酸;Glu:谷氨酸;Ala:丙氨酸;Gly:甘氨酸;Val:缬氨酸;Cys:半胱氨酸;Met:蛋氨酸;Ile:异亮氨酸;Leu:亮氨酸;Phe:苯丙氨酸;Tyr:酪氨酸;Lys:赖氨酸;His:组氨酸;Arg:精氨酸;DAA:鲜味氨基酸(天冬氨酸+谷氨酸);SAA:甜味氨基酸(丝氨酸+甘氨酸+丙氨酸);FAA:风味氨基酸(鲜味氨基酸+甜味氨基酸);EAA:必需氨基酸;TAA:总氨基酸;SFA:饱和脂肪酸;MUFA:单不饱和脂肪酸;PUFA:多不饱和脂肪酸;UFA:不饱和脂肪酸。*表示差异显著(P<0.05)。 Fig.3 Effects of mixed probiotics on muscle nutrient contents of largemouth bass Asp: aspartate; Thr: threonine; Ser: serine; Glu: glutamate; Ala: alanine; Gly: glycine; Val: valine; Cys: cysteine; Met: methionine; Ile: isoleucine; Leu: leucine; Phe: phenylalanine; Tyr: tyrosine; Lys: lysine; His: histidine; Arg: arginine; DAA: delicious amino acids (Asp+Glu); SAA: sweet amino acids (Ser+Gly+Ala); FAA: flavor amino acids (DAA+SAA); EAA: essential amino acids; TAA: total amino acids; SFA: saturated fatty acids; MUFA: monounsaturated fatty acids; PUFA: polyunsaturated fatty acids; UFA: unsaturated fatty acids. * mean significantly different (P<0.05). |
2.2.4 肌肉中土腥味物质含量分析
2.3 混合益生菌对大口黑鲈肠道健康的影响
2.3.1 肠道消化酶活性分析
2.3.2 肠道组织形态分析
图6 混合益生菌对大口黑鲈肠道组织形态的影响a~f:横切面肠道组织形态;a~c为放大50倍,d~f为放大150倍,a和d为CON组,b和e为MP-0.1%组,c和f为MP-1.0%组。M:肌层厚度;VW:绒毛宽度;VH:绒毛高度。 Fig.6 Effects of mixed probiotics on intestinal morphology of largemouth bass a to f: intestinal morphology in cross section; a to c magnification is 50, d to f magnification is 150; a and d were CON group, b and e were MP-0.1% group, c and f were MP-1.0% group. M: muscular layer thickness; VW: villous width; VH: villous height. |
2.3.3 肠道短链脂肪酸含量分析
表3 混合益生菌对大口黑鲈肠道短链脂肪酸含量的影响Table 3 Effects of mixed probiotics on intestinal short-chain fatty acid contents of largemouth bassmmol/mg |
| 项目 Items | 组别 Groups | ||
|---|---|---|---|
| CON | MP-0.1% | MP-1.0% | |
| 乙酸 Acetic acid | 18.51±3.09 | 18.94±1.95 | 19.50±3.19 |
| 丙酸 Propanoic acid | 3.27±1.34 | 3.39±1.04 | 3.56±0.93 |
| 丁酸 Butyric acid | 3.29±1.74 | 3.43±1.76 | 3.61±1.11 |
| 异戊酸 Isovaleric acid | 4.68±2.00a | 4.73±2.04a | 6.36±2.01b |
| 总酸 Total acid | 29.76±2.56a | 30.49±2.85ab | 33.03±4.69b |
2.3.4 肠道菌群分析
图8 混合益生菌对大口黑鲈肠道菌群组成的影响(相对丰度前10)Phylum level:门水平;Family level:科水平;Genus level:属水平。Firmicutes:厚壁菌门;Proteobacteria:变形菌门;Cyanobacteria:蓝藻门;Actinobacteriota:放线菌门;Bacteroidota:拟杆菌门;Patescibacteria:候选菌门;Fusobacteriota:梭杆菌门;Chloroflexi:绿弯菌门;Verrucomicrobiota:疣微菌门;Synergistota:互养菌门。Mycoplasmataceae:支原体科;Alcaligenaceae:产碱菌科;Moraxellaceae:莫拉氏菌科;Rhodospirillaceae:红螺菌科;Peptostreptococcaceae:消化链球菌科;norank_o_Chloroplast:叶绿体;Pseudomonadaceae:假单胞菌科;Lactobacillaceae:乳杆菌科;Lachnospiraceae:毛螺菌科;Sphingobacteriaceae:鞘氨醇杆菌科。Mycoplasma:支原体菌属;Pedobacter:土地杆菌属;Lactobacillus:乳酸杆菌属;Mycobacterium:分支杆菌属;Achromobacter:无色杆菌属;Acinetobacter:不动杆菌属;Pseudomonas:假单胞菌属;Romboutsia:罗姆布茨菌属。 Fig.8 Effects of mixed probiotics on gut microbiota composition of largemouth bass (top 10 relative abundance) A: histogram of the horizontal composition of the intestinal flora phylum; B: histogram of the horizontal composition of the intestinal flora family; C: pie chart of genus-level composition of the intestinal flora. |
图9 混合益生菌对大口黑鲈肠道菌群属水平组成的影响(相对丰度前30)Cyanobium:蓝藻菌属;Lactococcus:乳球菌属;Stenotrophomonas:寡养单胞菌属;Prevotella:普氏菌属;Succiniclasticum:琥珀酸弧菌属;Butyrivibrio:丁酸弧菌属;Saccharofermentans:产乙酸糖发酵菌属;Christensenellaceae R-7_group:克里斯滕森菌科R-7组;norank_f_norank_o_Clostridia_UCG-014:梭状芽孢杆菌属UCG-014;Lachnospiraceae_XPB1014_group:毛螺菌科XPB1014组;Weissella:魏斯氏菌属;Peptostreptococcus:消化链球菌属;Cetobacterium:鲸杆菌属。 Fig.9 Effects of mixed probiotics on genus level composition of gut microbiota of largemouth bass (top 30 relative abundance) * mean significant difference (P<0.05). |

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