饲料中添加牛乳铁蛋白肽对大口黑鲈幼鱼生长性能、消化酶活力、肠道组织结构及抗病力的影响

为探讨饲料中添加不同水平牛乳铁蛋白肽(Bovine lactoferricin, LfcinB)对大口黑鲈(Micropterus salmoides)幼鱼生长性能、消化酶活力、肠道组织结构及抗病力的影响,试验选取了初均重为(19.88±0.03) g的450尾大口黑鲈,随机分成5组,每组3个重复,分别在基础饲料中添加0(阴性对照组)、1000、1500和2000 mg/kg牛乳铁蛋白肽,并设置基础饲料+30 mg/kg氟苯尼考为阳性对照组,共5种试验饲料。试验周期为8周。结果表明:(1)随着牛乳铁蛋白肽添加量的增加,大口黑鲈的末均重(FBW)、增重率(WGR)和特定生长率(SGR)均呈现先升高后降低的趋势, 1000 mg/kg牛乳铁蛋白肽组大口黑鲈的生长性能最好且与对照组(阴性对照、阳性对照)对应数据差异显著(P<0.05)。(2)与两个对照组比, 1000 mg/kg牛乳铁蛋白肽组大口黑鲈的肠道胰蛋白酶、α-淀粉酶和脂肪酶活力均显著上升(P<0.05)。(3)与两个对照组比,饲料中添加1000 mg/kg牛乳铁蛋白肽可显著提高大口黑鲈前肠、中肠及后肠的绒毛高度和宽度(...

DIETARY SUPPLEMENTATION OF BOVINE LACTOFERRICIN ON GROWTH PERFORMANCE,DIGESTIVE ENZYMES ACTIVITY,INTESTINAL TISSUE STRUCTURE AND DISEASE RESISTANCE OF JUVENILE LARGEMOUTH BASS (MICROPTERUS SALMOIDES)

Largemouth bass (Micropterus salmoides), commonly known as California bass, has been introduced to China since the 1980s. After years of breeding development, it has now become one of the important species of freshwater aquaculture in China. However, with the rapid development of intensive aquaculture and irregular feeding methods, California bass diseases frequently occur. The traditional method to prevent and treat bacterial diseases in fish is to add antibiotics to aquafeeds. However, the abuse of antibiotics can lead to problems such as bacterial resistance, drug residues and environmental pollution. Therefore, the selection of suitable antibiotic substitutes for the aquaculture industry is an urgent matter, and it has far-reaching significance for the growing largemouth bass aquaculture industry. Research on alternatives to antibiotics has found that antimicrobial peptides are a kind of polypeptides produced by the non-specific immune system in organisms. Because of their unique biological activity, antibacterial and bactericidal mechanisms different from traditional antibiotics, they are not easy to produce drug resistance and no resistance. Pollution and other advantages are expected to be developed into a new type of high-efficiency antibacterial drugs, which have great potential to replace antibiotics in the field of feed additives. The bovine lactoferricin (LfcinB) used in this test is a cationic antimicrobial peptide containing 25 amino acid residues produced by pepsin hydrolysis of bovine lactoferrin under acidic conditions. It has a broad-spectrum and high-efficiency antibacterial ability and antiviral ability. However, its research as a feed additive has not been reported yet. This study investigated the effect of the dietary supplementation of bovine lactoferricin on growth performance, digestive enzymes activity, intestinal tissue structure and disease resistance against Aeromonas hydrophila in juvenile largemouth bass, aiming to evaluate its potential to replace antibiotics and provide a theoretical basis with the application of functional feed. A total of 450 tails largemouth bass with an average body weight of (19.88±0.03) g were randomly allocated into 5 groups with 3 replicates per group, and fed with basal diet (negative control), basal diet supplemented with 30 mg/kg florfenicol (positive control), basal diet supplemented with 1000, 1500, and 2000 mg/kg bovine lactoferricin, respectively. The experiment lasted for 8 weeks. The results showed that: (1) With the increase of the addition of bovine lactoferricin, final body weight (FBW), weight gain rate (WGR) and specific growth rate (SGR) of largemouth bass showed a trend of first increasing and then decreasing. The 1000 mg/kg bovine lactoferricin group had the best growth performance of largemouth bass, which was significantly different from the negative and positive control groups (P<0.05). (2) Compared with the negative and positive control groups, the intestinal trypsin, α-amylase and lipase activities of the 1000 mg/kg bovine lactoferricin group of largemouth bass increased significantly (P<0.05). (3) Compared with the negative and positive control groups, the addition of 1000 mg/kg bovine lactoferricin to feed could significantly increase the height and width of villi of the foregut, midgut and hindgut of largemouth bass (P<0.05). (4) After challenge with Aeromonas hydrophila, the survival rates of largemouth bass in the bovine lactoferricin groups were higher than that of the negative control group, but there were no significant differences from the positive control group (P>0.05). In summary, under the experimental conditions, the addition of bovine lactoferricin to feed could improve growth performance of juvenile largemouth bass, and the appropriate dosage was 1000 mg/kg. At the same time, bovine lactoferricin could increase the intestinal digestive enzyme activity of largemouth bass, improve intestinal tissue structure, and improve disease resistance.