Effect of Tryptophan on Growth Performance and Digestive Enzyme Activity of Juvenile Yellow Catfish
In this study, a 56-day culture experiment was carried out on yellow catfish (Pelteobagrus fulvidraco) to study the effects of different tryptophan concentrations in feed on the growth performance and digestive enzyme activity of juvenile yellow catfish. A total of 300 juveniles (1.77 ± 0.08 g) were randomly divided into 15 tanks in 5 groups with 3 replicates in each group. Different levels of tryptophan (0.44%, 0.68%, 0.85%, 1.08% and 1.32%) were added to the base feed to prepare five isonitrogen isolipids (protein level 39%, fat level 7%). Artificial feeding twice a day to achieve a state of apparent satiety. The results showed that: 1) With the increase of tryptophan level in the diet, the terminal body weight and specific growth rate of juvenile yellow catfish showed a trend of first increasing and then decreasing, reaching the maximum value in the 0.85% group. The terminal body weight of the 0.85% group was significantly higher than that of the other treatment groups (P < 0.05). 2) In the 0.85% group, the liver amylase activity of juvenile yellow catfish reached the highest, and the activities of gastric lipase, pepsin and liver lipase reached the highest in the 1.08% group. Conclusion: The level of tryptophan added to the feed is between 0.85% and 1.08%, which can increase the terminal body weight and specific growth rate of juvenile yellow catfish, and enhance the digestion and absorption capacity.
Yellow Catfish (Pelteobagrus fulvidraco)
黄颡鱼(Pelteobagrus fulvidraco)隶属于鲇形目、鲿科、黄颡鱼属。黄颡鱼肉质鲜嫩且无肌间刺,味道鲜美,营养丰富,具有滋补作用和药用价值
色氨酸对消化道的发育、稳态及生理功能具有调节作用,其调节作用主要是通过在小肠嗜铬细胞内转化成的褪黑色素和5-羟色胺等中间代谢产物以及诱导产生的胰岛素样生长因子(IGFs)而发挥作用的;并且,通过5-羟色胺、褪黑激素和IGFs等能够实现对动物机体免疫防御系统的调节
本试验拟通过研究饲料中色氨酸水平对黄颡鱼幼鱼生长性能和消化酶活性的影响,以期得出黄颡鱼幼鱼色氨酸的最适需要量,为黄颡鱼幼鱼配合饲料的生产提供可靠的理论依据。
以豆粕、鱼粉、玉米蛋白粉和小麦蛋白粉为蛋白质源,糊精为糖源,豆油、鱼油、大豆卵磷脂为脂肪源,添加色氨酸(L-色氨酸,纯度≥98%,购自北京索莱宝科技有限公司),配置成色氨酸水平分别为0.44%、0.68%、0.85%、1.08%和1.32%的5组等氮等脂的实验饲料。将饲料原料粉碎后,过筛(80目),采取逐级稀释法混合氨基酸和微量添加成分,添加豆油、鱼油和大豆卵磷脂以及适量的水,混匀,压制成粒径为2~3 mm的颗粒饲料。风干后分组收入密封袋,置于4℃冰箱保存备用。试验饲料组成及营养水平见
项目Items | 饲料色氨酸水平Dietary tryptophan level/% | ||||
0.44 | 0.68 | 0.85 | 1.08 | 1.32 | |
原料Ingredients | |||||
鱼粉Fish meal | 25 | 25 | 25 | 25 | 25 |
豆粕Soybean meal | 30 | 30 | 30 | 30 | 30 |
小麦蛋白粉Wheat gluten meal | 9 | 9 | 9 | 9 | 9 |
玉米蛋白粉Corn gluten meal | 6 | 6 | 6 | 6 | 6 |
豆油Soybean oil | 2.1 | 2.1 | 2.1 | 2.1 | 2.1 |
鱼油Fish oil | 2.1 | 2.1 | 2.1 | 2.1 | 2.1 |
大豆卵磷脂Soybean lecithin | 0.8 | 0.8 | 0.8 | 0.8 | 0.8 |
糊精Dextrin | 21.4 | 21.4 | 21.4 | 21.4 | 21.4 |
维生素预混料Vitamin premix | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 |
矿物质预混料Mineral premix | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 |
磷酸二氢钙Ca(H2PO4)2 | 1.5 | 1.5 | 1.5 | 1.5 | 1.5 |
氯化胆碱Choline chloride | 0.3 | 0.3 | 0.3 | 0.3 | 0.3 |
色氨酸Trp | 0 | 0.3 | 0.6 | 0.9 | 1.2 |
甘氨酸Gly | 1.2 | 0.9 | 0.6 | 0.3 | 0 |
合计Total | 100.00 | 100.00 | 100.00 | 100.00 | 100.00 |
营养水平Nutrient levels | |||||
粗蛋白质CP | 39.14 | 39.26 | 39.12 | 39.58 | 39.41 |
粗脂肪EE | 7.34 | 7.31 | 7.42 | 7.28 | 7.39 |
水分Moisture | 9.48 | 9.57 | 9.27 | 9.63 | 9.18 |
试验用鱼为购自广东市恒洋养殖发展有限公司的黄颡鱼幼鱼。养殖试验在室内循环水养殖系统中进行,养殖用水为过滤并曝气的自来水。试验开始前,将黄颡鱼幼鱼暂养14 d,期间投喂商品饲料,每日早晚1次(8:00和18:00)。之后,选取黄颡鱼幼苗(1.77 ± 0.08 g) 300尾,随机分为5组,每组3个重复,每个重复20尾鱼,以重复为单位放养于圆形水族桶内,分别投喂5种色氨酸水平的试验饲料。每日投喂2次。试验期为56 d。
试验结束后,停食24 h,对每个桶的黄颡鱼进行计数、称重。每桶内随机抽取5尾鱼,测量体长和体重,于冰上迅速解剖和分离出肝脏、肠道、胃组织,−20℃保存,用于消化酶活性的测定。
采用试剂盒(购自南京建成生物工程研究所)检测肝脏、胃和肠道组织的消化酶活性,具体操作方法参照说明书执行。
采用SPSS 17.0统计软件进行单因素方差分析(one-way ANOVA),并利用Duncan氏法进行组间的多重比较,差异显著性水平为P < 0.05。试验数据表示为平均值 ± 标准差(mean ± SD)。
通过在饲料中添加色氨酸,随着色氨酸水平的提高,黄颡鱼幼鱼的终末体重和特定生长率,呈现先升后降的趋势,在0.85%组达到最大值。0.85%组的终末体重显著高于其他组(P < 0.05)。随着色氨酸水平的提高,各组的特定生长率、肥满度、肝体比、脏体比和成活率没有显著差异(P > 0.05) (
通过在饲料中添加色氨酸,随着色氨酸水平的提高,黄颡鱼幼鱼的肝脏淀粉酶、肝脏脂肪酶、胃脂肪酶和胃蛋白酶活性,呈现先升后降的趋势。其中,0.85%组的肝脏淀粉酶活性显著高于0.44%组和0.68%组(P < 0.05)。1.08%组的胃脂肪酶和肝脏脂肪酶活性显著高于0.44%组、0.68%组和0.85%组(P < 0.05),与1.32%组的活性无显著差异(P > 0.05)。1.08%组的胃蛋白酶活性显著高于其他各组(P < 0.05) (
项目Items | 饲料色氨酸水平Feed tryptonphan levels/% | ||||
0.44 | 0.68 | 0.85 | 1.08 | 1.32 | |
初始体重IBW/g | 1.77 ± 0.08 | 1.79 ± 0.08 | 1.78 ± 0.08 | 1.78 ± 0.03 | 1.78 ± 0.05 |
终末体重FBW/g | 11.99 ± 0.75a | 12.25 ± 0.37a | 13.42 ± 0.70b | 12.29 ± 0.65a | 12.07 ± 0.77a |
特定生长率SGR/(%/d) | 1.47 ± 0.09 | 1.49 ± 0.09 | 1.56 ± 0.06 | 1.49 ± 0.08 | 1.48 ± 0.08 |
肥满度CF/% | 1.92 ± 0.45 | 1.97 ± 0.39 | 1.88 ± 0.34 | 1.93 ± 0.31 | 1.92 ± 0.46 |
肝体比HSI/% | 5.98 ± 1.62 | 6.11 ± 1.20 | 6.18 ± 1.04 | 6.19 ± 0.81 | 6.25 ± 0.90 |
脏体比VSI/% | 1.30 ± 0.10 | 1.31 ± 0.17 | 1.33 ± 0.13 | 1.38 ± 0.17 | 1.39 ± 0.18 |
成活率(SR, %) | 95.37 ± 1.57 | 98.55 ± 2.75 | 98.41 ± 2.94 | 96.17 ± 3.15 | 94.31 ± 3.67 |
注:同行数据肩标无字母或相同字母表示差异不显著(P > 0.05),不同小写字母表示差异显著(P < 0.05)。下表同。
项目Items | 饲料色氨酸水平Feed tryptonphan levels/% | |||||
0.44 | 0.68 | 0.85 | 1.08 | 1.32 | ||
淀粉酶Amylase/(U/mg prot) | 胃Stomach | 0.25 ± 0.06 | 0.21 ± 0.02 | 0.29 ± 0.01 | 0.27 ± 0.02 | 0.26 ± 0.08 |
肝脏Liver | 0.06 ± 0.01a | 0.09 ± 0.04a | 0.16 ± 0.02b | 0.12 ± 0.04ab | 0.09 ± 0.05ab | |
肠道Intestine | 0.20 ± 0.03 | 0.27 ± 0.01 | 0.29 ± 0.02 | 0.26 ± 0.02 | 0.21 ± 0.02 | |
脂肪酶Lipase/(U/g prot) | 胃Stomach | 98.69 ± 5.43a | 109.74 ± 20.79a | 101.45 ± 6.18a | 157.54 ± 17.99b | 129.40 ± 11.06ab |
肝脏Liver | 91.85 ± 7.76a | 83.59 ± 12.12a | 115.16 ± 4.90a | 138.70 ± 24.73b | 128.74 ± 2.79ab | |
肠道Intestine | 176.18 ± 22.55 | 169.03 ± 28.57 | 185.48 ± 28.51 | 181.88 ± 10.53 | 161.27 ± 24.37 | |
蛋白酶Protease/(U/mg prot) | 胃Stomach | 5.61 ± 0.22a | 6.05 ± 0.14a | 5.94 ± 0.24a | 6.42 ± 0.09b | 6.09 ± 0.17a |
肝脏Liver | 3.18 ± 0.25 | 3.21 ± 0.78 | 3.53 ± 0.27 | 3.65 ± 0.59 | 3.50 ± 0.37 | |
肠道Intestine | 5.97 ± 0.94 | 5.84 ± 1.18 | 6.50 ± 0.44 | 5.72 ± 1.29 | 5.58 ± 0.70 |
色氨酸是动物生长发育的必需氨基酸之一,不仅参与多肽及氨基酸的合成,而且对合成过程还具有调节作用。研究表明,色氨酸能够促进杂交江鲿
消化酶是生物机体分泌的消化液中所含有的一类特殊蛋白质,主要作用是将食物分解为机体能够吸收的小分子物质,为生长和发育提供各种营养物质
试验结果表明,饲料中添加色氨酸水平为0.85%~1.08%之间,可提高黄颡鱼幼鱼的终末体重和特定生长率,增强消化吸收能力。
江西省教育厅科学技术研究项目(GJJ205509);江西生物科技职业学院科研基金项目(19Y11)。