杂交对皖西白鹅繁殖性能的影响

本文阐述了利用繁殖性能高的四川白鹅、太湖鹅、豁眼鹅分别作父本,以皖西白鹅为母本进行杂交,再用3个杂交组F1代为母本,以皖西白鹅为父本,进行回交,设皖西白鹅为对照组,研究杂交对皖西白鹅繁殖性能的影响。结果表明四川白鹅、豁眼鹅与皖西白鹅杂交,其后代繁殖性能提高,其中以川皖鹅的繁殖性能最好。     

对种鹅进行人工授精是提高鹅群繁殖力的有效措施

<正>1种鹅的科学饲养管理1.1种鹅的选择我国地方种鹅的品种较多,常见白羽种鹅有:闽北白鹅、莲花白鹅、广丰白翎鹅、百子鹅、武风铜鹅、织金白鹅、四川白鹅、溆浦白鹅、白籽鹅、太湖鹅、浙东白鹅、豁眼白鹅、皖西白鹅等;常见灰羽种鹅有:永康灰鹅、狮头鹅、伊梨灰鹅、钢灰鹅、右江鹅、马岗鹅、阳江鹅、乌鬃灰鹅、丰城灰鹅、兴国灰     

四川白鹅催乳素基因内含子2的SNP及序列分析

以四川白鹅为材料,用PCR-SSCP方法检测了PRL基因内含子2扩增片段,结果在群体中共检测到AA、AB两种基因型。对不同基因型个体测序分析发现,四川白鹅PRL基因内含子2上存在一个新的SNP(A126G)位点。此外,将测序获得的四川白鹅PRL基因内含子2序列与GenBank上发表的皖西白鹅、浙东白鹅、马岗鹅、莱茵鹅PRL基因序列比对发现,鹅PRL基因内含子2区段存在一个(GA)n简单重复序列,且浙东白鹅、马岗鹅、莱茵鹅相比四川白鹅和皖西白鹅少一个GA重复,即存在一个简单重复序列多态性位点。     

聊城市引进良种鹅的适应性观察

对五龙鹅、四川白鹅、皖西白鹅和莱茵鹅等品种在鲁西北气候条件下进行饲养观测,12周龄体重分别达到3102g、3161g、3576g和3596g,当年9—10月开产至次年4月产蛋结束,产蛋持续时间183～210d,平均产蛋数42.0枚/只,产蛋率19.1%,四个引进品种适应性都较好。     

高温季节洋二元杂种经产母猪哺乳期对颗粒饲料赖氨酸需要量的初探

试验旨在研究饲粮不同蛋白质水平下添加合成氨基酸对夏秋季洋二元杂种经产母猪哺乳期生产性能的影响。选择60头长白×约克杂交母猪随机分成3个粗蛋白质水平组,即18.65%、18.15%、17.65%,但饲粮的赖氨酸均为粗蛋白质的6.3%(Lys/CP=0.063),即赖氨酸分别为1.17%、1.14%、1.11%。消化能14.23MJ/kg,赖氨酸与蛋+胱氨酸、苏氨酸、缬氨酸、异亮氨酸、色氨酸的比例均为100∶60∶73∶86∶60∶20,每组20个重复,饲养到28日龄断奶。结果表明:18.65%组仔猪断奶窝重和窝增重显著高于17.65%组(P<0.05),与18.15%组差异不显著(P>0.05)。蛋白质水平对母猪日采食量、背膘损失及断奶后发情间隔影响不显著(P>0.05)。由结果可知,夏秋季高温环境下(平均温度为30±5℃),洋二元杂种经产母猪哺乳期饲粮添加适宜合成L-赖氨酸和L-苏氨酸、L-缬氨酸、DL-蛋氨酸、L-色氨酸,饲喂粗蛋白质为18.65%(赖氨酸1.17%)颗粒饲料时洋二元杂种经产母猪哺乳期生产性能最佳。     

饲料中赖氨酸水平对克氏原螯虾生长、体组成与消化酶活性的影响

克氏原螯虾(Procambarus clarkii)购自盱眙某龙虾养殖场,初始体质量为(7.60±0.01)g。以酪蛋白、明胶、小麦面筋粉和晶体氨基酸为蛋白源配制7组蛋白质水平为28.26%、能量为17.15 kJ.g 1的等氮等能半纯和饲料,各组赖氨酸质量分数分别为0.76%、1.00%、1.22%、1.47%、1.69%、1.89%和2.18%。实验虾分为7组,每组设4个重复,每个重复12尾虾,分别投喂以上7种饲料。养殖实验于室外网箱(规格为60 cm×60 cm×60 cm)中进行,饲养周期为60 d。结果表明,随着饲料中赖氨酸水平的升高,增重率、特定生长率和饲料效率均显著升高(P<0.05),分别在赖氨酸水平1.69%、1.69%和1.22%组时,三者达到最大值;当赖氨酸水平进一步升高,三者均呈下降趋势。各组的成活率为89.58%~97.92%,组间无显著差异(P>0.05)。全虾水分含量以赖氨酸水平1.22%组最低,显著低于0.76%组(P<0.05)。全虾粗蛋白和粗脂肪含量分别以赖氨酸水平1.89%组和1.69%组最高,均显著高于0.76%组(P<0.05)。各组之间的全虾灰分含量、肌肉组成、肌肉氨基酸组成和消化酶活性均无显著差异(P>0.05)。以增重率为评价指标进行一元二次回归分析,得出克氏原螯虾的适宜赖氨酸需求量为1.66%,占饲料蛋白的5.87%。本研究旨在通过确定克氏原螯虾对饲料中赖氨酸的适宜需求量,为其人工配合饲料的研制提供基础数据和理论依据。     

饲料中补充晶体或微囊赖氨酸对草鱼生长和血浆总游离氨基酸的影响

为考察饲料中补充晶体或微囊赖氨酸对草鱼生长性能的影响,配制了豆粕含量为23%(高豆粕组),15%(低豆粕组)的两种实用饲料,在低豆粕饲料中补充晶体赖氨酸或微囊赖氨酸,使赖氨酸达到与高豆粕组一致的水平,共4个处理组,即高豆粕组、低豆粕组、低豆粕+晶体赖氨酸(晶体赖氨酸组)、低豆粕+微囊赖氨酸(微囊赖氨酸组),每处理设3个平行。饲养平均体重为(49.0±2.0)g的草鱼8周。结果表明,各组鱼体增重率分别为279.3%、239.7%、245.6%、277.5%,饲料系数为1.62、1.88、1.85、1.62。与低豆粕组相比,添加晶体赖氨酸对草鱼生长无改善(P>0.05),而添加微囊赖氨酸则提高草鱼增重率15.8%(P<0.05),降低饲料系数0.24(P<0.05),在增重率与饲料系数方面达到与高豆粕组基本一致的水平(P>0.05)。对草鱼摄食上述4种饲料0、1、2、3、4、5h后的血浆总游离氨基酸浓度测定结果表明,添加微囊赖氨酸血浆总游离氨基酸的变化趋势与高豆粕组、低豆粕组一致,即在饲后3h达到高峰,而添加晶体赖氨酸使血浆总游离氨基酸的吸收峰值提前。晶体赖氨酸经微囊化后,其水中溶失率显著降低(P<0.05),仅...     

3.8～8kg断奶仔猪可消化赖氨酸的需要量

广东省农业科学院畜牧研究所林映才、蒋宗勇等采用60头14日龄的三元杂交杜×(长×大)断奶仔猪,研究饲粮不同赖氨酸水平(1.05%、1.15%、1.25%、1.35%、1.45%、1.55%)对3.8～8kg断奶仔猪的生产性能和血清尿素氮的影响.结果表明,随饲粮赖氨酸水平升高,仔猪平均日增重极显著提高(P＜0.01)、采食量显著提高(P＜0.05)、料重比降低(P＞0.05)、血清尿素氮浓度显著降低(P＜0.05),但lys1.45%组和1.55%组仔猪生产性能很接近(P＞0.05).表明满足3.8～8kg超早期断奶仔猪生长的总赖氨酸需要量为1.45%,以回-直肠吻合术猪测定基础饲粮中各种饲料的赖氨酸的回肠消化率,计算出表观可消化和真可消化赖氨酸需要量分别为1.30%和1.38%.     

夏秋高温季节洋二元杂种初产母猪哺乳期对颗粒饲料粗蛋白质(赖氨酸)需要量的初探

试验旨在研究饲粮不同蛋白质水平下添加合成氨基酸对高温季节洋二元杂种初产哺乳母猪生产性能的影响。选择100头长白×约克杂交母猪随机分成5个赖氨酸水平组(1.35%、1.25%、1.15%、1.05%、0.95%),但饲粮的净能均为9.68MJ/kg,并且均在日粮中添加合成赖氨酸1.7kg/t使其各组日粮的氨基酸比例一致(各组日粮中额外添加合成的蛋氨酸、苏氨酸、色氨酸、缬氨酸,赖氨酸与蛋+胱氨酸、苏氨酸、缬氨酸、色氨酸、异亮氨酸的比例均为100:60:75:89:20:65,饲粮均制粒为4.0颗粒。),每组20个重复,每个重复1头,饲养到35日龄断奶。结果表明:21.85%组仔猪断奶窝重和窝增重显著高于其他4组(P<0.05)。蛋白质水平对母猪日采食量、背膘损失及断奶后发情间隔影响不显著(P>0.05)。由结果可知,夏秋季节高温环境下(平均温度为30±5℃),洋二元杂种初产母猪哺乳期饲粮添加合成L-赖氨酸1.7kg/t和适宜L-苏氨酸、L-缬氨酸、DL-蛋氨酸、L-色氨酸,饲喂粗蛋白质为21.85%(赖氨酸1.35%)颗粒饲料时洋二元杂种经产母猪哺乳期生产性能最佳。     

发酵豆粕部分替代鱼粉后凡纳滨对虾对赖氨酸的需求量

为研究发酵豆粕部分替代鱼粉后,饲料赖氨酸(Lys)水平对凡纳滨对虾生长、体组成与血清生化指标的影响,进而确定凡纳滨对虾对饲料赖氨酸的需要量,实验在基础饲料中分别添加0%、0.25%、0.50%、0.75%和1.00%的晶体赖氨酸配制成5种等氮等脂的实验饲料(含粗蛋白41.5%、粗脂肪7.5%),实测各组赖氨酸含量分别为2.43%、2.65%、2.87%、3.06%和3.24%,记为Lys0、Lys25、Lys50、Lys75和Lys100。选择初始体质量为(2.0±0.1) g的凡纳滨对虾随机分为5组,每组3个重复,每个重复50尾虾,在室内水泥池中进行为期56 d的养殖实验。结果显示,随着饲料赖氨酸水平的提高,凡纳滨对虾的增重率(WGR)和特定生长率(SGR)先升高后降低,在Lys75组达到最高,且该组饲料系数(FCR)最低;凡纳滨对虾成活率不受饲料赖氨酸水平的影响。Lys75组对虾肌肉粗蛋白和粗脂肪含量最高,而对虾肌肉粗灰分和水分含量则不受饲料赖氨酸水平的影响;肌肉必需氨基酸中的赖氨酸、缬氨酸(Val)、异亮氨酸(Ile)、苯丙氨酸(Phe)随着饲料赖氨酸水平的提高呈先升高后降低的趋势。随着饲料赖氨酸水平的提高,血清中谷丙转氨酶(ALT)、谷草转氨酶(AST)活性呈先升高后降低的趋势,甘油三酯(TG)含量呈逐渐升高的趋势,Lys75组超氧化物歧化酶(SOD)活性显著低于其他各组。对SGR、FCR与饲料赖氨酸水平进行二次曲线拟合分析,结果显示,凡纳滨对虾对赖氨酸的最适需求量分别为2.88%(饲料粗蛋白的6.94%)、2.89%(饲料粗蛋白的6.96%)。本实验通过探讨凡纳滨对虾在该饲料配方条件下对赖氨酸的最适需求量,旨在为其大规模配合饲料的生产提供参考。     

Growth performance and body composition of white seabream (Diplodus sargus) juveniles fed diets with different protein and lipid levels

An 83‐day feeding trial was carried out to determine the effect of different dietary protein and lipid levels on the growth performances and carcass composition of white seabream. Juveniles (10.7±0.2 g) were fed to satiation on four diets, varying in protein (15% and 28%) and lipid (12% and 16%) levels. The best growth performance was observed in fish fed on diets with higher protein level. Dietary lipids did not affect growth performance. Voluntary feed intake decreased with a increasing dietary protein level at both dietary lipid levels. Feed conversion ratio improved with the increase in dietary protein and lipid levels. Carcass composition remained unaltered by dietary protein levels (P>0.05). Carcass protein content tended to decrease, while lipid content tended to increase in groups fed on 16% lipid, compared with the 12% lipid groups. Additionally, protein retention was higher in fish fed on low‐protein and low‐lipid levels, compared with the high‐protein and high‐lipid group (29% vs. 19%). Lipid retention increased significantly with dietary protein level (P<0.001). Energy retention improved with dietary protein, but was not affected by dietary lipid levels. On the basis of our results, feeding white seabream on 15% dietary protein had a negative effect on growth and feed utilization. Dietary lipid did not induce a protein‐sparing action in Diplodus sargus juveniles.     

Dietary Lysine Requirement as Basis to Estimate the Essential Dietary Amino Acid Profile for Jundiá, Rhamdia quelen

The present study was designed to determine the optimal dietary lysine requirement for jundiá, Rhamdia quelen, fingerlings. Groups of 17 fish (1.4 ± 0.1 g) were stocked in 120‐L tanks and were fed semipurified diets (33% crude protein [CP] and 3500 kcal metabolizable energy) containing increasing concentrations of lysine (3.0, 4.0, 4.5, 5.0, 5.5, 6.0, and 6.5% CP). After 119 d, fish weight gain (WG), specific growth rate (SGR), feed intake and feed conversion (FC), apparent net protein utilization (ANPU), body composition (CP, fat, and ash), and vertebral collagen were determined. WG and SGR increased as dietary lysine concentration in protein increased up to 4.5%, reducing at 6.0 and 6.5% lysine. Fish that were fed the lowest lysine concentration presented the worst feed conversion (FC), which improved for fish fed with 4.5% or more lysine. Feed consumption followed the same trend as FC. The highest ANPU was observed in fish fed with 4.5% lysine. Fish fed diets containing 4.5, 5.0, and 5.5% lysine accumulated more body protein (P < 0.05). Collagen vertebral concentration was significantly higher in fish fed with the 4.5% lysine diet. Dietary requirement for lysine was 4.5 or 5.1% depending on the statistical model used for estimation: broken line or polynomial regression, respectively. The requirements for the other essential amino acids were estimated on the basis of the ideal protein concept and were similar to the requirements for other fish species, except for isoleucine, leucine, treonine, and valine, which were higher for jundiá.     

Quantitative l‐lysine requirement of juvenile black sea bream (Sparus macrocephalus)

An 8‐week feeding experiment was conducted to determine the quantitative l ‐lysine requirement of juvenile black sea bream Sparus macrocephalus (initial mean weight: 9.13 ± 0.09 g, SD) in eighteen 300‐L indoors flow‐through circular fibreglass tanks provided with sand‐filtered aerated seawater. The experimental diets contained six levels of l ‐lysine ranging from 20.8 to 40.5 g kg^?1 dry diet at about 4 g kg^?1 increments. All the experiment diets were formulated to be isoenergetic and isonitrogenous. Each diet was assigned to triplicate groups of 20 fish in a completely randomized design. Weight gain and specific growth rate (SGR) increased with increasing levels of dietary lysine up to 32.5 g kg^?1 (P < 0.05) and both showed a declining tendency thereafter. Feed efficiency ratio and protein efficiency ratio was poorer for fish fed the lower lysine level diets (P < 0.05) and showed no significant differences among other treatments (P > 0.05). All groups showed high survival (above 90%) and no significant differences were observed. The whole body crude protein and crude lipid contents were significantly affected (P < 0.05) by dietary lysine level, while moisture and ash showed no significant differences. The composition of muscle and liver also presented similar change tendency. Total essential amino acid and lysine contents in muscle both obtained the highest value when fish fed 32.5 g kg^?1 lysine diet (P < 0.05). Serum protein, cholesterol and free lysine concentration were affected by different dietary treatments (P < 0.05), triacylglyceride and glucose contents were more variable and could not be related to dietary lysine levels. Dietary lysine level significantly affected condition factor and intraperitoneal fat ratio of juvenile black sea bream (P < 0.05) except for hepatosomatic index. There were no significant differences in white blood cell count and red blood cell count (P > 0.05), however, haemoglobin level was significantly influenced by different diets (P < 0.05). Analysis of dose (lysine level)‐response (SGR) with second order polynomial regression suggested the dietary lysine requirement of juvenile black sea bream to be 33.2 g kg^?1 dry diet or 86.4 g lysine kg^?1 protein.     

Comparison of L‐lysine·HCl and L‐lysine sulphate in the feed of Penaeus monodon and re‐evaluation of dietary lysine requirement for P. monodon

Two trials were conducted to compare L‐lysine HCl and L‐lysine sulphate regarding its availability to Penaeus monodon, and further evaluate the optimum dietary lysine requirement. In experiment 1, five experimental diets were formulated (D1, D2, D3, D4 and D5), a basal diet (D1), aimed at a low‐lysine concentration (2.22% dry matter), with lysine concentration of the other four diets increasing in two 0.25% L‐lysine intervals from either L‐lysine HCl (D2 and D3) or L‐lysine sulphate (D4 and D5). Each diet was fed at a restricted rate to three groups of 40 shrimp for 74 days. The highest values of growth performance (weight gain, WG; specific growth rate, SGR) and survival were observed with shrimp fed the L‐lysine HCl diet. Feed efficiency (FE) of shrimp fed D2 was significantly higher than that of shrimp fed D1 and D5 (P < 0.05), but without significant difference with shrimp fed D3 and D4 (P > 0.05). In experiment 2, six diets (d1, d2, d3, d4, d5 and d6) were formulated with six graded levels of lysine (2.21%, 2.41%, 2.59%, 2.87%, 3.11% and 3.29% of diet). Each diet was randomly assigned to triplicate groups of 40 shrimp for 74 days. WG, SGR and survival increased increasing levels of lysine up to 2.41% of diet and reached an apparent plateau. Broken‐line model analysis on WG and SGR indicated that the optimum dietary lysine level for optimal growth of shrimp was 2.37% of diet, corresponding to 5.78% of dietary protein. In conclusion, results of this trial suggest that L‐lysine HCl is superior to L‐lysine sulphate when fed to Penaeus monodon and optimal growth can be obtained at lysine levels corresponding to 2.37% of diet, or 5.78% of dietary protein in this specie.     

Effects of Dietary Lysine Levels on Growth,Intestinal Digestive Enzymes,and Coelomic Fluid Nonspecific Immune Enzymes of Sea Cucumber,Apostichopus japonicus,Juveniles

A 56‐d feeding trial was conducted to evaluate the effects of dietary lysine levels on growth performance, intestinal digestive enzymes, and nonspecific immune response of Apostichopus japonicus juveniles. Five semipurified diets were formulated to contain graded levels of lysine (from 0.28 to 2.32% of dry matter). Although no significant differences (P > 0.05) were observed in survival rate, final weight (FW), and body weight gain (BWG), the FW and BWG increased from 0.28 to 1.19% with increasing dietary lysine levels, then showed a declining tendency. Broken‐line regression analysis of BWG indicated sea cucumber requires lysine at 0.76% of dry diet. Proximate composition, lysine content of the body wall, and total amino acid profiles were not affected by dietary treatments. Intestinal protease level increased with increasing dietary lysine level from 0.28 to 1.19%, then decreased. Acid phosphatase and superoxide dismutase activities of the sea cucumbers were not affected by various dietary lysine levels; however, significantly (P < 0.05) higher alkaline phosphatase activity was observed in sea cucumbers fed 2.32% lysine diet than those fed diets having 0.28 and 1.89% lysine. Overall, sea cucumber juveniles fed with diets containing between 0.76 and 1.19% lysine showed better growth performance, digestive enzymes, and nonspecific immune enzyme activities.     

Effects of feeding Atlantic salmon (Salmo salar L.) imbalanced levels of lysine and arginine

Two experiments were performed to study the effects of imbalanced levels of arginine and lysine in diets of Atlantic salmon ( Salmo salar L.) with Zein as the major dietary protein source. In the first experiment, the effects of high levels of lysine on marginal levels of arginine and high levels of arginine on marginal levels of lysine were compared in fish fed these amino acids at either marginal or high levels. Dietary contents of arginine/lysine were 30.0/29.4, 17.0/29.4, 30.0/14.4 and 17.2/14.5 g kg^–1, respectively. In the second experiment, fish were fed increasing levels of lysine in a diet containing arginine at the requirement level. Dietary levels of arginine/lysine in the second experiment were 23.0/17.0, 23.0/34.3, and 23.0/46.4 g kg^–1.
Atlantic salmon fed marginal levels of lysine showed better growth and feed utilization when fed diets supplemented with high levels of arginine. Fish fed diets marginal in arginine exhibited increased growth and feed utilization when fed diets supplemented with high levels of dietary lysine. Increasing dietary lysine did not significantly affect growth in fish fed arginine at the requirement level. Increased growth in fish fed high dietary arginine levels might be explained by increased tissue concentrations of ornithine acting as a precursor for in situ synthesis of polyamines. A slight correlation between specific growth rate (SGR) and concentration of spermidine in muscle and between condition factor and concentration of total polyamines in muscle was seen. Abdominal injection of U-C¹⁴ arginine may indicate lysine inhibition of arginine availability in muscle tissue.     

Effect of dietary lipid level on growth performance,feed utilization and body composition of grouper <Emphasis Type="Italic">Epinephelus coioides</Emphasis> juveniles fed isonitrogenous diets in floating netcages

An experiment was conducted to determine the effect of dietary lipid levels on growth performance and body composition of grouper Epinephelus coioides juveniles cultured in floating netcages (1.5 m × 1 m × 1.5 m). Six isonitrogenous diets (53% dietary protein) with increasing dietary lipid concentration (5.16, 7.38, 9.73, 12.36, 14.13, 16.04% of dry material, DM) were fed to satiation to triplicate groups of 20 fish (mean weight: 10.9 ± 0.1 g) for 56 days. Dietary energy levels were 300, 322, 340, 371, 382, 400 kcal/100 g DM, respectively. Fish fed the 9L diet had the highest weight gain (WG) and specific growth rate (SGR), but they were not significantly different from that of fish fed the 7L or 12L diet (p > 0.05). FI varied inversely with dietary lipid levels. The poorest FCR and the lowest PER were observed in fish fed the 5L diet but these parameters showed no significant differences (p > 0.05) for fish fed the dietary lipid level ranging from 9 to 16%. Nitrogen intake decreased with dietary lipid levels. Fish fed the 7L diet showed the highest N gain, which was not markedly different from that of fish fed the 9L and 12L diets (p > 0.05). N retention was significantly lower in fish fed the 5L diet than in the other groups. Lipid intake and lipid gain increased with dietary lipid levels. Lipid retention (%) of the 7L diet was lowest but showed no significant differences among other treatments (p > 0.05). Proximate composition of fish body was significantly affected by dietary lipid level (p < 0.05). Body lipid content increased in direct proportion to dietary lipid levels. In contrast, moisture content of whole-body was correlated negatively to dietary lipid level. Dietary lipid content had no significant effect on protein content in whole-body and white muscle (p > 0.05). Condition factor (CF), hepatosomatic index (HSI) and viscerosomatic index (VSI) increased with increasing dietary lipid level. Based on second-order polynomial regression analysis of WG against dietary lipid level, a breakpoint of 10.0% was indicated to be the optimal dietary lipid concentration for maximum growth for grouper Epinephelus coioides juveniles cultured in floating netcages.     

d‐lysine can be effectively utilized for growth by common carp (Cyprinus carpio)

An 8‐week feeding trial was conducted to compare the effects of different lysine isomers on growth, nutrient utilization and metabolic enzyme activity in common carp (Cyprinus carpio). A basic experimental diet (the control group) with 30% of dietary protein from fish meal and the remaining 70% from soybean meal was used either with or without supplementation of d‐ lysine, l‐ lysine or dl‐ lysine, respectively. The total feed intake was significantly improved by supplementation with lysine regardless of isomeric form (P < 0.05). Supplementation with d‐ lysine or l‐ lysine (but not dl‐ lysine) generally increased the weight gain, specific growth rate, feed efficiency ratio and protein efficiency ratio. Dietary lysine supplementation generally increased the apparent digestibility of dry matter, crude protein and crude lipid, but no statistically significant differences were observed between the control group and the lysine‐supplement groups (P > 0.05). The d‐ amino acid oxidase and d‐ aspartate oxidase activities were generally higher in the liver, kidney and intestine of fish fed diet containing d‐ lysine compared to fish fed diet containing l‐ lysine. The lysine, protein and lipid gains in fish were markedly increased by the supplementation with d‐ lysine or l‐ lysine, and the lysine (r = 0.618, P < 0.05) and protein gains (r = 0.671, P < 0.05) were linearly related to dietary lysine intake. Lysine retention efficiency linearly decreased with the increase of dietary lysine intake (r = ?0.579, P < 0.05). These results indicate that common carp are capable of utilizing the supplemental crystalline d‐ lysine·HCl (4 g kg^?1 dry diet) for growth when the rest of dietary amino acids are protein‐bound forms.     

酵母水解物对吉富罗非鱼生长、免疫力、抗氧化性及抗无乳链球菌感染的影响

本研究旨在探究饲料中添加酵母水解物对吉富罗非鱼(Oreochromis niloticus)生长性能、免疫力和抗病力的影响。在基础饲料中添加0 (对照组)、0.5%、1.0%、1.5%和2.0%的酵母水解物制成5种实验饲料,对5组初始体重为(25.80±0.45) g的吉富罗非鱼进行为期8周的养殖实验,每组 3个重复,每个重复30尾鱼。实验结束后,每个重复选择12尾鱼进行无乳链球菌(Streptococcus agalactiae)攻毒实验,每尾鱼腹腔注射0.2 mL浓度为8.3×105 CFU/mL的菌液,连续观察14 d,统计累积死亡率。结果显示,随着酵母水解物添加量的增加,吉富罗非鱼终末体质量(FBW)和特定生长率(SGR)均呈先显著上升(P<0.05)后下降的趋势。回归分析表明,当SGR达到最大值时,对应的酵母水解物添加量为1.29%。罗非鱼血清一氧化氮合酶、酚氧化酶、酸性磷酸酶、过氧化氢酶和超氧化物歧化酶活性均随饲料中酵母水解物添加量的提高呈先上升后下降的趋势(P<0.05),添加量为1.5%时达最大值。饲料添加酵母水解物对吉富罗非鱼无乳链球菌的抵抗力有显著影响(P<0.05),除添加量为0.5%的实验组死亡率与对照组差异不显著外,其他实验组罗非鱼的死亡率均显著低于对照组(P<0.05)。本研究中,饲料添加酵母水解物可有效提高吉富罗非鱼的生长性能、免疫力和抗病力,且在添加量为1.5%时,效果最显著。     

Dietary l‐lysine requirement of juvenile Chinese sucker,Myxocyprinus asiaticus

An 8‐week feeding trial was conducted to quantify the dietary l ‐lysine requirement of juvenile Chinese sucker with an initial weight of 1.81 ± 0.04 g reared in indoor flow‐through and aerated tanks. Six isonitrogenous and isoenergetic practical diets were formulated to contain graded levels of lysine (1.23%, 1.80%, 2.39%, 2.98%, 3.56% and 4.18% dry matter) at 0.6% increments from dietary ingredients and crystalline l ‐lysine. Each diet was randomly assigned to triplicate groups of 30 fish each and was fed to apparent satiation by hand three times a day (09:00, 13:00 and 17:00 hours) for 8 weeks. There were significant differences in growth performance and feed utilization among the treatments. Weight gain (WG), specific growth rate and protein efficiency ratio (PER) significantly increased with increasing lysine levels up to 2.39% of diet (P < 0.05) and remained nearly the same thereafter (P > 0.05). Feed efficiency was the poorest for fish fed the lowest lysine diet (P < 0.05) and showed no significant differences when dietary lysine level increased from 2.39% to 4.18%. The N retention (% N intake) significantly increased with dietary lysine level but did not attain a plateau (P < 0.05). Survival could not be related to dietary treatments. Whole body protein increased (P < 0.05) and whole body lipid decreased (P < 0.05) with increasing dietary lysine level. The condition factor and hepatosomatic index were significantly affected by dietary lysine levels, however, viscersomatic index, whole body moisture and ash did not differ significantly among dietary treatments. Broken‐line analysis on the basis of WG and PER showed that dietary lysine requirements of juvenile Chinese sucker were 2.43% and 2.40% dry diet (5.52% and 5.45% dietary protein) respectively. Based on the ideal protein approach and the A/E ratios determined from muscle amino acid profile an estimation of the EAA requirements of Chinese sucker juveniles were calculated.