饥饿对黑鲷血清生长激素、甲状腺激素以及白肌和肝脏脂肪、蛋白质含量的影响

饥饿处理黑鲷 (Sparusmacrocephalus) 2、 5、 10、 15和 30d ,分别测定血清生长激素 (GH)和甲状腺激素三碘甲状腺原氨酸 (T3 )浓度以及脂肪和蛋白质在白肌和肝脏中的含量 ;同时测量正常摄食动物的相应指标作为对照。数据分析结果显示 :①饥饿 15d后血清GH水平显著升高 ,T3 水平显著降低 ;②饥饿 15d后白肌蛋白质含量显著降低 ,而脂肪含量则在饥饿 2d就降低 ,并维持此低水平 ;③肝脏脂肪含量在饥饿 10d后显著升高 ,而蛋白质呈不规则波动。GH水平升高能强化储能物质的转化 ,而T3 水平降低可降低代谢水平。二者的协同作用很可能是该种应对饥饿胁迫的重要生理反应机制     

饲料蛋白和脂肪水平对青鱼大规格鱼种生长和体组成的影响

设计5个饲料蛋白水平（30%、33%、36%、39%和42%）和2个脂肪水平（6%和9%）的52的因子试验,配制10种试验饲料,分别饲喂10组三重复平均体重为95.5 g的二龄青鱼70d,以探讨不同蛋白和脂肪水平对青鱼生长和体组成等的影响。结果表明: 鱼体增重随饲料蛋白水平从30%提高到39%不断增加（P0.05）,进一步提高饲料蛋白水平至42%时,鱼体增重则不再显著变化（P0.05）;饲料系数随饲料蛋白水平从30%提高到39%而不断降低（P0.05）,进一步提高饲料蛋白水平至42%时,也不再显著变化;蛋白质效率和蛋白保留率随饲料蛋白水平呈下降趋势;以鱼体增重为指标,经折线模型进行回归分析求得适宜的饲料蛋白水平为占干饲料的40%。饲料蛋白、脂肪水平及其交互作用对的试验鱼成活率均无显著差异（P0.05）。饲料脂肪水平、饲料蛋白与脂肪的交互作用对鱼体增重、饲料系数、摄食率和蛋白质效率也均无显著影响（P0.05）。摄食蛋白水平为30%和33%饲料的青鱼与摄食蛋白水平36%-42%饲料的青鱼相比,有较低的水分和较高全鱼脂肪（P0.05）。青鱼脏体比和肌肉粗脂肪含量均随着饲料中蛋白水平的提高呈降低的趋势。摄食脂肪水平为9%的饲料的青鱼较摄食脂肪水平为6%的饲料的青鱼,有较高脏体比、全鱼脂肪含量和肌肉粗脂肪含量（P0.05）。上述结果说明,青鱼摄食低蛋白和高脂肪的饲料造成过多的体脂积累。在试验条件下,青鱼大规格鱼种饲养阶段适宜的饲料蛋白和脂肪水平分别为占干饲料的40%和6%。       

肌肽对奥尼罗非鱼生长性能的影响

本研究探讨了饲料中肌肽的添加对奥尼罗非鱼生长、血清激素水平及肌肉组织抗氧化能力的影响。选取罗非鱼360尾,随机分为A、B、C、D 4个组,每组3个重复,每个重复30尾。在A、B、C、D组的饲料中分别添加0、50、100、200mg/kg剂量的肌肽。常规饲养管理,试验周期60d。结果发现：在试验期间,B、C、D组鱼体的体重和体长均大于A组,特别是试验结束时,B组鱼体的体重、体重生长率（RSGR）和相对体长生长率（RLGR）均显著大于A组（p〈0.05）。在试验全期,B、C、D组鱼体血清生长激素（GH）、类胰岛素生长因子-1（IGF-1）和三碘甲状腺原氨酸（T3）水平均高于A组,但差异不显著。在第20天,B、C组鱼体肌肉组织中超氧化物歧化酶（SOD）活力显著高于A组（p〈0.05）,D组过氧化氢酶（CAT）活力显著低于A组（p〈0.05）;第40天,B、C、D组的谷胱甘肽过氧化物酶（GSH-Px）活力均显著高于A组（p〈0.05）。试验结果表明：在饲料中添加适宜剂量（50mg/kg）的肌肽,能改善鱼体肌肉组织的抗氧化能力,提高血清中相关的激素水平,促进鱼体内物质代谢,对鱼体生长性能产生积极影响。     

南方鲇继饥饿后的恢复生长

1996年1月至4月在27．5℃条件下,对南方鲇幼鱼（初始体重：73．65±9．82g）进行了不同时间的饥饿处理后再供食的恢复生长实验。实验鱼饥饿60d后,鱼体比能值、蛋白质含量及脂肪含量明显下降,灰分含量及含水量明显上升。分别将饥饿处理0（对照）、10、20、30、40、50和60d的南方鲇再恢复喂食,在饱足摄食水平下生长20d。各饥饿处理组的鱼体化学组成及比能值均接近,并恢复到对照生长组水平。饥饿处理50d组的干重及能量生长率,湿重、干重及能量摄食率显著高于对照组的相应值。通过讨论认为：（1）饥饿处理50d的南方鲇在恢复生长过程中产生了显著的补偿效应;（2）该补偿现象主要因摄食水平显著升高所致。     

饲料中棉粕替代鱼粉蛋白对草鱼的生长、血液生理指标和鱼体组成的影响

以初始体重（100.00.29） g的草鱼为研究对象,通过8周的生长实验,研究饲料中棉粕替代鱼粉蛋白对草鱼的生长、饲料利用,血液生理指标和鱼体生化组成的影响。实验设置7种等氮等能饲料,对照组（C）以鱼粉为唯一蛋白源,其余6组分别以棉粕替代饲料中鱼粉蛋白的20% （R20）、40% （R40）、60% （R60）、80% （R80）、90% （R90）、100% （R100）。研究结果表明:随着饲料中棉粕含量的升高,草鱼特定生长率呈下降的趋势,当替代比例达到60%,显著低于对照组（P0.05）;饲料效率、蛋白质贮积率和能量贮积率随着饲料中棉粕含量升高而显著降低（P0.05）。通过折线法分析,在实验条件下,棉粕可以替代鱼粉蛋白的43.3%而不影响草鱼的生长。各组草鱼之间血清谷丙转氨酶、谷草转氨酶和甘油三酯含量无显著差异（P0.05）;总胆固醇、高密脂蛋白胆固醇和低密胆固醇呈现下降趋势,当替代水平达到40%显著低于对照组（P0.05）。棉粕替代鱼粉蛋白显著影响鱼体的水分含量（P0.05）,当替代比例达到80%,鱼体的水分含量显著高于对照组（P0.05）;各组之间鱼体的蛋白质和灰分含量无显著性差异（P0.05）。R20组的鱼体脂肪和能量含量显著高于对照组（P0.05）,R100组的鱼体脂肪和能量含量显著低于对照组（P0.05）,其他各组之间和对照组无显著性差异（P0.05）。       

饲料中添加壳聚糖和益生菌对暗纹东方纯幼鱼生长及部分消化酶活性的影响

在基础饲料中分别添加不同浓度的益生菌(0.1%、0.2%、0.4%)、壳聚糖(0.2%、0.5%、1.0%)、壳聚糖与益生菌混合物、甘露聚糖与益生菌混合物,在室内水泥池(5.0m×2.0m×1.0m)中喂养暗纹东方鲀幼鱼(3.15±0.05g),用基础饲料投喂暗纹东方鲀作为对照,每组三个重复,60d后测定鱼体的生长、肌肉生化成分、肝胰脏、肠道蛋白酶和淀粉酶活性和白肌RNA/DNA。结果显示,对照组相对增重率为476.4%,饲料中添加0.2%的壳聚糖、0.1%的益生菌对暗纹东方鲀的促生长作用最明显,相对增重率显著提高。壳聚糖与益生菌混合物、甘露聚糖与益生菌混合物对生长无显著影响。对照组肌肉蛋白质和脂肪含量分别为82.94%、11.21%,壳聚糖、益生菌与甘露聚糖在饲料中的添加,能够显著降低肌肉脂肪含量,显著提高肌肉蛋白质含量,也能在一定程度上降低肝体比。0.2%壳聚糖和0.1%益生菌能使肠道淀粉酶活性显著增强(P<0.05),白肌RNA/DNA显著增大(P<0.05),说明肠道淀粉酶活性增强和蛋白质合成增加是壳聚糖和益生菌促进暗纹东方鲀生长的重要原因。     

鱼类生长激素生物活性和定量免疫测定技术的研究进展

生长激素(growth hormone, GH)是调节鱼类生长、发育和代谢的一种重要激素.为了弄清鱼体内GH水平与鱼体生长的关系, 以及研究外源GH基因在受体鱼体内的表达部位、表达效率和表达调控等问题, 首先必须建立鱼类GH灵敏、特异的微量检测技术.此外, 在进行鱼类GH分离纯化中, 很重要的一点就是鉴定所获得的GH制品是否具有生物活性, 同样也需要建立鱼类GH灵敏、特异的生物活性检测技术.     

N-氨甲酰谷氨酸对罗非鱼幼鱼生长、血液氨基酸组成及脂肪沉积的影响

为研究精氨酸对尼罗罗非鱼(Oreochromis niloticus)的生物学效应, 采用精氨酸内源合成途径的必需辅助因子N-氨甲酰谷氨酸(NCG)代替精氨酸, 研究不同剂量包被NCG制剂(实际NCG含量为80%)对尼罗罗非鱼生长及脂肪沉积的影响。实验共设6个制剂添加组, 分别为0.025%、0.05%、0.1%、0.2%、0.4%、0.5%及对照组。结果显示, 罗非鱼血液中所有NCG添加组(0.025%0.5%)和对照组相比, 赖氨酸、苏氨酸、亮氨酸、异亮氨酸、缬氨酸等必需氨基酸含量无显著性差异(P0.05), 而当NCG添加量为0.4%时, 精氨酸含量显著高于其他各组(P0.05), 且约为对照组的4倍, 继续提高NCG添加量至0.5%时, 精氨酸含量无显著提高(P0.05); 所有NCG添加组的末均重、特定生长率、饲料系数、内脏比和肥满度等指标与对照组相比均无显著性差异(P0.05), 当NCG添加量为0.2%时, 增重率和蛋白质效率均显著高于其他组(P0.05), 除了0.1%NCG添加组, 其他各组全鱼蛋白质含量均高于对照组; 脂肪沉积方面, 所有NCG添加组均显示肝体比显著低于对照组(P0.05), 全鱼干物质中脂肪含量显著高于对照组 (P0.05), 脂肪有从肝转移至肌肉的倾向。饲料中添加0.4%NCG, 对于血液中精氨酸含量的提高有较好的促进作用, 而且不影响其他氨基酸的吸收; 饲料中添加0.025%0.5% NCG有利于减少肝脏脂肪沉积而增加了肌肉中的脂肪沉积, 研究结果为进一步开展精氨酸影响鱼体脂肪沉积的机理研究提供了科学依据。       

谷氨酸和α-酮戊二酸对鳜生长、脱氨及糖代谢的影响

为探究谷氨酸(Glu)和α-酮戊二酸(AKG)对鳜(Siniperca chuatsi)摄食和氨排泄的影响,实验以鳜[初始体重(26.28±0.99) g]为研究材料,将Glu和AKG分别添加到鳜的基础日粮中(添加量2%),进行了60d的养殖实验,前40d等量投喂,后20d饱食投喂。通过设置对照组、Glu组和AKG组,比较了3种不同饲料饲喂下鳜的摄食与氨排泄差异情况。实验结果表明,在等量饲喂期间添加Glu、AKG显著提高鳜生长和降低饵料系数,且在一定程度上降低鳜的体外氨排泄量。在饱食投喂阶段, Glu、AKG组的血液中的葡萄糖含量增加,肝糖原、肌糖原含量降低。两个投喂阶段结果都表明,饲料中添加谷氨酸和α-酮戊二酸能显著促进鳜脑中npy表达并抑制pomc表达,显著提高蛋白质效率比和特定生长率,增加鱼体体重,促进鱼体生长且降低饲料系数。同时,肝脏中gdh表达及肌肉ampd表达均提高,脱氨代谢供能水平升高,最终导致其氨排泄量升高。此外,饲料中添加Glu和AKG可促进肝脏pepck、g6pase、pk和gk基因表达量增加,糖代谢增强,减少蛋白质的分解供能。综上所述,在饲料中添加谷氨酸和α-酮戊...     

西伯利亚鲟在高温下饥饿后的补偿生长

在高温(29±1)℃下将西伯利亚鲟幼鱼(21.61±0.03)g饥饿0(对照)、6、12和18d后恢复摄食3周, 研究摄食、生长和鱼体组成的变化。结果表明, 经过不同程度饥饿的鱼体重均显著低于对照组(P0.05), 而饥饿18d(S18组)的鱼体重显著低于对照(P0.05)。在饥饿过程中,鱼体脂肪含量和肝脏肝糖原含量下降的同时, 各饥饿组的灰分含量上升, 但仅S18组与对照差异显著(P0.05)。结果表明, 西伯利亚鲟在高温下表现出完全补偿现象, 且是通过同时提高摄食率和饲料效率来实现补偿生长的, 因此在夏季高温时对鲟鱼进行一段时间适度的饥饿可以在不影响生长和体成分的前提下节约饲料成本, 减少因过量投饵而引起的环境污染。       

达氏鲟生长激素基因cDNA克隆、表达及免疫荧光定位研究

为研究达氏鲟(Acipenser dabryanus)生长激素(Growth Hormone, GH)基因的功能, 合成了达氏鲟垂体SMART cDNA, 克隆得到GH全长cDNA序列。达氏鲟GH全长cDNA序列为1008 bp, 由52 bp的5'端非编码区(Untranslated region, UTR)、编码214个氨基酸的645 bp开放阅读框(Open reading frame, ORF)和311 bp的3'UTR构成。运用GH氨基酸序列构建进化树分析发现, 达氏鲟与两栖类、爬行类和哺乳类的一致性要高于真骨鱼类。实时荧光定量PCR结果表明, 达氏鲟GH mRNA主要在垂体和下丘脑中表达, 且垂体中GH的表达量约为下丘脑的110倍; Western-blot研究结果与qRT-PCR一致, 仅在垂体和下丘脑中检测到生长激素蛋白, 且垂体中GH的表达量远高于下丘脑。免疫荧光定位结果显示, GH主要定位于垂体中部, 下丘脑中也有少量荧光信号; 苏木精-伊红组织切片染色研究表明, GH主要是由嗜酸性的生长激素分泌细胞分泌。研究为深入研究脊椎动物生长激素基因的进化和人工养殖达氏鲟的生长调控提供了基础。       

Dietary copper supplementation enhances lipolysis in Rex rabbits

BackgroundCopper is an important regulator of lipid metabolism in mammals, as a cofactor of many enzymes and is involved in the lipolysis. Copper deficiency has been considered as a significant factor in human diseases related to abnormal lipid metabolism, while adding copper to the diet seems to be the simplest and most effective way to prevent copper deficiency.AimsThe aim of this study was to investigate the effects of dietary copper level on lipid metabolism in Rex Rabbits.MethodsA total of 120 90-d-old Rex Rabbits were randomly allotted into three treatments, with 40 replicates (20 males, 20 females) in each treatment (1 rabbit per replicate). The diets included 1) control (8.4 mg/kg), normal-copper diet (39.1 mg/kg), 3) high-copper diet (67.5 mg/kg). The trial including a one-week adaptation period and a five-week experimental period.ResultThe results showed that copper (39.1 mg/kg) diet increased average daily feed intake (ADFI) (P＜0.05, N = 34), and tended to increase the final body weight (FBW) (P = 0.0556, N = 34). Moreover, dietary copper addition (39.1 and 67.5 mg/kg) significantly increased the foreleg and hindleg weight (P＜0.05, N = 8), and decreased the weight of Perirenal fat and the concentration of triglycerides (TG) in the liver (P＜0.05, N = 8). The concentration of triglycerides (TG), epinephrine (EPI), and glucagon (GC) in serum were obviously higher than that in control group (P＜0.05, N = 8), and the concentration of insulin (INS), and very low-density lipoprotein (VLDL) in serum were significantly decreased (P＜0.05, N = 8). The copper group (39.1 mg/kg) showed up-regulated gene expression levels of carnitine palmitoyl transferases (CPT-1 and CPT-2) and peroxisome proliferator-activated receptor (PPAR-α) in liver (P < 0.05, N = 8) and down-regulated gene expression levels of fatty acid synthase (FAS) and Acetyl-CoA carboxylase (ACC) (P < 0.05, N = 8). In skeletal muscle, CPT-1, CPT-2, PPAR-α, fatty acid transport protein (FATP), fatty acid-binding protein (FABP) and lipoprotein lipase (LPL) levels were significantly up-regulated by copper treatment (P < 0.05, N = 8). Rex Rabbits receiving copper addition had higher CPT-1, CPT-2, PPAR-a and hormone-sensitive lipase (HSL) mRNA levels in adipose tissue (P < 0.05, N = 8).ConclusionCopper diets promoted skeletal muscle growth and reduced fat accumulation by enhancing fatty acid oxidation, at the same time, dietary copper inhibited De novo lipogenesis in the liver. PPAR-α signaling in liver, skeletal muscle and adipose tissues were involved in the regulation of lipid metabolism by copper.     

Metformin restores responses to insulin but not to growth hormone in Sprague-Dawley rats

Administration of growth hormone (GH) increases muscle mass in F344 x BN rats, but not in Sprague-Dawley (S-D) rats. S-D rats are insulin-resistant and insulin responsiveness is required for the anabolic actions of GH. We hypothesized that correction of insulin resistance with metformin might also restore anabolic effects of GH. Treatment with GH (0.25 or 1.0 mg/kg twice daily for 9 days) had limited anabolic effects, reducing weight gain by 14%, increasing muscle glycogen content by 40% and increasing exercise capacity by 24%, but failing to increase muscle mass or to reduce fat mass. GH also impaired insulin responsiveness and increased visceral fat TNF content of visceral fat by 77%. Metformin enhanced insulin responsiveness in skeletal muscle, but failed to enhance anabolic effects of GH. Rats aged 14 weeks were treated for 21 days with metformin (320 mg/kg/day) and for the last 9 days, with GH (0.25 mg/kg, twice daily). Metformin caused a 2.3-fold increase in insulin-stimulated muscle glucose transport and a 20% reduction in muscle fatty acid oxidation, indicating increased glucose utilization. However, metformin did not augment GH-induced weight reduction. Metformin decreased visceral fat by 22% and subcutaneous fat by 20%, but no decreases were observed in the GH/metformin group. GH increased muscle glycogen by 40%, but the effect was reversed by metformin. VO(2max) was increased 24% by GH and 17% by metformin, but was not elevated in the GH/metformin group. GH increased TNF in visceral fat and the effect was augmented by metformin (144% increase). We conclude that metformin enhances some aspects of insulin responsiveness, but does not enhance anabolic responses to GH. The latter may, in part, be explained by the failure of metformin to prevent GH-induced elevation of TNF in visceral fat.     

达氏鲟gpr54基因的克隆及Kisspeptin注射对其表达的影响

G蛋白偶联受体54(GPR54, G protein-coupled receptor 54)是kisspeptin (Kiss)的受体蛋白。Kisspeptin/GPR54系统通过调节促性腺激素释放激素(GnRH)的活性来参与鱼类生殖调控。为了研究Kisspeptin/GPR54系统对达氏鲟(Acipenser dabryanus)GnRH的调控功能, 克隆得到达氏鲟2个gpr54基因的全长cDNA序列, 命名为dsgpr54-1及dsgpr54-2, 分别编码379和368个氨基酸。氨基酸序列比对及进化树分析表明, 达氏鲟Gpr54与四足动物Gpr54序列一致性较高, 亲缘关系较近。荧光定量PCR研究发现, dsgpr54-1的转录本在精巢、卵巢、下丘脑、垂体、中脑及端脑等组织中均有表达, 且在下丘脑中转录水平最高; 而dsgpr54-2仅在脑组织中转录, 且在垂体、中脑及下丘脑中表达丰度均较高。为了研究Gpr54是否可以与其配体Kisspeptin结合调控下丘脑中gnrh基因的表达, 分别合成了达氏鲟Kiss-1和Kiss-2的核心十肽(10 nmol/L、1000 nmol/L), 腹腔注射到9月龄达氏鲟。结果表明, 不同浓度Kiss-1、Kiss-2注射均引起gpr54基因表达量升高, 并且10 nmol/L Kiss-2注射能够显著促进dsgpr54-2的表达(P<0.05)。另外, 不同浓度Kiss-1注射均造成了gnrh转录水平的下降; 而10 nmol/L Kiss-2注射使得gnrh1表达量上升, 而gnrh2的表达量下降, 1000 nmol/L Kiss-2注射则引起gnrh1表达量的下降, gnrh2的表达量没有显著变化。上述研究结果表明, 达氏鲟gpr54基因均能与其配体kiss-1、kiss-2相结合, 但表现出一定的受体-配体选择性差异。Kiss-1、Kiss-2通过激活Gpr54的活性, 调控下丘脑中gnrh基因的表达, 且其调控功能存在差异。     

饲料脂肪水平对杂交鲟幼鱼生长、饲料消化率、抗氧化水平和肌肉脂肪酸组成的影响

研究旨在探究饲料中不同脂肪水平对西伯利亚杂交鲟(Acipenser baerii Brandt ♀ × A. schrenckii Brandt ♂)幼鱼生长、饲料消化率、血清生化指标及肌肉脂肪酸组成的影响。以鱼油为脂肪源, 配制4种脂肪水平分别为5%(D05)、10%(D10)、15%(D15)和20%(D20)的等氮饲料。选用初始体重为(152.83±0.67) g的杂交鲟, 随机分为4组, 每组3个重复, 每个重复25尾鱼。养殖周期为12周。结果显示, 饲料中不同脂肪水平对杂交鲟的生长性能有显著影响(P<0.05)。其中, D15组杂交鲟幼鱼的末均重(FBW)、增重率(WGR)和特定生长率(SGR)显著高于D05、D10和D20组(P<0.05), 饲料效率(FE)显著高于D05和D10组(P<0.05)。随着饲料中脂肪含量的增加, 杂交鲟幼鱼脏体比(VSI)、肝体比(HSI)及肌肉、肝脏中的脂肪含量显著上升(P<0.05)。饲料中不同脂肪水平对干物质(ADC_d)、蛋白质(ADC_p)表观消化率无显著影响(P>0.05)。D10、D15和D20组脂肪表观消化率(ADC_f)显著高于D05组(P<0.05)。D15组能量表观消化率在各组中最高, 显著高于D05和D10组(P<0.05)。随着饲料中脂肪水平的增加, 血清超氧化物歧化酶(SOD)、总抗氧化能力(T-AOC)和髓过氧化物酶(MPO)的活性均显著升高, 谷胱甘肽过氧化物酶(GSH-Px)活性显著下降(P<0.05)。此外, 肝功能指标谷丙转氨酶(ALT)、谷草转氨酶(AST)、碱性磷酸酶(ALP)和乳酸脱氢酶(LDH)的活性也随饲料中脂肪水平的升高呈递增趋势(P<0.05)。肌肉中的各脂肪酸含量与饲料中脂肪酸含量呈显著的线性正相关(R2>0.90, P<0.05)。综合各指标因素判断, 西伯利亚杂交鲟幼鱼饲料中适宜的脂肪水平为15%, P/E为23.54 mg/kJ。     

Effects of dexamethasone and colostrum intake on the somatotropic axis in neonatal calves

Glucocorticoids and colostrum feeding influence postnatal maturation of the somatotropic axis. We have tested the hypothesis that dexamethasone (Dexa) affects the somatotropic axis in neonatal calves dependent on colostrum intake. Calves were fed either with colostrum or with a milk-based formula (n = 14/group), and, in each feeding group, one-half of the calves were treated with Dexa (30 micro g. kg body wt-1. day-1). Pre- and postprandial blood samples were taken on days 1, 2, 4, and 5, and liver samples were taken on day 5 of life. Dexa increased insulin-like growth factor (IGF)-I, but decreased growth hormone (GH) and IGF-binding protein (IGFBP)-1 and -2 plasma concentrations and increased GH receptor (GHR) mRNA levels in liver. Dexa increased IGF-I mRNA levels only in formula-fed calves and increased hepatic GHR binding capacity, but only in colostrum-fed calves. Colostrum feeding decreased IGFBP-1 and -2 plasma concentrations and hepatic IGFBP-2 and -3 mRNA levels. In conclusion, Dexa and colostrum feeding promoted maturation of the somatotropic axis. Dexa effects partly depended on whether colostrum was fed or not.     

大鳞副泥鳅、泥鳅和北方泥鳅肉质比较分析

文章采用组织切片、生化组分分析以及实时荧光定量PCR等方法, 研究了大鳞副泥鳅(Paramisgurnus dabryanus)、泥鳅(Misgurnus anguillicaudatus)和北方泥鳅(Misgurnus bipartitus)肉质差异。结果显示: 大鳞副泥鳅、泥鳅和北方泥鳅的肌纤维横截面积分别为 (3589.17±2326.01)、(2809.7±1818.69) 和(2511.93±1949.03) μm2。粗蛋白和粗脂肪含量均是大鳞副泥鳅最高[分别为(17.07±0.31)%和(2.57±0.38)%], 依次为泥鳅[分别为(14.57±0.59)%和(1.37±0.12)%]和北方泥鳅[分别为(12.33±0.15%和0.57±0.06%]。必需氨基酸指数(EAAI)依次为泥鳅(74.38)、大鳞副泥鳅(65.11)和北方泥鳅(60.14); 呈味氨基酸含量依次为泥鳅(32.60±1.64)%、大鳞副泥鳅(27.75±2.13)%和北方泥鳅(24.86±1.00)%; 除亚油酸以外的总多不饱和脂肪酸含量依次为北方泥鳅(24.43±0.26)%、泥鳅(24.18±1.99)%和大鳞副泥鳅(7.86±0.24)%。大鳞副泥鳅的肌肉生长相关基因myod的表达量高, myog和mrf4的表达量低; 泥鳅和北方泥鳅的myog和mrf4的表达量高, myod的表达量低。elovl5等8个脂肪代谢相关基因的表达特征: 大鳞副泥鳅整体表达水平最高, 北方泥鳅次之, 泥鳅最低。结果表明, 大鳞副泥鳅肉质油润, 但是质地相对粗糙; 泥鳅营养价值高且鲜味程度高; 北方泥鳅肉质细嫩, 但是氨基酸营养价值不高, 鲜味程度较差。三种鳅的上述肉质差异可能与肌肉生长和脂肪代谢活动不同有关。     

饲料中棕榈油替代鱼油和豆油对黄颡鱼生长和肌肉脂肪酸组成的影响

为研究不同棕榈油替代水平对黄颡鱼生长性能、肌肉脂肪酸组成、形体指标和肝脏组织结构的影响, 实验采用5组等氮(400 g/kg)等脂(100 g/kg)等能(15.70 MJ/kg)饲料饲喂黄颡鱼[(16.15±0.04) g], 对照饲料以鱼油鲶豆油1鲶2混合为脂肪源, 实验饲料以棕榈油分别替代10、25、40和55 g/kg的混合脂肪源。经过8周的养殖实验, 结果表明棕榈油替代水平对黄颡鱼的摄食量、终末体重、特定生长率、饲料效率和蛋白沉积率未产生显著性的影响(P>0.05), 但是上述指标均呈现先升高后略微下降的趋势, 并在25 g/kg替代组达到最大值。背肌肌肉中亚油酸和n-3HUFA含量随着棕榈油替代水平的上升而显著下降(P<0.05), 但n-3/n-6比值随着棕榈油替代水平的上升而显著上升(P<0.05), 棕榈油替代水平对各组黄颡鱼的肥满度和脏体比未产生显著性的影响(P>0.05), 但是55 g/kg棕榈油替代水平组肝体比显著高于25 g/kg棕榈油添加组(P<0.05), 且55 g/kg棕榈油替代水平组黄颡鱼的肝脏组织出现细胞肿胀, 细胞核移位, 肝血窦和脂肪细胞数量明显增多等不良影响。据上所述: 对于黄颡鱼幼鱼, 棕榈油可以替代25 g/kg的混合脂肪源(鱼油鲶豆油=1鲶2)不影响鱼体生长性能并且在一定程度上改善了背肌肌肉脂肪酸组成。     

High Lever Dietary Copper Promote Ghrelin Gene Expression in the Fundic Gland of Growing Pigs

This experiment was conducted to examine the effect of dietary copper supplementation on ghrelin mRNA expression level in the fundic gland of growing pigs. A total of 45 crossbred pigs were randomly assigned to three groups of 15 pigs, five replicates of three animals comprised each group. Pigs were allocated to diets that contained 5?mg/kg copper (as the control group), 125?mg/kg copper sulfate, or 125?mg/kg copper methionine. At the end of the experiment, five pigs were selected at random from each group, slaughtered, and collected the fundic gland for determination of ghrelin mRNA expression level. The results showed that average daily gain, average daily feed intake, absolute weight, serum growth hormone (GH) concentration, and ghrelin mRNA level were higher in pigs fed the diets with 125?mg/kg copper methionine and 125?mg/kg copper sulfate (P?<?0.05), than in pigs fed a diet with 5?mg/kg copper. These data suggest that high dietary copper (125?mg/kg) appears to increase feed intake and promote weight gain by enhancing the secretion of GH and ghrelin mRNA level in growing pigs.     

Effects of dietary grape proanthocyanidins on the growth performance,jejunum morphology and plasma biochemical indices of broiler chicks

Grape proanthocyanidins (GPCs) are a family of naturally derived polyphenols that have aroused interest in the poultry industry due to their versatile role in animal health. This study was conducted to investigate the potential benefits and appropriate dosages of GPCs on growth performance, jejunum morphology, plasma antioxidant capacity and the biochemical indices of broiler chicks. A total of 280 newly hatched male Cobb 500 broiler chicks were randomly allocated into four treatments of seven replicates each, and were fed a wheat–soybean meal-type diet with or without (control group), 7.5, 15 or 30 mg/kg of GPCs. Results show that dietary GPCs decrease the feed conversion ratio and average daily gain from day 21 to day 42, increase breast muscle yield by day 42 and improve jejunum morphology between day 21 and day 42. Chicks fed 7.5 and 15 mg/kg of GPCs show increased breast muscle yield and exhibit improved jejunum morphologies than birds in the control group. Dietary GPCs fed at a level of 15 mg/kg markedly increased total superoxide dismutase (T-SOD) activity between day 21 and day 42, whereas a supplement of GPCs at 7.5 mg/kg significantly increased T-SOD activity and decreased lipid peroxidation malondialdehyde content by day 42. A supplement of 30 mg/kg of GPCs has no effect on antioxidant status but adversely affects the blood biochemical indices, as evidenced by increased creatinine content, increased alkaline phosphatase by day 21 and increased alanine aminotransferase by day 42 in plasma. GPC levels caused quadratic effect on growth, jejunum morphology and plasma antioxidant capacity. The predicted optimal GPC levels for best plasma antioxidant capacity at 42 days was 13 to 15 mg/kg, for best feed efficiency during grower phase was 16 mg/kg, for best jejunum morphology at 42 days was 17 mg/kg. In conclusion, GPCs (fed at a level of 13 to 17 mg/kg) have the potential to be a promising feed additive for broiler chicks.