Optimal dietary carbohydrate to lipid ratio for juvenile yellowfin seabream (Sparus latus)

A growth experiment was conducted to determine the optimal carbohydrate‐to‐lipid (CHO: L) ratio for juvenile yellowfin seabream cultured in 340‐L indoor recirculating tanks. Seven isonitrogenous (450 g kg⁻¹ dietary protein) and isoenergetic (14.1 MJ kg⁻¹) diets with increasing CHO: L ratios (0.03–5.09 g: g) were fed to triplicate groups of 30 fish with an initial weight of 4.91 g for 56 days. Fish were fed to satiation twice a day and the water temperature ranged between 28 and 31.7 °C during the experimental period. Survival was high in all the groups and was not affected by dietary treatments. Best weight gain (WG) and specific growth rate (SGR) were observed in fish fed diets with CHO: L ratios of 0.29 and 0.72, which were not significantly different from that of 0.03, 1.26 and 1.92, but apparently higher than that of 3.22 and 5.09. Feed efficiency (FE), protein efficiency ratio (PER) and protein production value (PPV) followed the same general pattern as WG and SGR. Highest level of energy production value (EPV) was found in fish fed diets with CHO: L ratio of 0.72. Proximate compositions of fish whole body and tissues were markedly affected by dietary CHO: L ratios. Whole body, muscle and liver lipid increased as CHO: L ratios decreased, whereas moisture contents were reduced. Dietary CHO: L ratios had no significant effect on protein content in whole body and muscle. Plasma total cholesterol levels of fish fed diets with CHO: L ratios less than 0.72 were significantly higher than those of the other groups. Triacylglyceride levels decreased linearly as dietary CHO: L ratios increased. Viscerosomatic index (VSI) significantly increased as dietary CHO: L ratios decreased. Intraperitoneal fat ratio (IPF) of fish fed diets with CHO: L ratios less than 1.92 were significantly higher than those fed CHO: L ratios of 3.22 and 5.09. Hepatosomatic index (HSI) did not vary between the test diets. Based on second‐order polynomial regression analysis of WG against dietary carbohydrate and lipid levels, 84.1 g kg⁻¹ of carbohydrate and 136.3 g kg⁻¹ of lipid, corresponding to a CHO: L ratio of 0.62, in a diet holding 450 g kg⁻¹ of crude protein and 14 KJ g⁻¹ of metabolizable energy, proved to be optimal for juvenile yellowfin seabream.     

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.     

不同蛋白水平饲料对台湾东风螺生长性能和体组成的影响

以优质鱼粉、豆粕等原料制成蛋白质含量不同的6组饲料(粗蛋白含量分别为48.16%、45.64%、40.67%、35.68%、30.80%、25.96%),喂养台湾东风螺47 d,以投喂鲜杂鱼组作为对照,分别于15、27、37、47 d测定螺高、螺宽、螺体重等生长指标,计算不同处理组在不同时间段(27、37、47 d)的饲料系数和蛋白质效率,试验结束后测定东风螺螺肉的体组成和氨基酸含量,研究结果表明:投喂颗粒饲料比投喂鲜杂鱼的饲料系数显著高;而当颗粒饲料中蛋白质含量变化(25%~48%)时,对东风螺生长性能并无显著影响。但随着饲料蛋白含量的增加,东风螺对饲料的利用率在一定程度上有所提高。当饲料中粗蛋白含量低于25%时,47 d时其饲料系数2.3,显著高于其他饲料组;蛋白质效率1.74显著低于蛋白含量48.16%饲料组。从东风螺生长性能和饲料利用分析,颗粒饲料中蛋白质含量不应低于25%。所有组东风螺螺肉的粗蛋白、脂肪,总氨基酸组成均无显著差异,但是一些中性氨基酸(如亮氨酸、异亮氨酸和丙氨酸)和精氨酸随着饲料蛋白含量的降低而呈现出降低趋势,部分组产生了显著差异。投喂颗粒饲料的东方螺生长不如投喂鲜杂鱼组。     

东海区主要经济鱼类开捕规格的初步研究

根据1997-2000年东海区底拖网渔、№资源调查资料，以Beverton—Holt模型的单位补充量渔获最方程估算东海区18种主要经济鱼类的最适开捕年龄。运用von Bertalanffy，丰长方程估算最适开捕体长。结合鱼类生长的拐点年龄、临界年龄和初届性成熟年龄的体长，以及各鱼种实测最小性成熟体长，确定开捕规格。结果表明，目前东海区产量较高的带鱼（Trichiurus japonicus）和小黄鱼（Larimichthys polyactis）的建议开捕规格分别应为体长230mm和170mm。调整后的开捕规格与旧开捕规格相比，带鱼、短尾大眼鲷（Priacanthus macracanthus）、灰鲳（Pampus cinereus）、自姑鱼（Argyrosomus argentatus）均有所增大，小黄鱼、银鲳（Pampus argenteus）的开捕规格有所减小，变化较小的有蓝点马鲛（Scomberomorus niphonius）、日本鲭（Somber japonicus）、慌圆鲹（Decapterus maruadsi）等。建议以这18种主要经济鱼类为指标种类，制定新的法定开捕体长和幼鱼比例检查措施，实现东海区渔业资源的可持续利用。     

黑鲷耗氧率昼夜变化及与体重、水温的关系研究

研究了黑鲷(Sparus macrocephalus)耗氧率的昼夜变化规律及其与体重、水温的关系,结果表明,黑鲷耗氧率随水温的升高而升高,随个体的增大而降低;23:00耗氧率最高,为3.16±0.26μg·(g·min)-1,07:00左右耗氧率最低,为0.74±0.59μg·(g·min)-1。黑鲷白天的平均耗氧率为1.98±0.84μg·(g·min)-1,夜间的平均耗氧率为1.96±0.63μg·(g·min)-1,其代谢水平的昼夜变化不明显(n=10,t=0.034相似文献   

半滑舌鳎lnc-XR_003049606.1及其靶基因pmelb在无眼侧皮肤黑化过程中的表达

为探究人工养殖半滑舌鳎无眼侧皮肤经常出现黑化现象的成因,实验根据本课题组前期全转录组数据分析结果预测得出lnc-XR＿003049606.1与pmelb在基因层面上存在反式调控的关系。在半滑舌鳎无眼侧黑化皮肤中克隆获得pmelb的c DNA序列。生物信息学分析结果显示,pmelb的c DNA序列全长1 755 bp,编码584个氨基酸,其预测的蛋白分子量为63.94 ku,理论等电点为5.12,预测的二级蛋白结构含有1个Pleckstrin同源域、1个布鲁顿酪氨酸激酶富胱氨酸基序、1个Src同源3域、1个Src同源2域和1个酪氨酸激酶催化结构域。系统进化树分析显示,pmelb与其他鱼类对应的基因聚为一支。氨基酸同源性分析显示,半滑舌鳎的pmelb与大菱鲆和牙鲆的相似性最高(分别为68.05%和66.28%)。分别通过分析半滑舌鳎lnc-XR＿003049606.1和pmelb的表达分析发现,lnc-XR＿003049606.1在1龄半滑舌鳎的皮肤和肝脏中表达,皮肤中表达量在60 d达到顶峰,随着时间延长而降低;而pmelb则主要在皮肤中表达,表达量在时间线上先升高再降低。本研究初步探究...     

建鲤与异育银鲫生长、生化组成和饲料利用的比较

In order to investigate the difference in utilization of diets with different quality in Jian carp（Cyprinus carpio var. Jian）and allogynogenetic silver curcian carp(Carassius auratus gibelio), a 55 d growth trial was conducted and low quality diet (LQ-diet) and high quality diet (HQ diet) were tested. LQ-diet contained 33.91% dietary protein which is mainly from soybean meal while HQ-diet contained 45.59% dietary protein which is mainly from fish meal. The initial average body weights were from 5.58 g to 5.82 g for two fish strains. The trial was carried out in a system consisting of 12 self circulation 320 L tanks. During the experiment, the fish were fed to satiation twice a day (at 9: 00 and 15:00), and uneaten feed was collected 1 h after feeding and dried. Feces were collected twice a day (at 11:00 and 16:45) from the fecal traps and dried at 70 ℃. The results show that feed intake was higher in Jian carp than in allogynogenetic silver curcian carp when fed LQ diet, while there was no significant difference between weight gain, feed conversion efficiency, protein efficiency rate and apparent digestibility. When fed HQ diet, Jian carp showed a lower feed intake, but higher feed conversion efficiency and protein efficiency rate than allogynogenetic silver curcian carp while there was no significant difference in the weight gain and apparent digestibility of both species. For Jian carp, feed intake and protein efficiency rate for the fish fed HQ diet and LQ diet were not significantly different, while the fish fed HQ diet showed higher weight gain, feed conve rsion efficiency and apparent digestibility. For allogynogenetic silver curcian carp, the fish fed HQ diet showed significantly higher feed intake, apparent digestibility, weight gain, feed conversion efficiency and lower protein efficiency rate. For Jian carp, body contents of dry matter, protein, lipid and energy for the fish fed HQ diet and LQ diet were significantly higher. For allogynogenetic silver curcian carp, body contents of dry matter and protein was significantly higher, while body contents of lipid and energy were affected by diet qualities. Compared to Jian carp, allogynogenetic silver curcian carp showed better utilization when fed LQ diet while poorer utilization when fed HQ diet.     

Observation of virus particles in the spleen, kidney, gills and erythrocytes of Atlantic salmon, Salmo salar L., during a disease outbreak with high mortality

An annual disease problem with high levels of mortality in Atlantic salmon, Salmo salar L., on a freshwater farm was investigated. In 2000, mortalities began early in October and peaked in December, being unevenly distributed between tanks. Histopathological changes included severe hyperplasia of gill epithelium, with fusion of secondary lamellae, and extensive necrosis of the haematopoietic centres in the kidney and spleen, the latter being consistent with a diagnosis of phagocytolytic syndrome (PCLS). Moribund fish were anaemic, with multiple, circular basophilic inclusion bodies, 1–2 μm in diameter and suggestive of erythrocytic inclusion body syndrome (EIBS), being observed on blood smears. Thin section electron microscopy (EM) revealed primarily membrane-bound aggregates of non-enveloped virus particles (73 ± 7 nm) with an electron dense core (35 ± 3 nm) in spleen, kidney and gill tissue and the erythrocytes therein. These particles had morphology and distribution consistent with those previously described separately for both EIBS and PCLS. Virus isolation attempts in a wide range of cell lines were unsuccessful. In the absence of suitable alternative infectious or environmental explanations, it is postulated that the aetiology was primarily viral, with possible contributory secondary environmental factors. It is further hypothesized that the agents of EIBS and PCLS may be the same or closely related viruses.     

Dietary carbohydrate and growth,body composition and heat increment in rainbow trout (Salmo gairdneri)

A study was conducted to determine growth, body composition and heat increment (HI) of rainbow trout reared on isonitrogenous high digestible carbohydrate (HC) and high fat (HL) diets at 15°C. Trout reared on the HC diet had a significantly lower final body weight and carcass lipid content and a significantly higher feed:gain ratio and carcass protein content than trout reared on the HL diet after 12 weeks on the test diets. The lower carcass lipid composition indicates that trout do not readily convert dietary carbohydrates into fat. HI of trout reared on the HC diet was significantly higher than that of fish reared on the HL diet. Considering the poor utilization of dietary carbohydrates as an energy source and the apparently low conversion of dietary glucose into fat, the cause of the higher HI associated with the HC diet is not completely understood. However, it is possible the elimination of excess dietary glucose is an energy dependent process resulting in an increased heat production which would partly account for the increased HI. Furthermore, if the HC diet is a low net energy diet, then the metabolism and utilization of dietary and tissue proteins (amino acids) for energy by the trout may also be partly responsible for the increased HI of the trout reared on the HC diet.