Influence of dietary phosphorus levels on growth,body composition,metabolic response and antioxidant capacity of juvenile snakehead (Channa argus × Channa maculata)

A study was conducted to estimate the optimum requirement of dietary phosphorus (P) for Channa argus × Channa maculata. Effects of dietary P levels on the tissue composition, serum biochemical parameters and antioxidant status were also examined. Five practical diets were formulated to contain graded levels (4.8 g kg^?1, 6.4 g kg^?1, 7.9 g kg^?1, 9.4 g kg^?1 and 11.0 g kg^?1) of available P from dietary ingredients and monocalcium phosphate (MCP). Each diet was randomly assigned to triplicate groups of 30 juvenile fish (initial body weight, 20.50 ± 0.53 g) for 8 weeks. The results showed that the specific growth rate (SGR) and weight gain (WG) were all significantly improved by dietary P up to 9.4 g kg^?1 (P < 0.05) and then levelled off beyond this level. Broken‐line analysis showed maximum weight gain (WG) was obtained at dietary available P concentrations of 9.6 g kg^?1. With the increase in dietary P level, protein efficiency rate (PER) increased significantly and reached a plateau, while the feed conversion ratio (FCR), the mesenteric lipid somatic index (MSI) and the whole‐body lipid content significantly reduced (P < 0.05). Dietary P levels also affected the mineralization (ash and P) of whole body, vertebrae and scale (P < 0.05). Quadratic analysis based on P contents in whole body, vertebrae, scale and ash content in vertebra indicated that the available P requirements were 10.4, 9.8, 10.0 and 10.3 g kg^?1, respectively. However, no differences were found in the whole‐body moisture, crude protein, serum calcium (Ca) contents or Ca/P value, as well as the viscerosomatic index (VSI) and hepatosomatic index (HSI) among all the treatments (P > 0.05). Triglyceride (TG), total cholesterol (TC), high‐density lipoprotein cholesterol (HDL‐C) and low‐density lipoprotein cholesterol (LDL‐C) decreased significantly, while serum P content, HDL‐C/TC and HDL‐C/LDL‐C value increased significantly with dietary available P levels (P < 0.05). No significant changes in superoxide dismutase activity and malondialdehyde (MDA) content were observed (P > 0.05), but serum catalase (CAT) and glutathione peroxidase (GPx) activities and the ratio of CAT/SOD and GPx/SOD increased significantly with increasing dietary P levels (P < 0.05). In conclusion, the optimal P requirement of juvenile snakehead in practical feed was 9.6 g kg^?1. Signs of P deficiency were characterized by poor growth, slightly reduced mineralization and the antioxidant capacity and an increase in body lipid content.     

Comparison of age estimates from scale, opercular bone, otolith, vertebrae and dorsal fin ray in Labeo rohita (Hamilton), Catla catla (Hamilton) and Channa marulius (Hamilton)

The present study was undertaken with a view to compare the precision and reliability of the age readings obtained from different bony structures of some important freshwater teleosts viz., Labeo rohita (Hamilton), Catla catla (Hamilton) and Channa marulius (Hamilton). Standard procedures were followed to prepare and study the age structures. In L. rohita and C. marulius percent agreement between reader's age estimates was highest for scales, i.e. 96.3% and 90.5%, respectively and in C. catla percent agreement was highest (93.3%) for opercular bone. When scale ages were compared with other alternative structures viz., otoliths, opercular bone, vertebral centra and dorsal fin rays, percent agreement was found highest between scale and opercular bone age estimates (77.8%) in L. rohita and between scale and otoliths (94.8%) in C. marulius. In case of C. catla highest percent agreement was found between opercular bone and scale age estimates. In L. rohita each of the ageing structure showed significant (P < 0.05) underestimation of age in comparison to scales. In C. catla mean age estimates from opercular bone were comparable (P > 0.05) to the values obtained from all other structures except dorsal fin rays. In C. marulius mean age estimates from scales were comparable (P > 0.05) to those from all other structures except from dorsal fin rays. Results indicated scales to be the most suitable structure for ageing L. rohita and C. marulius and opercular bone for C. catla. However, in C. catla also scales may be used as a non-destructive method of age estimation with satisfactory results.     

鳢流行性溃疡综合征病原分离鉴定与病理形态学观察

为寻找冬春季鳢(Channa maculata)烂身病的病原,应用组织压片、组织切片、扫描电镜技术、HE 常规染色法和 Grocott 六胺银染色法、霉菌分离纯化及 ITS 的序列分析等对冬春季患疑似溃疡综合征的烂身病鳢进行了病原学与病理学研究。病变组织压片观察到大量直径 10~20 μm,分枝较少、纤细菌丝。扫描电镜观察到肌肉组织中延伸出大量的纤细的丝状真菌。患病鳢皮肤和肌肉表现为变性、坏死与炎性细胞浸润,溃疡灶肌肉内可见大量的慢性肉芽肿结节和炎性细胞浸润。结节基本结构由类上皮细胞和多核巨细胞、炎性细胞、霉菌菌丝(横断面呈圆形,斜断或纵断呈丝状)组成,霉菌位于结节中央。Grocott 六胺银染色观察到结节中有大量棕色菌体。无菌分离培养可观察到典型丝状霉菌;霉菌在灭菌池塘水 20℃过夜, 12 h 后可观察原代孢子群形成,真菌 ITS 序列分析表明其与侵袭丝囊菌(Aphanomyces invadans)同源性为 100%。侵袭丝囊霉菌(A. invadans)是杂交鳢溃疡综合症病的主要病原,为鱼类流行病学调查和疾病防治的深入研究奠定基础。     

乌鳢血液指标的研究

对乌鳢的红、白细胞数、血红蛋白等血液指标进行了研究。结果如下:乌鳢的红细胞数为(369.83±51.03)万个/mm3;白细胞数为(5.88±1.27)万个/mm3;血红蛋白为(9.54±0.61)g/100ml;白细胞分类计数中淋巴细胞占(58.23±5.67)%;嗜中性细胞占(28.10±4.36)%;单核细胞占(9.10±4.02)%;嗜碱性细胞和嗜酸性细胞观测到的数目很少;血沉为(1.50±0.12)mm/h;红细胞膜最大抵抗值为(0.38±0.02)%;红细胞大小为(10.02±0.52)μm×(7.01±0.24)μm(长径×短径);红细胞核为(4.22±0.27)μm×(1.96±0.18)μm(长径×短径)。     

pH对月鳢蛋白酶活性的影响

对月鳢(Channa asiatica)消化系统不同部位蛋白酶活性的最适pH进行了研究，结果表明：月鳢成鱼胃黏膜组织、前肠黏膜组织和肝胰脏蛋白酶活性的最适pH分别为6．2、5．4和5．4，不同消化部位的该酶活性最大时的pH有所差异。     

二种引进鳢科鱼类的染色体组型

本文报道纹鳢和巨鳢的染色体组型。其结果是：纹鳢，２ｎ＝４４，核型公式为，４ｍ＋２ｓｍ＋１６ｓｔ十２２ｔ，ＮＦ＝５０；巨鳢，２ｎ＝４４，核型公式为，２ｍ十４２ｔ，ＮＦ＝４６。本文还讨论了这两种鱼的进化地位问题。     

一株鳢科鱼源弹状病毒的分离及鉴定

为研究近来鳢科鱼类疫病频发的病因,实验对采集的患病杂交鳢病料分别从细菌学和病毒学两方面进行病原分离和鉴定。排除细菌感染的可能后,通过细胞培养技术、回归感染实验、电镜技术、分子生物学技术等进行病毒学分析,最终分离到一株弹状病毒,命名为HSHRV-C1207(Hybrid Snakehead Rhabdovirus-C1207)。实验结果显示,该病毒在EPC、FHM、GSB、SFC、CIK等 8种细胞中都能复制,并对其中6种细胞产生明显的细胞病变效应(CPE)。用分离的病毒进行回归感染实验,可使感染的杂交鳢复制出自然发病鱼的相同症状,且死亡率达90%。感染病料组织液的EPC细胞固定后经电镜观察,发现细胞质内有大量子弹状病毒聚集,直径约60 nm,长度约为160 nm,形态和排列方式与已报道的鱼类弹状病毒相似。参考OIE中传染性造血器官坏死病毒(IHNV)、病毒性出血性败血症病毒(VHSV)、鲤春病毒血症病毒(SVCV)的检测引物及根据乌鳢弹状病毒(SHRV)、鳜鱼弹状病毒(SCRV)、比目鱼弹状病毒(HIRRV)的G蛋白基因设计特异性引物,分别对自然发病病料组织、接种病料组织的细胞进行RT-PCR扩增,仅针对SCRV的引物能扩增出大小约350 bp 的片段。对HSHRV-C1207株的G基因进行序列测定和分析,结果表明其核苷酸序列同SCRV和SHRV的同源性分别为93.8% 和 20.4%,推导的氨基酸序列同源性分别是93.7%和18.3%。用G基因推导氨基酸序列与其它弹状病毒的G蛋白进行系统进化树分析,表明该毒株与水泡性病毒属聚为一支,其中与SCRV的亲缘关系最近,而与属于诺拉弹状病毒属的SHRV相距甚远,可能为SCRV的变异株或一个新的毒株。     

喷雾干燥微胶囊化罗非鱼油的研究

为满足消费者对美味鱼汤产品的需求,提高乌鳢 (Channa argus) 加工副产物的利用价值,以前期制备的乌鳢鱼头汤为原料,用麦芽糊精作助干剂,采用喷雾干燥法制备乌鳢鱼头汤粉末,以干燥粉末的水分质量分数、色泽、溶解性、堆积密度、冲调时间以及粘壁情况为评价指标对喷雾干燥工艺优化进行研究。结果表明,麦芽糊精能够有效提高喷雾干燥的集粉率、粉体亮度、溶解性,改善粘壁情况;麦芽糊精质量浓度为15 g·L ^{− 1}、喷雾干燥进风温度为170 ℃、进料速度为6 mL·min ^{− 1}时喷雾效果和产品品质最佳,所制得的乌鳢鱼头汤粉末具有含水量较低、堆积密度较大、溶解度较高、吸湿性较低和颗粒均匀等特性。综上,喷雾干燥法可作为乌鳢鱼头汤粉末的制备方法。     

金黄色乌鳢染色体核型分析

为了解金黄色乌鳢的细胞遗传学特性,便于今后对其种质进行评估与鉴定,以金黄色乌鳢为材料,通过活体腹腔注射植物血球凝集素及秋水仙素,用常规冷滴片法制备染色体标本,分析研究其染色体核型.结果显示,金黄色乌鳢染色体数为48,核型公式为2 n=4 sm+22 st+22 t,臂数NF=52.本试验中未发现随体、次缢痕及异形性染色...