Effect of Dietary Lipid Sources on Production of Leukotriene B by Head Kidney of Channel Catfish Held at Different Water Temperatures

Abstract

Separate and combined effects of dietary fatty acids and water temperature on the production of leukotriene B (LTB) by the head kidney of channel catfish Ictalurus punctatus were investigated. Fish were fed semipurified diets containing 7% lipid as beef tallow, corn oil, linseed oil, menhaden oil, or a mixture (1:1:1) of menhaden oil, beef tallow, and corn oil. At 28°C, fish fed corn oil produced the greatest amount of LTB, and fish fed beef tallow produced the least. At 17°C, production of LTB by fish fed the beef tallow diet was again lowest; production of LTB by fish fed the corn oil diet was highest but was not significantly different from that obtained with the mixed-oil or menhaden oil diet. Production of LTB for the other diets was intermediate. This is the first report that the head kidney of channel catfish produces LTB; this production was affected by dietary lipid sources but not by the two water temperatures tested. Production of LTB was not related to weight gain. Moreover, the pattern of LTB production does not explain survival rates of channel catfish observed in a previous experiment in response to pathogen challenge. However, LTB concentration does appear to be roughly proportional to the amount of eicosanoid precursors (arachidonic acid and eicosapentaenoic acid) previously reported for liver phospholipids of channel catfish fed diets containing different amounts of essential fatty acids.     

Ultrastructure of Developing and Mature Caprine Leukocytes

Transmission electron microscopy demonstrated that, based on the structural uniqueness of the granules, caprine granulocytes are easily distinguishable from each other from the promyelocyte stage onwards. The neutrophils had the smallest granules which varied in size and were, in mature cells, either spherical to dumb-bell in shape; in mature cells the granule contents were compact and finely granular. The primary granules were smaller than the secondary granules. The eosinophil granules were large and typically had internal crystalloid structures; a second group of spherical granules with moderately coarse non-crystalloid sub-structure was present in smaller numbers in promyelocytes and myelocytes only. The basophil granules were also large, lackes crystalloids but showed variation in coarseness of granule substance, ranging from finely granular to markedly coarse. Mature granulocytes lackes Golgi apparatus and rough endoplasmic reticulum and ribosomes which were present in promyelocytes, myelocytes, metamyelocytes and bands. The monocytes had moderate numbers of spherical granules, rough endoplasmic reticulum, mitochondria and ribosomes, as well as prominent Golgi apparatus, and the cytoplasm had many small vacuoles.     

不同遗传型鸡肌纤维超微结构的研究

电镜观察红宝鸡,苏北地方鸡及杂种鸡肌纤维超微结构表明,不同遗传型肌原纤维在直径、肌节长度、Ⅰ带、A带长度不仅存在差异,而且在肌原纤维间肌质、线粒体、肌糖元、脂肪滴含量亦存在差异。分析表明,鸡肌纤维的超徼结构与鸡生长速度,肉质有密切关系。     

Enteric Septicemia Resistance in Blue Catfish and Three Channel Catfish Strains

Abstract

Seven full-sib families in each of three strains of channel catfish Ictalurus punctatus (mean weight, 10.7 g; SD, 2.6 g) and one family of blue catfish I. furcatus (mean, 10.9 g; SD, 0.4 g) were challenged by immersion with the bacterium Edwardsiella ictaluri, the causative agent of enteric septicemia, to evaluate variation in disease resistance. Blue catfish were resistant to infection and had only 0.7% mortality. Significant (P < 0.001) variation in channel catfish resistance was found among strains, families, and body weights. Red River strain channel catfish were the most resistant (14.9% mortality), followed by Mississippi-select fish (67.1%) and Mississippi-normal fish (72.3%). Mean family mortality of channel catfish ranged from 1.3% in a Red River family to 95.3% in a Mississippi-select family. Although weight had a significant effect on survival, the regression slope of survival on weight was ?0.10 (SE, 0.02). Sources of variation in channel catfish mortality adjusted for weight were 67.3% from strains, 29.7% from families, and 3.0% from replicate tanks. The mechanism for differential resistance presently is unknown. Results indicate considerable potential for reducing disease losses by using E. ictaluri-resistant catfish strains in aquaculture and for genetic improvement in resistance via selective breeding programs.     

Responses of Blue Catfish and Channel Catfish to Environmental Nitrite

Abstract

In nitrite-exposure experiments, percent methemoglobin, plasma nitrite concentration, and plasma chloride ion concentration were compared between channel catfish Ictalurus punctatus and blue catfish I. furcatus exposed to sublethal levels of nitrite for 48 h at 25°C. In nitrite-recovery experiments, fish exposed to elevated environmental nitrite for 12 h were transferred to freshwater, and blood characteristics were monitored during the 24-h recovery period. Blue catfish appeared to be more resistant to environmental nitrite than channel catfish. Methemoglobin levels (percent of hemoglobin in methemoglobin form) were significantly lower in blue catfish than in channel catfish. Maximum plasma nitrite concentrations were 137 mg NO₂-/L plasma in blue catfish and 164 mg NO₂-/L plasma in channel catfish. Percent methemoglobin and plasma nitrite concentration were closely correlated. Plasma chloride decreased initially with exposure to nitrite but quickly returned to control levels. Blue catfish exposed to nitrite at 10°C required 1 week to recover when placed in nitrite-free water. The methemoglobin reductase enzyme apparently functioned at a slow rate in fish acclimated to cold temperatures.     

Effect of Waterborne Potassium Permanganate Exposure on Manganese Content in Liver and Axial Muscle of Channel Catfish

Abstract

Adult channel catfish Ictalurus punctatus were exposed to waterborne potassium permanganate for 12 weeks to determine if such exposure would alter the manganese content of axial muscle or liver tissue. Continuous exposure to 0.5 mg KMnO₄/L or exposure to 1 or 2 mg KMnO₄/L on alternate days did not cause a significant increase in manganese in axial muscle or liver tissue. The mean (±SE) concentration of manganese in axial muscle of unexposed controls was 0.262 ± 0.018 mg/kg (wet weight). Means of manganese concentrations in axial muscle of the three exposure groups during the 12 weeks of exposure were 0.289 ± 0.021 mg/kg, 0.269 ± 0.018 mg/kg, and 0.239 ± 0.013 mg/kg for 0.5 (continuous), 1, or 2 mg/L (alternate days), respectively. At specific sampling times there were differences between controls and exposure groups; however, no trend toward higher or lower manganese concentrations in muscle could be detected within groups. The mean (±SE) concentration of manganese in liver tissue of controls was 1.67 ± 0.09 mg/kg (wet weight). Manganese concentrations in liver tissue of the three exposure groups were 1.57 ± 0.07 mg/kg, 1.68 ± 0.08 mg/kg, and 1.58 ± 0.10 mg/kg, for 0.5 (continuous), 1, or 2 mg/L (alternate days), respectively. Manganese was thought to accumulate in liver tissue, however, there were no statistically significant differences between those groups and the controls. Results suggest that potassium permanganate used as a waterborne disease therapeutant for channel catfish does not alter manganese content of edible muscle of channel catfish and should not present any hazard to human consumers.     

Longevity of Bolbophorus damnificus Infections in Channel Catfish

Abstract

The digenean Bolbophorus damnificus infects commercial channel catfish Ictalurus punctatus, causing mortality, lower feed consumption, and reduced growth in surviving fish. The purpose of this study was to determine the length of time for which B. damnificus prodiplostomulum metacercariae (juvenile trematode stage that infects fish) would remain viable (parasite appearing to be intact or exhibiting movement) in channel catfish. Fish (n = 210) were infected with molecularly confirmed B. damnificus cercariae harvested from naturally infected marsh rams-horn snails Planorbella trivolvis. During the first sampling (at 20 d postinfection), 8.3 ± 3.6 metacercariae/fish (mean ± SD) were found in the host muscle and visceral organs. The channel catfish were then acclimated to a water temperature of either 18°C or 28°C. After 11 months, 6.8 ± 3.5 and 5.9 ± 3.0 metacercariae/fish were found in groups held at 18°C and 28°C, respectively. The mean number of parasites per fish did not significantly differ between fish held at the two temperatures and did not significantly decline over time at either temperature. Fish examined from 13 to 30 months postinfection all contained viable metacercariae that were morphologically and molecularly identified as B. damnificus. At 18 months, 12 metacercariae (of which 11 were intact and 10 displayed movement) were found in the one fish sampled; at 30 months, the last fish sampled contained three intact metacercariae (one displayed slight movement). Our results indicate that B. damnificus metacercariae can remain viable in channel catfish for at least an 18–30-month production cycle during which they have the potential to affect fish growth; in addition, infected fish may serve as intermediate hosts for these metacercariae for at least 2.5 years postinfection.

Received July 14, 2010; accepted March 6, 2011     

斑点叉尾(鱼回)营养需求和饵料开发研究进展

本文主要综述了近年来国内外对斑点叉尾(鱼回)在营养需求方面的一些研究进展.主要包括蛋白质与氨基酸、脂肪、碳水化合物、维生素与矿物质等需要量的研究进展,人工配合饵料的研制情况.对斑点叉尾(鱼回)在饲料开发方面存在的问题结合我国国情作了一定的分析与讨论,并就斑点叉尾(鱼回)营养和饲料研究对其在我国养殖业中产生的影响作了展望.     

Efficacy of Potassium Permanganate in Treating Ichthyophthiriasis in Channel Catfish

Abstract

Epizootics of ichthyophthiriasis can be controlled with potassium permanganate (KMnO₄), but its effectiveness has not been confirmed by controlled studies. The purpose of this study was to determine the concentration of KMnO₄ needed to halt an active Ichthyophthirius multifiliis infestation in channel catfish Ictalurus punctatus. Juvenile channel catfish were exposed to fish infested with I. multifiliis until they developed immature trophonts. They were then moved to individual static containers with 2 L of filtered well water, where they were treated with KMnO₄ daily for 10 d. The lowest effective dose of KMnO₄ required to eliminate theronts was 1.25 mg/L. The results indicate that KMnO₄ is effective for controlling I. multifiliis epizootics at low concentrations in clean water. However, effective treatment in ponds will be strongly influenced by detoxication of KMnO₄ depending on the concentration of easily oxidizable substances in the water.     

Induction and Evaluation of Proliferative Gill Disease in Channel Catfish Fingerlings

Abstract

Proliferative gill disease (PGD) was first reported in channel catfish Ictalurus punctatus at commercial farms in 1981 and is caused by the myxozoan parasite Henneguya ictaluri. The disease affects the gills and is characterized by severe branchial inflammation, epithelial hyperplasia, lamellar fusion, and lysis of chondrocytes. Presumptive diagnosis is based on the presence of lytic areas in the cartilage of the primary lamellae on microscopic examination and is confirmed histologically by the presence of the organism. In these trials, PGD was induced by exposing channel catfish fingerlings to fresh or aged infectious water collected from a pond containing fish diagnosed with severe PGD. The severity of disease was graded by histological scoring and microscopic examination of wet mounts to determine the percentage of gill filaments containing chondrolytic lesions. Exposure of fish to infectious pond water was shown to produce pathological lesions consistent with PGD, and the percentage of gill filaments containing chondrolytic lesions was positively correlated with histological scoring of gill pathology. The number of trophozoite stages in the gills was shown to increase with the severity of the disease. In most cases, however, parasitic cells were not observed in tissue samples with chondrolytic lesions during the early stages of infection. These observations indicate that pathology and lysis of chondrocytes can occur prior to detection of the organism by histopathology. Exposing fish to infectious pond water that was aged for 1 d produced negligible gill pathology and implies that the infectivity of the H. ictaluri actinospore stage is short lived. Removing fish from the source of infection promoted repair of damaged gill tissue; within 14 d of fish transfer to clean water, gill pathology associated with the acute infection was negligible.     

不同咸蛋腌制温度对禽流感毒灭活的影响

经人工接种H9亚型禽流感病毒(AIV)的鸭蛋,分别在12℃、22℃和32℃条件下按常规方法腌制于饱和盐水中,同时以置饱和盐水中的禽流感病毒和未经处理禽流感病毒样品作为对照,通过MDCK细胞培养、间接免疫荧光方法定期进行禽流感病毒毒力测定,结果在12℃、22℃和32℃条件下腌制鸭蛋中的禽流感病毒分别于49天、27天和4天失去毒力,置饱和盐水中的禽流感病毒分别在27天、9天和2天失去毒力,而未经处理的禽流感病毒分别在92天、29天和17天失去毒力;不同试验温度条件下,以荧光RT-PCR检测腌制鸭蛋和对照样品中的禽流感病毒,在100天后仍可检出病毒核酸(Ct<30)。以上检测结果表明,在腌制鸭蛋时于常温下置饱和盐水腌制40天以上的传统咸蛋生产工艺,可使禽流感病毒完全失去毒力,腌制的鲜咸蛋携带或传播禽流感病毒的风险极低或不存在风险。     

Experimental Induction of Proliferative Gill Disease in Specific-Pathogen-Free Channel Catfish

Abstract

Specific-pathogen-free channel catfish Ictalurus punctatus were exposed to sediment and mud from a pond containing channel catfish with proliferative gill disease. In one experiment, fish were to exposed to mud and sediment for 2 months in water maintained at 19°C. Fish were necropsied weekly, and certain tissues were examined histologically and ultrastructurally. Four trials were conducted with sediment samples from different epizootics of proliferative gill disease. In a second experiment, fish were exposed to sediment for 7 d in water maintained at 16, 19, or 26°C; the fish were then moved to clean water held at 16, 19, or 26°C. Fish were necropsied before transfer to clean water and weekly thereafter for 2 months. Channel catfish held at 19°C developed proliferative gill disease within 2 d of exposure to sediment. Primary cells of a uninucleate myxosporean parasite were present in the gills at the base of lamellae. These developed into plasmodia with numerous secondary cells, and some primary cells disintegrated, releasing their internal secondary cells. Similar development was observed in internal organs 1 week after appearance of the parasite in gills. Complete sporogony did not occur over the 2 months of this study. Plasmodia became necrotic and were not detected after 60 d. In fish exposed to sediment for 7 d at 16, 19, and 21°C, similar organisms were detected, but clinical disease occurred only at 19 and 26°C. Proliferative gill disease may be attributed to extrasporogonic stages of a myxosporean resembling Sphaerospora spp.     

奶皮子的制作及其贮藏期间理化性质的变化

主要研究在冷冻和冷藏两个不同贮藏温度下,奶皮子的总脂肪含量、蛋白质分解率、氨基酸、感官品质随贮藏时间的变化规律。结果发现蛋白质分解率、氨基酸随贮藏时间的延长而增加,随贮藏温度的上升而增加;而总脂肪的含量随着贮藏时间的延长和温度的上升,逐渐的下降。     

Spleen Index and Mannose-Binding Lectin Levels in Four Channel Catfish Families Exhibiting Different Susceptibilities to Flavobacterium columnare and Edwardsiella ictaluri

Abstract

Edwardsiella ictaluri and Flavobacterium columnare are two bacterial pathogens that affect channel catfish Ictalurus punctatus aquaculture. At the Catfish Genetics Research Unit (U.S. Department of Agriculture, Agricultural Research Service), some progress has been made in selectively breeding for resistance to E. ictaluri; however, the susceptibility of these families to F. columnare is not known. Our objectives were to obtain baseline information on the susceptibility of channel catfish families (maintained as part of the selective breeding program) to E. ictaluri and F. columnare and to determine whether the spleen index and plasma levels of mannose-binding lectin (MBL) are predictive indicators of susceptibility to these pathogens. Four channel catfish families were used: family A was randomly chosen from spawns of fish that were not selectively bred for resistance; families B, C, and D were obtained after selection for resistance to E. ictaluri. All four families were immersion challenged with both bacterial pathogens; the spleen index and plasma MBL levels of unchallenged fish from each family were determined. Mean cumulative percent mortality (CPM) after E. ictaluri challenge ranged from 4% to 33% among families. Families A and B were more susceptible to F. columnare (mean CPM of three independent challenges = 95% and 93%) than families C and D (45% and 48%), demonstrating that there is genetic variation in resistance to F. columnare. Spleen index values and MBL levels were not significantly different, indicating that these metrics are not predictive indicators of F. columnare or E. ictaluri susceptibility in the four tested families. Interestingly, the two families that exhibited the highest CPM after F. columnare challenges had the lowest CPM after E. ictaluri challenge. Further research on larger numbers of families is needed to determine whether there is any genetic correlation between resistance to E. ictaluri and resistance to F. columnare.

Received November 18, 2011; accepted February 23, 2012     

Electron Microscopy of Infection by Saprolegnia spp. in Channel Catfish

Abstract

Saprolegnia sp. isolated from channel catfish Ictalurus punctatus grew slower than S. parasitica on cornmeal agar (CMA). Oogonia in Saprolegnia sp. appeared frequently, whereas oogonia were rarely seen in S. parasitica on CMA. In experimental exposures of injured channel catfish to fungal spores, infections were apparent after 3–4 d, but were most common after 7–9 d. Multiple lesions were usually seen in naturally infected fish, whereas a single lesion appeared at the injured site of experimentally infected fish. No obvious differences were found between lesions caused by S. parasitica and those caused by Saprolegnia sp. Most of the epidermal cells in fungusinfected lesions were necrotic. In some lesions, the epidermis was completely sloughed and the dermis was exposed. Both Saprolegnia parasitica and Saprolegnia sp. penetrated the dermis, causing damage to fibroblasts and collagen lamellae.     

牛冷冻精液解冻后在不同温度下的存活时间

牛冷冻精液解冻后在3～8℃、室温及37℃条件下保存,分别于2、4、8、12及24小时,观察其活力变化。结果表明:环境温度对精子的存活时间影响很大,活力的下降速度有明显差异。     

不同温度湿法挤压膨化全脂大豆在仔猪饲料中的应用效果

本试验采用 4个膨化温度处理全脂大豆饲喂断奶前后的仔猪 ,研究不同膨化温度生产的全脂大豆对仔猪生产性能以及腹泻的影响。结果表明 ,断奶前仔猪采食量低 ,其生产性能受母猪泌乳能力影响远远大于日粮因素影响 ;4种膨化全脂大豆日粮可提高断奶后仔猪的生产性能 ,其中以采食 135℃膨化大豆日粮仔猪的生产性能最好 ;与其它 3种膨化大豆日粮相比 ,15 0℃膨化大豆日粮可减轻仔猪过敏反应 ,降低仔猪腹泻 ,与豆粕 +油日粮相比 ,膨化大豆日粮可明显缓减断奶仔猪腹泻     

不同温度挤压膨化全脂大豆对肉仔鸡生产性能和养分利用率的影响

为评定膨化全脂大豆的营养价值及膨化加工的适宜条件参数,用肉仔鸡进行了为期４９天的饲养试验和一个预试及正试期各３天的交叉代谢试验。饲养试验选用４０４只１日龄哈巴德母系公雏肉仔鸡,分成４组,每组１０１只。以豆粕＋豆油日粮为对照,分别用北京建中机器厂“Ｂ９９－１”干法挤压膨化机生产的１３０、１４０和１５０℃膨化全脂大豆替代对照日粮中部分豆粕和全部豆油。于饲养试验的第４２天在每个处理中选４笼鸡进行代谢试验,喂给与饲养试验相同的日粮,用全收粪法测定养分消化率。结果表明,在螺旋转速为４５０～５５０ｒｐｍ、大豆水分为１３．１％时,“Ｂ９９－１”膨化机对全脂大豆的适宜膨化温度为１４０～１５０℃。在此条件下,用膨化全脂大豆替代日粮中部分豆粕和全部豆油,可使肉仔鸡全程日增重提高１．９％～２．３％,饲料转化率提高３．４％～４．４％（Ｐ＜０．０５）,氮表观消化率提高４．５％～５．１％,脂肪表观消化率提高５．３％（Ｐ＜０．０５）～５．８％（Ｐ＜０．０５）,日粮部分氨基酸利用率略有改善。     

Efficacy of Copper Sulfate for the Treatment of Ichthyophthiriasis in Channel Catfish

Abstract

Ichthyophthirius multifiliis is a protozoan that may infest and significantly damage cultured fish species. The purpose of this study was to measure the efficacy of copper sulfate in treating ichthyophthiriasis. Fingerling channel catfish Ictalurus punctatus exposed to at least 2,000 theronts of I. multifiliis per liter of water developed consistent infestations of I. multifiliis (20 or more trophonts on the dorsal surface of the head of the fish). Infestation was observed in untreated controls at day 5 after exposure and mortality occurred after day 10. Coexposure studies with theronts and different concentrations of copper sulfate revealed that all theronts were killed at concentrations greater than 0.05 mg/L. To determine the effect of copper sulfate in the treatment of ichthyophthiriasis, fish were exposed to the parasite until trophonts were observed (day 5), and they were subsequently treated with copper sulfate. The lowest effective concentration of copper sulfate for treatment of ichthyophthiriasis (i.e., after infestation was observed in the fish) was 0.4 mg/L. To assess the effects of various water quality conditions on copper treatment, total suspended solids (TSS) and pH were varied during treatment of ichthyophthiriasis. Concentration of TSS was inversely correlated to the efficacy of copper sulfate for I. multifiliis infestations, whereas no relationship was observed between pH and efficacy of a single copper sulfate dose. The results indicated that copper sulfate can be used to treat ichthyophthiriasis at concentrations of 0.4 mg/L for at least 5 d under the specific water conditions used in this study (pH, 7.45 ± 0.27; temperature, 20.5 ± 0.7°C; alkalinity, 176.6 ± 28.1 mg/L as CaCO₃) and that efficacy of copper sulfate was affected more by TSS concentration than by pH.     

Electrophoretic and Immunochemical Characterization of Lipopolysaccharide of Edwardsiella ictaluri from Channel Catfish

Abstract

Lipopolysaccharide (LPS) was purified from 40 isolates of Edwardsiella ictaluri by two methods: (1) enzyme digestion and hot aqueous phenol extraction and (2) enzyme digestion and gel exclusion chromatography. Purified LPS was examined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and by immunoblot analysis. Both methods of purification yielded smooth LPS as evidenced by a ladderlike pattern of more than 40 LPS bands. With silver staining, both low- and high-molecular-mass LPS bands were seen. Lower-molecularmass LPS stained more intensely than higher-molecular-mass LPS bands, indicating a preponderance of lower-molecular-mass LPSs. Lipopolysaccharide bands from the 40 isolates migrated similarly within SDS-PAGE gels, indicating a high degree of structural similarity among the isolates examined. The ladderlike array was more easily seen with immunoblot analysis than with silver staining of SDS-PAGE gels. Additionally, immunoblot analysis revealed a high degree of antigenic similarity among the 40 isolates.