Development of Thiamine Deficiencies and Early Mortality Syndrome in Lake Trout by Feeding Experimental and Feral Fish Diets Containing Thiaminase

Abstract

We conducted a laboratory investigation on the consequences of feeding predatory salmonids either experimental diets low in thiamine or diets containing alewife Alosa pseudoharengus. In experiment 1, adult lake trout Salvelinus namaycush were fed experimental diets containing bacterial thiaminase. In experiment 2, adult lake trout were fed natural prey species, alewives, and bloaters Coregonus hoyi. The diets consisted of four combinations of alewives and bloaters from Lake Michigan (100% alewives, 65% alewives–35% bloaters, 35% alewives–65% bloaters, and 100% bloaters), alewives from Cayuga Lake, a casein bacterial thiaminase, and a commercial trout diet. We assessed the effects of each diet on egg thiamine concentration and incidence of an embryonic early mortality syndrome (EMS). In experiment 1, incidence of EMS ranged from 0% to 100%. Significant relationships were found between the incidence of EMS and thiamine. In experiment 2, adult lake trout fed 100% alewives from either Lake Michigan or Cayuga Lake or fish fed the casein bacterial thiaminase diet produced eggs with low thiamine and swim-up fry with EMS. At either 35% or 65% alewives in the diet, egg thiamine was significantly lowered. The number of females that produced offspring that died from EMS were low but demonstrated the negative potential if feral lake trout foraged on either 35% or 65% alewives. Depleted egg thiamine and the onset of EMS required diets containing thiaminase for a minimum of 2 years in lake trout initially fully thiamine replete. We conclude that EMS can be caused by extensive feeding on 100% alewives and dietary levels of 35% or greater may prove detrimental to sustainable reproduction of salmonids in the Great Lakes. The data are consistent with that observed in feral lake trout, and it is concluded that EMS is the result of a thiamine deficiency.     

Implications of Thiamine Deficiency in Great Lakes Salmonines

Abstract

Our recent experimental work and ecoepizootiological assessments provide mechanistic data supporting a plausible hypothesis for an association between a prey base comprised of a large biomass of nonnative alewives Alosa pseudoharengus and the recruitment difficulties currently experienced by Great Lakes salmonines. We hypothesize that the thiamine deficiency induced by alewives, a species harboring high thiaminase activity, represents an ongoing cause of fry and adult mortality in salmonines. Overall ramifications of the thiamine deficiency on recruitment have not been firmly established but may represent a substantial bottleneck for natural recruitment in feral salmonine populations in the Great Lakes.     

卵黄抗体及其在家禽生产中的应用

1 IgY的性质及特点卵黄抗体(IgY)是禽类B淋巴细胞在抗原物质刺激下所产生,是母鸡将血液中的特异性抗体选择性地(主要是IgG)转移并沉积到卵黄,能与抗原发生特异性反应的一种球蛋白,是禽类在长期进化过程中形成的用于提高雏禽抵抗力的物质[1].     

奶牛生产中常见应激及对生产的影响

奶牛应激在生产中是很常见的,且各种应激原常常相互作用.简述了奶牛生产中常见的应激如热应激、生产繁殖应激、挤奶应激和免疫应激,以及这些应激产生的原因,机制及对奶牛生产的影响.     

Initial Detection and Molecular Characterization of Namaycush Herpesvirus (Salmonid Herpesvirus 5) in Lake Trout

A novel herpesvirus was found by molecular methods in samples of Lake Trout Salvelinus namaycush from Lake Erie, Pennsylvania, and Lake Ontario, Keuka Lake, and Lake Otsego, New York. Based on PCR amplification and partial sequencing of polymerase, terminase, and glycoprotein genes, a number of isolates were identified as a novel virus, which we have named Namaycush herpesvirus (NamHV) salmonid herpesvirus 5 (SalHV5). Phylogenetic analyses of three NamHV genes indicated strong clustering with other members of the genus Salmonivirus, placing these isolates into family Alloherpesviridae. The NamHV isolates were identical in the three partially sequenced genes; however, they varied from other salmonid herpesviruses in nucleotide sequence identity. In all three of the genes sequenced, NamHV shared the highest sequence identity with Atlantic Salmon papillomatosis virus (ASPV; SalHV4) isolated from Atlantic Salmon Salmo salar in northern Europe, including northwestern Russia. These results lead one to believe that NamHV and ASPV have a common ancestor that may have made a relatively recent host jump from Atlantic Salmon to Lake Trout or vice versa. Partial nucleotide sequence comparisons between NamHV and ASPV for the polymerase and glycoprotein genes differ by >5% and >10%, respectively. Additional nucleotide sequence comparisons between NamHV and epizootic epitheliotropic disease virus (EEDV/SalHV3) in the terminase, glycoprotein, and polymerase genes differ by >5%, >20%, and >10%, respectively. Thus, NamHV and EEDV may be occupying discrete ecological niches in Lake Trout. Even though NamHV shared the highest genetic identity with ASPV, each of these viruses has a separate host species, which also implies speciation. Additionally, NamHV has been detected over the last 4 years in four separate water bodies across two states, which suggests that NamHV is a distinct, naturally replicating lineage. This, in combination with a divergence in nucleotide sequence from EEDV, indicates that NamHV is a new species in the genus Salmonivirus.

Received April 20, 2015; accepted October 11, 2015     

Effects of Salinity on Yersinia ruckeri Infection of Rainbow Trout and Brown Trout

Abstract

Juvenile rainbow trout Oncorhynchus mykiss and brown trout Salmo trutta acclimated to freshwater or salinities of 9.0‰ or less were exposed to Yersinia ruckeri, the bacterial pathogen that causes enteric redmouth disease (ERM). Both species of fish were kept in the same recirculating systems after bacterial exposure. Rainbow trout mortality was significantly (P < 0.05) different in each salinity: 96.5% in freshwater, 89.5% in water of 1.1‰ salinity, 81.3% in 3.0‰ salinity, and 75.0% in 9.0‰ salinity (model SE = 1.0). All deaths occurred between 3 and 12 d after exposure to Y. ruckeri. Only 2.3% of brown trout in all salinities died, and differences among treatments were not significant. For both fish species, Y. ruckeri was isolated from liver, spleen, and trunk kidney of fish dying during this experiment, and lesions of rainbow trout were consistent with ERM. Yersinia ruckeri was not isolated from brown trout surviving for 21 d after bacterial exposure but was isolated from 3 of 24 surviving rainbow trout; a polymerase chain reaction assay detected the DNA of Y. ruckeri in 3 additional rainbow trout survivors. Neither the lesions of fish with ERM nor the percentage of surviving fish subclinically infected with Y. ruckeri was affected by salinity. Bacterial growth in vitro was not affected by low (≤9.0‰) salinity; however, bacterial adhesion to polystyrene was significantly reduced as salinity increased. Although mortality caused by Y. ruckeri was significantly lower for rainbow trout in water with slightly increased salinity, none of the salinities tested was effective in preventing serious losses caused by this pathogen in recirculating systems.     

Lead Poisoning in Chickens and the Effect of Lead on Interferon and Antibody Production

The effect of aqueous lead acetate given per os to chickens for 35 consecutive days and the effect of lead on interferon and antibody production was investigated. Chickens were found to tolerate levels of lead as high as 160 mg/kg/day without exhibiting clinical signs or hematological changes in spite of very high levels of lead in the blood (6.2 ppm). It is apparent from these findings that chickens are more resistant to lead poisoning than humans, horses, dogs and wild fowl such as ducks.

Subclinical lead doses did not affect interferon induction in response to statolon and Newcastle Disease virus (NDV)-B₁. Interferon concentrations and duration in serum were markedly decreased in chickens which received lead at the 320 mg/kg level.

Long time lead exposure had no marked effect on antibody production to NDV in chickens. No consistent correlation was observed between blood lead concentration and antibody titer.

The results of these studies indicate that long term subclinical lead intake suppresses neither interferon nor antibody production in chickens.

     

兽用抗体制品制造技术与应用

重点介绍了目前我国兽用抗血清、卵黄抗体和单克隆抗体等方面的发展情况,并以实例对制品的理论、制造技术和应用作以简要说明。     

血清抗体检测技术在畜禽养殖生产中的应用

在血清抗体效价检测技术应用到畜禽生产中时,需要对疫病预防加以了解,并且制定相关的养殖场免疫程序,其中较为主要的内容包含母源抗体检测和免疫接种时间等方面的完善,随后修订相关的免疫程序,实施疫病的诊断和处理,对疫苗接种的结果进行有效检测,明确养殖场存在的问题,对其中存在的问题进行有效解决。     

Impact of BSE on Livestock Production System

A total of 240 unvaccinated day-old broiler chicks, which had been found to be negative for antibodies against FAV-4, were divided into four groups of 60 chicks each. Group A was fed aflatoxin at 1 ppm from 7 days to 7 weeks of age. Group V was infected intra-abdominally at 14 days of age with 0.2 ml of FAV-4, having a titre of 10^5.5 TCID₅₀ per 0.2 ml. The combined group AV was given the aflatoxin and infected with FAV-4. The fourth group C served as the control. More pronounced clinical signs, a higher mortality rate (56.7%), and reductions in body weight gain and in the organ to body weight ratios of the bursa and spleen were recorded in group AV. A significant (p<0.01) reduction in the HI antibody titre following vaccination against Newcastle disease, and of skin thickness in the delayed hypersensitivity test following sensitization with DNCB, indicated an additive immunosuppressive effect from aflatoxin and FAV-4 on the humoral and cell-mediated immune responses in group AV compared to groups A and V. Microscopically, marked depletion and degeneration of lymphocytes in the thymus, bursa, spleen and caecal tonsils were observed in group AV up to 5 weeks PI.     

Effectiveness of Egg Immersion in Aqueous Solutions of Thiamine and Thiamine Analogs for Reducing Early Mortality Syndrome

Abstract

Protocols used for therapeutic thiamine treatments in salmonine early mortality syndrome (EMS) were investigated in lake trout Salvelinus namaycush and coho salmon Oncorhynchus kisutch to assess their efficacy. At least 500 mg of thiamine HCl/L added to egg baths was required to produce a sustained elevation of thiamine content in lake trout eggs. Thiamine uptake from egg baths was not influenced by a pH ranging from 5.5 to 7.5 or by a water hardness between 2 and 200 mg CaCO₃/L. There was poorer thiamine uptake when initial thiamine levels were low, suggesting that current treatment regimes may not be as effective when thiamine levels are severely depressed and that higher treatment doses are necessary. Exposure of eggs to the more lipid-soluble thiamine analog allithiamine (1,000 mg/L) during water hardening increased egg thiamine levels by 1.5–2.5 nmol/g and was completely effective at reversing EMS. Another more lipid-soluble thiamine analog, benfotiamine (100 mg/L), reduced EMS but did not produce detectable increases in egg thiamine content. Although benfotiamine may be more effective than thiamine at mitigating EMS, it is more expensive than thiamine HCl or allithiamine. In addition, there still needs to be a more thorough examination of dose–response relationships. We conclude that allithiamine is an alternative to the use of thiamine in egg baths as a therapeutic treatment for salmonid EMS.     

Gill Ectoparasites of Juvenile Rainbow Trout and Brown Trout in the Upper Colorado River

Abstract

During 1996 and 1997, 112 rainbow trout Oncorhynchus mykiss and 204 brown trout Salmo trutta, all young of the year, were sampled from a 40-km study area of the upper Colorado River and were examined for gill parasites. Ambiphrya, Chilodonella, Ichthyobodo, Apiosoma, Trichodina, Trichodinella, Tripartiella, Epistylis, and an unidentified cochliopodid amoeba were the representative protozoan genera observed on fish examined. Significant month–year–species interactions (P = 0.0295) were revealed, reflecting the changes in infestation prevalence among months, years, and species of salmonid. Greater ectoparasite richness was observed in downstream sections of the study area, most notably near Hot Sulphur Springs, Colorado. Peaks of infestation intensity and ectoparasite richness occurred in August and September of both years, presumably because of high mean water temperatures and low flows during that time.     

硫胺素在鸡肌肉中的沉积规律研究

为研究鸡肌肉组织中硫胺素的沉积规律,以如皋鸡和文昌鸡为素材,分不同家系、周龄、组织进行取样,采用高效液相色谱法检测样品中的硫胺素含量。结果显示,不同品种、家系、周龄及组织间硫胺素含量均存在显著或极显著差异（P<0.05或P<0.01）。此外,硫胺素含量的遗传力为0.494,与体重的遗传相关为-0.404。以上结果初步表明,硫胺素在机体的沉积受遗传因素影响,且表现为一定的时间和组织变化规律,可以通过选择进行提高。     

动物福利政策对欧洲家禽业的影响

<正>在欧洲,主要由欧洲委员会和欧盟两个组织主管动物福利立法。在已获通过的公约中,包括由欧洲委员会通过的覆盖所有家养动物的立法(1976)和欧盟通过的相类似的规范(98/58/CE,     

非洲猪瘟疫情对我国生猪生产与市场的影响

非洲猪瘟疫情对中国生猪产业可能产生巨大且长期的影响。一方面因为生猪饲养量大幅度减少,造成供给不足;另一方面,尽管猪肉消费在短期受到了一定程度的抑制,但由于消费偏好无法短期内改变,猪肉“刚需”仍然存在。预计2019年中国猪肉供需缺口将在1000万t左右,全年猪价将呈现“先抑后扬”态势,生猪价格将可能在近两年内都处在较高水平。猪价上升可能通过产业链波及至食品全行业,导致物价水平整体上涨。建议加大生猪生产扶持力度,调动生猪养殖积极性;明确政府管理权责,确保猪肉稳定供应;遵从产消对接、区域互补原则,以农牧结合为前提,构建生猪生产消费均衡区域布局。     

放牧强度对环青海湖高寒草原群落物种多样性和生产力的影响

通过2年的连续放牧试验,采用比较样地法,调查了不同放牧强度对环青海湖高寒草原生物多样性和生产力的影响,并探讨了植物物种多样性与草地生产力之间的关系,为高寒草原的合理利用提供基础资料。结果表明:物种丰富度和多样性指数随放牧强度的增加基本呈单峰变化,即在中度放牧下多样性最高,重度放牧下群落物种丰富度、多样性指数和均匀度指数均表现为最小;群落生产力随放牧强度的增加而降低(P<0.05);莎草科地上生物量差异不显著,禾本科和豆科生产力降低(P<0.05),杂类草生物量有增加趋势;禾草和豆科比例减小,莎草和杂类草比例增加;草地生产力与Simpson多样性指数和Alatalo均匀度指数呈显著的单峰函数关系(R²=0.910, P=20.027; R²=0.953, P=20.010),结合Simpson多样性指数和Alatalo均匀度指数才能更好地反映维持草地生产力水平的多样性指标。放牧强度是影响群落物种多样性和生产力及其关系的重要因素。     

我国水禽养殖户兼业化经营对水禽产业的影响研究

我国水禽产业中存在着广泛的兼业现象。对湖北、河北、安徽、浙江、江苏,山东六省的水禽养殖户进行的调查结果表明,纯养殖户所占比例仅为17.84%,而一兼、二兼养殖户所占比例分别为59.11%和23.05%,兼业养殖户所占比例远远超过了纯养殖户。结合调研数据,对我国水禽产业的兼业情况进行了描述,分析了兼业化经营对水禽产业的积极影响和消极影响。针对兼业化现象,提出促进水禽产业发展的政策建议。     

环青海湖地区牦牛藏羊的生产函数分析

在环青海湖地区的天峻，海晏和共和三县进行天然草场放牧牦牛和藏羊的生长发育测定。从各县选取至少6个不同年龄组的牦牛和藏羊，每个年龄组至少50头试验动物，进行连续3天的放牧前空腹称重。用非线性回归法分析数据，用Brody模型和三次方程预测牦牛和藏羊的生长曲线。结果表明：（1）三次方程是最适合牦牛和藏羊的生长曲线；（2）天峻牦牛的生长效率最高，尽管海晏牦牛的初生重量大，但其生长速率最低；（3）根据生产函数曲线确定牦牛和藏羊的最佳出栏时间。     

The Impact of Egg Ozonation on Hatching Success,Larval Growth,and Survival of Atlantic Cod,Atlantic Salmon,and Rainbow Trout

The direct exposure of fish eggs to ozonated water has generated interest as a means of ensuring pathogen-free eggs without the use of harsh chemicals. However, there are numerous knowledge gaps, including safe contact times, exposure levels, and potential long-term effects on aquaculture species in both freshwater and seawater. The effect of different ozone (O₃) doses (0.5–1.0, 1.5–2.0, and 2.5–3.0 mg of O₃/L for 90 s) on recently fertilized eggs of Atlantic Cod Gadus morhua and eyed eggs of Atlantic Salmon Salmo salar and Rainbow Trout Oncorhynchus mykiss was evaluated in comparison with the effects of two commercial disinfectants: Perosan (0.004 mg/L) and Ovadine (100 mg/L). The impact of ozone application was evaluated based on hatching success, larval nucleic acid concentration, larval growth, and survival. Overall, results indicated that ozonation of Atlantic Cod eggs at a dose less than 3.0 mg/L for 90 s produced no negative effect on the larvae up to 30 d posthatch. Furthermore, ozonation of Atlantic Salmon and Rainbow Trout eggs generated no negative effect on the larvae, based on monitoring until 85% yolk sac re-absorption (16 d posthatch).

Received May 6, 2014; accepted October 24, 2014