No description available.

Four experiments were conducted to determine the reproductive, metabolic, growth and IGF-I response to ultrasound selection for increased breast muscle thickness (MT) in Pekin ducks. Selection for body weight had a negative ( P < 0.05) effect on the reproductive performance while the selection for greater breast muscle thickness resulted in egg production, fertility and hatchability similar to those of the control line (C). Males from the MT line reached market weight at 6 wk but the breast muscle thickness improved from 6 to 7 wk. Compared to females from the C line, MT females had higher (P < 0.05) carcass yield, plasma glucose, and body protein; lower fat and plasma uric acid; and no difference (P > 0.05) in plasma triglycerides and total cholesterol. Males responded more efficiently to increasing dietary protein than females, and males selected for greater MT can be slaughtered at an earlier age when a high protein feeding program (HP) was followed. Males receiving HP had greater (P < 0.05) pectoralis muscles yield, longer keel bone, and lower breast skin and total skin fat yields. Female dissection data show similar (P > 0.05) effects of high and medium protein programs. Increasing dietary protein reduced (P < 0.05) carcass fat and increased (P < 0.05) crude protein (CP). In vivo breast muscle measurement correlated positively (P < 0.05) with body weight, pectoralis yield, and keel bone length. Birds with higher pectoralis yield tended to have more CP and less fat in their carcasses. A low correlation (r = 0.19) was found for the caliper measurement of breast skin plus fat thickness and carcass fat. We determined the metabolic differences between lean and fat male and female ducks, associated metabolic parameters and body composition, and assessed the difference between two feeding solutions for the determination of metabolic endogenous losses. There was a positive correlation between breast muscle:total breast muscle thickness ratio (MT/TO

published_or_final_version / Zoology / Doctoral / Doctor of Philosophy

The black-bellied tree duck (Dendracygna autumnal is) 1 is one of eight tree ducks (whistling ducks) in the genus Dendracygna . This group shares enough characteris tics--reticulated tarsus and symmetrical syrinx structure, among others--with the swans and geese Ia warrant a cam man subfamily, Anserinae of the waterfowl family Anatidae. De Iacour and Mayr ( 1945) make a tribal distinction, however, between the tree ducks (Dendracygnini) and the swans and geese (Anserini) based, in part, an differences in size, vertebrae number, and downy plumage . These same authors remark that the tree ducks are the leas t known of the waterfowl largely because there are no life history studies for any of the species. Of the two species found in the continental United States, the fulvous (_Q . bicolor) and black-bellied tree ducks , the ecology of the last named seemed singularly unknown.

Influenza virus is a RNA virus that exists as different types and subtypes. Influenza A virus strains are known to cause disease in several bird and mammalian species. Wild birds are believed to constitute the natural reservoir for influenza A virus. In humans, influenza A virus causes yearly seasonal influenza epidemics of respiratory disease resulting in high morbidity and severe economic consequences. Due to the virus’ ability to change its antigenic properties by mutation, yearly vaccination is required for protection from the disease. There are many different subtypes of influenza virus which are characterized according to two surface structures - the hemagglutinin and neuraminidase proteins - , for example; H5N1. These subtypes have the ability to recombine, and thereby creating new variant combinations. If a subtype that the living population of humans has not encountered before starts to spread among humans, it can result in a pandemic. Pandemic outbreaks have occurred at irregular intervals throughout history and have had a devastating impact on mankind. For example the Spanish influenza pandemic of 1918 is thought to have killed more than 50 million people. Influenza A virus is also an important cause of disease in poultry where virus strains of some subtypes may change into forms that are highly pathogenic. These virus strains may transmit directly to man and multiple other species. This has been the case in the ongoing outbreak that started in South East Asia in 2003. All known subtypes of influenza A virus have been isolated from wild birds living in aquatic environments, mainly dabbling ducks. These species are considered to be the reservoir for influenza A virus. The virus causes sub clinical gastrointestinal infection in ducks. High amounts of virus are excreted in the feces and spread via the fecal-oral route through water where it can persist for a prolonged time. There are still many unknowns about the ecology of influenza virus in the wild bird reservoir. This thesis includes five articles where data are presented that add new knowledge on this subject. We add proof that wild ducks are indeed the host for most influenza A virus subtypes by presenting data from a meta-analysis on all published screening data from wild birds and by presenting data from a four year screening of migratory ducks that were caught and sampled at Ottenby Bird Observatory. Our investigations have shown that the prevalence of influenza virus in the wild duck population of western Eurasia shows temporal differences in comparison to the results found in studies in North America. The prevalence in western Eurasian ducks is high during the period August to December and also rises in the spring. These findings are of importance for the understanding of how influenza virus is perpetuated in nature. During the course of the study only low pathogenic subtypes were isolated. Of concern is the high frequency of isolation of virus strains of the H5 and H7 subtypes that are prone to change into highly pathogenic variants in poultry. Many of the strains isolated in our study are similar to the ones that have caused influenza outbreaks in poultry in Europe during the last seven years. This indicates that wild bird surveillance for influenza A virus can be of major value as a sentinel system to prevent outbreaks in domestic poultry. Studies on Black-headed Gulls (Larus ridibundus) revealed a previously unknown subtype, H16. This finding widened the spectra of known influenza A virus subtypes in nature. Influenza A virus was also isolated in samples from Guillemots (Uria aalge) in the Baltic Sea. This was the first time influenza A virus was isolated from this species in Europe. The isolated virus strains contained a mix of genes, some of which must have been derived from influenza A virus strains present in the North American bird population. This finding proves that limited exchanges between the virus strains present on the American and the Eurasian continents exist, which is of concern for evaluating the risk of spread of highly pathogenic virus strains by wild birds to the Americas. / Influensavirus är RNA virus och indelas i olika typer och subtyper. Influensa A virus orsakar sjukdom hos ett flertal fågel- och däggdjursarter. Vilda fåglar anses utgöra den viktigaste reservoaren för influensa A virus. Hos människa orsakar influensa A virus årliga epidemier av luftvägssjukdom med hög sjuklighet och stora ekonomiska konsekvenser för samhället. Eftersom frekventa mutationer orsakar ändringar i virusets ytstrukturer krävs årlig vaccination med nytt anpassat vaccin för att ge skydd mot sjukdom. Det finns många olika subtyper av influensa A virus. Dessa karaktäriseras med två av virusets ytstrukturer; hemagglutinin och neuraminidas, vilket till exempel skrivs H5N1. Virus av olika subtyper kan rekombinera och på så sätt skapa nya varianter. Om en subtyp som tidigare ej cirkulerat bland världens befolkning orsakar ett utbrott kan detta leda till en världsomfattande epidemi, en så kallad pandemi. Pandemier har drabbat mänskligheten med viss regelbundenhet genom historien och haft förödande konsekvenser. Till exempel orsakade pandemin ”Spanska sjukan” under åren 1918-1920 mer än 50 miljoner dödsfall. Influensa A virus orsakar också förödande utbrott i fjäderfäbesättningar. Virus av vissa subtyper kan mutera till högpatogena varianter och orsaka så kallad högpatogen aviär influensa. Dessa högpatogena varianter kan även överföras till och orsaka sjukdom hos människa och andra djur vilket varit fallet under det pågående utbrott av H5N1 som startade i sydöstra Asien 2003. Alla kända subtyper av influensa A virus har isolerats i material från vilda fåglar vilka lever i vattenmiljö, framförallt från änder. Dessa arter anses därför utgöra influensavirusets reservoar i naturen. Hos änder orsakar viruset framförallt en subklinisk infektion i gastrointestinalkanalen och sprids genom faekal-oral överföring via vatten i vilket viruset kan förbli aktivt en längre tid. Det finns fortfarande många obesvarade frågor angående influensa A virus ekologi bland vilda fåglar. I denna avhandling presenteras fem artiklar som tillför ny kunskap inom detta område. I avhandlingen styrks bevisen för att vilda änder utgör virusets reservoar i naturen dels genom en metaanalys av samtliga publicerade data rörande fynd av influensa A virus hos vilda fåglar, dels med hjälp av data från fyra års provtagning från flyttande vilda änder vid Ottenby fågelstation. Resultaten påvisar temporala skillnader i influensvirusets prevalens i den västeuroasiatiska andpopulationen jämfört med den nordamerikanska. Prevalensen i den västeuroasiatiska andpopulationen är hög under perioden augusti till december och i viss mån även under våren. Dessa fynd talar för att influensavirus kontinuerligt cirkulerar i andpopulationen. Under studien av förekomsten av influensa A virus hos änder isolerades enbart olika lågpatogena subtyper. Subtyperna H5 och H7 var vanligt förekommande. Dessa subtyper är benägna att utvecklas till högpatogena varianter om de sprids till fjäderfäbesättningar med svåra konsekvenser som följd. Genom studier av virus släktskap visas att de virus vi isolerat från vilda änder är snarlika de som orsakat utbrott bland fjäderfä i Europa under de senaste sju åren. Detta styrker värdet av att övervaka förekomsten av influensavirus hos vilda fåglar för att på så sätt förhindra utbrott av sjukdom bland fjäderfä. Undersökning av prover från skrattmås (Larus ridibundus) ledde fram till upptäckten av en helt ny subtyp av influensavirus; H16. Därmed utvidgades spektret av kända subtyper i naturen. Influensa A virus isolerades från sillgrisslor (Uria aalge) i Östersjön vilket inte tidigare gjorts hos denna art i Europa. Dessa virus innehöll gener från både nordamerikanska och euroasiatiska fågelpopulationers virus. Det visar att det finns ett utbyte av virus mellan fågelpopulationerna på de skilda kontinenterna. / On the day of the defence data the status on article IV was Submitted and the title was "Multi-year surveillance of influenza virus type A in migratory waterfowl in northern Europe".

Ball State University LibrariesLibrary services and resources for knowledge buildingMasters ThesesThere is no abstract available for this thesis.

We collected 6,823 cloacal swabs over four years (2005–2006: 1,460; 2006– 2007: 2,171; 2007–2008: 2,424; and 2008–2009: 768) from 30 potential avian host species. Most samples (88.3 percent) were from dabbling ducks (genus Anas), while diving ducks (genus Aythya) accounted for 5.0 percent, and geese (genera Anser, Chen, and Branta) 3.0 percent of the samples tested. Waterfowl (Anatidae) comprised 98.7 percent of samples, with 1.8 percent from non-migratory dabbling ducks (genus Anas). All samples were screened for avian influenza virus (AIV) by AIV-matrix real-time RT-PCR (rRT-PCR); all rRT-PCR positive samples (541) were processed for virus isolation as well as 4,473 rRT-PCR negative samples. Differences were observed in apparent prevalence estimates over the four years between virus isolation (0.5, 1.3, 3.9, and 0.7 percent) and rRT-PCR (5.9, 6.5, 11.2, and 5.5 percent). We isolated 138 AIVs, of which two were obtained from rRT-PCR negative samples. Unlike previous reports of seasonal variation in AIV prevalence, we documented differences in prevalence estimates among months using rRT-PCR only during 2008–2009 and by virus isolation only during 2006–2007 and 2007–2008. Several of the AIV subtypes we identified are common in North America (e.g., H3, H4, and H6); H3N8 and H4N6 were the most common subtype combinations isolated. Similar to most surveillance studies, we found no significant difference in AIV infection based on host sex, but did find that juveniles were more likely to be positive for AIV than adults. We also documented that dabbling ducks were more likely to be positive for AIV than diving ducks, although not all dabbling ducks are equally likely to be positive. Molecular sequence analysis revealed no insertions of multiple basic amino acids at the cleavage site, which supported the identification of low pathogenic AIV. Phylogenetic anlyses performed on H5, H6, H7, N1, N2, N3, and N4 subtypes sequenced indicated similarity to other North American isolates with the exception of seven H6 which were more similar in amino acid translation to an isolate from Japan. In sum, this is the first multiyear study of avian influenza viruses on waterfowl wintering grounds of the Central Flyway, a historically understudied area of North America.

Thesis--Ph. D., University of Hong Kong. / Typewritten.

No description available.

Bibliography: leaves 184-218. / xx, 218, [135] leaves, [15] leaves of plates : ill. (chiefly col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / The research in this thesis describes the development and use of assays to detect cellular immune responses in ducks with application to duck hepatitis B virus (DHBV) infections. This animal model is used to provide an additional area of research which complements the study of hepadnaviruses. The introduction contains an outline of the significance of hepadnavirus research, including hepatitis B virus (HBV) epidemiology, structure, replication and clinical manifestations of the diseases caused by the virus. / Thesis (Ph.D.)--University of Adelaide, Dept. of Microbiology and Immunology, 1997