Gizzard erosions in broiler chickens in Sweden caused by fowl adenovirus serotype 1 (FAdV-1): investigation of outbreaks, including whole-genome sequencing of an isolate.

The present paper describes the investigation of the first outbreaks of adenoviral gizzard erosions (AGE) in Sweden, in five broiler flocks. The investigation included whole viral genome sequencing and investigation of genomic organization and sequence relationships with other adenoviruses. All five flocks had a history of decreased growth and uneven size of birds since 9-10 days of age. Macroscopically, lesions consistent with AGE (detached koilin layers, discolouration, bleeding, erosions) were identified in gizzards in all five flocks. In four flocks histology was performed, and degeneration and inflammation of the koilin layer and gizzard mucosa were identified in all four. In one flock, intranuclear inclusion bodies typical for fowl adenovirus (FAdV) were detected in trapped epithelial cells in the koilin layer. In four flocks in situ hybridization was performed, and cells positive for FAdV serotype 1 (FAdV-1) were demonstrated in the koilin layer and gizzard mucosa. FAdV species A (FAdV-A) was detected in gizzard, liver, caecal tonsils and bursa of Fabricius by polymerase chain reaction (PCR) and sequencing. Ten out of ten examined parent flocks of the affected chickens were seropositive for FAdV, indicating former or on-going infection. However, FAdV was not detected in embryos from seropositive parent flocks and thus vertical transmission was not demonstrated. The entire nucleotide sequence of one sample was determined and found to be 43,856 base pairs (bp) in length. The genome sequence and organization were found to be similar to that of the reference apathogenic avian adenovirus "chicken embryo lethal orphan" (CELO). RESEARCH HIGHLIGHTSAGE in Swedish broilers: necropsy, histopathology, ISH, PCR, whole-genome sequencing.Whole FAdV-genome analysed: 43,856 bp, found to be most similar to CELO (U46933.1).Multiple point mutations, site insertions and deletions identified compared to CELO.Paper adds knowledge about European disease situation and pathogenic FAdV-strains.

Retrospective analysis of post-mortem findings in domestic ducks and geese from non-commercial flocks in Sweden, 2011-2020.

BACKGROUND: Small poultry flock ownership has become a popular hobby in Europe and North America in recent years but there is a general lack of information regarding bird health and welfare. This retrospective analysis of routine post-mortem cases of non-commercial anseriform poultry aimed at providing information on causes of mortality mostly in relation to mortality events. For this purpose, birds that were submitted for routine post-mortem diagnostics to the National Veterinary Institute (SVA) in Sweden in 2011-2020 were retrospectively reviewed to determine main causes of mortality. RESULTS: Records from 79 necropsy submissions involving 120 birds (domestic ducks n = 41, Muscovy ducks n = 45, hybrid ducks n = 2 and domestic geese n = 32) were retrieved and analysed. Most submissions (72.2%) represented flock disease events and unexpected mortality was the most common cause of submission (70.9% of submissions). Twenty-two submissions (27.8%) were referred by veterinarians. There was a wide range of diagnoses of infectious and noninfectious aetiologies. Infectious causes of mortality included parasitic (19.2%), bacterial (13.3%), fungal (10.0%) and viral infections (3.3%) (at bird level of all 120 birds). Some of these infections such as duck virus enteritis (DVE), highly pathogenic influenza (HPAI H5N8) in Muscovy ducks and leucocytozoonosis (Leucocytozoon sp.) in all three species were most likely acquired from contact with wild free-living waterfowl. Generalised yeast infection (Muscovy duck disease) was diagnosed in Muscovy ducks and in a Muscovy duck/domestic duck hybrid. Other diseases were related to generalised noninfectious causes (27.5% of all birds) including diseases such as kidney disease, amyloidosis, cardiac dilatation, reproductive diseases and idiopathic inflammatory conditions. Nutritional or management-related diseases were diagnosed in 14.2% of all birds including rickets and gastrointestinal impaction/obstruction. Congenital/developmental, neoplastic, toxic and traumatic causes of mortality were rare. CONCLUSIONS: The information obtained in this study can be used to identify and evaluate risks and help owners and veterinarians to prevent disease and provide adequate veterinary care for non-commercial anseriform poultry.

Investigations into an Outbreak of Botulism Caused by Clostridium botulinum Type C/D in Laying Hens.

This case report describes a recent botulism outbreak in commercial laying hens with a history of increased mortality and flaccid paralysis. Routine diagnostic gross examination and microscopy from seven hens were inconclusive, but botulinum neurotoxin (BoNT) in peripheral blood was neutralized with both type C and type D antitoxins in the mouse bioassay. During a farm visit, 10 additional hens from a 34-wk-old flock on the farm were selected for clinical examination and further sampling. Nine hens were observed in sternal recumbency, with flaccid paralysis of the neck, drooping wings and tail, inability to escape, and bilateral ptosis, and one hen showed nonspecific clinical signs. Samples from cecum and liver were collected, and the gene coding for BoNT was detected by PCR in all 10 cecal samples and in four of the liver samples. Clostridium botulinum mosaic type C/D was isolated from 5 out of 10 hens from either cecum or liver, and the isolates were subjected to pulsed-field gel electrophoresis subtyping. All five isolates produced the same banding pattern, which was identical or showed >90% similarity to isolates from three different outbreaks on broiler farms in Sweden and Denmark during the 2007-10 period. However, they were clearly distinguishable from the predominantly reported pulsotype associated with avian botulism outbreaks in Europe. The authors are unaware of any previous report of C. botulinum mosaic type C/D isolates from laying hens.

Reproductive performance in pigs reared under organic conditions compared with conventionally reared pigs.

BACKGROUND: To achieve a competitive reproductive performance in organic pig farming is a major challenge for this farming practise. Practices and research data regarding conventional pig production are not always applicable to organic production, why field studies are needed to identify differences in performance between organic and conventional pig farms in order to identify areas for improvement. RESULTS: Performance data for one year was collected from 5 organic herds that had more than 30 sows in production and used a computerized recording system, and data from five nearby conventional farms with more than 30 sows and the same recording system were used as a comparison. In total data from 4697 farrowings were analyzed. In the organic pig herds, there were a higher total number of piglets born per litter (p=0.001), a higher number of piglets stillborn per litter (p<0.001), but a tendency (p<0.06) to lower number of weaned pigs per litter and longer nursing period (p<0.001) and farrowing interval (p<0.001). CONCLUSIONS: The reproductive performance was lower in the organic herds and the variation in reproductive performance among the organic herds was larger than among the conventional ones, suggesting options for improvement in the organic herds.