Metapopulation dynamics, abundance, and distribution in a microecosystem

The experimental fragmentation of landscapes of a natural ecosystem resulted in declines in the abundance and distribution of most species in the multispecies animal community inhabiting the landscapes and the extinction of many species. These declines caused the deterioration of the positive interspecific relation between local population abundance and distributional extent in this community. However, when patches were connected by habitat corridors, an immigration "rescue effect" arrested declines in both abundance and distribution and maintained the observed positive relation between them. These results demonstrate the importance of metapopulation dynamics and landscape connectivity for the persistence of populations in fragmented landscapes.     

Effects of acidic meltwater on chemical conditions at nearshore spawning sites

Chemical conditions at lake charr (Salvelinus namaycush) spawning sites were monitored during snowmelt in low alkalinity lakes in Ontario, Canada. Embryos within the interstitial water of the spawning substrate were exposed to abrupt and potentially toxic levels of H⁺ and inorganic Al as acidic runoff water inundated the shallow nearshore sites. Early runoff events, those that occurred while the lake ice was still snow-covered and under-ice water temperatures were <2°C, appeared to be most threatening, because of deep penetration of the runoff water. These highly site-specific events exhibit wide temporal and spatial variability.     

Effects of pre-rigour filleting on quality aspects of Atlantic cod (Gadus morhua L.)

Aquaculture is promising in increasing the amount of fresh Atlantic cod available all year around. The aim of this study was to investigate the effects of pre‐rigour filleting on fillet quality of wild and farmed cod. Pre‐rigour filleting resulted in significantly less fillet gaping than in fillets produced post rigour. The pre‐rigour fillets were, however, 12–13% shorter post rigour. In spite of the significantly lower water content of the muscle 6 days post mortem, a significantly higher liquid loss was seen in the pre‐rigour group. Differences in gaping score and muscle pH were dependent on whether the fish were wild or fed. Fillet gaping increased with storage time and was particularly pronounced for well‐fed cod. Fed cod had a significantly higher hydroxyproline (Hyp) content and significantly lower amount of glycosaminoglycans (GAGs) than wild cod. The ratio between GAGs and Hyp was thus significantly lower in fed cod. A connection between connective tissue components and fillet gaping may exist. However, further investigations are required.     

Haematological studies on frizzled and naked neck genotypes of Nigerian native chickens

Variation in haematological parameters of Nigerian native chickens was studied using 60 clinically normal frizzle-feathered, naked-neck, and normal-feathered native chickens. These included red blood cell count, haemoglobin, packed cell volume, white blood cell count, mean corpuscular volume, mean corpuscular haemoglobin concentration, serum glucose, urea, cholesterol, albumin, globulin and creatinine. Normal-feathered birds had higher (p < 0.05) mean values compared to frizzled and native neck genotypes except for albumin, red blood and white blood cells, and mean cell haemoglobin concentration. Males generally had higher mean values than their female counterparts across all genotypes. Correlation coefficients among the parameters were significant (p < 0.001) with r values ranging from 0.26 between red blood cell and mean corpuscular haemoglobin to 0.92 between red blood cell and cholesterol. Sufficient genetic variation therefore exists for haematological parameters among Nigerian native chickens that may represent indicator traits for further study. However, the application of molecular tools will provide better understanding and application of these differences.     

Diversity of Bartonella species detected in arthropod vectors from animals in Australia

A variety of Bartonella species were detected in two species of ticks and three species of fleas collected from marsupial hosts; brush-tailed bettong or woylie (Bettongia penicillata) and western barred bandicoots (Perameles bougainville) and from a rodent host; Rattus fuscipes in Western Australia. Bartonella species were detected using nested-PCR of the gltA gene and the 16S–23S ribosomal internal transcribed spacer region (ITS), and species were characterized using DNA sequencing of the 16S rRNA, gltA, rpoB, ftsZ genes and the ITS region. Bartonella rattaustraliani and B. coopersplainsensis were detected in Ixodes spp. ticks and fleas (Stephanocircus pectinipes) respectively collected from rodents. Two novel Bartonella species were detected from marsupials; Candidatus Bartonella woyliei n. sp. was detected in both fleas (Pygiopsylla hilli) and ticks (Ixodes australiensis) collected from woylies and Candidatus Bartonella bandicootii n. sp. was detected in fleas (Pygiopsylla tunneyi) collected from western barred bandicoots. Concatenated phylogenetic analysis of all 5 loci clarified the marsupial cluster of Bartonella species in Australia and confirmed the species status of these two Bartonella species in ticks and fleas from woylies and western barred bandicoots, which are classified as threatened species and are vulnerable to extinction.     

The British pig health schemes: integrated systems for large-scale pig abattoir lesion monitoring

Pig health schemes based on abattoir inspections provide an integrated system to optimise the postmortem detection and the reporting of pathological lesions. In Great Britain, two initiatives have been implemented by the pig industry: Wholesome Pigs Scotland (WPS) and the BPEX Pig Health Scheme (BPHS). These schemes record the presence of a range of pathological lesions detected by means of detailed inspection of the pluck and the skin of the slaughtered pigs. The lesions are those associated with a reduction in performance traits or are indicators of animal welfare problems. This paper aims to provide an overview of the objectives behind the BPHS and their activities, outlining similarities and differences between WPS and BPHS on five main operational topics: the lesions monitored, the administration of the schemes, flow of the information, inspection strategies and the major idiosyncratic characteristics of the schemes. These initiatives inform individual producers and their veterinarians of the occurrence of pathological conditions affecting their pig herds. Additionally, they offer the added value of providing nationwide disease monitoring information and have the potential to be a useful surveillance tool for emerging and enzootic conditions.     

Epidemiology and impact of Neospora caninum infection in three Queensland tropical dairy herds

This study investigated the epidemiology of Neospora caninum in three tropical dairy herds in North Queensland, Australia. All animals in the herds were bled, and the sera were tested by ELISA for N. caninum antibodies. Herd records were examined, and the number of calves carried to term and the number of abortions which occurred over the lifetime of each animal were recorded to determine the abortion rate for each animal. Pedigrees were constructed for two of the herds to investigate whether vertical transmission was occurring. The seroprevalence of N. caninum ranged from 23% to 34%. The abortion rate in seropositive animals was significantly (p < 0.001) higher than in seronegative animals in all three herds (12-20.1% cf. 3.6-7%). Overall, the probability of a calf being seropositive was 3.5 times higher when the dam was also seropositive than when the dam was seronegative. Subsequent selective breeding employed by one herd reduced the N. caninum seroprevalence from 23% to 5% over a 9-year period. This study shows that N. caninum infection is prevalent in North Queensland dairy cattle, and both post-natal infection and vertical transmission are common.