Herd and sow-related risk factors for mortality in sows in group-housed systems

Mortality of sows is a major problem for pig production worldwide. In this study, we used hierarchical multivariable logistic analyses to investigate different risk factors for mortality at the sow and herd level in herds with group-housed pregnant sows. Data included 3652 pregnant and 1266 lactating sows from 34 sow herds. A clinical examination for 16 clinical signs was carried out for each sow, and information about 16 herd related factors was obtained by interviews. Farm records were used to obtain information about whether or not sows died suddenly or were euthanized within 3 months after the clinical examination. Factors increasing the risk of sow mortality in the gestation unit were solid pen floors (OR = 1.87), presence of vulva bites (OR = 1.73) and unwillingness to stand when approached (OR = 1.62). Factors increasing the risk of sow mortality in the lactation unit were pale vulva color (OR = 12.69), body leanness (OR = 4.11), and presence of shoulder ulcers (OR = 2.89). The estimated between herd variation was small. Thus, the findings for the sow level variables may be generally applicable for sows in herds with group housed systems.     

Genetic relatedness and netB prevalence among environmental Clostridium perfringens strains associated with a broiler flock affected by mild necrotic enteritis

In a previous study we investigated pulsed-field gel electrophoresis (PFGE) genotype diversity and prevalence of the netB toxin gene in Clostridium perfringens (CP) isolates recovered from a broiler flock (flock 1) affected by necrotic enteritis (NE). In this follow-up work, we examined samples collected before placement of flock 1, to see if NE during rearing could be traced back to the cleaned and empty building or the day-old chicks. Litter from the next flock in the same building (flock 2) was also examined. We detected 25 different PFGE genotypes, five of which were found only in litter from flock 2. Six genotypes which had been found in flock 1 during rearing were detected in samples collected before placement. NetB positive isolates belonging to two of these genotypes had been recovered from NE lesions during rearing, suggesting that virulent strains were transmitted from the cleaned and disinfected broiler house. NetB frequency among isolates from the empty building was 45%, indicating that netB positive strains were prevalent in a building that previously had housed a healthy flock offered in-feed narasin (flock 0). NetB frequency among isolates from litter used by flock 2 was 22%, indicating that netB positive strains were present in the environment of a 14-days-old healthy flock offered in-feed narasin. Two prevalent genotypes were consistently either netB negative or netB positive. However, the presence of genotypes represented by both negative and positive isolates may suggest that the gene can spread horizontally among different CP strains.     

Vaccination elicits a prominent acute phase response in horses

European and American guidelines for vaccination against tetanus and influenza in horses recommend annual and annual/semi-annual vaccinations, respectively, against the two pathogens. Too-frequent vaccination may, however, have adverse effects, among other things because an inflammatory response is elicited with subsequent alterations in homeostasis. The objective of the study was to compare the acute phase response (APR) in 10 horses following administration of two different types of vaccines, namely, an inactivated Immune Stimulating COMplex (ISCOM) vaccine and a live recombinant vector vaccine. Blood was sampled before and after vaccination to measure levels of serum amyloid A (SAA), fibrinogen, white blood cell counts (WBC) and iron. Vaccination induced a prominent APR with increased WBC, elevated blood levels of SAA and fibrinogen, and decreased serum iron concentrations. The ISCOM vaccine caused significantly (P<0.05) greater SAA, fibrinogen and WBC responses than the vector vaccine. During the APR muscle catabolism and liver and kidney metabolism are altered. Also drug metabolism may change during the APR. The findings of the present study may be relevant for advising horse owners about convalescence after vaccination.     

Comparison of Postfire Soil Water Repellency Amelioration Strategies on Bluebunch Wheatgrass and Cheatgrass Survival

Soil water repellency can limit postfire reseeding efforts and thus increase the susceptibility of a site to weed invasion. We evaluated the effectiveness of wetting agents and simulated anchor chaining for improving seedling growth and survival in water-repellent soil, for the native perennial bluebunch wheatgrass (Pseudoroegneria spicata) and invasive annual cheatgrass (Bromus tectorum). Research was performed in a glasshouse, on 20-cm-diameter soil cores that were excavated from underneath burned Utah juniper (Juniperus osteosperma) trees. The experiment was arranged as a randomized split-plot design, with the two grass species sown separately under four soil treatments: 1) no treatment (control), 2) simulated anchor chaining (hereafter referred to as “till”), 3) wetting agent, and 4) till plus wetting agent. Soil water content was highest in the wetting agent treatment, lower for till, and lowest in the control. Overall, the response of bluebunch wheatgrass and cheatgrass was similar among treatments. At the conclusion of the study, wetting agent cores had twice as many seedlings as the control, while the till and control were similar. Despite a lower number of seedlings, tilling in general resulted in the same level of biomass as the wetting agent treatment. Overall, biomass in the till and wetting agent treatments was at least twofold higher than the control. No benefit was found in applying both till and wetting agent treatments together in comparison to just applying wetting agent. Because of a lack of correlation between glasshouse and field settings the results of this study need to be interpreted with caution. Our data may indicate that if cheatgrass is not already present on the site, anchor chaining or treating the soil with wetting agent can increase establishment of seeded species.     

Moderate nitrogen retention in temperate heath ecosystem after elevated CO2, drought and warming through 7 years

Nitrogen (N) dynamic is one of the main controlling factors of responses to climate change in N-limited terrestrial ecosystems, which rely on nutrient recycling and retention. In this study we investigate the N partitioning in ecosystem compartments of a grassland heath, and the impact of multiple climate change factors on long-term N retention after ¹⁵N pulse labelling. The impacts of elevated carbon dioxide (eCO₂), warming and drought and the treatments in combination on ecosystem N retention were investigated in a field scale manipulation experiment. A 6-year time-course was assessed by pulse-labelling with the stable N isotope ¹⁵N and by sampling after 1 day, 1 year and 6 years. After 6 years we observed that the total ecosystem retained 42% of the amended ¹⁵N across treatments (recovery of the amended ¹⁵N in the pool). The fate of the applied ¹⁵N was mainly stabilization in soil, with 36% ¹⁵N recovery in soil, while the plant compartment and microbial biomass each retained only 1%–2% of the added ¹⁵N. This suggests a moderate retention of N, for all treatments, as compared to similar long-term studies of forest ecosystems. A decreased ammonium and vegetation N pool combined with higher ¹⁵N retention in the soil under eCO₂ treatments suggests that eCO₂ promoted processes that immobilize N in soil, while warming counteracted this when combined with eCO₂. Drought treatments contrastingly increased the vegetation N pool. We conclude that as the organic soil layer has the main capacity for N storage in a temperate heathland-grassland, it is important for buffering nutrient availability and maintaining a resilient ecosystem. However, the full treatment combination of drought, warming and eCO₂ did not differ in ¹⁵N recovery from the control, suggesting unchanged long-term consequences of climate change on retention of pulse added N in this ecosystem.     

Immunochemical analyses of serum antibodies from pig herds in a Salmonella non-endemic region.

In a large comparative survey of Danish and Swedish slaughter pig herds performed prior to this work, it was unexpectedly found that some Swedish herds harbored seropositive pigs. Serum samples from the Swedish herds had moderate responses in the Salmonella mix-ELISA (detecting serogroup B and C1 infections) compared to the Danish herds classifying some of them as seropositive using a cut-off value at 40 OD%. In Sweden, extensive Salmonella control is carried out by bacteriological screening of feces and lymph nodes, and the overall prevalence has been proven to be below 0.1%. The serological positive results were therefore unexpected; hence the reactivities of the Swedish sera were studied by a number of immunochemical analyses (Western blot, indirect ELISA, inhibition ELISA, avidity ELISA) and compared to sera from Danish pig herds with verified Salmonella infections ("the reference sera").In Western blot, the Swedish sera had high binding reactivities against Salmonella Typhimurium LPS of different molecular weights, and gave binding patterns similar to that of the reference sera. Pre-incubation with free S. Typhimurium LPS or PS (the polysaccharide part of LPS) was able to inhibit the reactivity of the Swedish sera in the mix-ELISA. Reactivities against other related bacterial LPS such as Citrobacter freundii LPS and Yersinia enterocolitica O:3 LPS were observed in the Swedish sera, but these LPS antigens were unable to inhibit the reactivities in the mix-ELISA as efficiently as S. Typhimurium LPS. Furthermore, the Swedish sera did not bind Salmonella LPS of another serogroup (S. Meleagridis LPS, serogroup E1) or rough Salmonella LPS, both lacking the specific O-antigenic parts of S. Typhimurium LPS. The avidity of the Swedish sera was much lower than the avidity of the reference sera, which could indicate the presence of transient low-dose infections or stimulation by inactivated bacteria in feed. The results obtained in this investigation strongly indicate that the Swedish sera contain antibodies directed against the O-antigenic part of LPS from S. Typhimurium or possibly on as yet unknown bacterium.     

Climate Change Impacts Due to Biogenic Carbon: Addressing the Issue of Attribution Using Two Metrics With Very Different Outcomes

Although not without its critics, considerable recognition has been given to the climate cooling benefits provided by storing carbon from biomass in various storage pools. However, it has recently been found that depending on the storage pool/period and source of biomass, the associated climate impacts may be a burden or a benefit. It is important that carbon accounting schemes and life cycle assessment practitioners take these carbon/CO₂ flux dynamics and the climate impacts that they create into consideration. In this work we illustrate these climate impacts with a Norwegian case study using a material flow analysis of the biogenic carbon in harvested wood products derived from a 2006 harvest year. We illustrate the dynamic carbon balance over time and show how the climate impacts can diverge greatly between two well-known climate impact metrics: global warming potential (GWP) and global temperature potential (GTP). We also show how these climate impacts can be attributed to contributing parties with an example of a glue laminated beam value chain which is stored in a long-lived building. We discuss the associated attribution issues that will inevitably arise and we offer recommendations on how best to minimize them.