Polymorphonuclear proteolytic activity and milk composition change

Relationships between Quarter Milk Cell Count (QMCC) and Tank Milk Cell Count (TMCC) with milk biochemical and technological parameters in milk and dairy products were investigated. All parameters measured were affected by the increase of TMCC and QMCC between 0 and 600 000 cells/mL. The variable effect of lactation stage which is different for different authors, is discussed. The three mechanisms, measured during the inflammation of the udder, implicated in the modification of milk quality are described (a decrease in synthesis, a decrease in the milk barrier permeability and an increase in proteolytic activities). The direct effect of plasmin in caseinolysis is well known; the specific role of the increase of somatic cells (especially PMN) in the modification of milk quality is described. Several specific proteolytic activities of PMN are described and the impact of these activities on caseinolysis is evaluated. Two hypothetical mechanisms of caseinolysis by PMN are suggested and a synthetic scheme of the role of plasmin, bacteria and somatic cells in caseinolysis is discussed.     

Variation of pesticide sorption isotherm in soil at the catchment scale

The variation of the sorption isotherm of pesticides has seldom been explored at the catchment scale. Such a study was conducted at the scale of a 187-ha agricultural catchment for three herbicides: atrazine, isoproturon and metamitron. Partition coefficient (Kd) values were measured in batch experiments on 51 topsoil samples, and showed moderate variability at the catchment scale (coefficient of variation CV approximately 30%). Values of Kd ranged from 0.47 to 1.70 litre kg(-1) for atrazine, 0.47 to 1.81 for isoproturon, and 0.55 to 2.21 for metamitron. A clustering method was used to reduce the number of samples on which to measure sorption isotherms to 14. Sorption isotherms agreed with the Freundlich rather than the linear model. Kf parameters had CV values similar to those for Kd, with values ranging from 0.78 to 2.13 mg(1 - Nf) litre(Nf) kg(-1) for atrazine, 0.61 to 1.82 for isoproturon, and 0.69 and 2.58 for metamitron. Nf exponents showed little variation (CV < 5%). Nf values were between 0.86 and 0.98 for atrazine, 0.85 and 0.90 for isoproturon, and 0.82 and 0.87 for metamitron. More than 97% of the Kf catchment-scale variations could be explained by the variations of the soil organic carbon content.     

Early hepatic immune response in rats infected with Fasciola hepatica

We investigated the phenotype of the T cells (CD4+ and CD8+) that produced Th1 (IFN-gamma) and Th2 cytokines (IL-4 and IL-10) during the firsttwo weeks of experimental fasciolosis in rats. We also followed the kinetics of the cytokine and proliferative responses of hepatic mononuclear cells (HMNC) over the same period. We found that HMNC were more numerous in the infected animals than in the controls. The percentage of CD4+ cells increased significantly after infection, whereas the percentage of CD8+ cells did not change. Moreover, the frequency of the cells producing (CP) cytokine changed after infection. The frequency of CP IFN-gamma on 7 days postinfection (pi) was similar to that in control animals. However, the frequency of CP IFN-gamma was clearly lower on day 14 pi, whereas the frequency of CP IL-4 and CP IL-10 had increased. The CP IL-10-were mostly CD4+. Mitogenic stimulation (phorbol myristate acetate/ionomycin) of HMNC led to an increase in the amounts of the Th2 cytokines in the supernatant on days 7 and 14 pi, with the increase more pronounced on day 14. In contrast, IFN-gamma levels also increased by day 7 pi but then decreased to below control levels by day 14. In addition, HMNC proliferation in response to mitogen followed a similar pattern to IFN-gamma production. These findings suggested that, during the first 2 weeks of infection, F hepatica induced a transient ThO cytokine profile followed by downregulation of the cellular response and the induction of a Th2 cytokine profile.     

Influence of ozone on cold acclimation in sugar maple seedlings

During summer 1994, sugar maple (Acer saccharum Marsh.) seedlings were grown in open-top chambers supplied with air containing near ambient ozone concentration (control, low O(3)) or three times the ambient ozone concentration (high O(3)). The rate of CO(2) assimilation was significantly reduced by chronic exposure to a high concentration of ozone during the summer. During fall, seedlings were removed from the open-top chambers and acclimated to cold under natural conditions. In both species during cold acclimation, the starch concentration decreased, whereas the sucrose concentration increased. There was no treatment effect on the freezing tolerance of roots, even though roots in the high-O(3) treatment accumulated higher concentrations of the cryoprotective oligosaccharides raffinose and stachyose than control roots. Cold acclimation occurred earlier and stachyose concentration of stems was higher in high-O(3)-treated seedlings than in low-O(3)-treated seedlings. Cold acclimation was associated with an earlier accumulation of ABA in the xylem sap of high-O(3)-treated seedlings compared with low-O(3)-treated seedlings.     

Disentangling the effect of topography and microtopography on near-ground growing-season frosts at the boreal-temperate forest ecotone (Québec,Canada)

New Forests - Permanent landscape attributes such as topography (elevation [m]) and microtopography (local variation in elevation [cm]) can increase the risk of cold air drainage down-slopes and in...     

Use of monthly collected milk yields for the detection of the emergence of the 2007 French BTV epizootic

Two culicoides-borne diseases, Bluetongue (BTV) and Schmallenberg, have emerged in the European cattle population since 2006. Other diseases transmitted by these vectors could emerge. This justifies the development of syndromic surveillance programs whereby one or several indicators would be routinely monitored for the early detection of emerging diseases. The aim of this study was to evaluate milk yield from milk recording in dairy cattle as an indicator to be included in an emerging disease surveillance system. It was hypothesized that emergences would result in episodes of low milk production clustered in space and time. The 2007 BTV epizootic in France was used as a case study. Because it had already emerged in neighbouring countries, the disease emergence was expected and notification was mandatory. Herd-test-day milk productions were predicted for the entire country for 2006 and 2007 from herd historical data using linear mixed models. The differences between observed and predicted milk productions were averaged per week and per municipality and used as input for a space-time prospective scan statistic. Log likelihood ratios (LLR) associated with clusters were used to define alarms. The threshold chosen was a trade-off between detection timeliness and the number of false alarms per week. The first four BTV notifications occurred on the 12th (two notifications), 13th and 27th of July 2007. The 12th of July was considered to be the date of emergence. Alarms occurring before the 1st of March 2007 were considered to be false alarms. Using an LLR of 50, there were an average of 1.7 false alarms per week and the BTV emergence was detected seven weeks after emergence. Using an LLR of 100, there were an average of 0.8 false alarms per week and the BTV emergence was detected 9 weeks after emergence. Detection may have been delayed because of a discontinuation of milk recording between mid-July and mid-August. The first cluster with an LLR > 100 located in the emergence area was further investigated. A difference between observed and predicted production of >1 kg/cow/day was observed around the time of emergence. However, a difference of equal magnitude was observed during the year preceding the outbreak. Milk production predicted from herd history alone did not allow the detection of the 2007 BTV emergence in France. Further research should be conducted on improving the prediction of test-day milk yield and on combining it with other indicators based on routinely collected data.     

The Schmallenberg virus epidemic in Europe—2011–2013

During the Schmallenberg virus (SBV) epidemic, the European Food Safety Authority (EFSA) collected data on SBV occurrence across Europe in order to provide an assessment of spread and impact. By May 2013, twenty-nine countries were reporting to EFSA and twenty-two countries had reported cases of SBV. The total number of SBV herds reported was 13,846 and the number of SBV laboratory confirmed herds was 8730. The surveillance activities were based on the detection of SBV clinical cases (either adults or newborns). Malformation in newborns was the most commonly reported clinical sign of SBV-infection. All countries were able to provide the date when the first suspicion of SBV in the herd was reported and nineteen could report the location of the herd at a regional level. This allowed the spread of SBV in Europe to be measured both temporally and spatially. The number of SBV confirmed herds started to increase in December 2011 and two peaks were observed in 2012 (February and May). Confirmed herds continued to be reported in 2012 and into 2013. An increase during winter 2012 and spring 2013 was again observed, but the number of confirmed herds was lower than in the previous year. SBV spread rapidly throughout Europe from the initial area of detection. SBV was detected above the latitude of 60° North, which exceeds the northern expansion observed during the bluetongue virus serotype 8 epidemic in 2006–2009. The impact of SBV was calculated as ratio of the number of herds with at least one malformed SBV positive foetus and the total number of herds in this region. The 75th percentile of the malformations ratio in the various affected countries for the whole reporting period was below 1% and 3% for cattle and sheep herds, respectively. International data collection on emerging diseases represents a challenge as the nature of available data, data quality and the proportion of reported cases may vary widely between affected countries. Surveillance activities on emerging animal diseases are often structured only for case detection making the estimation of infection/diseases prevalence and the investigation of risk factors difficult. The impact of the disease must be determined to allow risk managers to take appropriate decisions. Simple within-herd impact indicators suitable for emerging disease outbreaks should be defined that could be measured as part of routine animal health surveillance programmes and allow for rapid and reliable impact assessment of emerging animal health diseases.     

Dairy sheep production research at the University of Wisconsin-Madison,USA-a review

Commercial milking of sheep is a new agricultural industry in the United States starting approximately 30 yr ago. The industry is still small, but it is growing. The majority of the sheep milk is used in the production of specialty cheeses. The United States is the major importer of sheep milk cheeses with 50 to 60% of annual world exports coming to the United States during the past 20 yr. Therefore, there is considerable growth potential for the industry in the United States. The only dairy sheep research flock in North America is located at the Spooner Agricultural Research Station of the University of Wisconsin-Madison. The research program started in 1993 and has been multifaceted; dealing with several areas important to commercial dairy sheep farmers. The East Friesian and Lacaune dairy breeds were compared and introduced to the industry through the research program. Both dairy breeds produced significantly more milk than traditional meat-wool breeds found in the U.S., but the two breeds differed in their production traits. East Friesian-cross ewes produced more lambs and slightly more milk than Lacaune-cross ewes whereas Lacaune-cross ewes produced milk with a higher percentage of fat and protein than East Friesian-cross ewes. Lactation physiology studies have shown that ewes with active corpora lutea have increased milk yields, oxytocin release during milking is required to obtain normal fat percentages in the milk, large udder cisterns of dairy ewes can allow for increased milking intervals, and short daylengths during late pregnancy results in increased milk yield. In the nutrition area, legume-grass pastures and forages with a higher percentage of legume will result in increased milk production. Grazing ewes respond to additional supplementation with increased milk yield, but it is important to match the supplement to the quality of the grazing. Ewes on high quality legume-grass pastures that are high in rumen degradable protein respond with increased milk production to supplements high in energy and/or     

White pine (Pinus strobus L.) regeneration dynamics at the species’ northern limit of continuous distribution

The abundance of eastern white pine (Pinus strobus L.) has been significantly reduced across its distribution range over the past few centuries. The species’ regeneration dynamics is well documented in the centre of its range, but is poorly understood at the northern limit of continuous distribution. To address this knowledge gap, we quantified natural white pine regeneration in unmanaged mature stands, identified the most important variables influencing it, and evaluated the impact of damaging agents, namely white pine blister rust (Cronartium ribicola J.C. Fisch.), white pine weevil (Pissodes strobi Peck), and herbivory. We also quantified the influence of remnant stands and residual trees on the spatial distribution of regeneration in logged sites. The results reveal continuous but low recruitment in mature stands. The basal area of balsam fir (Abies balsamea (L.) Miller) had a strong negative effect on white pine regeneration. Regeneration was more abundant than expected on moister substrates, including moss, decaying wood and organic matter. White pine regeneration was noted in recently logged areas, where distance from remnant stands had a significant effect on the abundance of white pine regeneration. The northern limit of continuous distribution holds potential for white pine restoration, for example by preserving remnant white pine stands that can provide seed sources for natural regeneration in a shelterwood cut system, or in adjacent clearcut areas. This study illustrates that different management strategies should be used near northern range limits, where effects of site conditions and disturbance agents are different than in the center of a species’ range.