Factors affecting population dynamics of Eurasian woodcocks wintering in France: assessing the efficiency of a hunting-free reserve

The Eurasian woodcock Scolopax rusticola is a migratory bird of major importance for hunting, which is susceptible to habitat loss and the stochastic effects of severe winter weather. Conservation issues mostly concerned regulation of hunting, but the efficiency of hunting-free reserves has never been investigated. We studied causes of mortality and survival probabilities of 98 radio-tagged woodcocks in a reserve with no hunting and in an adjoining hunting area in Brittany (France). Predation, mostly by mammalian predators on fields at night, was similar among adults and yearlings, while hunting mortality was more important in yearlings. Overall winter survival probabilities were 0.86 ± SE 0.07 in adults and 0.63 ± SE 0.07 in yearlings. Survival probabilities of both age classes increased as birds spent more time in the reserve. Equality of predation in both reserve and hunting areas suggests an additive mortality due to hunting over the winter. Population matrix models predicted that such low survival probabilities cannot sustain long term viable populations. These results call for caution in the harvesting of woodcock populations wintering in western France and could be a forewarning of a decline. The regulation of hunting by setting bag limits or reducing the length of shooting seasons, or the creation of reserves might be appropriate tools for the sustainable management of woodcock populations.     

Dynamic MRI and thermal simulation to interpret deformation and water transfer in meat during heating

Understanding and controlling structural and physical changes in meat during cooking is of prime importance. Nuclear magnetic resonance imaging (MRI) is a noninvasive, nondestructive tool that can be used to characterize certain properties and structures both locally and dynamically. Here we show the possibilities offered by MRI for the in situ dynamic imaging of the connective network during the cooking of meat to monitor deformations between 20 and 75 °C. A novel device was used to heat the sample in an MR imager. An MRI sequence was developed to contrast the connective tissue and the muscle fibers during heating. The temperature distribution in the sample was numerically simulated to link structural modifications and water transfer to temperature values. The contraction of myofibrillar and collagen networks was observed at 42 °C, and water began to migrate toward the interfascicular space at 40 °C. These observations are consistent with literature results obtained using destructive and/or nonlocalized methods. This new approach allows the simultaneous monitoring of local deformation and water transfer, changes in muscle structure and thermal history.     

Influence of culture medium pH on internalization, growth and phenotypic plasticity of Neospora caninum

Neospora caninum, a strictly intracellular protozoan, is a major leading cause of parasite-induced abortion in cattle. A widely held view of N. caninum infection is that both cellular proliferation and stage interconversion (tachyzoite-bradyzoite transformation) are triggered, perhaps even modulated by, changes in cultural conditions. This study tested the hypothesis that exposure of N. caninum tachyzoites to different pH culture media affects the parasite's entry, proliferation and cyst formation in cultured cells. The endocytic pathway for N. caninum entry into the K562 cell line was found to be mediated by low pH of culture medium. Internalization of N. caninum by host cells was significantly increased in acidic and alkaline culture medium compared to cells maintained in neutral medium as revealed by transmission electron microscopy. Parasite proliferation within Vero cells was assessed by plaque formation assay and was found to be highest when pH level was optimum, paralleled by a decrease in the number of cysts. In contrast, parasite encystation increased when the pH level was alkaline or acidic, as evaluated by indirect immunofluorescence and immunocytochemical analyses. Acidic pH regardless of state of host cell infection suppressed the rate of host cell division. These findings suggest that culture medium pH has a determinable effect on the host cell-N. caninum interaction and support the hypothesis that pH of culture medium influence the entry, growth, and phenotypic plasticity of N. caninum in mammalian cells.     

Performance of Four Rice Cultivars Transplanted Monthly over Full Year under Irrigated Conditions in Tanzania

In Tanzania,the phenology and seasonal variations of the yields of different rice cultivars have rarely been studied,especially under fully-irrigated conditions. A trial was conducted to identify the most suitable calendar for rice production in Tanzania under fully-irrigated conditions. Four popular rice cultivars,NERICA1,Wahiwahi,IR64 and TXD306,were transplanted monthly from January to December 2011. The four cultivars recorded similarly higher or lower yields than the annual means when transplanted in July(0.50–0.57 kg/m2) and April(0.07–0.31 kg/m2). A yield-ranking analysis showed that plants transplanted in July was the most productive while those transplanted in April was the least productive,and also revealed a yield-seasonality for irrigated rice in Tanzania,a low-yield season(April–May),a high-yield season(June–August),and an unstable-yield season(September–March). These yield seasons would appear to be closely linked to seasonal temperature variations. When transplanted in April–May,plants were exposed to very low temperatures between panicle initiation and flowering,apparently reducing yield through cold-induced sterility. Those transplanted in June–August prolonged their growth under relatively low temperatures and increased yield through increasing biomass production. In September–March,yield levels varied greatly due to the shortened phenological growth durations at higher temperatures. We conclude that under fully-irrigated conditions in Tanzania,rice should be transplanted in July to ensure the maximum production and yield stability. The yield-seasonality suggests that implementing measures to protect plants from low and high temperature stress at critical phenological stages may allow year-round rice production under fully-irrigated conditions in Tanzania.     

Colostral antibody induced interference of inactivated bluetongue serotype-8 vaccines in calves

Since its introduction into northern Europe in 2006, bluetongue has become a major threat to animal health. While the efficacy of commercial vaccines has been clearly demonstrated in livestock, little is known regarding the effect of maternal immunity on vaccinal efficacy. Here, we have investigated the duration and amplitude of colostral antibody-induced immunity in calves born to dams vaccinated against bluetongue virus serotype 8 (BTV-8) and the extent of colostral antibody-induced interference of vaccination in these calves. Twenty-two calf-cow pairs were included in this survey. The median age at which calves became seronegative for BTV was 84 and 112 days as assayed by seroneutralisation test (SNT) and VP7 BTV competitive ELISA (cELISA), respectively. At the mean age of 118 days, 13/22 calves were immunized with inactivated BTV-8 vaccine. In most calves vaccination elicited a weak immune response, with seroconversion in only 3/13 calves. The amplitude of the humoral response to vaccination was inversely proportional to the maternal antibody level prior to vaccination. Thus, the lack of response was attributed to the persistence of virus-specific colostral antibodies that interfered with the induction of the immune response. These data suggest that the recommended age for vaccination of calves born to vaccinated dams needs to be adjusted in order to optimize vaccinal efficacy.     

1-Hydroxypyrene in milk and urine as a bioindicator of polycyclic aromatic hydrocarbon exposure of ruminants

Urinary 1-hydroxypyrene (1-OH-pyrene) is now largely considered to be a valuable biomarker of exposure of man and animals to pyrene and other polycyclic aromatic hydrocarbons (PAHs). However, from a practical and agronomic standpoint, the question remains whether such biomarking capability still holds when 1-OH-pyrene is analyzed in milk produced by ruminants. To assess this hypothesis, four goats were daily submitted to three different amounts of pyrene oral ingestion, together with phenanthrene and benzo(a)pyrene (1, 7, and 49 mg/day during 1 week each). An HPLC-fluorometric analysis of 1-OH-pyrene in milk revealed a perfect correlation between pyrene doses and 1-OH-pyrene detected in milk, thus fully confirming the biomarking capability of 1-OH-pyrene and providing information on its transfer coefficient toward milk. Transfer equations such as the ones found in the present study could be used as a valuable and practical risk assessment tool in (i) the accurate monitoring of exposure of ruminants to pyrene and (ii) the evaluation of occupational and environmental exposure of ruminants to PAH mixtures.     

Ocular penetration of oral doxycycline in the horse

OBJECTIVE: To investigate intraocular penetration of orally administered doxycycline in the normal equine eye and to compare intraocular and serum doxycycline concentrations. Procedures Six mares were administered doxycycline at 10 mg/kg every 12 h by nasogastric tube for 5 days. Blood, aqueous, and vitreous samples were collected on days 1 and 5. All samples were assayed for doxycycline concentrations. Aqueous and vitreous samples were also assayed for protein quantitation. RESULTS: Doxycycline was rapidly absorbed after the first dose (T(max) value of 1.42 +/- 1.28 h); and elimination of doxycycline occurred slowly (median t(1/2) = 10.88 h). Doxycycline could not be detected in the aqueous on days 1 and 5, nor could it be detected in the vitreous on day 1. On day 5, the mean vitreous doxycycline concentration was 0.17 +/- 0.04 microg/mL at 2 h after drug administration. CONCLUSIONS: Repeated oral administration of doxycycline in the horse resulted in steady state serum concentrations of < 1 microg/mL; however, it did not result in appreciable concentrations of drug in the aqueous and vitreous in normal eyes.