Impact of increasing shade levels on the dry-matter yield and botanical composition of multispecies forage stands

Botanical diversity has been linked to increased biomass production of grasslands, but these relationships have not been explored as extensively in silvopasture systems where shade impacts on forage mass are variable due to the unique structure and environment of each system. The objective of this study was to evaluate the impact of multiple artificial shade levels on the DM yield and botanical composition of three cool-season forage mixtures near Blackstone, Virginia, USA. Mixtures were as follows: simple = tall fescue [Schedonorus arundinaceus (Schreb.) Dumort., nom. cons.] and white clover (Trifulium repens L.); intermediate = simple + orchardgrass (Dactylis glomerate L.) and red clover (Trifolium pretense L.); and complex = intermediate + Kentucky bluegrass (Poa pratensis L.), birdsfoot trefoil (Lotus corniculatus L.) and alfalfa (Medicago sativa L.). Slatted structures created conditions of 30%, 50% and 70% shade relative to a full sun control. Forages were harvested mechanically (no grazers present). Annual yield (DM kg/ha) did not differ among mixtures. As compared to full sun, annual yield was no different at 30% shade, but was reduced by 22 and 36% at 50 and 70% shade respectively. In contrast to other species in the mixtures, orchardgrass increased in proportion when grown beneath all shade levels and is recommended for silvopasture use. Orchardgrass is not particularly well-adapted to the transition zone between the northern temperate and southern subtropical United States; therefore, these results indicate that silvopastures may be an effective way to integrate marginally adapted, shade-tolerant cool-season forages into transition zone grazing systems.     

Differences in the effect of bolus weight on flavor release into the breath between low-fat and high-fat products

The maximum intensity of flavor release increased as the weight of food introduced into the mouth (the bolus) was increased for a range of different foods. The relationship was not directly proportional (1:1) but followed a power law function. Low-fat (< or = 1 g/100 g) foods showed a different relationship than high-fat (> or = 5 g/100 g) foods, but all low-fat and all high-fat foods were broadly similar irrespective of food type or flavor molecule chemistry. For low-fat foods the intensity of flavor release increased with increasing bolus weight to a greater extent than high-fat foods. This may be associated with the capacity of fat to selectively adhere to the surfaces of the oral cavity, thereby changing the effective surface area for the release of lipophilic flavors.     

Influence of dietary fat and vitamin E on antioxidant status of muscles of turkey

The aim of this study was to better understand the effects of more or less unsaturated fat source (tallow/soy oil/rapeseed oil) and/or vitamin E dietary supplementation (200 ppm) on the antioxidant status (at day 1 post-mortem) of turkey muscles [pectoralis major (Pm) and sartorius (S)]. More particularly, when turkeys were fed tallow, supplementation was sufficient to improve significantly the vitamin E status. Feeding rapeseed oil increased the antioxidant enzyme (AOE) activities (catalase, superoxide dismutase, glutathion reductase), glutathione concentration, and value from the benzoic acid test. Dietary soy oil increased glutathione peroxidase activity, compared to other dietary fat sources. With tallow, most of AOE activities were lower than with rapeseed or soy oil. Whatever the feeding mode, vitamin E supplementation did not affect the AOE activities, glutathione concentration, or values from the benzoic acid test. AOE activities were always higher in the oxidative S muscle than in the glycolytic Pm muscle. After feeding tallow, 9 days of storage increased TBA-RS and carbonyl contents, whereas the activity of many antioxidant enzymes and the total antioxidant activity (TEAC test and benzoic acid test) decreased.     

Cardiac disorders in farmed adult brown trout, Salmo trutta L.

During summer in Brittany, France, sea farmed brown trout, Salmo trutta L., regularly experience a high mortality rate which is associated, at least in part, with cardiac disorders (aneurysms and infarcts). The present study is preliminary to a more extensive research programme, the objective of which is to determine to what extent the physiological performance of the cardiovascular system of brown trout is affected by the environmental conditions the fish experience in farm cages. We conducted a 2-week in situ experiment during which the heart rate of eight sea water acclimatized individuals was telemetered using acoustic tags. During the experimental period, water temperature ranged from 16.0 to 17.6 °C. Water oxygen saturation was above 80% at all times and salinity was very high (35.5‰) but stable. Although they were unfed and not active, seven of out the eight tagged animals displayed near maximum heart beat frequencies, which ranged between 83 and 98 beats per minute (bpm). On the other hand, the eighth animal exhibited medium-range heart rates (50–70 bpm). Using phase delay maps, we established that the maximum heart rate of brown trout at 17 °C was in the range of 96–100 bpm. This result suggests that in our experimental conditions, the heart rate of most of our inactive fish was between 85 and 100% of maximum myocardial performance. We hypothesize that the cardiac failures observed in brown trout during summer are most likely a result of strenuous workloads imposed on the cardiovascular system by a combination of elevated temperature, high salinity and possibly season-related decreased hypo-osmoregulatory abilities.     

Effects of macro and micro-environmental factors on the species richness of terrestrial tardigrade assemblages in an Iberian mountain environment

Tardigrade communities are affected by micro and macro-environmental conditions but only micro-environmental variables, and altitudinal gradients have been studied. We review previous reports of altitudinal effects and evaluate the influence by interacting macro- (climate, soils, biome, and others) and micro-environmental (vegetation, moss and leaf litter) factors on tardigrade assemblages at the Sierra de Guadarrama mountain range (Iberian Central System Mountains, Spain). Terrestrial tardigrade assemblages were sampled using standard cores to collect leaf litter and mosses growing on rocks. General Linear Models were used to examine relationships between Tardigrada species richness and abundance, and macro- and micro-environmental variables (altitude, habitat characteristics, local habitat structure and dominant leaf litter type, and two bioclimatic classifications). Variation partitioning techniques were used to separate the effects of altitude and habitat variation, and to quantify the independent influences of climate and soil, vegetation structure and dominant type of leaf litter. Altitude shows a unimodal relationship with tardigrade species richness, although its effect independent of habitat variation is negligible. The best predictors for species richness were bioclimatic classifications. Separate and combined effects of macro-environmental gradients (soil and climate), vegetation structure and leaf litter type are important determinants of richness. A model including both macro- and micro-environmental variables explained nearly 60% of tardigrade species richness in micro-scale plots. Abundance was significantly related only to soil composition and leaf litter type. Tardigrade abundance was not explained by macro-environmental gradients analysed here, despite a significant correlation between abundance and richness.     

Suspected primary hematomyelia in 3 dogs

Primary hematomyelia refers to hemorrhage occurring within the spinal cord without an identifiable etiology. Clinical signs, magnetic resonance imaging characteristics, and histopathological findings are described. Diagnosis was made through histological analysis and rule-outs for underlying factors. Following removal of the hematoma, neurologic deficits improved, although some residual deficits persisted.     

Pre- and post-mortem use of grape seed extract in dark poultry meat to inhibit development of thiobarbituric acid reactive substances

Diets containing grape seed extract (GSE)-control, GSE [low GSE, low GSE + methionine, high GSE, and high GSE + methionine], or alpha-tocopherol-were fed to broiler chicks to estimate the antioxidative activity of GSE in processed meat. GSE was detrimental to the growth of chicks, and methionine did not reverse the detrimental effect. GSE with 85.4 g of gallic acid equiv/100 g (GAE 85.4) was added to ground dark turkey meat to obtain treatments with no GSE, 1.0% GSE, and 2.0% GSE and then processed as unsalted or salted and unheated or heated. Processed treatments were analyzed for thiobarbituric acid reactive substances (TBARS) and percent expressible moisture (%EM). GSE at 1.0 and 2.0% decreased TBARS values nearly 10-fold as compared to the control. GSE (1.0%) had a %EM value significantly greater than that of the control. GAE 85.4 decreased TBARS values more than GAE 88.9.     

Spatial learning as an adaptation in hummingbirds

An ecological approach based on food distribution suggests that humming birds should more easily learn to visit a flower in a new location than to learn to return to a flower in a position just visited, for a food reward. Experimental results support this hypothesis as well as the general view that differences in learning within and among species represent adaptations.