B-mode and M-mode echocardiography of endurance horses raised in São Paulo State, Brazil

This study aimed to evaluate cardiac dimensions and indexes of cardiac function in endurance horses using bidimensional- (B-) mode and guided unidimensional- (M-) mode echocardiography. Thirty-five Arabian and crossbred Arabian male and female horses, aged 5 to 18 years old, with an average weight of 415.51 ± 36.76 kg and at least 1 year of endurance training and competition experience, were used. The following values were obtained for B-mode echocardiography in the right parasternal window (see “Materials and Methods” for expanded terms): RVIDd 2.54 ± 0.56 cm; RVIDs 2.08 ± 0.68 cm; IVSd 2.60 ± 0.31 cm; IVSs 3.90 ± 0.44 cm; LVIDd 10.07 ± 0.85 cm; LVIDs 6.65 ± 0.92 cm; LVFWd 2.50 ± 0.30 cm; LVFWs 3.74 ± 0.35 cm; Aod 7.86 ± 0.72 cm; LAs 10.84 ± 0.93 cm; Vd 578.40 ± 108 cm³; Vs 232.68 ± 70.61 cm³; FS% 34.99% ± 8.02%; EF% 60.13% ± 8.29%; E-point 2.25 ± 0.49 cm; and LAs:Aod 1.38 ± 0.16 cm. Using guided M-mode, the following values were obtained: RVIDd 2.04 ± 0.55 cm; RVIDs 1.61 ± 0.71 cm; IVSd 2.68 ± 0.29 cm; IVSs 4.17 ± 0.42 cm; LVIDd 9.72 ± 0.72 cm; LVIDs 5.94 ± 0.96 cm; LVFWd 2.69 ± 0.32 cm; LVFWs 4.23 ± 0.69 cm; Aod 7.21 ± 0.75 cm; Vd 534.24 ± 87.53 cm³; Vs 181.75 ± 67.69 cm³; FS% 39.06% ± 7.66%; EF% 66.38% ± 9.41%; and E-point 1.96 ± 0.58 cm.

Introduction

In equine sports medicine, it is important to evaluate the cardiovascular condition of the athlete. More recently, echocardiography has been used for this purpose.Echocardiography is an invaluable diagnostic aid, since it is non-invasive and easy to perform,[1, 2 and 3] while offering a dynamic and functional evaluation of the heart. [2, 3, 4 and 5].Initially, studies on the M-mode were made, including measurements of normal cardiac dimensions in horses[6 and 7] and foals and for the diagnosis of several cardiac diseases. [1] With the introduction of the B-mode technique in the mid-1980s and its validation, a more detailed anatomic evaluation was possible, [2, 8 and 9] thus allowing the observation of cardiac abnormalities. [10]Though echocardiographic examination could be used to predict the athletic condition of individuals,[11] this is possible only if normal echocardiographic reference values are established. As different breeds have different biotypes and develop different aptitudes, it is necessary to provide enough information for each type of work or breed. Research includes data for the Thoroughbred racehorse [3, 12 and 13] and Standardbred trotter, [14 and 15] which perform essentially anaerobic work.The endurance race is a modality that is growing significantly in Brazil, both in number of participants and in quality and training of the animals. The endurance horse demands a physical conditioning that differs from that required for racehorses, especially owing to the development of aerobic work. In addition, the animals are mainly Arabian or Arabian crossbred, which have a particular biotype. Because of these facts, and the lack of data about the echocardiographic behavior of endurance horses, this study aimed to determine the dimensions and indexes of cardiac function for horses with endurance training using B-mode and guided M-mode echocardiography.

Materials and methods

Thirty-five clinically normal endurance Arabian and Arabian crossbred male and female horses between 5 and 18 years old, with an average weight of 415.51 ± 36.76 kg, were included in the study. All animals had at least 1 year of training and experience in competitions and were kept under similar hygienic, sanitary, and nutritional management. Training consisted of trail rides, alternating walking, trotting, and galloping, from 20 to 40 km per day, 3 to 4 times per week.The echocardiographic examination was performed with a Sonosite model 180 Plus v. 1.9 echocardiograph, using a 2-4–MHz electronic microconvex transducer with a maximal depth of 24 cm.The animals were prepared as previously reported,[4, 16 and 17] the hair being coated with large amounts of acoustic coupling gel. During the examination, the animals were at rest, calm, and physically restrained only by the halter, in a quiet and dark room.The following echocardiographic measurements, in B-mode as well as guided M-mode, were performed: the left atrium internal diameter in systole (LAs), only in B-mode, in the long axis view, dorsal to the annulus[15]; the right ventricle internal diameter, in diastole (RVIDd) and in systole (RVIDs); the interventricular septum thickness, in diastole (IVSd) and in systole (IVSs); the left ventricle internal diameter, in diastole (LVIDd) and in systole (LVIDs); and the left ventricle free wall thickness, in diastole (LVFWd) and in systole (LVFWs), from the left ventricle short axis view at the chordal level; and the aortic root internal diameter (Aod), from the aortic valve short axis view. The B-mode measurements were taken according to Patteson et al, [12] and the M-mode measurements were based on Long et al. [18]Images were obtained from the right hemithorax. The position used for the transducer to obtain the standardized images for B-mode and guided M-mode were determined and used as described in Reef.[4 and 17]The echocardiographic examination began using the B-mode echocardiography, with the establishment of the tomographic planes, evaluating morphology of the cardiac structures and their movement in a global manner.The first image obtained was the right parasternal long axis view, with the observation of the ventricle inlets, atrioventricular valves, and both atria. With the transducer positioned to optimize visualization of the left atrium, usually with a minimal dorsal angulation, the LAs measurement was made, immediately before the opening of the mitral valve (Fig 1).     

Relationships between longissimus glycolytic potential and swine growth performance,carcass traits,and pork quality

The relationships between glycolytic potential and growth performance, carcass traits, and pork quality were investigated in a group of 72 pigs from the same genetic line. Glycolytic potential (GP) was determined on live-animal biopsy samples and postmortem samples taken from the longissimus muscle, and free glucose concentration was measured on the exudate from the longissimus muscle taken postmortem. The mean live-animal and postmortem GP and free glucose values were 201.6 micromol/g (range = 113.8 to 301.1), 149.8 micromol/g (range = 91.0 to 270.5) and 110.1 mg/dL (range = 30.0 to 406.0), respectively. Correlations between live-animal and postmortem GP and free glucose ranged from 0.47 to 0.70; however, all three measures were weakly related to growth and carcass traits (r = 0.03 to -0.22; P > 0.05). Correlations of GP and free glucose values with fresh pork quality measurements were moderate (r = 0.23 [P < 0.05] to -0.63 [P < 0.001]). Regression analysis suggested that a one standard deviation increase in live-animal and postmortem GP and free glucose resulted in an increase in L* values (0.99, 1.32, and 2.05, respectively) and drip loss (0.85, 1.10, and 1.39 percentage units, respectively), as well as a decrease in ultimate pH (0.05, 0.11, and 0.16, respectively). Correlations between GP and cooking loss and tenderness and juiciness scores ranged between 0.16 (P > 0.05) to 0.34 (P < 0.01). Free glucose concentration showed no relationship (P > 0.05) with cooking loss, tenderness, and juiciness. Regression analysis suggested that a one standard deviation increase in live-animal and postmortem GP increased cooking loss (1.26% and 1.65%, respectively) and would improve taste panel tenderness (0.54 and 0.44, respectively) and juiciness (0.40 and 0.48, respectively) scores. Increasing GP and free glucose was also associated with decreased longissimus fat and protein, and increased moisture contents (r = 0.14 [P > 0.05] to -0.45 [P < 0.001]). Overall, relationships with fresh meat quality characteristics were stronger for free glucose values than either live-animal or postmortem GP. Results from this study indicate that decreasing longissimus GP and free glucose concentrations may improve pork color and water-holding capacity.     

Species composition and abundance of aphids in Australian hop gardens and their impact on spatiotemporal patterns of Carlavirus epidemics

The species composition and abundance of aphids in commercial cv. Agate and cv. Super Pride hop gardens in Tasmania, Australia, were characterized over three seasons (1999–2001). Gunns Plains recorded 14 aphid species and Bushy Park 11 species, with nine of these common to both sites. The majority of aphids were trapped in the first 2 months (October and November) of active hop growth in all three seasons. Cultivar and geographical location had significant effects on the abundance of total aphids (species pooled) trapped and several individual aphid species in the three seasons. In general, significantly more aphids (total and individual species) were trapped in cv. Agate than cv. Super Pride gardens, and higher numbers were trapped at Bushy Park than at Gunns Plains. This coincided with a higher incidence of plants infected by carlaviruses in cv. Agate gardens at both locations. Differences in the spatiotemporal dynamics of Carlavirus epidemics were described by fitting a stochastic model to the data, with parameters for local spread within the garden (contagion) and background infection (disease increase unrelated to infected plants within the gardens). Local spread of Hop latent virus (HpLV) and Hop mosaic virus (HpMV) was indicated within all gardens. For HpMV in cv. Agate at Gunns Plains, however, infections caused by immigrant viruliferous aphids were also apparent. Using join-count statistics, spatial aggregation of both virus diseases was found for all years, except for the initial year (1999) when incidence was low. Clusters of diseased plants extended to greater distances for HpLV than for HpMV. Based on spatial and spatiotemporal analyses, local spread (mechanical transmission and/or aphid movement within the garden) appears to be the dominant factor in the epidemics of HpLV. Aphid immigration from outside the crop over time may play a more significant role for HpMV epidemics, at least for one location.     

From seedlings to trees: Using ontogenetic models of growth and survivorship to assess long-term (>100 years) dynamics of a neotropical dry forest

Long-term tree and seedling growth and survivorship data from permanent sample plots established in a neotropical dry forest in Jamaica from 1998 to 2008 were used to (1) model growth (periodic annual increment) and survivorship dynamics, (2) cluster structural and functional types, and (3) estimate the age of selected tropical dry forest tree species. A statistical comparison of parameter estimates derived from a generalized linear model (GLM) of each species to a reference species was used to group individuals based on size (DBH and height), and demographic dynamics (periodic annual increment and survivorship). We identified two groups of species based on structural types (canopy and sub-canopy species), three groups of species based on periodic annual increment (fast, intermediate, and slow growing) and four groups of species based on the probability of survivorship of seedlings and trees (very low probability of seedling survivorship but high tree survivorship (two groups); high survivorship throughout the DBH classes; very low survivorship, regardless of stem size). The composition of the groups was mixed, and included individuals of both structural types, and with different periodic annual increment and survival probabilities. The dichotomy of guilds found in tropical rainforests (pioneer and climax species) was not found in this forest. Individual and group GLMs incorporating empirical relationships between periodic annual increment and survivorship, across a spectrum of ontogenies and DBH’s, were also generated. The periodic annual increment models were then used to estimate the time taken by a newly germinated seedling to reach the largest recorded DBH. The fastest growing species was the hemi-cryptophyte Clusia flava which was estimated to take 74 years to reach its maximum recorded size (12.1 cm DBH), whereas the slowest growing species, Ziziphus sarcomphalus, was estimated to take 399 years to reach its maximum size (24.4 cm DBH). These dry forest trees were estimated to reach their maximum size (which was one-half or one-third of the largest DBH recorded for tropical rainforests) in a time similar to tropical rainforest trees. Some of the tree species are ubiquitous to other neotropical dry forests; therefore, our equations for periodic annual increment and survivorship can be applied elsewhere in the region.     

Quantifying stomatal and non-stomatal limitations to carbon assimilation resulting from leaf aging and drought in mature deciduous tree species

Gas exchange techniques were used to investigate light-saturated carbon assimilation and its stomatal and non-stomatal limitations over two seasons in mature trees of five species in a closed deciduous forest. Stomatal and non-stomatal contributions to decreases in assimilation resulting from leaf age and drought were quantified relative to the maximum rates obtained early in the season at optimal soil water contents. Although carbon assimilation, stomatal conductance and photosynthetic capacity (V(cmax)) decreased with leaf age, decreases in V(cmax) accounted for about 75% of the leaf-age related reduction in light-saturated assimilation rates, with a secondary role for stomatal conductance (around 25%). However, when considered independently from leaf age, the drought response was dominated by stomatal limitations, accounting for about 75% of the total limitation. Some of the analytical difficulties associated with computing limitation partitioning are discussed, including path dependence, patchy stomatal closure and diffusion in the mesophyll. Although these considerations may introduce errors in our estimates, our analysis establishes some reasonable boundaries on relative limitations and shows differences between drought and non-drought years. Estimating seasonal limitations under natural conditions, as shown in this study, provides a useful basis for comparing limitation processes between years and species.     

Tropical dry forest succession and the contribution of lianas to wood area index (WAI)

The transmission and interception of light through the canopy is an important indicator of forest productivity in tropical forest ecosystems, and the amount of light that eventually reaches the forest floor is influenced by its interactions with leaves, branches, fruits, and flowers among many different canopy elements. While most studies of forest canopy light interception focus on leaf area index (LAI), very few studies have examined wood area index (WAI), which may account for a substantial component of light interception in tropical forests. The influence of lianas on the interception of light and their overall contribution to WAI is a potentially important factor, but it is generally overlooked because of its difficulty to assess. In this paper we evaluate the relative contribution that lianas have to the overall WAI and canopy openness as function of successional stage via a latitudinal comparison of sites across the Americas (Mexico, Costa Rica and Brazil). Our results suggest that lianas significantly increase WAI and decreases canopy openness. However, lianas were absent at all of our study sites where canopy openness exceeded 60%. Our data are the first to explicitly document the role of lianas in the estimation of WAI and, overall, they will contribute to better estimations of ecosystem level LAI in tropical environments, where there is a lack of data on WAI.     

Exploring below ground complementarity in agroforestry using sap flow and root fractal techniques

Indices of shallow rootedness and fractal methods of root system study were combined with sapflow monitoring to determine whether these ‘short-cut’ methods could be used to predict tree competition with crops and complementarity of below ground resource use in an agroforestry trial in semi-arid Kenya. These methods were applied to Grevillea robusta Cunn., Gliricidia sepium (Jacq.) Walp., Melia volkensii Gürke and Senna spectabilis syn. Cassia spectabilis aged two and four years which were grown in simultaneous linear agroforestry plots with maize as the crop species. Indices of competition (shallow rootedness) differed substantially according to tree age and did not accurately predict tree:crop competition in plots containing trees aged four years. Predicted competition by trees on crops was improved by multiplying the sum of proximal diameters squared for shallow roots by diameter at breast height², thus taking tree size into account. Fractal methods for the quantification of total length of tree root systems worked well with the permanent structural root system of trees but seriously underestimated the length of fine roots (less than 2 mm diameter). Sap flow measurements of individual roots showed that as expected, deep tap roots provided most of the water used by the trees during the dry season. Following rainfall, substantial water uptake by shallow lateral roots occurred more or less immediately, suggesting that existing roots were functioning in the recently wetted soil and that there was no need for new fine roots to be produced to enable water uptake following rainfall. This revised version was published online in June 2006 with corrections to the Cover Date.     

Pseudopestalotiopsis elaeidis associated with leaf spots on Cycas revoluta in Brazil

Cycas revoluta (Cycadaceae) is commonly cultivated as an ornamental tree in several countries. In April 2015, C. revoluta leaves showing brownish spots with a yellow halo that progressed to leaflet necrosis were observed in Belém, Pará state, Brazil. This study aimed to determine the aetiology of this disease on sago palm in Brazil. Based on DNA sequence-based phylogeny, morphology, and colony characterization, the fungus was identified as Pseudopestalotiopsis elaeidis. To the best of our knowledge, this is the first report of P. elaeidis associated with leaf spots on C. revoluta worldwide.     

Sources of within- and between-stand variability in specific leaf area of three ecologically distinct conifer species

Specific leaf area (SLA) is an important ecophysiological variable, but its variability within and between stands has rarely been simultaneously examined and modeled across multiple species. Extensive datasets on SLA in coastal Douglas-fir (Pseudotsuga menziesii var. menziesii (Mirb.) Franco), hybrid spruce (Picea engelmannii Parry × Picea glauca (Moench) Voss × Picea sitchensis (Bong.) Carr.), and ponderosa pine (Pinus ponderosa Dougl. ex P. & C. Laws.) were used to estimate variability of SLA within a canopy and its relationship to tree- and stand-level covariates, and to predict SLA at various locations in tree crowns. Also, in the case of hybrid spruce, variation in SLA due to different relative horizontal lengths from the bole was examined. In all species, SLA systematically increased from tree tip to crown base and decreased with foliage age class. Cardinal direction did not have a highly significant influence in either Douglas-fir or hybrid spruce, but SLA did significantly decrease from branch tip to bole in hybrid spruce. Tree- and stand-level (e.g. density, site index) factors had relatively little influence on SLA, but stand age did have a significant positive influence. For ponderosa pine, a significant relationship between canopy mean current-year SLA and carbon isotope discrimination was also found, suggesting the importance of water stress in this species. An equation was fitted to estimate SLA at various points in the canopy for each species and foliage age class using absolute height in the canopy, relative vertical height in the tree, and stand age.