Primary production of grazed annual natural pasture and of grazed wheat in a semi-arid region of Israel

The effect of grazing on the above-ground primary production and water use of a fertilised annual pasture and of fertilised sown wheat was studied. Similar studies were made of the effect of cutting on sown wheat. Two simple models—one exponential, the other logistic, both based on the dry weight of the above-ground biomass—were used to describe the primary production in all treatments.The production of undisturbed pasture and undisturbed wheat was 6480 and 7080 kg DM/ha, respectively. Grazing had no significant effect on the total production of the pasture but reduced the DM yield of wheat by up to 32%. Cutting of the wheat reduced the yield by 56%. Water use was similar in all treatments of pasture and wheat and was not directly related to production. The predicted production by both models was similar to observation in the early part of the season but differed from observation in the later part. Possible reasons for the discrepancies are discussed.     

Plasma endotoxin concentration in horses: a methods study

Background: Accurate determination of plasma endotoxin concentration is critical for ex vivo and in vitro cellular and molecular studies of endotoxemia in horses. However, reports are conflicting with respect to anticoagulant, handling, and sample preparation.

Objective:

Objective: The purpose of this study was to determine the effect of blood sample fraction and handling time on measurement of endotoxin concentration in horses.

Methods:

Methods: Whole blood, anticoagulated with 3.8% (0.12 M) sodium citrate (9:1), was collected from 5 healthy horses. Whole blood (WB), platelet-rich plasma (PRP), and platelet-poor plasma (PPP) were spiked with endotoxin (2 EU/mL). Endotoxin-spiked WB samples were centrifuged immediately to generate PRP for measurement. Endotoxin concentration was subsequently measured by Limulus amebocyte assay at 0, 15, 30, 45, and 60 minutes. Assays were performed in triplicate and results were analyzed using Student's t -test, with significance set at P < .05.

Results:

Results: Mean endotoxin concentrations in 2 EU/mL-spiked WB were significantly different from those in PPP at all time points tested. Recovery of endotoxin in PRP generated from WB was significantly diminished after just 15 minutes.

Conclusion:

Conclusion: PRP generated from WB is significantly more reliable than PPP in determining endotoxin concentration ex vivo. Measurement of endotoxin in PRP generated from WB was significantly diminished after 15 min, identifying a time frame within which to process blood samples for endotoxin analysis.     

The effect of speed and gradient on hyperextension of the equine carpus

The equine carpus has a well-defined limit to joint extension at approximately 180 degrees . During locomotion however, the carpus hyperextends during stance phase. Hyperextension is resisted by the carpal bones and ligaments, and it has been proposed that large increased hyperextension might relate to potentially damaging stress levels in the carpus. The aim of this study was to investigate the relationship between peak hyperextension of the carpus (PCE) and speed during locomotion on the level and on an incline. Five Thoroughbred horses were exercised on a treadmill at speeds between 1.8 and 10 m/s at 0% and +7.5% gradients. PCE was obtained using optical motion capture and linear regression used to describe the relationship between PCE and speed on each gradient. PCE increased linearly with speed during locomotion. The rate of increase was greater on a +7.5% gradient. The fit of the regression equations was increased considerably by subtracting standing carpal angle from PCE during locomotion.     

Impacts of biodiversity loss on ocean ecosystem services

Human-dominated marine ecosystems are experiencing accelerating loss of populations and species, with largely unknown consequences. We analyzed local experiments, long-term regional time series, and global fisheries data to test how biodiversity loss affects marine ecosystem services across temporal and spatial scales. Overall, rates of resource collapse increased and recovery potential, stability, and water quality decreased exponentially with declining diversity. Restoration of biodiversity, in contrast, increased productivity fourfold and decreased variability by 21%, on average. We conclude that marine biodiversity loss is increasingly impairing the ocean's capacity to provide food, maintain water quality, and recover from perturbations. Yet available data suggest that at this point, these trends are still reversible.     

Surface crystallization in a liquid AuSi alloy

X-ray measurements reveal a crystalline monolayer at the surface of the eutectic liquid Au82Si18, at temperatures above the alloy's melting point. Surface-induced atomic layering, the hallmark of liquid metals, is also found below the crystalline monolayer. The layering depth, however, is threefold greater than that of all liquid metals studied to date. The crystallinity of the surface monolayer is notable, considering that AuSi does not form stable bulk crystalline phases at any concentration and temperature and that no crystalline surface phase has been detected thus far in any pure liquid metal or nondilute alloy. These results are discussed in relation to recently suggested models of amorphous alloys.     

Ibex-associated malignant catarrhal fever-like disease in a group of bongo antelope (Tragelaphus eurycerus)

A private zoological facility experienced an outbreak of malignant catarrhal fever (MCF) in 3 bongo antelope (Tragelaphus eurycerus). All cases were periparturient bongos that presented acutely anorectic beginning ~6 weeks after being housed with a Nubian ibex. Disease quickly progressed to respiratory distress and death within 24-72 hours of onset of clinical signs. Consistent gross findings in affected bongos were pulmonary edema and small pale tan foci in the livers. Histological lesions included a nonsuppurative vasculitis in multiple tissues, which is well recognized in MCF, but additionally included necrotizing cholangiohepatitis and neutrophilic, necrotizing myocarditis. Ibex-associated viral DNA was detected by polymerase chain reaction and was identical in sequence whether derived from bongos or ibex. The sequence closely matched an MCF viral DNA fragment that had been amplified from an ibex and bongo in a previous case report.     

Spleen index and mannose-binding lectin levels in four channel catfish families exhibiting different susceptibilities to Flavobacterium columnare and Edwardsiella ictaluri

Edwardsiella ictaluri and Flavobacterium columnare are two bacterial pathogens that affect channel catfish Ictalurus punctatus aquaculture. At the Catfish Genetics Research Unit (U.S. Department of Agriculture, Agricultural Research Service), some progress has been made in selectively breeding for resistance to E. ictaluri; however, the susceptibility of these families to F. columnare is not known. Our objectives were to obtain baseline information on the susceptibility of channel catfish families (maintained as part of the selective breeding program) to E. ictaluri and F. columnare and to determine whether the spleen index and plasma levels of mannose-binding lectin (MBL) are predictive indicators of susceptibility to these pathogens. Four channel catfish families were used: family A was randomly chosen from spawns of fish that were not selectively bred for resistance; families B, C, and D were obtained after selection for resistance to E. ictaluri. All four families were immersion challenged with both bacterial pathogens; the spleen index and plasma MBL levels of unchallenged fish from each family were determined. Mean cumulative percent mortality (CPM) after E. ictaluri challenge ranged from 4% to 33% among families. Families A and B were more susceptible to F. columnare (mean CPM of three independent challenges = 95% and 93%) than families C and D (45% and 48%), demonstrating that there is genetic variation in resistance to F. columnare. Spleen index values and MBL levels were not significantly different, indicating that these metrics are not predictive indicators of F. columnare or E. ictaluri susceptibility in the four tested families. Interestingly, the two families that exhibited the highest CPM after F. columnare challenges had the lowest CPM after E. ictaluri challenge. Further research on larger numbers of families is needed to determine whether there is any genetic correlation between resistance to E. ictaluri and resistance to F. columnare.     

Effect of Ergopeptines Associated with Tall Fescue Ingestion on Recovery of Horses Subjected to Standardized Exercise Tests

Ten horses were paired by body weight, age, and skill level, and one of each pair was assigned to one of two groups. Horses were fed alfalfa hay and a mixture of commercial sweet feed and pellets. Horses in group A were fed fescue seed that contained both ergovaline and ergotamine (E+), whereas those in the other group were fed seed that was free from ergot alkaloids (E−). After the first 35 days, horses were switched to the opposite seed treatment. Seed was fed at 8.2% of the diet, resulting in 406 ppb of ergotamine plus ergovaline in the E+ diet. During weeks 3, 5, 7, and 10, horses were subjected to two separate standardized exercise tests (SETs). The aerobic test consisted of walking, trotting, and loping and was designed to maintain horse's heart rate (HR) to less than 150 beats per minute (bpm). The anaerobic test consisted of 40 turns in less than 4 minutes in response to the movements of a mechanical cow and was designed to increase the horse's HR to more than 150 bpm. There were no treatment effects on water consumption or sweat production. There were also no treatment effects on rectal temperature at rest or during recovery from the anaerobic SET. However, rectal temperatures were higher (P < .05) 1 and 30 minutes after the aerobic SET for horses consuming E+ seed. When horses were on the E+ treatment, HRs were lower (P < .05), both at rest and during the SET. HRs were also lower (P < .05) for the E+ treatment at 1 minute after the aerobic test and 5 and 10 minutes after the anaerobic test. Respiration rates were higher (P < .05) 30 minutes after the aerobic SET and 30 and 60 minutes after the anaerobic SET for the E+ treatment. Horses may have increased respiration rates to compensate for a reduction in the efficiency of evaporative cooling, which resulted from vasoconstriction of peripheral blood vessels.