HARNESSING ECOLOGICAL PRINCIPLES AND PHYSIOLOGIC MECHANISMS IN DIVERSIFYING AGRICULTURAL SYSTEMS FOR SUSTAINABILITY: EXPERIENCE FROM STUDIES DEPLOYING NATURE-BASED SOLUTIONS IN SCOTLAND

To achieve the triple challenge of food security, reversing biodiversity declines plus mitigating and adapting to climate change, there is a drive to embed ecological principles into agricultural, value-chain practices and decisionmaking. By diversifying cropping systems at several scales there is potential to decrease reliance on inputs, provide resilience to abiotic and biotic stress,enhance plant, microbe and animal biodiversity, and mitigate against climate change. In this review we highligh...     

ULTRASOUND‐GUIDED CERVICAL CENTESIS TO OBTAIN CEREBROSPINAL FLUID IN THE STANDING HORSE

Horses with intracranial lesions and severe ataxia are not good anesthesia candidates; however, only one method to obtain cerebrospinal fluid (CSF) from the cervical region in a standing horse has been reported. This method is not performed routinely due to the difficulty for sample acquisition. Our hypothesis is that standing cervical centesis can be performed in horses without complication. Ultrasound‐guided centesis of the CSF between C1 and C2 in 11 clinically normal horses and two horses with neurologic signs were performed. Horses were sedated and ultrasound was used to identify the subarachnoid space and spinal cord between C1 and C2. With ultrasound guidance, a needle was introduced into the dorsal aspect of the subarachnoid space using a lateral approach. Ten milliliters of CSF was obtained and analyzed. Two normal horses in this study had moderate red blood cell contamination in the CSF (940 and 612 RBC/μl). One horse had 11 RBC/μl and the remaining horses had <4 RBC/μl. The total procedure time was approximately 2 min. No reaction was observed and no complications were detected up to 48 h after the procedure. Ultrasound‐guided centesis between C1 and C2 is a rapid procedure that causes minimal to no reaction in standing, sedated horses used in this study. The use of ultrasound to guide a standing C1–2 centesis of the subarachnoid space provides an additional route to obtain CSF for analysis in the equine patient.     

AIR AND WATER PERMEABILITY OF COMPACTED UNSATURATED COHESIVE SOIL

The air and water permeabilities of unsaturated cohesive soils have been measured in a modified triaxial cell permeameter which maintains separate continuity of both the air and water phases during permeation. Three different cohesive soils have been tested and the results interpreted in terms of the cluster concept of soil structure, which recognizes the existence of both macro- and micro-pores. Both air and water permeability are shown to be dominated by the geometry and degree of saturation of the intercluster macro-pores. Compression of the soil always reduces the air permeability but can increase the water permeability by increasing the membrane flow around the clusters. The relations between soil suction, occlusion of the air channels, and compaction water content have also been studied.     

Use of a Vascular Skeletal Muscle Graft for Canine Esophageal Reconstruction

A technique for reconstruction of the thoracic esophagus was evaluated in 13 dogs. A 9 x 10 cm section of transversus abdominis muscle was harvested, fashioned into a tubular graft, and vascularized via the greater omentum. The vascularized tube was advanced into the caudal thorax through the diaphragm at a second surgery 20 to 44 days after harvesting the section of the transversus abdominis muscle. A 5 cm section of caudal thoracic esophagus was replaced with the vascular tubular graft. One dog died because of incarceration of the intestine within the tube and two dogs were euthanized because of infected tubes. One dog died due to an anesthetic complication, one dog had a diaphragmatic hernia and died, and one dog died from pyothorax. Leakage of luminal contents at the anastomoses did not occur in any dog. Seven dogs survived both surgeries but showed deglutitory difficulty 6 days postoperatively due to the grafted esophageal segments becoming severely strictured in each case. Angiography demonstrated vascularization of the full thickness of the graft in each of the seven dogs. An unacceptably high incidence of infection and stricture formation made this technique unsuitable for clinical use.     

Suppressive ability of selected fodder plants on the growth of Parthenium hysterophorus

Parthenium hysterophorus is an invasive weed in Australian rangelands. It displaces valuable fodder plants and causes significant production losses within the cattle industry. Glasshouse screening trials were used to test 20 selected fodder species (test species) for their suppressive ability against P. hysterophorus growth. The trials used two planting densities (four or six plants per pot) and five planting frequencies. Each density by planting frequency was replicated three times. The dry shoot biomass of the test species was used to calculate a suppression index, in order to rank the relative suppressive abilities of the test plants. Setaria incrassata, Panicum maxicum and Cenchrus ciliaris were ranked as strongly suppressive, while Astrebla squarrosa, Bothriochloa pertusa, Themeda triandra, Astrebla elymoides, Bothriochloa decipens, Eulalia aurea and Lablab purpureus were moderately suppressive. The other test species had only poor suppressive abilities. A second glasshouse trial assessed the growth characteristics of the test plants at 13, 27 or 40 days after transplantation (DAT). Test species that strongly suppressed the growth of Parthenium hysterophorus had several attributes that included the ability to attain a greater height, the rapid production of tillers or a branched canopy and an extensive leaf area and root system; these growth attributes were present as early as 13 DAT. The present glasshouse screening approach identified several fodder species for further testing in field trials, and because the attributes that allow the test species to suppress Parthenium hysterophorus are present at the earliest stages of the plant’s life cycle, a rapid screening method is proposed that assesses these attributes at 27 DAT.