RELATIVE EFFECTS OF TRACTOR WEIGHT AND WHEEL-SLIP IN CAUSING SOIL COMPACTION

The results presented are from field studies in which soil compaction was measured under tractors working with different wheel loads and levels of wheel-slip. Wheelslip proved to be more important in causing compaction than additional wheel loading, and this effect was more pronounced for more powerful tractors. In most agricultural circumstances the aim is to secure the best compromise between weight and slip as alternative means of achieving greater work output from tractors. The results indicate that in situations where there is a need to avoid compaction, particular attention should be given to providing sufficient wheel loading and the possibility of moving faster to take up more power at lower slip. For the range of soil moistures encountered sinkage was the most convenient and satisfactory method of assessing total reduction in porosity, and differentiated between treatments better than any of the other methods (see below) apart from water-entry rates. Measurement of soil density at three levels to 15 cm depth accounted for less than 50 per cent of the loss of porosity estimated from sinkage and the method did not detect differences due to treatment. Shear strength measured at one depth (3.5 cm) differentiated between treatments, but penetration resistance at 7.5 cm did not. Water-entry rates sensitively detected treatment differences but the method was too time-consuming for comparison of all treatments. The efficiency of traction of four- and two-wheel-drive tractors was measured at intervals during the winter on a clay loam and the results related to surface moisture contents. After a steep reduction in efficiency, when the soil returned to field capacity, subsequent changes in efficiency were small.     

PEAT WASTAGE IN THE EAST ANGLIAN FENS

Measurements of the decline in peat depth between 1941 and 1971 were taken at 14 sites across the East Anglian Fens. Rates of wastage in the period before 1955 and in the more recent period varied widely from site to site. Wastage rates were higher at all sites but one, in the period before 1955. The mean value for wastage rate over the entire period covered was 1.37 (± 0.78) cm/yr.     

Foliar absorption and translocation of fosamine and 2,4,5-T in blackberry (Rubus proceras P. J. Muell.)

Fosamine (ammonium ethyl carbamoylphosphonate) formulated as a 1% w/v solution in 0–25%v/v Tween 20 was absorbed slowly by detached leaves of Rubus procerus P.J. Muell., 35% of the applied herbicide being absorbed after 96 h. Fosamine does not appear to be rainfast, as up to 80% of the applied herbicide and 99.9% of the removable herbicide were removed from the leaves by washing for 5 min in distilled water. Translocalion of fosamine was rapid in small R. procerus plants and followed a pattern similar to that taken by assimilates: 2,4,5–T did not translocate to the root system as readily as fosamine or assimilates.     

Identification of Polymorphisms in the Osteopontin Gene and Their Associations with Certain Semen Production Traits of Water Buffaloes in the Brazilian Amazon

The osteopontin gene may influence the fertility of water buffaloes because it is a protein present in sperm. The aim of this work was to identify polymorphisms in this gene and associate them with fertility parameters of animals kept under extensive grazing. A total of 306 male buffaloes older than 18 months, from two farms, one in the state of Amapá and the other in the state of Pará, Brazil were used in the study. Seven SNPs were identified in the regions studied. The polymorphisms were in gene positions 1478, 1513 and 1611 in the region 5′upstrem and positions 6690, 6737, 6925 and 6952 in the region amplified in intron 5. The SNPs were associated with the traits, namely scrotal circumference, scrotal volume, sperm motility, sperm concentration and sperm pathology. There were significant SNPs (p < 0.05) for all the traits. The SNP 6690 was significant for scrotal circumference, sperm concentration, sperm motility and sperm pathology and the SNP 6737 for scrotal volume. The genotype AA of SNP 6690 presented the highest averages for scrotal circumference, sperm concentration and motility and the lowest total number of sperm pathologies. For the scrotal volume trait, the animals with the largest volume were correlated with the presence of the genotype GG of SNP 6737. These results indicate a significance of the osteopontin gene as it seems to exert a substantial influence on the semen production traits of male buffaloes.     

Partial Maxillectomy in the Dog Comparison of Suture Materials and Closure Techniques

This study compares the healing of oronasal defects created by partial maxillectomy when closed using two different suture materials and two different suture patterns. In experiment 1, 24 dogs were divided into four equal groups. Partial maxillectomy was performed on each dog and was closed using either a two-layer simple interrupted suture pattern (12 dogs) or a modified Mayo mattress pattern (12 dogs) with either polyglactin 910 (12 dogs) or polypropylene (12 dogs) sutures. On the seventh postoperative day, the dogs were euthanized, suture line bursting pressures were measured, and wound healing was evaluated grossly and histopathologically. Suture line dehiscence occurred in one dog from each of the four groups. These were the only dogs in which electrocoagulation had been used. The healing of suture lines closed with the two-layer simple interrupted pattern was superior to that of those closed with the modified Mayo mattress pattern based on the degree of gross oral ulceration, suppurative inflammation, fibrosis and oral epithelial covering at the suture line, and the number of necrotic sites in the adjacent tissue. The healing of suture lines closed with polypropylene was superior to that of those closed with polyglactin 910 based on suture line bursting pressures and the degree of suppurative inflammation and tissue necrosis at the suture sites. In Experiment 2, partial maxillectomies were performed on four dogs, and closure was achieved using a two-layer simple interrupted suture pattern with either polyglactin 910 (two dogs) or polypropylene (two dogs). On the 30th postoperative day, the dogs were euthanized, and wound healing was evaluated grossly and histopathologically. All suture lines were well healed. All polyglactin 910 oral sutures were absent, while all polypropylene oral sutures were still present.     

A review of foliar absorption and translocation of 2,4-D and 2,4,5-T

This review is restricted to an examination of the literature on the environmental and chemical factors that affect foliar absorption and translocation of 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4,5-trichloro-phenoxyacetic acid (2,4,5-T) by plants. Most of the papers covered by this review have been published since 1965. Earlier works have been reviewed elsewhere by other authors (Currier & Dybing, 1959; Sargent, 1965; Franke, 1967; Robertson & Kirkwood, 1969; Hull, 1970). Often absorption and translocation of herbicides are considered together; here the two will be considered separately wherever possible.     

Plate Luting* A Preliminary Report of Its Use in Horses

Plate luting, a new method of interfacing a compression plate to bone for the repair of fractures, was proposed as a method to help facilitate immediate full weight bearing following internal fixation with plates and screws in horses. Theoretical mechanisms relating bone-plate contact and screw support were discussed. Preliminary mechanical testing showed increased endurance of luted bone-plate composites to cyclic loading when compared with the same devices without plate luting. Screw loosening, which often precedes plate failure, did not occur. In vivo studies showed results similar to in vitro experiments.     

DECREASED RADIOPHARMACEUTICAL UPTAKE (PHOTOPENIA) IN DELAYED PHASE SCINTIGRAPHIC IMAGES IN THREE HORSES

Decreased radiopharmaceutical uptake, photopenia, in delayed phase scintigraphic images is recognized in people but has only been reported rarely in horses. We describe three horses with septic osteitis, bone sequestrum formation, or distal limb thrombosis that had photopenia of the affected extremity. Photopenia may indicate the presence of ischemia and can be used to facilitate clinical decision making and prognosis assessment     

Perceptions of gender dynamics in small‐scale fisheries and conservation areas in the Pursat province of Tonle Sap Lake,Cambodia

The Tonle Sap Lake of Cambodia is one of the most productive ecosystems in the world, supporting millions of small‐scale fisher livelihoods. Women's contributions in these fisheries are often overlooked due to socio‐cultural expectations of roles and responsibilities. This is a crucial omission since climate and anthropogenic influences increasingly threaten lake inhabitants. Addressing these challenges requires the full participation of both men and women who use the lake, thus it is necessary to first understand the social dynamics of these communities. We investigated whether there were differences between men's and women's perceptions of (i) fishing and non‐fishing practices; (ii) power, access and control over fishing resources; and (iii) perceptions towards conservation and conservation areas in Pursat, Cambodia. We interviewed fishers and key informants, and found differences in perceptions of fishing and non‐fishing practices between fishermen and fisherwomen. Men more openly acknowledged unequal power dynamics, access to and control over fishing resources when compared with women. We found contrasting ideas of community fisheries and conservation between men and women, and health and safety challenges they faced in conservation areas. Findings suggest that community perspectives and unequal power relations established specific roles for women that limited their active participation in fisheries management.