Holding Power of Orthopedic Screws in Equine Third Metacarpal and Metatarsal Bones: Part II. Adult Horse Bone

Comparison was made of the holding power of 5.5 and 4.5 mm cortical orthopedic screws inserted into third metacarpal and metatarsal cadaver bones from 3- and 8-year-old horses. The tensile strength of these screws was tested mechanically. In nine comparative trials of these screws, 5.5 mm screws pulled out of bone in five trials at an average of 116.0 kg tensile force and broke in four trials at an average of 1383.2 kg. A 4.5 mm screw pulled out of bone at 834.5 kg in one trial, and screws broke at an average of 849.2 kg in eight trials. The larger 5.5 mm screw required a significantly greater (p = 0.022) pullout force than the mean force at 4.5 mm screw breakage. Fixation failure was due to screw breakage or bone shear, with 5.5 mm screws occasionally creating bone fragmentation during pullout. The average tensile breaking strengths of the 5.5 mm screws (1391.4 kg) and 4.5 mm screws (832.7 kg) determined mechanically were similar to forces at screw breakage during pullout testing in bone. Since the 5.5 mm screws have greater holding power and tensile strength than 4.5 mm screws, the use of the 5.5 mm screw in fracture repair in adult horses is recommended.     

Medial Plating for the Repair of Middle and Distal Diaphyseal Fractures of the Humerus in Dogs

Six middle and distal humeral shaft fractures in dogs were repaired by the application of a bone plate along the medial shaft of the humerus. In all animals, clinical and radiographic evidence of normal bone healing was observed. The bone plate and ancillary implants were removed from five dogs by 10 months. In none of the six dogs were any untoward effects of placing the bone plate along the medial shaft of the humerus detected nor were there any difficulties encountered with the medial humeral soft tissues.     

The Influence of Soil Type and Pine Species on the Carabid Community of a Plantation Forest with a History of Pine Beauty Moth Infestation

The community composition of Carabid beetles, some species ofwhich are known predators of pine beauty moth, was examinedwithin a Scottish plantation forest. Sites differing in soiltype and the species of trees planted were sampled with pitfalltraps in most weeks of a 3—year period. There were faunaldifferences between sites with lodgepole pine on deep peat andother sites in the study (lodgepole pine on iron-pan soil, speciesmixture of lodgepole and Scots pine, and pure stands of Scotspine). In general deep peat sites supported fewer species andindividuals of carabids. Three Carabus species were implicatedas likely predators of Panolis flammea pupae and each was lessabundant on the sites with lodgepole pine. It is suggested thatthe susceptibility to pine beauty moth of lodgepole pine growingon deep peat substrates is at least partly attributable to impoverishedpredator faunas.     

Acceleration of Early Growth of Seedlings and Rooted Cuttings of Quercus robur L.

The normal delays in the production of useful planting materialin tree species such as Quercus robur from both seedlings andcuttings can be overcome by growing the plants at relativelyhigh temperature and in continuous light. Top growth could befurther accelerated by application of gibberellic acid (GA3)as foliar spray. There were, however, distinct differences inresponse between seedlings (with a high root: top dry matterratio, 4:1), and freshly rooted cuttings. The latter evincedonly onefifth the seedling response, but when cuttings attainedsimilar root:top ratios, their response reached that of seedlings. GA3 treatment accelerated top growth at the expense of rootgrowth, but a root dip for 4h in 100 ppm indole-3yl-butyricacid (IBA) given to 4-month-old cuttings restored root growthto normal even with GA3 treatment. During rooting, cutting commonlybecame dormant but this was prevented by foliar GA3 sprays.Growth was further and substantially improved by inclusion ofcytokinin in such sprays (benzylandenine purine, BAP). Furtherimprovements of growth were obtained by 5% sucrose suppliedto the foliage. In field experiments, assessing ‘establishment’of seedlings and cuttings, the latter established well but after550 days still had not attained the same root:shoot ratio asseedlings. GA3 (50 ppm) again greatly promoted shoot growth,while BAP increased branching and leaf number; when given togethermaximum leaf numbers and shoot dry weight were obtained, yetroot growth remained normal. Further addition of IBA raisedshoot growth still further, but other characters measured sufferedreductions. The potential use of these findings is discussed.     

PROGRESS ON IMPROVING AGRICULTURAL NITROGEN USE EFFICIENCY: UK-CHINA VIRTUAL JOINT CENTERS ON NITROGEN AGRONOM

● Virtual joint centers on N agronomy were established between UK and China. ● Key themes were improving NUE for fertilizers, utilizing livestock manures, and soil health. ● Improved management practices and technologies were identified and assessed. ● Fertilizer emissions and improved manure management are key targets for mitigation. Two virtual joint centers for nitrogen agronomy were established between the UK and China to facilitate collaborative research aimed at improving nitrogen use efficiency (NUE) in agricultural production systems and reducing losses of reactive N to the environment. Major focus areas were improving fertilizer NUE, use of livestock manures, soil health, and policy development and knowledge exchange. Improvements to fertilizer NUE included attention to application rate in the context of yield potential and economic considerations and the potential of improved practices including enhanced efficiency fertilizers, plastic film mulching and cropping design. Improved utilization of livestock manures requires knowledge of the available nutrient content, appropriate manure processing technologies and integrated nutrient management practices. Soil carbon, acidification and biodiversity were considered as important aspects of soil health. Both centers identified a range of potential actions that could be taken to improve N management, and the research conducted has highlighted the importance of developing a systems-level approach to assessing improvement in the overall efficiency of N management and avoiding unintended secondary effects from individual interventions. Within this context, the management of fertilizer emissions and livestock manure at the farm and regional scales appear to be particularly important targets for mitigation.     

Polka-dot grouper, Cromileptes altivelis, can utilize dietary fat efficiently

Polka‐dot grouper, Cromileptes altivelis, a highly‐prized fish in Asian live fish markets, is a slow‐growing species. Long‐chain (LCF) or medium‐chain fatty acids (MCF) were fed to polka‐dot grouper (14 g initial weight) for 8 weeks to see if growth could be stimulated. Five dietary treatments were compared: a control diet with low fat (56 g kg^?1) or diets that contained either moderate (150 g kg^?1) or high (300 g kg^?1) supplements of fat that were added either as olive oil for the LCF or coconut oil for the MCF. Control fish performed well; they grew at 2.2 g week^?1, had a dry matter feed conversion ratio of 1.0 and deposited dietary protein and energy at efficiencies of 25 and 26%. Fish fed LCF at moderate levels performed better than controls but, when fed LCF at high levels or MCF at any level, their performance was inferior to controls. We conclude that dietary supplementation with 150 g kg^?1 of LCF stimulates growth and improves protein retention of polka‐dot grouper whereas higher levels, or the same or higher levels of MCF, depress performance.     

Hepatocellular carcinoma and fatty infiltration in the Atlantic tomcod, Microgadus tomcod (Walbaum)

Abstract. The livers of Atlantic tomcod, Microgadus tomcod (Walbaum), from the Hudson and Pawcatuck Rivers were evaluated histologically and described using paraffin and plastic sections. Fatty infiltration, basophilic foci, areas of cellular alteration and hepatocellular carcinoma were widespread in Hudson River samples. In fact, no truly normal tissues were found. Pawcatuck samples had variable levels of lipid and a low prevalence of other alterations. Evaluation of the histological evidence suggests that hepatocellular carcinoma in Hudson River tomcod results from multiple DNA lesions and that areas of cellular alteration give rise to the larger, more invasive form of hepatocellular carcinoma. Glutaraldehyde and OsO₄ fixed livers were used to determine differences in cell types and lipid levels. Pawcatuck samples possessed hepatocytes and dark cells forming the parenchymal tissue, whereas Hudson samples lacked dark cells. Hepatic lipid levels were significantly higher in Hudson River fish than in Pawcatuck fish, 36·3 and 11·0% respectively. The elevated hepatic lipid levels in Hudson River tomcod may represent a metabolic response to detoxification.     

Characterization of a host response to the myxosporean parasite, Ceratomyxa shasta (Noble), by histology, scanning electron microscopy and immunological techniques

Abstract. The tissue response of Salmo gairdneri Richardson, against the myxosporean parasite. Ceratomyxa shasta (Noble), was investigated using histological techniques, scanning electron microscopy and immunological methods. The progress of infection in C. shasta -susceptible and resistant steelhead and rainbow trout was examined by standard histological techniques and by indirect fluorescent antibody methods using monoclonal antibodies directed against C. shasta antigens. Trophozoite stages were first observed in the posterior intestine and there was indication that resistance was due to the inability of the parasite to penetrate this tissue rather than to an inflammatory response. Examination of a severely infected intestine by scanning electron microscopy showed extensive destruction of the mucosal folds of the posterior intestine. Western blotting and indirect fluorescent antibody techniques were used to investigate the immunological component of the host response. No antibodies specific for C. shasta were detected by either method.     

The isolation of a rickettsia-like organism causing disease and mortality in Chilean salmonids and its confirmation by Koch's postulate

Abstract. A rickettsia-like organism (RLO) was isolated from infected coho salmon, Oncorhynchus kisutch (Walbaum), in cultures from six fish cell lines, but could not be cultured on 41 artificial media. The organism was confirmed by Koch's postulates as the aetiological agent of a systemic disease causing signifieant mortality among coho in Chile. The organism was a Gram-negative, obligate intracellular pathogen frequently observed within intracyto-plasmic vacuoles or inclusions of host cells, and appears to belong to the order Rickettsiales, family Rickettsiaceae and possibly the tribe Ehrlichiae. The organism, as well as the clinical signs and pathology it produces, is described. The disease, originally observed only in coho raised in seawater net pens, was reproduced experimentally in fish in both freshwater and seawater aquaria. Horizontal transmission without parasite vectors was observed in fish in both aquaria. The organism was shown, for the first time, to cause disease and mortality in Atlantic, Salmo salar L., and Chinook, O. tshawytscha (Walbaum), salmon and rainbow trout, O. mykiss (Walbaum). Because of the systemic nature of the disease, it is proposed that it be called 'salmonid rickettsial septicaemia'.