Prototype agricultural land evaluation systems for Canada: I. Overview of systems development

Abstract. Information on land resources and the capacity of land to support agricultural production is a prerequisite for the formation of sound agricultural policies. This paper summarizes Canadian experiences in developing national and regional land evaluation systems. Potential users expected the system to estimate the degree to which changes in biophysical and socio-economic conditions would alter options for land use and production, and to provide a context for more detailed analysis.
A broad-scale land evaluation system was designed to serve the needs identified by representative user groups. Two prototype systems were developed from available information to test the major features of the system design. Neither prototype was complete; one was national in extent and capable of addressing issues of national and provincial importance, the other covered a sub-provincial area but allowed for more detailed evaluation of the effects of soil modifying processes. A full range of applications was demonstrated using one or other of the prototype systems. As a result of this project, the broad-scale land evaluation system design was improved and verified, ongoing research and data collection activities were adjusted to ensure that they meet the needs of a macroscale land evaluation system, and approaches were developed to overcome problems of land evaluation system development.     

Experimental and natural infection with the enzootic leukosis virus of cattle

A trial was performed with heifers at the age of six to seven months. The animals were experimentally infected with the lymphocytes of a virus-productive donor. Infection was produced in all the nine cases, as demonstrated by means of the positive syncytial test. As indicated by the results of the trial, the antibodies to the enzootic bovine leucosis virus (BLV) were produced soon after experimental infection. A high sensitivity of the serum-neutralization test and the ELISA method was demonstrated in this connection: by these methods, the antibodies were identified already two to three weeks after experimental infection whereas by the immunodiffusion test they could be detected only after five weeks. Twenty-four animals were exposed to natural contact infection. Within 270 days of the trial, the disease after contact was recorded only in one heifer out of the four that were in close contact with the experimentally infected animals. In this case, as compared with experimental infection, the antibodies were produced much later--after 85 to 93 days. Leucosis was recorded in none of the remaining animals. The reasons why such a favourable result was obtained were the thorough disinfection of the stables after blood collections and the strict observance of the aseptic conditions. The results of experimental infection in three cows were identical with those obtained in young cattle. In the experimentally infected dairy cows, antibodies in milk were determined by the ELISA method. As found, in milk the antibodies to BLV appear two to three weeks later than they do in serum. The ELISA method of BLV antibody detection can be used for the identification of infected animals in herds where enzootic bovine leucosis occurs.     

Chemopreventive efficacy of lycopene on 7,12-dimethylbenz[a]anthracene-induced hamster buccal pouch carcinogenesis.

The chemopreventive efficacy of lycopene on 7,12-dimethylbenz[a]anthracene (DMBA)-induced hamster buccal pouch (HBP) carcinogenesis was examined using lipid peroxidation, reduced glutathione (GSH), glutathione peroxidase (GPx), glutathione S-transferase (GST) and glutathione reductase (GR) as biomarkers of chemoprevention. Twenty four male Syrian hamsters were divided into four groups of six animals each. The right buccal pouches of the animals in group 1 were painted with a 0.5% solution of DMBA in liquid paraffin three times a week. The animals in group 2 were painted with DMBA as in group 1 and in addition received 2.5 mg/kg body weight lycopene orally three times a week on days alternate to DMBA application. Group 3 animals received lycopene as in group 2. Animals in group 4 received neither DMBA nor lycopene and served as control. The hamsters were killed after an experimental period of 14 weeks. Biochemical measurements were carried out in tumour and normal tissues. All hamsters painted with DMBA alone for 14 weeks developed well-differentiated squamous cell carcinomas. Diminished lipid peroxidation in the oral tumour tissue was accompanied by a significant increase in the levels of GSH, GPx, GST and GR. Administration of lycopene significantly suppressed DMBA-induced oral carcinogenesis as revealed by the absence of carcinomas. The results of the present study suggest that lycopene may exert its chemopreventive effects by modulating lipid peroxidation and enhancing the activities of the enzymes in the glutathione redox cycle.     

Application of Airway Pressure Therapy in Veterinary Critical Care: Part II: Airway Pressure Therapy

As the specialties of emergency medicine and critical care have grown and evolved in both human and veterinary medicine, so has the need for more advanced care of patients with primary lung disease. Treatment of acute respiratory failure has been the focus of several articles in the human medical literature of the past few years.^1,8 This paper deals with airway pressure therapy and its application in cases of acute respiratory failure in veterinary medicine. The reader is referred to part I of this paper for a reveiw of respiratory mechanics and hypoxemia as they apply to respiratory therapy.     

Compatible measurements of volumetric soil water content using a neutron probe and Diviner 2000 after field calibration

Field calibrations for a neutron probe and a capacitance sensor (Diviner 2000) for measuring the soil water content of a shrinking–swelling clay soil were substantially different from commonly used default values. Using our field calibrations, the two instruments estimated similar changes in the cumulative water content of a soil profile (0–1 m depth) over one growing season.     

Hematological parameters and visceral lesions relationships in rabbit viral hemorrhagic disease.

Twenty rabbits were inoculated with a suspension of Viral Hemorrhagic Disease virus. Hemostatic functions were assessed every sixth hour from 6 to 60 hours post-inoculation. Tissue samples obtained at the same intervals allowed the study of the development of lesions throughout the experiment. Biological signs of Disseminated Intravascular Coagulation (DIC) were detected on and after 30 h post-inoculation and consisted of prolonged One Stage Prothrombin Time and Activated Partial Thrombin Time, the decrease of factors V, VII, and X and high levels of soluble fibrin monomer complexes and D-dimers. A reduction of thrombocyte numbers, heterophils and lymphocytes was associated. The close association of DIC and necrotizing hepatitis lesions suggested the hepatic lesions to be the most important DIC triggering factor. Other mechanisms are discussed.     

Physiological Analysis of Yield Variation in Mungbean (Vigna radiata [Roxb.] Wilczek)

Two mungbean varieties, Guj-1 and PIMS-1 differing in their productivity potential, were examined to investigate their photosynthetic system at various stages of growth in relation to yield with two different dates of sowing. Vertical leaves were found to be beneficial. On the other hand, excessive leaf area during the later stages of growth may be detrimental to yield. Lower LAD at seedling stage and overall high NAR values may be reflected in higher grain yield. NAR declined as season progressed and this, in turn, may be related with increase in LAI. The grain yield was considerably more at the first date of sowing as compared to second date of sowing, the effect was being more pronounced in var. PIMS-1 . Various environmental factors recorded at two different dates of sowing and at various stages of growth indicated that these factors may have influenced the yield potential at two different dates of sowing.     

Response time of broiler chickens to cimaterol: meat tenderness, muscle composition fiber size, and carcass characteristics.

The response time to cimaterol (CIM), a beta-adrenergic agonist, by broiler chickens for carcass characteristics, muscle composition, muscle fiber size, catheptic enzyme activity, and tenderness was determined. Two trials were conducted in which chickens were fed a control diet (CON) containing 0 ppm of CIM or a diet containing 1 ppm of CIM. Trial 1 consisted of 55, 31-d-old broiler chickens individually fed for up to 48 h. At 0, 6, 12, 18, 24, and 48 h, five CON and five CIM-fed chickens were killed. Trial 2 consisted of 160, 33-d-old broiler chickens group-fed for up to 14 d. At 2, 4, 6, 8, 10, 12, and 14 d, 10 CON and 10 CIM-fed chickens were killed. The breast muscle (BM) and leg muscle (LM) weight, cathepsin B and L activities, DNA, RNA, and protein concentration, and BM shear force value (SFV) were measured in both trials. Thigh muscle (TM) SFV were measured in Trial 2 only. Fiber size of BM was measured (five birds per treatment) at d 2, 6, 10, and 14. In Trial 1, BM weight and SFV were lower in CIM-fed birds at 6 h (P less than .05). In Trial 2 BM SFV were higher at d 8 (P = .06) and d 10 (P less than .05) in CIM-fed chickens. The SFV of CIM-fed chickens were higher at d 4, 8, 10, 12, and 14 (P less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Nephrolithiasis resulting in intermittent ureteral obstruction in a cow

Bilateral nephrolithiasis with intermittent ureterolithiasis was diagnosed in a 7-year old Holstein cow. Two episodes of ureterolithiasis resulted in severe azotemia which resolved after spontaneous movement of the stone. A third episode of obstruction one year after the initial episode resulted in rupture of one kidney, necessitating euthanasia. The histopathological examination of the kidney was diagnostic for chronic pyelonephritis. Corynebacterium sp. was cultured from a nephrolith. In this case it is believed that the chronic pyelonephritis predisposed to the calculi formation.