Radiation Balance Components of Maize Hybrids Grown at Various Plant Densities

Components of the energy and heat balances were examined in two maize hybrids grown at three different plant densities (40, 70 and 100 thousand plants per hectare). One of the hybrids was drought tolerant, while the other was bred for cultivation under irrigated conditions. An increase in plant density influenced not only the size of the leaf area, but also the distribution of the leaves at various plant heights. The extinction coefficient, which provides a quantification of radiation penetration, was higher in the irrigated treatments. By contrast to the other two treatments, the plant canopy in the thinly sown stands remained open throughout the vegetation period, and thus behaved quite differently to the closed stands, making it impossible to compare them. Smaller albedo values were recorded for the hybrid bred for irrigation and in thinly sown stands. The low plant density allowed more energy to reach the soil, from which it was reflected, making a considerable contribution to the final temperature in the stand. The latent heat, in keeping with the quantity of water transpired, was the greatest in the densely sown stands. There was little difference between the latent heat values of the normal and dense stands in either hybrid, indicating that they both had a similar sensitivity to increased stand density. If sufficient water is available it would appear that the stand density could be increased even for the drought-tolerant hybrid.     

Outcome of limb amputations in wapiti: 13 cases (1995-2001).

The object of this investigation was to determine the outcome of limb amputation in wapiti. Medical records of 13 wapiti that underwent limb amputation were reviewed to determine age, weight, sex, injury preceding amputation, limb amputated, amputation location, length of hospital stay, complications, and outcome. Ages ranged from 3 months to 8 years and weights from 70 kg to 280 kg. All animals were female. Eleven animals sustained catastrophic long bone fractures prior to amputation. Five animals had front limb amputations and 8 had hind limb amputations. Of these animals, 1 with a front limb amputaiton and 5 with hind limb amputations survived. Postsurgical inability to stand is associated with hospitalization of > 1 day. Of the 13 wapiti reviewed, 5 with hind limb amputations have produced and reared offspring. Hind limb amputation can be considered a viable alternative to euthanasia when catastrophic orthopedic injuries occur in female wapiti.     

Enhanced recovery of avian influenza virus isolates by a combination of chicken embryo inoculation methods.

Since 1993, 14 cases of avian influenza from four different states in the U.S.A. have been diagnosed by virus isolation from eight avian species. Only 11 of the 14 avian influenza virus (AIV) primary isolations would have been successful if only the standard protocol for AIV isolation, i.e., inoculation of specific-pathogen-free embryonating chicken eggs (ECEs) by the chorioallantoic sac (CAS) route, had been followed. Primary isolation attempts were negative for AIV in three cases in which ECEs were inoculated by the CAS route; AIV could not be detected by hemagglutinating activity, agar gel immunodiffusion test or negative stain electron microscopy. However, in these three cases, primary isolations of AIV were achieved by inoculation of ECEs into either the yolk sac or onto the chorioallantoic membrane.     

Physical characteristics and chemical composition of Greater Rhea (Rhea americana) eggs from wild and captive populations.

1. Eggs from wild and captive populations of Greater Rhea (Rhea americana) were studied to determine their physical and chemical characteristics. 2. Significant differences were found among populations in almost all chemical parameters studied, whereas within physical parameters only shell weight (as a proportion of the entire egg) and density showed differences. 3. Eggs from wild populations had the highest protein and linolenic acid and the lowest total lipid contents, while cholesterol levels of these eggs and of those from the largest captive area were the lowest.     

Evaluation of Five Most Commonly Grown Cotton Cultivars (Gossypium hirsutum L.) Under Mediterranean Conditions: Productivity and Fibre Quality

Studies were conducted in four regions of central Greece (Larisa, Karditsa, Livadia, Thiva), to evaluate the productivity and fibre properties (fibre strength and fibre length) of the five most commonly grown cotton cultivars in these regions. The experiments lasted for 6 years (1995–2000). All the characteristics tested were strongly influenced by the factors ‘year’, ‘cultivar’ and ‘region’. Significant cultivar × region, year × cultivar, region × year and cultivar × region × year interactions occurred for all the characteristics studied. The cultivar Alegria had the highest seed‐cotton and lint yield, while Aria had the lowest ones. Both cultivars gave the highest mean lint percentage but the lowest mean boll weight (MBW). Alegria had the lowest fibre strength, while Aria had the highest. The Acala‐type cultivars, Acala SJ2 and Zeta 2, had intermediate seed‐cotton and lint yield, while Vered 171 had high seed‐cotton and satisfactory lint yield. The three cultivars mentioned above had the highest MBW and very good fibre strength. Positive correlation was observed between fibre strength and length. In spite of the fact that mean fibre length was statistically the same in all cultivars, it was influenced by the factor ‘year’, as a result of different weather conditions. The year 1996 was the most unfavourable one for seed‐cotton yield and MBW, because it was characterized by lower than average air temperatures and rather dry conditions for all study sites. The factor ‘region’, a combination of different climatic conditions and cultural practices, influenced significantly all the parameters studied.     

Pharmacokinetics of midazolam administered concurrently with ketamine after intravenous bolus or infusion in dogs

Brown, S.A., Jacobson, J.D., Hartsfield, S.M. Pharmacokinetics of midazolam administered concurrently with ketamine after intravenous bolus or infusion in dogs. J. vet. Pharmacol. Therap. 16 , 419–425. Midazolam, a water-soluble benzodiazepine tranquilizer, has been considered by some veterinary anaesthesiologists to be suitable as a combination anaesthetic agent when administered concurrently with ketamine because of its water solubility and miscibility with ketamine. However, the pharmacokinetics of midazolam have not been extensively described in the dog. Twelve clinically healthy mixed breed dogs (22.2–33.4 kg) were divided into two groups at random and were administered ketamine (10 mg/kg) and midazolam (0.5 mg/kg) either as an intravenous bolus over 30 s (group 1) or as an i.v. infusion in 0.9% NaCl (2 ml/kg) over 15 min. Blood samples were obtained immediately before the drugs were injected and periodically for 6 h afterwards. Serum concentrations were determined using gas chromatography with electron-capture detection. Serum concentrations were best described using a two-compartment open model and indicated a t_½α of 1.8 min and t_½β.p of 27.8 min after i.v. bolus, and t_½α f 1–35 min and t_½β of 31.6 min after i.v. infusion. The calculated pharmacokinetic coefficient B was significantly smaller after i.v. infusion (429 ± 244 ng/ml) than after i.v. bolus (888 ± 130 ng/ml, P = 0.004). Furthermore, AUC was significantly smaller after i.v. infusion (29 800 ±6120 ng/h/ml) than after i.v. bolus (42 500 ± 8460 ng/h/ml, P < 0.05), resulting in a larger Cl_B after i.v. infusion (17.4 ± 4.00 ml/min/kg than after i.v. bolus (12.1 ± 2.24 ml/min/kg, P < 0.05). No other pharmacokinetic value was significantly affected by rate of intravenous administration.     

Quantitative analysis of canine plasma lipoproteins

A combined ultracentrifugationl/precipitation method for the measurement of lipoprotein cholesterol concentrations was developed and validated for use with canine plasma. Very low density lipoproteins (VLDL) were isolated by flotation ultracentrifugation and low density lipoproteins (LDL) separated from high density lipoproteins (HDL) by precipitation with heparin-manganese chloride. Effective separation of these classes was confirmed by agarose gel electrophoresis of native lipoproteins and by sodium dodecyl sulphate polyacrylamide gel electrophoresis of their apolipoprotein distributions. There was trace contamination of the LDL precipitate with HDL, but this represented less than 4 and 9 per cent of the total plasma HDL in normo- and hypercholesterolaemic dogs, respectively. The intra-assay and interassay coefficients of variation for LDL- and HDL-cholesterol concentrations were between 3·3 and 6·9 per cent, and 7·2 and 9·0 per cent, respectively, for plasma cholesterol concentrations between 2·67 and 8·14 mmoll/litre. The intra-assay coefficient of variation for VLDL-cholesterol was 53·8 and 18·4 per cent at plasma cholesterol concentrations of 2·67 and 8·14 mmol/litre, respectively. The interassay coefficient of variation for VLDL was 22·5 per cent. Storage of plasma at -20°C for between two and eight weeks did not affect VLDL-cholesterol concentrations, but led to an increase in LDL-cholesterol and a decrease in HDL-cholesterol concentrations of approximately 10 per cent. The method described is appropriate for the measurement of lipoprotein concentrations in plasma from normo- and hypercholesterolaemic dogs, but samples should not be subjected to prolonged storage before analysis.     

Radiographic interpretation of normal skeletal variations and pseudolesions in the equine foot.

Effective radiographic interpretation requires a veterinarian who is knowledgeable of equine limb anatomy and the various principles that affect the resulting image. The normal and its variations must be recognized and understood before the abnormal can be confidently identified as pathologic. Proper patient positioning and sound radiographic technique are mandatory if reliable diagnostic radiographs are to be produced. This review emphasizes equine foot radiographic variations of normal and pseudolesions that occur with commonly used radiographic views performed in equine practice.