Initial Moisture Content and Density and Drying Rate of Three Pine Species Growing in the Natal Midlands

In this the first of a two-part report, results are given of investigations into the vertical distribution of the moisture content and density of wood and bark, as well as into bark thickness, bark mass and bark volume of two age groups of Pinus elliottii and P. patula trees and one of P. taeda. Variation in wood and bark properties was affected more by position in the stem than by species and age. This precludes the determination of reliable mass/volume conversion figures if stem position is not taken into consideration. The mass loss of logs of the above species after various periods of drying and the development of mass/volume conversion figures will form part of a further report.     

Influence of high levels of vitamin E on semen parameters of cocks

This study was an attempt to find whether the reproductive performance of cocks would be influenced by oral administration of different amounts of dietary vitamin E over a long period of time. For that purpose 60 cocks were divided into five dietary groups of 12 animals each, and supplemented with 0 (control group), 100, 1,000, 10,000 or 20,000 IU alpha-tocopherol/kg diet, respectively, over a period of 12 months. The effect on semen parameters and biochemical parameters measured in pooled semen samples and the weight of the testes were determined. The weight of testes decreased with increasing amounts of supplemented vitamin E. Volume, pH, colour, consistency and motility were not influenced by the diets, but density of ejaculate (sperm/microl), total amount of spermatozoa and morphology of sperm were significantly lowered by increasing amounts of supplemented vitamin E. The alpha-tocopherol concentration in ejaculates increased significantly in relation to the diet whereas phospholipid content and thiobarbituric acid-reactive substances (TBARS) of the semen samples decreased significantly with increasing vitamin E supplementation. The reproductive performance of cocks was negatively influenced by high doses of vitamin E although decreased TBARS indicated rising oxidative defence.     

Current statistical issues in Weed Research

The correct design of experimental studies, the selection of the appropriate statistical analysis of data and the efficient presentation of results are key to the good conduct and communication of science. The last Guidance for the use and presentation of statistics in Weed Research was published in 1988. Since then, there have been developments in both the scope of research covered by the journal and in the statistical techniques available. This paper addresses the changes in statistics and provides a reference work that will aid researchers in the design and analysis of their work. It will also provide guidance for editors and reviewers. The paper is organised into sections, which will aid the selection of relevant paragraphs, as we recognise that particular approaches require particular statistical analysis. It also uses examples, questions and checklists, so that non-specialists can work towards the correct approach. Statistics can be complex, so knowing when to seek specialist advice is important. The structure and layout of this contribution should help weed scientists, but it cannot provide a comprehensive guide to every technique. Therefore, we provide references to further reading. We would like to reinforce the idea that statistical methods are not a set of recipes whose mindless application is required by convention; each experiment or study may involve subtleties that these guidelines cannot cover. Nevertheless, we anticipate that this paper will help weed scientists in their initial designs for research, in the analysis of data and in the presentation of results for publication.     

Radio and plasma wave observations at Saturn from Cassini's approach and first orbit

We report data from the Cassini radio and plasma wave instrument during the approach and first orbit at Saturn. During the approach, radio emissions from Saturn showed that the radio rotation period is now 10 hours 45 minutes 45 +/- 36 seconds, about 6 minutes longer than measured by Voyager in 1980 to 1981. In addition, many intense impulsive radio signals were detected from Saturn lightning during the approach and first orbit. Some of these have been linked to storm systems observed by the Cassini imaging instrument. Within the magnetosphere, whistler-mode auroral hiss emissions were observed near the rings, suggesting that a strong electrodynamic interaction is occurring in or near the rings.     

Serological responses of adult dogs to revaccination against distemper, parvovirus and rabies

Serum antibody titres to canine distemper virus (CDV), canine parvovirus (CPV) and rabies were measured in dogs that had not been revaccinated annually and compared with the titres in a control group of regularly vaccinated animals; 83 per cent (171 of 207) of the dogs vaccinated against CDV one or more years earlier had serum neutralising antibody titres equal to or greater than 16; 64 per cent (136 of 213) of the dogs vaccinated against CPV one or more years earlier had haemagglutination inhibiting titres equal to or greater than 80; and 59 per cent (46 of 78) of the dogs vaccinated against rabies two or more years earlier had serum neutralising antibody titres equal to or greater than 0.5 iu/ml. Three weeks after a single booster vaccination the dogs' antibody titres against CDV had increased above the threshold level in 94 per cent of the dogs, against CPV in 68 per cent, and against rabies in 100 per cent.     

Subacute effects of moderate feed loads of isolated Fusarium toxin deoxynivalenol on selected parameters of metabolism in weaned growing piglets

In 36 female weaned piglets, the effect of different dosages (0, 300, 600 and 1200 microg/kg feed) of isolated, pure Fusarium toxin deoxynivalenol (DON) was examined during a period of 8 weeks. Standardised trial conditions were provided. Pigs were fed restrictively to allow a complete feed intake of all animals. Parameters of liver integrity, haematological data and blood concentrations of some selected metabolic components of energy and protein metabolism were examined weekly. Enzyme aspartate aminotransferase was affected subclinically by age and significantly by dosage, which was proved by Wald F-test. Some additional enzymes, for instance alanine aminotransferase, gamma glutamyl transferase, glutamate dehydrogenase and sorbit dehydrogenase, showed no clear systematic effect. Urea and glucose in the blood were inter-related. Depending on DON load with increasing glucose concentrations, the urea level declined. Albumin and total protein in serum showed no significant DON-related effect. Haemoglobin in blood was found to be significantly affected by DON, which was proved by the Wald F-test, where the effect was more pronounced with 600 microg DON/kg diet compared to 1 200 microg DON/kg. An obvious DON-related affection of liver, N-metabolism and stimulation of haematopoiesis depending on dosage and time is discussed.     

Calcium homeostasis and intact plasma parathyroid hormone during exercise and training in young Standardbred horses

Physical exercise is known to affect calcium homeostasis in horses, but there is little information on the hormonal regulation of calcium metabolism during exercise. In order to evaluate the effects of exercise and training on calcium homeostasis and intact plasma parathyroid hormone, 7 untrained Standardbred horses were studied in a 6 week training programme. These horses were accustomed to running on the treadmill 3 weeks before onset of training and were exercised on a high-speed treadmill with an initial incremental standardised exercise test (SET 1: 6 incremental steps of 5 min duration each; first step 5 m/s, increase 1 m/s). SET 1 was followed by a lactate-guided training programme (6 weeks in total) with 2 types of exercise in alternating order with a day of rest after each work day: high-speed exercise (HSE) of 15 min duration, starting at VLa4, continuous increase in speed every 60 s by 0.3 m/s (14 incremental steps); and low-speed exercise (LSE) at a constant velocity at VLa2.5, duration approximately 60-90 min. The whole training programme consisted of 8 HSE and 8 LSE sessions. HSE and LSE were calculated to require the same energy expenditure. A final SET (SET 2) finished the training programme. Blood samples for lactate, plasma total calcium [Ca], blood ionised calcium [Ca2+], blood pH, plasma inorganic phosphorus [P(i)] and plasma intact parathyroid hormone [PTH] were collected before, during and after SETs 1 and 2, before and after the first and eighth HSE and LSE. During SETs 1 and 2, HSEs 1 and 8 there was a decrease in ionised Ca2+ and pH and a rise in lactate, intact PTH and P(i). LSEs 1 and 8 resulted in an increase in pH, whereas lactate, ionised Ca2+, total Ca, P(i) and intact PTH were not affected. No changes in calcium metabolism were detected during training. Results of this study suggest that intact PTH is a mediator in counter-regulation of exercise-induced hypocalcaemia.