Herbage intake by cattle on tarchonanthus veld in the Northern Cape as affected by stocking rate and grazing system 1

Abstract

In a trial with young Bonsmara cattle, four different stocking rates (10, 7, 6 and 4 ha/large stock unit) were applied in both a rotational and continuous grazing system. Feed intake was estimated during spring, summer, autumn and winter for four consecutive years starting in 1977.

Irrespective of the grazing system, feed intake declined with an increase in stocking rate. On average the highest intake was recorded in January and reached the lowest levels in October and July.

Livemass gain was found to be closely related to feed intake.     

Grass species composition,yield and quality under and outside tree crowns in a semi‐arid rangeland in south‐western Zimbabwe

Abstract

A two‐year study was conducted in lightly grazed areas of Matopos Research Station, Zimbabwe, to evaluate the impact of widely spaced trees on understorey grass composition, yield and quality. The study trees were Terminalia sericea and Acacia karroo. Ordination techniques using grass density and biomass as indices separated quadrats according to soil type but not grass species according to understorey or open areas or according to tree species. Grass yield under tree crowns was similar to open areas, in contrast with most reports where understorey areas had higher yields. The high understorey grass quality that has been reported from savanna areas exhibiting grass composition differences was not expressed. Selective grazing of palatable perennial grasses growing in association with tree crowns and their eventual replacement by low‐yielding and less‐palatable grasses that normally grow in open areas is proposed as an explanation of the unique tree‐grass interaction scenario of this study. In areas where this replacement has occurred, recovery may require management interventions.     

Effect of different blood‐guided conditioning programmes on skeletal muscle ultrastructure and histochemistry of sport horses

The effects of three different blood‐guided conditioning programmes on ultrastructural and histochemical features of the gluteus medius muscle of 2‐year‐old sport horses were examined. Six non‐trained Haflinger horses performed three consecutive conditioning programmes of varying lactate‐guided intensities [velocities eliciting blood lactate concentrations of 1.5 (v_1.5), 2.5 (v_2.5) and 4 (v₄) mm respectively] and durations (25 and 45 min). Each conditioning programme lasted 6 weeks and was followed by a 5‐week resting period. Pre‐, post‐ and deconditioning muscle biopsies were analysed. Although training and detraining adaptations were similar in nature, they varied significantly in magnitude among the three different conditioning programmes. Overall, the adaptations consisted in significant increases in size of mitochondria and myofibrils, as well as a hypertrophy of myofibrillar ATPase type IIA muscle fibres and a reduction in number of type IIx low‐oxidative fibres. Together, these changes are compatible with a significant improvement in both muscle aerobic capacity and muscle strength. The use of v_1.5 and v_2.5 as the exercise intensities for 45 min elicited more significant adaptations in muscle, whereas conditioning horses at v₄ for 25 min evoked minimal changes. Most of these muscular adaptations returned towards the pre‐conditioning status after 5 weeks of inactivity. It is concluded that exercises of low or moderate intensities (in the range between v_1.5 and v_2.5) and long duration (45 min) are more effective for improving muscle features associated with stamina and power in sport horses than exercises of higher intensity (equivalent to v₄) and shorter duration (25 min).     

原油管道YOYO系统流动安全性

原油管道因故停输时,在非事故站间采用YOYO系统可以使原油在站间往返流动,避免凝管事故发生。YOYO系统由分别设置在两个相邻泵站的储罐和螺杆泵组成,其运行过程与正反输工艺相似,但两者使用目的不同。详细说明了YOYO系统的工作流程,建立了其运行过程的传热数学模型,讨论了正反向输送时的初始条件和高程差。基于算例管段,计算讨论了YOYO系统运行过程中的温降规律,分析了采用YOYO系统后管输原油的流动安全性,结果表明：该方法对于事故停输管道是一种潜在可行的安全措施。     

含蜡原油流动特性与热历史和剪切历史的关系

含蜡原油的低温(析蜡点温度以下)流动特性与其所经历的热历史和剪切历史有关,但以往的研究主要侧重于对具体原油进行试验测试和试验规律的定性讨论,总体上没有上升到具有普遍意义的定量规律研究的层次。综述了含蜡原油流动特性与热历史和剪切历史关系的研究现状,并就进一步在定量层次上研究含蜡原油流动性参数与热历史和剪切历史的关系提出了建议。     

On determination of chitin content in mushrooms

Nitrogen compounds constitute the greatest proportion of the dry weight of mushrooms. These nitrogen compounds are partly protein and partly non-protein. A modified Heneberg-Stohman's method was used to separate non-protein from protein nitrogen, as well as to determine raw fiber content in mushrooms, since the methods used previously for this purpose are time-consuming and complicated. Elemental analysis of crude fiber was performed to confirm the uniformity of isolated products. The content of total crude fiber (fungin) and the proportion of chitin and cellulose in it were determined. The chitin content of 15 species of field grown edible mushrooms was in the range of 1.87–6.93% of total dry mass and 34.51–67.72% of isolated fungin.     

小熊猫日粮营养成分分析

对成年小熊猫日粮的采食量以及日粮中的主要营养成分含量进行了测定。试验结果表明,平均每只小熊猫每天摄入蛋糕77.61g、馒头96.28g、苹果456.83g和竹叶90.97g;平均每只小熊猫每天摄入粗蛋白48.28g、粗脂肪13.56g、粗纤维65.30g、灰分23.39g;总日粮的干物质中,粗蛋白含量为26.82%、粗脂肪含量为7.53%、粗纤维含量为36.28%、灰分含量为12.99%、水分含量16.37%。     

Rice bran, a potential source of biodiesel production in Indonesia

Biodiesel is a biodegradable, renewable, non-toxic and environmentally friendly alternative fuel. The cost of raw materials comprises 60-88% of the production cost in commercial biodiesel (fatty acid methyl esters, FAMEs) production. Therefore, the use of low-cost raw material as a substrate and an in situ process for biodiesel production are being preferred. In this case, rice bran, which contains 13.5% oil, was an interesting substrate. In situ esterification of high-acidity rice bran with methanol and sulfuric acid catalyst was investigated. The individual and interaction effects of methanol to rice bran ratio, sulfuric acid catalyst concentration and reaction time on purity and recovery of biodiesel were discussed. Our results suggest that under the following operation conditions: methanol to rice bran ratio of 5 mL/g, sulfuric acid concentration in methanol of 1.5 vol.%, and reaction time of 60 min, an in situ esterification operated on rice bran could yield FAMEs with a high purity and recovery. By applying an in situ esterification with n-hexane/water extractions, Indonesia will be succesfull in obtaining biodiesel from rice bran up to 96,000 ton per year.     

Effects of plant growth regulator treatments on stem vascular tissue development in linseed (Linum usitatissimum L.)

Linseed (Linum usitatissimum L.) is a widely grown source of industrial and edible oil. Other varieties of the same species (flax) are cultivated for the long, strong bast fibres of their stems. The bast fibres of linseed generally go unused, although there is growing interest in developing linseed into a dual-purpose flax from which both seed and fibre could be utilized. Towards this objective, an improved understanding is required of the role of plant growth regulators in stem and fibre development in linseed. We have tested the effects of applying varying combinations of gibberellic acid (GA₃), the auxin indole-3-acetic acid, and a GA biosynthesis inhibitor (paclobutrazol) to an elite linseed variety (CDC Bethune). Results showed that GA stimulated stem elongation, stem expansion and the proliferation, expansion, elongation and cell wall thickening of xylem fibres. The impact of GA on phloem tissues was less apparent, although GA had a positive effect on the number of bast fibres observed in stem transverse section, and GA₃ application in combination with IAA increased the thickness of bast fibre secondary walls nearly two-fold. Other than the bast fibre cell walls, IAA treatments (alone or in combination with GA₃) did not affect most aspects of linseed stem development, suggesting that the observed effects of GA were not mediated by cross-talk with IAA. The relationships defined here between GA, stem architecture, and bast fibre properties in linseed provide a useful framework for manipulation of fibre properties through breeding, biotechnology, and field treatments.     

都兰县天然草地中药材资源现状及开发利用

阐述了都兰县概况及其天然草原中药材种类、分布和蕴藏量,该县境内中药材共330种,其中包括动物、植物和矿物药材资源且明显呈垂直分布,但其蕴藏量在分布上极不均匀。同时分析了都兰县中药材开发利用现状并为今后保护、开发利用提出合理化建议。