Feeding value of pastures for ruminants

Perennial ryegrass is the primary forage component of ruminant diets in New Zealand. It is persistent and palatable, and immature ryegrass has a high nutritive value (NV). However, seed-head development substantially lowers its feeding value (FV) as fibre concentration increases, the rate and extent of digestibility decreases, and voluntary intake declines. Ryegrass pastures are susceptible to accumulation of endophytic and saprophytic fungi in dead material at the base of the sward, especially when mature and laxly grazed. Feeding forage legumes to ruminants grazing grass-dominant pastures will improve animal performance and lessen the reliance on a single species to meet all nutritional requirements.

The FV of forage is a function of intake and NV, measured by chemical analyses and animal feeding trials. Performance of individual animals grazing forages is usually limited by energy intake because structural fibre can slow digestion and clearance from the rumen and because of competition between individuals for available feed. The use of metabolisable energy (ME) content of forage to signify FV can give a reasonable indication of animal performance, but it should be used in conjunction with chemical analyses to improve the accuracy of predictions.

The relationship between FV, pasture production, animal performance and profitability is complex. The importance of skilled management to maintain pasture quality and optimise animal performance under inconsistent climatic conditions should not be underestimated. Acceptable animal performance with minimal veterinary intervention requires good nutrition, but the genetic potential of livestock in New Zealand cannot be met solely by grazing pasture, especially when a high utilisation of pasture is required to maintain quality and profitability.

Producers are responding to industry demands to reduce the seasonality in supply of milk and meat by changing lambing and calving dates, and extending lactation length in dairy cows. Social changes include adoption of once-daily milking in the dairy industry. Some changes have necessitated increased use of supplements and others can be met by feeding forages with a higher FV than ryegrass, all of which require an improved knowledge of feed quality. This information is available through rapid and inexpensive near infrared spectroscopy (NIRS) analysis, enabling animal nutritional needs to be balanced by appropriate nutrient supply. It is essential that producers continue to improve animal welfare, limit excessive use of fertilisers and meet the demands of overseas consumers. Good nutrition, with an increased use of legumes and other forages to complement ryegrass pastures, will enable these objectives to be achieved.     

番茄黄化曲叶病毒安徽分离物的基因组结构特征及变异分析

利用滚环扩增（RCA）技术从安徽淮北番茄温室表现曲叶症状的番茄上获得番茄黄化曲叶病毒（tomato yellow leaf curl virus, TYLCV）的2个分离物全基因组。 2个TYLCV DNA-A核苷酸序列全长均为2 781 nts,共编码6个ORF。序列比对结果表明,2个TYLCV安徽分离物DNA-A核苷酸序列同源性为99.7%,与已报道的国内外其他24个TYLCV各分离物同源性高达97.8% ~ 99.9%。系统进化分析显示,TYLCV安徽分离物与来自吉林、沈阳、天津、邯郸和山东的5个TYLCV分离物亲缘关系最近。     

水泵机组状态监测与故障诊断系统研究

从20世纪60年代到21世纪,我国的泵站工程为输水、供水以及防洪减灾提供了有力保障。针对水泵机组的状态监测与故障诊断进行研究,建立水泵机组状态监测与诊断的软件及各分析模块与数据库,进行机组性能的预测研究,为水泵机组的状态维修提供支持。     

Dietary phosphorus requirement of GIFT strain of Nile tilapia Oreochromis niloticus reared in freshwater

A study was conducted to estimate the optimum requirement of dietary available phosphorus for GIFT strain of Nile tilapia Oreochromis niloticus. Six purified diets were formulated to contain graded levels (0 (control diet), 2.9, 4.8, 7.6, 9.1 and 10.9 g kg^?1 diet) of available phosphorus. Each diet was fed to triplicate groups of 12 fish with initial average weight (46.03 ± 2.14) g for 8 weeks. The results showed that fish fed the three lowest phosphorus diets (0, 2.9 and 4.8 g kg^?1) had significantly lower weight gain rate, specific growth rate (SGR) and feed efficiency than those fed the other diets (P < 0.05). The survival rate of fish fed the control diet was significantly lower than that of the fish fed the other diets (P < 0.05). Whole body viscerosomatic index and crude lipid content decreased significantly with increasing dietary available phosphorus levels (P < 0.05), while the contents of crude ash, calcium, phosphorus in the whole body and vertebrae showed the opposite trend (P < 0.05). The blood chemistry analysis showed that dietary available phosphorus had significant effects on serum phosphorus concentration, enzyme activities of alkaline phosphatase and parathyroid hormone level. Quadratic curve analysis based on SGR indicated that the minimum dietary requirement of available phosphorus for maintaining optimal growth of tilapia was 8.6 g kg^?1.     

Leaf stoichiometry of Leontopodium lentopodioides at high altitudes on the northeastern Qinghai-Tibetan Plateau,China

Altitude affects leaf stoichiometry by regulating temperature and precipitation, and influencing soil properties in mountain ecosystems. Leaf carbon concentration(C), leaf nitrogen concentration(N),leaf phosphorous concentration(P), and their stoichiometric ratios of Leontopodium lentopodioides(Willd.)Beauv., a widespread species in degraded grasslands, were investigated to explore its response and adaptation strategy to environmental changes along four altitude gradients(2500, 3000, 3500, and 3...     

结肠癌术后早期肠内营养治疗25例临床分析

目的探讨结肠癌患者术后早期（24 h内）应用肠内营养的效果.方法回顾分析吉林医药学院附属医院2008年1月—2008年12月25例结肠癌患者术后早期给予肠内营养支持的临床资料.结果本组病例术后无任何并发症,疗效满意.结论结肠癌患者术后早期应用肠内营养支持,平均住院时间缩短,治疗费用降低,患者术后恢复快,是安全有效的方法.     

动力机械设备的故障诊断技术

介绍了动力机械设备故障诊断技术,分析了制约其发展的主要因素,阐述了动力机械设备故障诊断技术的发展趋势。

Abstract：

The mechanical equipment diagnosis technology is introduced,the main factors restricting the development of mechanical equipment fault diagnosis technology are analyzed and the development trend of mechanical equipment fault diagnosis technology is stated     

田间枣树叶片复杂目标图像综合分割方法

设计了一种复杂图像分割的综合算法。首先对图像进行预处理,锁定大致目标范围,对图像进行增强,再基于阈值分割和Canny算子对图像进行初步分割。然后结合形态学处理方法及各种逻辑运算对分割结果进行优化处理,得到精确完整的目标图像。以田间枣树叶片图像为例进行实验,证明了该算法的可行性和有效性。该算法对叶片重叠、叶片灰度不均匀等复杂图像都有很好的分割效果,获得了边缘清晰、平滑、定位精确的边缘图像。     

基于电磁感应的典型干旱区土壤盐分时空变异快速诊断

选取南疆典型干旱区研究其土壤盐分时空变异,在研究区域选取校正点测定表观电导率(ECa),并同时采集土壤样品,研究表明土壤盐分含量与大地表观电导率具有良好相关性(R =0.935),可由此建立土壤盐分电磁感应解译模型.构建移动式磁感调查系统对研究区域进行调查,获取足量表观电导率信息,结合GIS和地统计等相关知识研究土壤盐...     

Effect of Two Nitrogen Forms on the Growth and Iron Nutrition of Pea Cultivated in Presence of Bicarbonate

ABSTRACT

Two cultivars of pea: ‘PS210713’ (‘PS’), sensitive to iron deficiency, and ‘Marveille de Kelvedon’ (‘MK’), tolerant, were cultivated in controlled climatic conditions during one month, on a nutrient solution containing either nitrate (NO₃ ^?, 4 mM) or ammonium (NH₄ ⁺, 4 mM) and in the presence of bicarbonate (10 mM). The effects of these nitrogen forms on the growth and the mineral nutrition, and especially iron nutrition are analyzed.

The reduction of growth by bicarbonate was approximately 30% in case of NO₃ ^? nutrition in the two cultivars, whereas in ammoniacal treatment the reduction is only 6% and 18% respectively in ‘PS’ and ‘MK’ cultivars.

In presence of bicarbonate, the plant growth is not stimulated by NO₃ ^?relatively to its growth on ammoniacal medium, as often noticed when plants are cultivated on medium without bicarbonate: In presence of this compound, the biomass production of plant pea, was not influenced by the nitrogen forms. The nitric source led to a ferric chlorosis in the sensitive cultivar plants whereas any chlorosis was noted when ammoniacal source was applied. On the other hand, nitric nitrogen form decreased the nitrogen feeding of plants and increased the potassium one, while the effect of the ammoniacal nitrogen form on these nutrients was quite the inverse. In addition, the later increased the allocation of iron towards shoots. Besides, with this nitrogen source there was not accumulation of nitrate in the plant tissues. In nitric feeding case, the nitrate is mainly accumulated in the roots of the two cultivars. It is noticeable that the sensitive cultivar (‘PS’) accumulates three times more nitrate than the tolerant one (‘MK’).

On the level of the whole plant, the iron and phosphorus nutrition seems unaltered by the nitrogen form.