坡地养分流失研究现状及控制技术

指出了养分流失直接导致丰富表土流失、土地退化、生产力水平降低等问题。探讨了坡面产流产沙及坡耕地养分流失特征的研究现状及养分流失的控制技术,为坡地养分流失研究提供理论参考。     

深圳市主要水体水环境污染经济损失研究

分别采用恢复费用法及计量经济学法,计算了深圳市河流水系及水库的水环境污染的经济损失。结果表明,2007年深圳市7个流域主要河流的污染经济损失总和为1.07亿元;四大水库2003～2007年年平均经济损失为10.56亿元,经济损失呈现逐年下降的趋势,政府加强水环境治理和保护起到了积极的效果。该计算结果可看作是实际经济损失的下限值,属于较为保守和可靠的数据。     

排管库在香梨贮藏中的优化设计及其优势分析

根据库尔勒香梨的贮藏特性,优化排管库的设计,并针对排管库的使用及运行管理中存在的问题提出解决的办法。同时,通过在排管库和风机库内贮藏香梨效果的对比试验,对两种类型的冷库进行优势分析。结果表明,按香梨在相同库容的排管库和风机库内贮藏8个月计算,优化的排管库可比风机库节电约33%,香梨果实失重率显著降低(P0.05),保鲜效果良好,优势明显。     

小滦河谷地土壤侵蚀速率的定量测算

野外调查和地貌学、生物学分析表明,发生水土流失的坡面上生长的独树或树丛定点记录了坡面水土流失的全过程,可以作为定量测算坡面侵蚀速率的标志.因坡面侵蚀而悬空的树干基部高出当前地面的垂直距离,即为其生长期间坡面侵蚀的厚度;而树木的年轮记录提供了时间尺度.据此,测算出河北省承德市小滦河谷地无成片森林覆盖的亚黏土坡面,在1681～2010年期间的平均侵蚀速率为2.1 mm/a;而有冲沟发育的风沙土坡面,在1961～2010年期间的平均侵蚀速率达24.0mm/a.     

Height growth recovery and crown development in top‐damaged Pinus sylvestris trees

Leader shoot damage was imposed on young Scots pines (3 m high) in four ways: by caging the uppermost whorl including the leader shoot with 10 pine shoot beetles; by caging the two uppermost whorls with 20 beetles; by topping the tree below the 1984 whorl; by topping the trees as above and removing all current shoots in whorl 1983. Six years later, top‐damaged trees were still significantly shorter than undamaged controls, although the annual height growth rate had recovered to the pre‐damage level within 3 years. Recovery occurred in two ways: lateral branches from the nearest intact whorl took dominance over the damaged leader or secondary branches developed from interfascicular buds on the damaged leader shoot. Approximately one and two years of height growth were lost in the former and latter case, respectively. Only 5 of the 34 top‐damaged trees escaped technical defects (crooks and/or vertical branches). Stem diameter and crown development were slightly affected.     

The Effect of Soaking on Protein and Mineral Loss in Orchardgrass and Alfalfa Hay

Nonstructural carbohydrates are usually targeted for reduction during hay soaking, however, other essential nutrients may also be lost. The objectives of this research were to determine the impact of water temperature and time of soaking on reduction of protein and minerals from alfalfa and orchardgrass hay. The experimental design was a randomized complete block with six replications (n = 192). Hay types included bud and flowering alfalfa (Medicago sativa L) and vegetative and flowering orchardgrass (Dactylis glomerata L). Flakes were soaked for 15, 30, and 60 minutes in 25 L of cold (22°C) and warm (39°C) water, and for 12 hours in cold water. Changes in crude protein concentration after soaking had no effect (P > .05) on alfalfa-bud or flowering orchardgrass hay. However, crude protein concentration increased (P = .02) as soaking length increased in vegetative orchardgrass, and decreased as soaking length increased (P < .001) in flowering alfalfa hay. Soaking did not affect (P > .05) calcium (Ca) concentrations in flowering alfalfa and orchardgrass; however, Ca (P < .001) was reduced as soaking length increased in alfalfa-bud and vegetative orchardgrass hay. Reductions in phosphorus (P), potassium, and magnesium concentrations occurred with longer soaking times, resulting in high Ca:P ratios after 12 hours of soaking (P < .001). Soaking for 15-60 minutes did not result in nutrient deficiencies based on the requirements of a 500-kg horse in light work. However, supplementation of P after feeding hay soaked for 12 hours would be necessary to address high Ca:P ratios.     

不同品种牛背最长肌抗氧化性能的研究

本试验旨在研究不同品种牛肌肉的抗氧化特性,为优质牛肉的生产提供试验数据。选用5个品种牛(利木赞牛、中国西门塔尔牛、鲁西牛、秦川牛、晋南牛)的背最长肌,测定肌内脂肪含量、24小时的滴水损失以及在0～4℃下肉色、过氧化物值(PV)及硫代巴比妥酸反应物(TBARS)在72h内的变化动态。结果表明,背最长肌的肌内脂肪含量与24小时滴水损失率在不同品种牛肌肉之间没有显著差异(P>0.05);在整个储存时期(0～72h),5个品种牛肌肉的a*、b*值均呈下降趋势;4～72h内,利木赞牛肌肉的a*值均是最高的,且在冷藏8、12h时,利木赞牛肌肉的a*值显著大于鲁西牛肉和秦川牛(P<0.05),24h后利木赞牛的a*值显著大于西门塔尔牛(P<0.05);随着储存时间的延长,5个品种牛背最长肌的PV和TBARS值均有不同程度的增加,利木赞牛肌肉的PV和TBARS值增加最慢,秦川牛和鲁西牛肌肉的PV和TBARS值增加较快。结果表明,5个品种牛的肌内脂肪含量和滴水损失差异不显著,利木赞牛肌肉能够较长时间保持肉色和抗氧化特性。     

Measurement of transepidermal water loss from clipped and unclipped anatomical sites on the dog

Objectives   To establish a standardised clipping method for the measurement of transepidermal water loss (TEWL) with a VapoMeter® in Beagle dogs and to identify the optimal anatomical site for TEWL measurement.
Procedure   TEWL values obtained from skin sites on five healthy Beagles clipped using two different blade angles (standard vs non-standard) were compared. TEWL values for 48 h were also obtained from seven different anatomical sites that had differing hair density. The hair was clipped in the intensively haired anatomical sites (head, lower and upper back and tail), but not clipped in the sparsely haired sites (ear, inguinal region, footpad).
Results   The TEWL values for the standard and non-standard clipping sites were 6.3 ± 1.31 and 27.2 ± 1.11 g/h/m², respectively. We found the upper back among the clipped sites was the most appropriate site for TEWL measurement over 48 h after clipping, whereas among the unclipped sites the ear was the most appropriate, because the TEWL values from those anatomical sites had the least fluctuation and were less affected by movement.
Conclusion   The clipping method and anatomical site should be standardised in order to minimise the experimental variation in TEWL measurement in dogs.     

Usability of normal force distribution measurements to evaluate asymmetrical loading of the back of the horse and different rider positions on a standing horse

Pressure measurement devices in equine sports have primarily focused on tack (saddle pads and saddle fitting methods). However, saddle pressure devices may also be useful in evaluating the interaction and distribution of normal forces between the horse and rider, including rider position and riding technique. This study examined the validity, reliability, repeatability and possibilities of using a saddle pressure device to evaluate rider position. All measurements were performed using a standing horse. Validity was tested by calculating the correlation coefficient between measured normal force and the weight of the rider. Repeatability was tested by calculating intra-class correlation coefficients. The use of normal force measurements to evaluate horse–rider interaction was tested by adding a known weight to saddle or rider and collecting measurements with the rider sitting in four different positions.The device was found to be valid and reliable for force measurements when the measurement device was not replaced. The system could be used to determine the expected differences with added weight and in different rider positions. The normal force distribution measurement device proved to be a valid and reliable tool for studying the interaction between a rider and a static horse provided it is positioned carefully and consistently relative to both the horse and the saddle.     

Body weight changes and subsequent lambing rates of western whiteface ewes grazing winter range

The objective was to describe body weight change (BWC) and subsequent lambing performance of Columbia, Polypay, Rambouillet, and Targhee ewes that grazed shrub-dominated range in winter of 1989, 1990, and 1991. In December (winter), after breeding each year (yr; October to December), ewes were moved to range. Depending upon severity of climatic conditions and vegetation accessibility, ewes grazed winter range for 30 to 60 days (d). Body weights were measured 2 d before grazing commenced (initial) and 2 to 7 d after ewes were transported off range (exit). Total BWC was calculated by subtracting finial BW from initial BW. All data were analyzed within each breed, as repeated measures using mixed models with age and year included in the model. For all breeds, 2-yr-old ewes were lightest going on to winter range and had the lowest lambing rate. Ewes lost weight while grazing winter range, but mature BW, once achieved, was restored annually with the exception of the 7-yr-old Columbia and Targhee ewes. Regardless of breed or age, ewes were able to achieve lambing rates > 1.5 lambs following early- and mid-pregnancy weight loss. Lambing rates were greater in older ewes, which generally experienced substantial negative BWC during winter grazing.