苇河林业局实施林价制度的模式初探     

许俊杰  马潮夫 《东北林业大学学报》1992,20(1):69-76

文中指出林价属经济范畴,其含义有广义与狭义之分。作者认为经国务院批复同意,在东北、内蒙古国有林区实行林价制度,这里所说的林价是狭义的林价概念。在此基础上阐述了全国林业改革试验区苇河林业局,在先行实施林价制度的过程中,逐步建立的实行林价制度的管理系统模式。该局林价管理系统由局实施林价领导小组、管理局驻局森林资源监督专员办、森林资源管理科、森调队、诸林场、财务科组成。林价管理系统工作程序是:伐区调查设计、伐区批复、伐区拨交验收、征收林价、资源变档。  相似文献   

Relative survival of calves in 16 traditionally managed herds in Bauchi, Nigeria     

A.C Kudi  J.U Umoh  L.O Eduvie  J Gefu 《Preventive veterinary medicine》1998,36(4):169-312

An actuarial life-table approach was used to study the mortality of 277 calves born alive in 16 traditionally managed herds in Bauchi, Nigeria from 1993 to 1995. The proportion of calves in the herds surviving for the first 12 months was 53.8%. The probability of dying was greatest during the first month of life and decreased with age. The proportion of calves surviving in the herds has been increasing for the last 2 years. We suspect that this is probably due to improvements in management practices. Septicaemia, malnutrition and injury were the common causes of calf mortality. We recommend that more attention be given to improving the management of calves early in life in order to reduce mortality of calves and hence reduce economic losses to the herd owner.  相似文献   

Management-related risk factors for M. paratuberculosis infection in Michigan, USA, dairy herds     

Yvette J. Johnson-Ifearulundu  John B. Kaneene 《Preventive veterinary medicine》1998,37(1-4):41-54

A cross-sectional study was conducted from June through December 1996 to identify management-related risk factors for herd-level M. paratuberculosis infection. Data were collected from 121 participating herds. A two-part questionnaire was administered to gather data on current and previous management practices and herd productivity. A random sample of cows aged ≥24 months was selected from each herd and tested for antibodies to M. paratuberculosis using the IDEXX Antibody ELISA (sensitivity 64%, specificity 96%). A positive herd was one in which ≥2 animals tested positive for antibodies to M. paratuberculosis. A negative herd was one in which no animal tested positive. Herds in which only one animal tested positive were dropped from statistical analysis to reduce the risk of including false-positive herds in the statistical analyses.

There were 80 herds with one or more positive animals and 41 herds with no positive animals in the sample (66% herd-level prevalence). Twenty-six herds (21%) were dropped from further analyses because they had only one positive cow. Twelve herds (10%) were dropped from analysis because of missing data. The resulting sample used for statistical modeling included 46 positive herds and 37 negative herds (55% herd-level prevalence). A multi-variable logistic-regression model was used to evaluate the results. The variable ‘use of an exercise lot for lactating cows' was associated with a three-fold increase in odds of a herd being positive for M. paratuberculosis infection (O.R.=3.01, C.I.=1.03–8.80); ‘cleaning of maternity pens after each use' was associated with a three-fold reduction in odds of a herd being positive for M. paratuberculosis infection (O.R.=0.28, C.I.=0.08–0.89); ‘application of lime to pasture areas in 1993' resulted in a ten-fold decrease in odds of a herd being positive for M. paratuberculosis infection (O.R.=0.10, C.I.=0.02–0.56).  相似文献   

Research article Canopy dynamics and human caused disturbance on a semi-arid landscape in the Rocky Mountains,USA     

Daniel?J.?ManierEmail author  N.?Thompson.?Hobbs  David?M.?Theobald  Robin?M.?Reich  Mohammed?A.?Kalkhan  Mark?R.?Campbell 《Landscape Ecology》2005,20(1):1-17

Invasion of grasslands by woody plants has been identified as a key indicator of changes in ecosystem structure and function in arid and semi-arid rangelands throughout the world. We investigated changes in the balance between woody and herbaceous components of a semi-arid landscape in western Colorado (USA) using historical aerial photography. Aerial photographs from 1937, 1965–67, and 1994 were sampled at matched locations within overlapping photographs. We modeled change in spatial pattern and heterogeneity across the entire landscape and found a small, net decrease in woody canopy cover; however means disguised normal distributions of change that demonstrated offsetting increases and decreases. We described a region of widespread canopy decline within piñon-juniper forests between 2300 and 2600 m (7500–8500 feet) and a region of predominant increase at lower elevations, between 1800 and 2250 m (5900–7400 feet). It remains unclear whether this shift was driven by climate or by human-caused or natural disturbance. Mean conifer cover decreased within coniferous forests, which counteracted a trend of increased conifer cover in mixed forests, savanna-like woodlands, and the shrub steppe. Disturbance had a significant interaction with cover change in several communities, including forests, savanna and shrublands. Anthropogenic disturbances counteracted successional trends toward canopy closure more than wildfires, but this did not entirely explain observed canopy decline. The natural dynamics in this region also caused diverse changes rather than a simple progression towards increased forest cover. Importantly, temporal change in vegetation varied spatially across the landscape illustrating the importance of landscape level, spatially explicit analyses in characterizing temporal dynamics.  相似文献   

Herd-level risk factors for infectious diseases in Swedish dairy calves aged 0-90 days   总被引：1，自引：0，他引：1  

Lundborg GK  Svensson EC  Oltenacu PA 《Preventive veterinary medicine》2005,68(2-4):123-143

The effect of environmental factors and management routines on the risk of diarrhoea, respiratory disease and other infectious diseases was investigated in 3081 heifer calves 0–90 days old in 122 Swedish dairy herds. The farmers kept records on cases of diseases in their heifer calves and in addition, project veterinarians clinically examined all calves every 2–3 months. At each visit, the veterinarians also measured the ammonia concentration and relative air humidity in the housing facilities for the calves. The cleanliness of the animals and their environment was recorded as a measure of the hygienic status of the farm. The presence or absence of draught (i.e. wind velocity > 0.5 m/s) was recorded twice during the study period. The effect of these factors, as well as the placing of the calf pens, the nature of the pen walls, air volume per animal, management factors (such as the status of the caretaker and feeding routines) and presence or absence of a bovine viral diarrhoea virus (BVDV) infection in the herd, was evaluated by means of a two-level variance component logistic model. The placing of calf pens along an outer wall was significantly associated with the risk of diarrhoea (odds ratio (OR): 1.92, P < 0.01). The risk for respiratory disease was significantly associated with an ammonia concentration below 6 ppm (OR: 0.42, P < 0.05) while the odds ratio for moderately to severely increased respiratory sounds was significantly associated with a BVDV infection in the herd (OR: 2.39, P < 0.05) and draught (OR: 3.7, P < 0.02). Absence of draught was significantly associated with the risk for infectious diseases other than diarrhoea and respiratory disease (OR: 0.42, P < 0.01).  相似文献   

Associations between management, climate, and Escherichia coli O157 in the faeces of feedlot cattle in the Midwestern USA     

Sargeant JM  Sanderson MW  Smith RA  Griffin DD 《Preventive veterinary medicine》2004,66(1-4):175-206

Our objective was to generate hypotheses for potential on-farm control strategies for Escherichia coli O157 by identifying associations between management practices and climate, and the presence of E. coli O157 in feedlot cattle. Faeces were obtained from 10,622 cattle in 711 pens on 73 feedlots between May and August 2001. Management and climate information was obtained by questionnaire and observation at the time of sampling. The prevalence of E. coli O157 was 10.2% at the sample level, 52.0% at the pen-level, and 95.9% at the feedlot-level. The factors associated with the presence of E. coli O157 in cattle faeces were the frequency of observing cats in the pens or alleys (most common when observed daily), the presence of E. coli O157 in the water tanks (positive association), the historical use of injectable mass medication (positive association), the use of antibiotics in the ration or water (negative association), the wetness of the pen, number of cattle in the pen (negative association), wind velocity (positive association), and height of the feed bunk (positive association).  相似文献   

池塘养鱼高产优质高效目标管理模式     

王道尊  朱锦根 《水产科技情报》1994,21(4):147-151

池塘养鱼生产经营效益关系到产业自身的巩固和发展,作者经过多年的生产,科研和调查研究,并在１９９－１９９３年以上海市淀山湖联营养殖场为试点,探索池塘养鱼高效益管理模式,归纳为“一个目标,二个保证,三种动力”的“１－２－３管理模式”。具体实施后,淀山湖联营养殖场１９９３年获池塘养鱼每公顷净产１１５６５公斤,每个职工平均产值达４２３７５．３２元,实现了高产,优质,高效益的管理目标。  相似文献   

Reproductive seasonality in female goats adapted to a subtropical environment persists independently of food availability   总被引：2，自引：0，他引：2  

Duarte G  Flores JA  Malpaux B  Delgadillo JA 《Domestic animal endocrinology》2008,35(4):362-370

The aim of this study was to determine whether the seasonal change in food availability provides a predictive cue that synchronizes the breeding season in goats adapted to the subtropical conditions of Northern Mexico. Groups of multiparous intact (n = 7) and ovariectomized does bearing a subcutaneous implant constantly releasing estradiol-l7β (OVX+E; n = 12) were allocated in two pens and received a constant amount of feed. Another group of OVX+E does (n = 10) was incorporated into a flock raised under natural grazing conditions with seasonal fluctuations in food availability. Blood samples were taken twice weekly. Ovulation of intact goats was inferred from plasma progesterone levels. In OVX+E does plasma levels of LH were measured. Intact does displayed seasonal variations in ovulation and the breeding season lasted from September to February. OVX+E goats displayed large seasonal variations in LH secretion regardless of whether they were fed constantly indoors or kept under natural grazing conditions (P < 0.0001). The mean date of increase in LH secretion varied between years (P < 0.0001) but did not differ between groups (naturally grazed: August 13 ± 10 days; constantly fed: August 26 ± 10 days). In contrast, the seasonal decline in LH secretion differed between groups: it was consistently delayed in constantly fed animals compared to those feeding naturally (naturally grazed: January 28 ± 4 days; constantly fed: February 24 ± 6 days, group effect, P < 0.01). These results show that local female goats from subtropical Mexico display large reproductive seasonality independently of food availability.  相似文献   

The Relationship of Cow Comfort and Flooring to Lameness Disorders in Dairy Cattle     

《Veterinary Clinics of North America: Food Animal Practice》2017,33(2):227-233

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浅谈苗圃的经营与管理     

冯志超 《热带林业》2010,38(3):27-29

苗圃是培育苗木的基地,其经营的好坏影响到苗木的供给。随着林业生产迅猛发展,为苗木产业发展带来了机遇。如何提高苗圃生产水平,以适应林业发展和林业现代化的需要,已成为当务之急。文章通过阐述影响苗圃生产的因素,苗圃如何合理规划,提出苗圃生产经营的管理要点,为行业工作者提供一定的理论参考。  相似文献