Factors affecting egg production and layer bird mortality in private poultry farms in the subhumid zone of Nigeria

Egg production and layer bird mortality data obtained from five different private farms in Zaria within the subhumid zone of Nigeria, over a 6‐year period (1994–1999) were subjected to least squares analysis to determine the effects of age, season and year. It was demonstrated that age had a highly significant influence (P < 0.01) on egg production in that birds falling within the age group 30–39 weeks produced the highest number of eggs (3255 ± 109), while birds over 100 weeks of age produced the lowest number of eggs (1206 ± 412). Similarly, seasonal variation in egg production was also significant (P < 0.05); the highest egg production (2926 ± 90) was obtained during the early dry season, and the lowest (2423 ± 95) during the late wet season. Mortality was generally low (0.0–0.9%) and not significantly different from 20 to 49 weeks of age (P > 0.05). However, from 50 to 100 weeks of age, highly significant differences (P < 0.01) in mortality were observed, with the 90–100 weeks age group recording the highest mortality of 15.7 ± 1.3%. Furthermore, yearly variations in egg production and mortality were highly significant (P < 0.01) with 1999 producing the most eggs (4410 ± 102) and recording the lowest mortality (1.4%). It was concluded that due to the significant seasonal, age and yearly variations, data on egg production and mortality need to be adjusted for these effects to enable unbiased comparison between and within farms. Furthermore, farmers can make adequate feeding preparations commensurate with each season for optimal egg production.     

潮间带垒石蒙网养鲍技术研究

1994年4月～1995年10月，在4个岩礁区共设置136个石垛，放养壳长1．3～3．0cm鲍苗55．1万只，进行潮间带垒石蒙网养鲍试验。对场址选择、放养密度、规格、投饵方法等进行了研究。结果：产商品鲍19．254t，平均亩产1397．8kg，平均壳长6．81cm，平均个体重39g，成活率89．6％，实现产值693.144万元、利润352.81万元。专家鉴定认为，养殖方式为国内首创，技术水平属世界先进。     

平曲线超高与缓和曲线

本文对平曲线超高、缓和曲线长度的确定进行了简单的介绍,并对超高提出具体设计方法。     

陕北丘陵沟壑区仁用杏丰产栽培技术体系

适地适栽、良种选择、提高苗木成活率和保存率、合理修剪、提高座果率等是仁用杏丰产稳产的主要措施。     

围栏封育对草原植被及多样性的影响

通过对乌鲁木齐地区典型草原围栏内外植被特征、多样性指数、土壤种子库及地下生物量的调查研究,结果表明:2年围栏后,草原植物群落的盖度、产量有大幅度提高,显著高于围栏外,且优势种表现更加明显;围栏内外物种丰富度指数S、优势度指数D和Shannon-Wiener指数H'、均匀度指数Jsw差异不显著;围栏内0～5 cm和10～15 cm土层中的地下生物量明显高于围栏外,但地下总生物量差异不显著,且主要分布在0～15 cm的土层中;围栏后的土壤种子总数及分层种子数明显高于围栏外,且种子主要集中在0～5 cm的土层中.     

兰州经济区土地利用空间结构变化分析

兰州经济区位于西陇海-兰新经济带甘肃段中段,是黄河上游经济区的核心。本文在全面分析了兰州经济区1990~2000年土地利用数量变化、空间变化的基础上,提出了今后兰州经济区土地空间结构优化的思路,从而为土地资源的管理和持续利用提供有效的决策支持。     

建立中国草原生态补偿机制的依据、原则及配套政策研究

重林轻草、重政府投入轻民间参与、重有形价值轻无形价值已经成为我国生态建设中的普遍现象。本文从研究草地的价值贡献和我国草地严重的退化与沙化现状出发,分析了进行草原生态补偿的必要性和紧迫性,并在此基础上提出了对草原生态补偿的理论依据、原则和相应的政策建议。     

中国东天山北坡40年来水热组合变化与古气候的关系

利用东天山北坡山区和平原共6个气象站40年来的降水量及气温记录,对各季、年的水热组合状况及其变化进行了统计分析,并与新疆5 000 aB P(中晚全新世)以来的水热组合主要规律进行了对比讨论.得到的基本结论为:(1) 从变化趋势看,除1987年相对暖湿(平原和秋冬两季表现尤其明显)外,40年来其它时段基本以暖干气候为主,也有冷湿气候出现;(2) 该结果与新疆历史时期百年尺度的水热组合变化规律存在一定的差异;(3)在一定程度上体现了中晚全新世以来,新疆气候以冷湿、暖干为主的水热组合规律只能代表百年尺度的变化,而年际尺度的变化规律还需要更多更深入地研究.     

Growth and its partitioning in Prunus rootstocks in response to root zone temperature

Rootstocks for stone fruit varieties differentially influence tree physiology and one possible explanation for these differences is that varieties vary in their response to root zone temperature (RZT). To examine the effects of RZT, two trials using actively growing plants of five different Prunus rootstocks with chill requirements between 100 and 1100 h were undertaken. Plants were grown at RZTs of 5, 13 and 19 °C for 6 weeks after which total dry matter accumulation and its partitioning amongst roots, stems and leaves was determined. In general, the magnitude of total dry matter and its component parts positively correlated with RZT and significant differences were found among varieties in the magnitude of total dry matter accumulation. Individual varieties ranked differently at the three RZTs with respect to total dry matter: in general, the same ranking was also seen in the ranking of each growth component. RZT significantly influenced partitioning causing differences in leaf, stem and root mass ratios. These differences were greatest at low RZTs and became less as RZT increased. Several patterns of partitioning were found. Firstly, the low chill varieties (Okinawa and Flordagold) were little affected by RZT with similar partitioning occurring at each RZT. Secondly, the higher chill varieties, Green Leaf Nemaguard (GL), Golden Queen (GQ) and Fay Elberta (FE), reacted more strongly to RZT and were particularly affected by the lowest RZT. For these varieties, the root mass ratio rose and stem mass ratio fell as RZT increased. However, with respect to leaf mass ratio, two different trends were found: the leaf mass ratio for FE and GQ positively correlated with RZT whilst the relationship for GL was negative. These findings suggest that the response to RZT is related to a variety's chill requirement; offer an explanation for differences in performance of rootstock–scion combinations at different locations; and will aid the development of more accurate tree performance models by taking RZT into account.     

Effect of cyclosporin A on isolated mitochondria from normal and ischemic rat brain

AIM: The purpose of this study was to investigate the effect of cyclosporin A on the isolated mitochondria from normal and ischemic rat brains and to observe the possible effect of mitochondrial ATP sensitive potassium channel on mitochondrial permeability transition. METHODS: The swelling of mitochondria isolated from normal and ischemic rat brain was evaluated by pectrophotometry. RESULTS: Cyclosporin A at concentrations of 0.5 μmol/L or 1 μmol/L and diazoxide at concentration of 30 μmol/L significantly decreased the swelling of the normal brain mitochondria induced by 200 μmol/L calcium, which was abolished by atractyloside at 100 μmol/L. However, cyclosporin A at concentration of 5 μmol/L did not affect the mitochondrial swelling. On the mitochondria isolated from ischemic brain, cyclosporin A at 0.5 μmol/L but not 1 μmol/L significantly decreased the mitochondrial swelling, which was cancelled by atractyloside at concentration of 100 μmol/L. Diazoxide at concentration of 30 mol/L had the similar effect with cyclosporin A at 0.5 μmol/L, which was locked by atractyloside at 100 μmol/L or 5-hydroxydecanoate at 100 μmol/L and 200 μmol/L. CONCLUSIONS: Compared with the mitochondria isolated from normal brain, mitochondria from ischemic brain are more sensitive to the inhibition of mitochondria permeability transition pore opening. Activation of mitochondrial ATP potassium channel may be one of the mechanisms by which the opening of mitochondrial permeability transition pore is inhibited.