Effect of cutting height and frequency on Leucaena leucocephala forage and wood production

Abstract

Leucaena leucocephala is a fast‐growing tree that can provide both high quality forage and firewood. The objective of this trial was to determine the optimum height and frequency of cutting for both wood and forage production. Cutting heights at 0.3 m, 0.6 m and 1.0 m were superimposed on 3‐month and 6‐month cutting frequencies on mature rows of L. leucocephala for three years. Effects of year or its interaction with the other factors were not significant (P≥0.10). There was an increase (P=0.07) in wood production but not forage production (P≥0.10) with the longer interval. Cutting height had an effect on forage (P<0.001) production, with 5.47 t ha^?1 a^?1 for the 0.3‐m height, 7.62 t ha^?1 a^?1 for the 0.7‐m height, and 8.71 t ha^?1 a^?1 for the 1.0‐m height. Cutting height also had an effect on wood production (P<0.001), with 7.22 t hd^?1 a^?1 for the 0.3‐m height, 9.33 t ha^?1 a^?1 for the 0.7‐mheight, and 11.55 t hd^?1 a^?1 for the 1.0‐m height. In this experiment, the six‐month interval produced more wood than the three‐month interval, but there were no differences in quantity of forage dry matter in L. leucocephala; there were advantages in both wood and forage production with the taller trunk base.     

蒙古栎秋播种育苗技术的研究

自１９９３年起对本局大趟子苗圃进行了蒙古栎秋播育苗试验,并对蒙古栎从采种、种子调制、田间管理及起苗、留床、造林等环节上形成了一套完整的科学育苗方法,避免了春播育苗种子储藏和鼠害等一系列不利问题,研究探索了最佳播种量和最佳经营密度。     

田间环境参数动态监测系统平台设计与实现

信息技术飞速发展,农业不再是简单的田间的播种、收割农作物,而是对于农作物成长过程的更多的管理。面对多变的天气,及时快速的发现异常,则能够让农户减少损失。本设计是用PHP+MySQL数据库开发的,基于B/S结构的田间环境参数动态监测系统平台,它将网络应用技术运用到农业生产中来,使之能够监测农作物生产环境的动态并及时反馈,让农户能够随时随地查看农场环境信息。通过提供农业相关资讯,环境监测以及农户们交流的服务平台,本平台让农民们可以利用信息技术进行科学化管理,学习更多的技术和知识,最终实现提高单位面积产量的目标。     

应用间接荧光抗体技术研究水中嗜水气单胞菌的数量与鱼类出血性败血病的关系

应用间接荧光抗体技术（ＩＦＡＴ），并结合嗜水气单胞菌（Ａｈ）地区优势血清型，对鱼类出血性败血病的致病菌Ａｈ进行水中数量的测定。ＭＭ感染试验和对生产鱼塘调查的结果表明，水中Ａｈ菌量与疾病呈正相关，致病浓度又随鱼体健康低下、水中氨氮偏高、溶氧偏低等多种因子的影响而下降。本试验方法快速简便，检测对象为水体，非常适用于预测疾病的发展趋势。     

草莓快速繁殖技术的研究

本文探讨了利用茎尖离体培养法进行草莓快速繁殖的方法。主要摸索了激素对试管苗的分化、生根的影响及移栽成活的技术要点。     

不同比例游离脂肪酸对体外发酵参数的影响

采用体外培养方法研究添加不同比例的亚油酸和亚麻酸对瘤胃发酵的影响。以微晶纤维素为发酵底物,混合酸的添加量为5mg,添加比例分别为0∶0、5∶0、4∶1、3∶2、1∶1、2∶3、1∶4和0∶5,每个处理设4个重复。结果表明:随着游离脂肪酸不饱和度的增加提高了培养液中pH值和NH3-N浓度,降低了挥发脂肪酸、24h微晶纤维素的消失率和产气量。     

Influence of storage time and processing on chemical composition and in vitro ruminal fermentation of olive cake

Olive oil extraction generates olive cake (OC) that could be used in ruminant feeding. However, the chemical composition of OC is affected by multiple factors, being therefore highly variable. The objective of this study was to analyse the influence of storage time and further processing: crude, exhausted (subjected to a second oil extraction) and cyclone (obtained from a cyclone separator) on nutritive value of OC samples. Twelve samples (six crude and six exhausted) were obtained monthly from the same pond from 1 to 6 storage months, and nine samples (three crude, three exhausted and three cyclone) were obtained monthly from a different pond from 6 to 9 months storage. Chemical composition was analysed, and OC samples were fermented in vitro with sheep rumen fluid. Increasing storage time up to 6 months decreased sugars and total soluble polyphenols content but increased fibre content in OC. Dry matter effective degradability (DMED) decreased linearly (p < 0.001) by 35.9 and 45.5% as storage time augmented from 1 to 6 months for crude and exhausted OC, respectively. Crude OC had lower DMED values than exhausted OC (averaged values 0.255 and 0.294 g/g, respectively). Both potential production and rate of gas production were lower (p ≤ 0.018) in crude compared with exhausted OC, which was attributed to the high fat content of crude OC (≥86 g/kg dry matter). For samples stored longer than 6 months, cyclone had greater (p < 0.05) DMED than crude and exhausted OC (averaged values 0.207, 0.164 and 0.164 g/g, respectively). The results indicate that ruminal degradability of OC is reduced with advancing storage time, but only subtle changes were observed during the first two months. Cyclone showed greater degradability than crude and exhausted OC, but differences between crude and exhausted OC became negligible after five storage months.     

牛烂蹄坏尾病致病弯角镰刀菌代谢产物分离鉴定

取金寨县耕牛烂蹄坏尾病致病弯角镰刀菌的玉米培养物，用丙酮提取，硅胶净化，制备型硅胶大板分离，得到无色针状结晶体，经质谱和红外光谱分析，并经相关谱图数据库联机检索、甄别，按其分子量、化学式及结构式确定为麦角甾醇，从而证实了致牛烂蹄坏尾病的弯角镰刀菌可产生麦角甾醇。     

Growth of Preimplatation Bovine Embryos

Development of mammalian embryos in vitro is functionally and temporally inferior to embryo development as it occurs inside the female reproductive tract. The deficiencies of cultured embryos range from slow cleavage rates to complete developmental arrests or blocks, occurring at particular stages in many species. A variety of approaches have been used to overcome the blocks, including most extensively the coculture of preimplantation embryos with various somatic cells. However, even with coculture, development of embryos in vitro is still not equivalent to that in vivo. In most laboratories, only 25–40% of inseminated oocytes develop into morulae and blastocysts in spite of numerous variations on the basic technique. A better understanding of the factors governing embryonic growth is required before we can hope to achieve results comparable with those occurring in vivo.     

Protective effect of vitamin C and lycopene on the in vitro fertilization capacity of sex-sorted bull sperm by inhibiting the oxidative stress

The fertilization capacity of sex-sorted sperms is seriously decreased, which inhibits its wide application. However, little information is still available about the effect of vitamin C (VC) and lycopene (Lyc) on the fertilization capacity of sex-sorted bull sperm. In this study, the washing medium and fertilization medium of sex-sorted sperm from three bull individuals were supplemented with different concentrations of VC (0, 1 × 10^–3, 1 × 10^–4, 1 × 10^–5, 1 × 10^–6 M) or Lyc (0, 1 × 10^–4, 1 × 10^–5, 1 × 10^–6, 1 × 10^–7). After washing twice and incubation for 1.5 hr, the malondialdehyde (MDA) level, phosphatidylserine (PS) translocation, membrane potential (Δψm) and IVF (in vitro fertilization) ability of sex-sorted sperm were investigated. For the sex-sorted sperm of bulls A, B and C, 1 × 10^–3 M VC or 1 × 10^–4 M Lyc treatment significantly decreased their MDA levels and PS translocation and increased their Δψm levels and cleavage rates after IVF. When blastocysts were concerned, 1 × 10^–4 M Lyc significantly improved the blastocyst rates and their IFN-tau expression of bulls A and C. In conclusion, supplementation of 1 × 10^–3 M VC or 1 × 10^–4 M Lyc in washing and fertilization medium contributed greatly to improving the fertilization capacity of sex-sorted bull sperm during IVF procedure.