多年生暖季型草地补播多花黑麦草生产系统研究

于2009年5月在亚热带中山地区引入宽叶雀稗(Paspalum wettsteinii)、威提特东非狼尾草(Pennisetum clandestinum cv.Whittet)、纳罗克非洲狗尾草(Setaria sphacelata cv.Narok)和贝斯莉斯克伏生臂形草(Bra-chiaria decumbens cv.Basilisk)4种多年生暖季型牧草,并于当年10月在4种暖季型禾草草地上分别补播多花黑麦草(Lolium multifolorum),组成不同的互补饲草生产系统(Complementary forage system);通过对各补播系统牧草全年产量、生长速率和密度变化的研究分析,以期建立全季型优质高产的互补饲草组合模式,为解决该地区饲草供应季节不平衡提供可行方案。结果表明:补播能显著增加产草量(P<0.05),干草产量最高的系统是臂形草+多花黑麦草(26337.1 kg·hm^-2);粗蛋白年产量最高的为东非狼尾草+多花黑麦草系统(2903.6 kg·hm^-2);各系统可形成良好的饲草季节配置,多花黑麦草在冬春季节成为优势种,产量占全年饲草总产量的40%。     

羊驼视网膜组织学结构

用光镜观察了羊驼视网膜的组织学结构,以及3级神经元的细胞胞核层数及胞核特点。结果表明:羊驼视网膜结构与昼行性的哺乳动物的视网膜结构相似,但米勒细胞较明显、水平细胞为一层、内网层细胞很厚等形成了羊驼视网膜结构的特性,显示了羊驼视网膜结构和机能与其行为学特性的一致性。     

Lens formation in the absence of optic cup in rat embryos irradiated with soft X-ray

In order to investigate the effect of soft X-ray irradiation on ocular development, pregnant rats were exposed to a single 12.5 Gy irradiation on embryonic day 9 (ED 9). The embryos obtained by laparotomy on ED 12 and 21 were examined for ocular abnormalities under a binocular stereo-microscope and a light microscope. The ED 12 embryos were stained with osmium tetroxide to facilitate the observation. The stereo-microscopic examination on ED 12 and 21 revealed various types of ocular abnormalities characterized primarily by aplasia or hypoplasia of the optic cup and invaginated lens placode. The light microscopic examination further confirmed these findings histomorphologically, and the hypoplastic abnormalities were classified into three types: (1) hypoplasia of the optic cup and invaginated lens placode, (2) complete malformation of the optic cup and hypoplasia of the invaginated lens placode, and (3) complete malformation of the optic cup and invaginated lens placode. Because the lens was formed in the complete absence of the retina, the development and differentiation of the retina and lens do not seem to be tightly synchronized. Thus, this sequential analysis on ocular abnormalities during the early stage of development supports the notion that the presence of the retina is not always necessary for the development of the lens.     

肉羊信息管理与育种分析系统的研究

采用面向对象编程技术和可视化的界面设计方法,运用SQL Server 2005为后台数据库并结合Visual Studio 2005,采用C#为程序设计语言,研发了肉羊信息管理与育种分析系统。根据肉羊育种实际需求,设计了用户管理、数据管理、育种分析和系统帮助四大模块,以实现肉羊育种资料的科学化管理,提高肉羊选种选配的准确度和工作效率。     

ORIGINAL ARTICLE: The approach to the mechanism of calcitonin gene‐related peptide‐inducing inhibition of food intake

The aim of this study was to investigate the anorectic mechanism of calcitonin gene‐related peptide (CGRP) in rats. Intraperitoneal injection of CGRP (50 μg/kg) resulted in decline (p < 0.05) in the food intake of rats at 0.5, 1, 2 and 4 h in comparison with saline control. Compared with saline‐treated group, the levels of hypothalamic 3′,5′‐cyclic adenosine monophosphate (cAMP) and plasma glucagon were increased (p < 0.05) in CGRP‐treated group, but insulin level was decreased (p < 0.05). No significant changes (p > 0.05) in the plasma leptin were observed between two treatment groups. Calcitonin gene‐related peptide injection down regulated (p < 0.05) both neuropeptide Y (NPY) and melanin‐concentrating hormone (MCH) genes at mRNA levels, but up regulated (p < 0.05) the expression of cholecystokinin (CCK) gene. The correlations analysis showed that food intake was negatively correlated (p < 0.05) with CCK mRNA, cAMP and glucagon levels. Moreover, there existed negative correlations (p < 0.05) between MCH mRNA and glucagon levels, and positive correlations (p < 0.05) between insulin and leptin levels. The results showed that cAMP acting as the second messenger may play a vital role in the anorectic effects of CGRP. Calcitonin gene‐related peptide could stimulate anorexigenic neuropeptides (i.e. CCK) and/or inhibit orexigenic neuropeptides (i.e. NPY and MCH) expression, and ultimately suppressed food intake that was functionally coupled to cAMP/PKA pathway activation.     

应用杆状病毒系统高效表达猪繁殖与呼吸综合征病毒GP5基因

将猪繁殖与呼吸综合征病毒CH_la株囊膜糖蛋白 (GP5 )基因定向亚克隆到杆状病毒转移载体pBlueBacHisB中 ,与杆状病毒线性DNA(Bac_N_BlueTMDNA)共转染昆虫细胞sf9,经过三轮蚀斑纯化后 ,获得重组杆状病毒rBac_GP5。用该重组病毒感染sf9细胞后 ,应用间接免疫荧光试验、SDS_PAGE和Westernblot检测表明 ,GP5基因在杆状病毒系统中获得了高效表达 ,表达产物因糖基化程度差异 ,表观分子量有 2 2、2 5和 30kDa三种总计约占细胞蛋白总量的 2 6 .4%。     

Studies on Bovine Leukosis

Summary

An enzyme linked immunosorbent assay (ELISA) and the agar gel immunodiffusion test with bovine leukosis virus glycoprotein as antigen (AGIDT‐BLV gp) were further used to test 633 bovine sera for antibodies to BL V. Both tests detected the same number of sera positive (149) or negative (464) for antibodies. Nine sera were negative in the ELISA but found to be weakly positive (2 sera) or bending the control line (7) in the AGIDT‐BLV gp. On the other hand 11 sera were scored negative in the AGIDT‐BLV gp but were weakly positive (9 sera), positive (1), and strongly positive (I) in the ELISA. Both tests are used routinely in this Institute as they complement each other, specially if sera with low antibody titers are under investigation. It is concluded that ELISA can fully replace radioimmunoassays in the serodiagnosis of enzootic bovine leukosis.     

The Potch System: An approach to the management of semi‐arid grasslands in southern Africa

A host of grassland management systems have been published and recommended. Whereas earlier approaches to grassland management emphasized the systematic resting aspect, the systems published since 1966 have tended to stress the degree of utilization of the grassland sward. In an attempt to accommodate the periodic dry periods that are so typical of the semi‐arid grasslands of western Transvaal, the Potch system of management was evolved. It aims at the development of a fodder reserve, firstly by delaying the commencement of summer grazing, and secondly, by allowing prolonged periods of absence in the grazing rotation. High utilization grazing within the concept of controlled selective grazing is prescribed. This approach was tested and demonstrated over a period of five years in an experiment comprising 240 beef breeding cows. It appeared that generally, summer grazing only commenced after the third week of November, and that the mean period of occupation amounted to 20 days, with a period of absence of 87 days. A conception rate of 85% of all the cows and heifers mated, was achieved. A stocking rate of 0.53 LSU ha^?1 could be maintained in an area where the general grazing capacity is 0.33 LSU ha^?1.     

Measurement of enteric methane from ruminants using a hand-held laser methane detector

Abstract

This study investigated the effectiveness of the proprietary laser methane detector (LMD) in enteric methane monitoring from individual dairy cows and sheep. Three experiments were carried out. First, the relationship between LMD and indirect open-circuit respiration calorimetric chamber measurements was tested. Sensitivity and specificity for cows were 95.4% and 96.5%. For sheep, sensitivity was 93.8% and specificity was 78.7%. Second, the effect of cow's activity on enteric methane emissions was investigated. During drinking and feeding, cows produced significantly more (p<0.001) methane emissions than when idle. Third, effect of different micrometeorological factors on LMD measurements under outdoor grazing conditions was investigated. Wind speed, relative humidity, pressure and wind direction relative to methane point-source had significant effect on methane measurements (p<0.001) under outdoor conditions. With further validation, the LMD has potential to provide reliable estimates from ruminants and hence provide a useful technique for on-farm monitoring and decision support for greenhouse gas mitigation strategies.     

Evaluation of a new strategy to modulate skeletal development in Thoroughbred performance horses by imposing track-based exercise during growth

REASON FOR PERFORMING STUDY: No data exist on the intensity of exercise required or on possible harmful effects of increasing exercise in foals over the natural level when free at pasture. OBJECTIVES: To investigate whether an increase in workload over free pasture exercise in the period from directly after birth to the start of training is tolerated by Thoroughbred (TB) foals without increasing injury rate or producing other undesired side effects. METHODS: Thirty-three TB foals were allocated to one of 2 exercise groups directly after birth. One group (PASTEX) was raised on pasture and the other (CONDEX) kept under identical circumstances, but was additionally subjected to an exercise protocol of gradually increasing intensity. Foals were monitored periodically and scored for the presence of clinical signs related to the musculoskeletal system (joint effusion, pain at flexion, occurrence of physeal swelling), and radiographs taken at the end of the conditioning phase. Also, behavioural studies were performed to detect any changes in behaviour related to the exercise programme. Cortisol levels were measured in both groups, to assess the level of stress. RESULTS: Workload in the CONDEX group was significantly higher than in the PASTEX group (approximately 30%). Conditioning increased the likelihood for joint effusion in the antebrachiocarpal joint, but reduced tarsocrural effusion and physeal swelling at the lateral distal radius, the third metacarpal bone (medial aspect) and lateral and medial aspects of the third metatarsal bone. CONCLUSIONS: The 30% increase in workload did not affect the animals' welfare, effects of conditioning exercise on clinical musculoskeletal health were few and there were no adverse effects. POTENTIAL RELEVANCE: This study supports the feasibility of imposing early conditioning exercise in horses and is a benchmark for its effects on the development of equine musculoskeletal tissues.