合作市发展农业特色优势产业途径调查研究

本文对合作市高寒农业特色优势产业发展进行了多视角的实地调查研究,掌握合作市发展高寒农业特色优势产业发展的现状、存在问题的基础上,结合当地高寒地区实际情况,提供操作性强的意见、建议。     

Production and Environmental Implications of Equine Grazing

Horses' physical and digestive well-being is often enhanced when allowed to graze on pastures. Furthermore, a well-managed pasture can contribute to economic viability. Grazing can however have deleterious effects on the environment if not properly managed. Although equine grazing, defecating, and ground trampling behavior is unique from that of other livestock species, pasture management practices are often based on those derived from cattle grazing. This review summarizes the current knowledge of impacts of equine grazing on pasture quality and environment and identifies gaps where further information is needed to formulate and recommend sustainable grazing methods specific to equine.     

Tetracycline-resistance genes of Clostridium perfringens, Clostridium septicum and Clostridium sordellii isolated from cattle affected with malignant edema

The minimal inhibitory concentrations (MICs) of 10 antimicrobial agents against a total of 33 isolates of Clostridium perfringens, Clostridium septicum and Clostridium sordellii from cattle affected with malignant edema in Japan was determined. The low MIC activities of benzylpenicillin confirm the place of benzylpenicillin as the antibiotics of choice for treatment of malignant edema. Five (22%) of 23 C. septicum strains, five (71%) of seven C. perfringens strains and all strains of C. sordellii showed resistance to oxytetracycline. These oxytetracycline-resistant strains carried tetracycline-resistance genes [tetA(P), tetA408(P), tetB(P) and tetM]. The sequences of the tetracycline-resistance genes of some C. septicum strains were completely or nearly completely identical to those of strains belonging to other clostridiual species. This is the first report of resistance of C. septicum to tetracycline.     

Selection for breed-specific long-bodied phenotypes is associated with increased expression of canine hip dysplasia

Hip dysplasia (HD) is the most common skeletal disease in purebred dogs. Radiographic schemes developed to reduce prevalence through selective breeding have had limited success, but the role of selecting for morphological characteristics prized in the show-ring and dictated by breed standards has not been fully explored. This study correlated published scores of hip pathology with measurements of body length to height ratio from photographs of Best-of-Breed specimens from 30 breeds (n = 12/breed) to establish whether selection criteria could be compromising welfare by increasing susceptibility to HD.Relative body length correlated strongly with higher rates of HD by breed data from the Orthopedic Foundation for Animals (Spearman r = 0.727, P < 0.001), the British Veterinary Association (r = 0.701, P < 0.001), and the Australian Veterinary Association (r = 0.577, P < 0.01). By favouring body shapes that are longer than they are tall, judges may be inadvertently selecting for conformational attributes predisposing dogs to HD, suggesting that ambiguity in breed standards and extreme relative body length phenotypes can engender serious welfare consequences and need to be re-evaluated.     

水稻重要农艺性状的QTL分析和主效QTL近等基因系的构建

水稻许多重要农艺性状都是数量性状,水稻遗传改良的大部分工作就是改良这些数量性状。1980年以后,随着分子标记的出现,水稻高密度遗传连锁图谱的大量绘制,各种作图群体的迅猛构建,功能强大的各种统计学软件的快速开发,全基因组序列测序的完成,特别是多个QTL精细定位和先后克隆,使得我们对数量性状的认识得到了长足的进步,QTL的研究正在走进新时代。     

Field evaluation of insect-resistant transgenic Populus nigra trees

The performance of insect-resistant transgenic poplar trees (Populusnigra) expressing a Cry1Ac gene from Bacillus thuringiensis subsp. Kurstaki HD-1 against poplar defoliators was evaluated in the field at the Manas Forest Station in Xinjiang Uygur Autonomous Region during1994–1997. The results showed that the average percentage of highly damaged leaves on the transgenic trees was 10% while that on the control trees in nearby plantations reached 80–90%. The average number of pupae per m² of soil at 20cm depth in transgenic poplar plantation was 18 which was only 20% of that found in the non-transgenic control field. The number of pupae and the leaf-damage on transgenic trees described above are all far below the threshold set for chemical protection measures. The non-transformed poplar trees grown in the same plantation with the transgenic trees were also protected indicating that cross protection occurred between these two kinds of trees. Insect-resistant transgenic poplar trees have a potential application value in afforestation. This revised version was published online in August 2006 with corrections to the Cover Date.     

Effect of stachyose supplementation on growth performance, nutrient digestibility and caecal fermentation characteristics in broilers

1. The objective of this study was to evaluate whether the oligosaccharide stachyose enhances gastrointestinal tract health by fermentation and proliferation of desirable bacteria species and thus affects growth performance and nutrient digestibility in broilers. 2. A total of 432 1-d-old male Arbor Acres (AA) broilers were randomly allocated to one of 6 treatments, with 12 replicate pens per treatment and 6 birds per pen. Chicks were fed a maize-hamlet protein 300 (HP300) basal diet with 0, 4.0, 8.0, 12.0 or 16.0 g/kg stachyose. A sixth diet contained no HP300 but soybean meal (SBM) and provided 8.7 g/kg stachyose and 3.1 g/kg raffinose. The duration of the study was 42 d. 3. Stachyose contents above 12.0 g/kg depressed group body weights, average daily gain and feed/gain but not feed intake during the whole experimental period. Broiler growth decreased linearly and quadratically with increasing stachyose content. No differences were detected between diets supplemented with 12.0 g/kg stachyose and SBM. 4. Nutrient digestibility tended to decrease but not significantly with increasing stachyose. 5. Stachyose content had no significant positive effects on caecal pH, microflora population and the resulting short-chain fatty acid (SCFA) metabolites during the 42 d experiment, with only butyrate differing significantly in the initial period.