绵羊矿物质营养研究的最新进展及其对中国养羊生产可能产生的影响

对影响绵羊健康和生产性能的一些重要的矿物质营养方面进展和可能会对中国养羊生产产生的影响进行了介绍和讨论，其中着重讨论了以下几个方面的专题：硒和碘，蠕虫感染与矿物质营养，食土和铁的代谢，镉及其与硫和相互作。结果表明对放牧绵羊的矿物质营养进行优化决策，对于最大限度地提高草原养羊业的生产力是完全必要的。     

The response of two contrasting limestone grasslands to simulated climate change

Two different UK limestone grasslands were exposed to simulated climate change with the use of nonintrusive techniques to manipulate local climate over 5 years. Resistance to climate change, defined as the ability of a community to maintain its composition and biomass in response to environmental stress, could be explained by reference to the functional composition and successional status of the grasslands. The more fertile, early-successional grassland was much more responsive to climate change. Resistance could not be explained by the particular climates experienced by the two grasslands. Productive, disturbed landscapes created by modern human activity may prove more vulnerable to climate change than older, traditional landscapes.     

WHITE MUSCLE DISEASE OF SHEEP AND ASSOCIATED TISSUE SELENIUM LEVELS IN WESTERN AUSTRALIA

White Muscle Disease of sheep occurs in Western Australia as distinct syndromes in lambs and weaner sheep. Mean liver selenium concentrations of lambs and weaners with WMD and unaffected by WMD were 0.19 and 0.46 ppm, and 0.20 and 0.41 ppm (dry weight) respectively. There was considerable overlap between levels suggesting that selenium status was not the only factor involved in the development of WMD.     

Uterine malignant mixed Müllerian tumor (Metaplasic carcinoma) in the cat: clinicopathologic features and proliferation indices

A homologous malignant mixed Müllerian tumor of the uterus occurring in an 8-year-old Persian cat was described with regard to its clinical and pathologic features. A polypoid multinodular mass of the right uterine horn was shown by an ultrasound examination. Grossly, the right uterine horn was enlarged because of a vegetative and infiltrating tumor, grayish-white in color, that penetrated the uterine wall to the level of the perimetrium. Many metastatic nodules were found in abdominal and thoracic cavities. Histologically, the neoplasm had both carcinomatous and sarcomatous components and was diagnosed as an uterine malignant mixed Müllerian tumor. This is the fourth case reported in cats. The histologic features and proliferation rate of this tumor were similar to the corresponding human neoplasms, which occur mainly in postmenopausal women. The possible hormone dependence of the tumor is briefly discussed.     

Insect dispersal does not limit the biological recovery of streams from acidification

• 1. The ecological recovery of streams from large‐scale perturbations, such as acidification, requires aquatic insects to disperse between catchments. While adults can usually fly, dispersal is seldom observed directly. Catches of insects in transects of traps perpendicular from streams suggest that lateral adult dispersal is limited. This paper evaluates whether this could explain limited biological recovery in streams recovering chemically from acidification.
• 2. At the replicate Llyn Brianne experimental catchments (Wales), Malaise traps (2000) and benthic sampling (1985–2005) were used to appraise inter‐catchment dispersal in acid‐sensitive Ephemeroptera, Plecoptera and Trichoptera. The results provide direct evidence for inter‐catchment dispersal: eight species from three Orders were caught as adults alongside acid streams where larvae never occurred in 21 years' benthic sampling.
• 3. These data refute the hypothesis that limited dispersal per se explains delayed biological recovery from acidification in Welsh streams. Other factors affecting colonization (e.g. ‘propagule pressure’, mating or oviposition behaviour) and persistence (e.g. continued acid episodes) must be involved, with the first of these possibilities still poorly understood. These data add to a growing body of literature illustrating insect dispersal between catchments, and they have wider relevance to the recovery and restoration of river ecosystems following basin‐scale impacts.

Copyright © 2006 John Wiley & Sons, Ltd.     

月季新品种‘糖果雪山’

 ‘糖果雪山’是从现代切花月季品种‘雪山’栽培群体中选育出来的芽变新品种。花色为白 底深粉边,花径10 ~ 13 cm;温室栽培单枝切花生育期为38 ~ 42 d,切枝长度90 ~ 110 cm,年产量280 ~ 300 枝 · m^-2。