The new diketopiperazine dimer 1, as well as the known compounds TMC-256A1 (2), TMC-256C1 (3), and demethylkotanin (4), were isolated from a culture of Aspergillus niger. The gross structure of 1 was determined by 2D NMR studies and comparison with literature data, and the absolute stereochemistry was elucidated by chiral HPLC analysis of the hydrolysis products.
. 2000. Bloat in cattle grazing alfalfa cultivars selected for a low initial rate of digestion: A review. Can. J. Plant. Sci. 80: 493-502. The occurrence of frothy bloat limits the practice of alfalfa grazing in spite of the availability of strains bred specifically for pasture. Bloat is a chronic condition, endemic to cattle. Prophylactics and management techniques are available to reduce its incidence but they are expensive, difficult to administer, conflict with traditional grazing management regimens and do not eliminate bloat in all circumstances. A program to breed and evaluate a bloat-reduced strain of alfalfa was initiated in 1980 to overcome some of these limitations. A review of the results of grazing and feeding trials using alfalfas with low initial rates of digestion (LIRD) shows that this new strain reduces the incidence and severity of frothy bloat on pasture. Their effectiveness in controlling bloat was related to feeding or grazing management practices, the maturity of the plants and the season of use. Graziers may reduce the risk of occasional livestock losses from bloat by using LIRD cultivars, like AC Grazeland, or managing species/cultivar mixtures in ways that reduce the initial rate of digestion. Other bloat preventive strategies, including coseeding with bloat-free legumes and using bloat-controlling prophylactics in combination with a LIRD alfalfa, are being investigated. Le problème du météorisme spumeux restreint le pâturage de la luzerne malgré la disponibilité de souches sélectionnées spécifiquement pour cette utilisation. Le météorisme est une affection chronique, endémique chez les bovins. Il existe des techniques préventives et des méthodes de conduite qui réduisent sa fréquence, mais en plus du fait qu'elles n'éliminent pas toujours le trouble, elles coûtent cher, leur application difficile et elles ne s'insèrent pas facilement dans les régimes classiques de gestion du pâturage. Pour surmonter certaines de ces contraintes, un programme de sélection et d'évaluation d'une souche de luzerne à effet météorisant moins prononcé était mise en place en 1980. La lecture des résultats publiés des essais de pâture et de distribution en vert conduits sur des lignées de luzerne à faible taux initial de digestion (FTID) révèle que ces nouvelles lignées réduisent la fréquence d'apparition et la gravité des cas de météorisme spumeux au pâturage. Leur efficacité à cet égard dépendait des pratiques de distribution en vert ou de pâturage employées ainsi que du stade de croissance des plantes et de la saison d'utilisation. Les exploitants de pâturage peuvent diminuer les risques de pertes occasionnelles de bestiaux pour cause de météorisme en utilisant des cultivars FTID, comme AC Grazeland ou en conduisant le pâturage d'associations spécifiques ou variétales de manière à réduire le taux initial de digestion. On envisage actuellement d'autres protocoles de prévention du météorisme, notamment l'inclusion de légumineuses non météorisantes dans les mélanges à pâturage et l'emploi de substances antimété...
. 1994. Effect of level of dietary potassium on the absorption and excretion of calcium and magnesium by lactating cows. Can. J. Anim. . This study was undertaken lith the objective of providing more-basic information on ihe absorption and excretion of calcium (Ca) and magnesium (]\!e) bV lactating co*, *h.n high levels 5f potassium (K) are fed. Employingpotassium carbonate as the source of supplemental K total mixed rations were f6rmulated to contain i.O [ow), 3.t lm6dirim;1ia q.en ftigh) K. The three rations were fed to 15 For personal use only.
During the screening of fungi for inhibitors of squalene synthase, Phomasp. C2932 was found to produce three structurally related novel inhibitors. These compounds,designated the squalestatins, exhibited potent activity against both mammalian (rat liver) and fungal {Candida albicans) squalene synthase. Furthermore, they also had broad spectrum in vitro antifungal activity.
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