Effect van bijproducten op de slacht- en vleeskwaliteit van vleesvarkens = Effect of food waste products on slaughter and meat quality of growing finishing pigs

Uit literatuuronderzoek en uit deze praktijkmonitoring blijkt dat het verstrekken van gangbare bijproducten de slacht-, vlees- en vetkwaliteit niet negatief beïnvloeden. De vleeskwaliteit van de varkens die brijvoer kregen is in veel opzichten juist beter dan die van de varkens die droogvoer kregen. Zeer opvallend is het lager dripverlies (1,1 %) en een tendens tot een lager kookverlies (0,6%) bij de brijvoergroep, mogelijk als gevolg van de hogere zoutgehalten in het brijvoe

Predicting evolution and visualizing high-dimensional fitness landscapes

The tempo and mode of an adaptive process is strongly determined by the structure of the fitness landscape that underlies it. In order to be able to predict evolutionary outcomes (even on the short term), we must know more about the nature of realistic fitness landscapes than we do today. For example, in order to know whether evolution is predominantly taking paths that move upwards in fitness and along neutral ridges, or else entails a significant number of valley crossings, we need to be able to visualize these landscapes: we must determine whether there are peaks in the landscape, where these peaks are located with respect to one another, and whether evolutionary paths can connect them. This is a difficult task because genetic fitness landscapes (as opposed to those based on traits) are high-dimensional, and tools for visualizing such landscapes are lacking. In this contribution, we focus on the predictability of evolution on rugged genetic fitness landscapes, and determine that peaks in such landscapes are highly clustered: high peaks are predominantly close to other high peaks. As a consequence, the valleys separating such peaks are shallow and narrow, such that evolutionary trajectories towards the highest peak in the landscape can be achieved via a series of valley crossingsComment: 12 pages, 7 figures. To appear in "Recent Advances in the Theory and Application of Fitness Landscapes" (A. Engelbrecht and H. Richter, eds.). Springer Series in Emergence, Complexity, and Computation, 201

Fitness effects of fixed beneficial mutations in microbial populations

Beneficial mutations are intuitively relevant to understanding adaptation [1-3], yet not all beneficial mutations are of consequence to the long-term evolutionary outcome of adaptation. Many beneficial mutations - mostly those of small effect - are lost due either to (1) genetic drift [4, 5] or to (2) competition among clones carrying different beneficial mutations, a phenomenon called the "Hill-Robertson effect" for sexual populations [6] and "clonal interference" for asexual populations [7]. Competition among clones becomes more prevalent with increasing genetic linkage and increasing population size, and it is thus generally characteristic of microbial populations [8, 9]. Together, these two phenomena suggest that only those beneficial mutations of large fitness effect should achieve fixation, despite the fact that most beneficial mutations produced are predicted to have very small fitness effects [10,11]. Here, we confirm this prediction - both empirically and theoretically - by showing that fitness effects of fixed beneficial mutations follow a distribution whose mode is positiv

Effect van bijproducten op de slacht- en vleeskwaliteit van vleesvarkens = Effect of food waste products on slaughter and meat quality of growing finishing pigs

Uit literatuuronderzoek en uit deze praktijkmonitoring blijkt dat het verstrekken van gangbare bijproducten de slacht-, vlees- en vetkwaliteit niet negatief beïnvloeden. De vleeskwaliteit van de varkens die brijvoer kregen is in veel opzichten juist beter dan die van de varkens die droogvoer kregen. Zeer opvallend is het lager dripverlies (1,1 %) en een tendens tot een lager kookverlies (0,6%) bij de brijvoergroep, mogelijk als gevolg van de hogere zoutgehalten in het brijvoe