1,542 research outputs found
Development of a Model of Growth of Grass/White Clover Swards for a Grassland Management Support System
Aging, Cognitive Abilities, and Word Frequency as Factors Affecting the Speed of Lexical Access
The present study evaluated the impact of age and several individual difference measures on lexical access. Additionally, eight different levels of frequency were evaluated for the stimulus words. These frequency levels were derived from the frequency of usage of these words in common reading materials. The response measured was latency of reading words out loud as they appeared on a screen. The results indicated no difference between older and younger adults on measures of anxiety, depression, or overall health. The older adults scored higher on a measure of vocabulary skills, while the younger adults scored higher on tasks involving abstract reasoning and perceptual motor problem solving.
The main finding was that younger adults were significantly faster in their latency of response to words at all levels of frequency. Both the younger and older adult groups demonstrated a pattern of quicker responding to high-frequency words and a gradual increase in response time as the level of frequency was lower. The age x frequency interaction was significant statistically but not meaningful to interpretation. The data suggest a similar response pattern for both age groups according to word frequency variable, although the younger subjects consistently responded with shorter response latencies. However, further analysis of the data suggests that a significant slowing with age or naming time independent of age slowing in peripheral responses. The present results would be consistent with a theory of overall slowing of cognitive operations in older adults
Temperate Forage Grass-Legume Mixtures: Advances And Perspectives
The paper summarises some of the advances which have been made a) in increasing understanding of the grass-legume association, especially grass-white clover, so that the association can be more predictably exploited and b) in overcoming limitations in the use of such mixtures. The contribution which forage legumes make to the N economy of mixtures is reviewed with estimates approaching 400 kg N ha-1 for some. Uptake by grass of legume- derived N (N transfer) reduces soil mineral N levels and increases the proportion of fixed N in the total legume N relative to legume monoculture. Although N transfer also causes inconsistent contribution of legume to mixed swards, models of the effect of legume derived N on the interaction between grass and legume are helping to predict likely grass-legume balance, even when grazed.
The higher nutritive value and intake of legumes relative to grass is due to a range of factors including faster rate of particle breakdown, faster digestion in the rumen, more non- ammonium N reaching the small intestine and higher efficiency of energy utilization although efficiency of N utilization is lower. Poor utilization is not an issue with birdsfoot trefoil and sainfoin due to their herbage having a high content of condensed tannins which protect protein from degradation in the rumen. Breeding programmes using conventional and biotechnological methods are aiming to improve nutritive value such as increasing protein quality and introducing condensed tannins into clovers and lucerne. Breeding of legumes to reduce antiquality factors, such as bloat, is underway. Breeding to reduce oestrogenic effects has been successful in red clover and subclover.
Advances are leading to improved legume consistency in mixture including improvement in tolerance to biotic and environmental stress by breeding and increased understanding of the role of companion grasses. Research which underpins management techniques to improve predictability of grass-legume balance is also discussed, including the positive and negative role of the grazing animal.
The potential and limitations of grass-legume swards to reduce N loss, including NO3 leaching, in whole farm systems is evaluated where grass/white clover can reduce leaching by 50% compared with a high fertilizer N system at only 20% reduction in output. Other factors which may result in increased reliance on forage legumes, in addition to the improvements in forage legumes resulting from research, include de-intensification policy decisions to reduce stocking rates, increased uptake of organic farming, increased cost of N fertilizer relative to commodity prices. Shared research effort between countries is advocated to supply adequate resources to solve some of the remaining problems in grass/legume associations and effective technology transfer should include development of decision support systems due to the complexity of the association
Grass Growth Modelling: to Increase Understanding and Aid Decision Making On-Farm
Key points
Crop and grass growth models have been developed over the last 50 years, or so, but general appreciation of their benefits and potential has been recognised only relatively recently. The most popular application of grass growth models has traditionally been for knowledge understanding.
There is growing awareness of the potential of models in decision support systems (DSS) applications to aid pasture management and grassland budgeting on dairy farms.
Although some models have been developed for DSS, their widespread uptake in industry has been slow; challenges still exist which need to be addressed in order to improve their precision and user-friendliness
GrassCheck: Monitoring and Predicting Grass Production in Northern Ireland
Grass budgeting is a key management practice on dairy farms to balance grass supply on paddocks with grass demand by the grazing herd. Grass budgets must be pre-emptive to be effective. The uncertainty of grass production and the difficulty in quantifying both current and forecasted rates of growth hamper effective budgeting and paddock management. Grass growth rates are highly variable both in time and space. Therefore, they vary greatly between locations at any given time and also across the season at any given location. Figure 1 shows the pattern of growth rates recorded at the Agricultural Research Institute of Northern Ireland (ARINI) in the two seasons before this project. The GrassCheck project was established in Northern Ireland to quantify current rates of grass growth and grass quality and to predict growth rates for up to 2 weeks in advance. The project will run from 2004 until 2006. This paper outlines the project and reports on its findings after one year
Erratum for “Effects of a Breast-Health Herbal Formula Supplement on Estrogen Metabolism in Pre- and Post-Menopausal Women not Taking Hormonal Contraceptives or Supplements: A Randomized Controlled Trial”
Full open access to this and thousands of other papers a
- …