1,720,966 research outputs found
Influence of watering frequency on nutritional characteristics of cattle in Southeastern Kenya.
No full textThe effect of watering frequency on forage consumption, water intake and performance of Zebu-type steers was investigated under three treatments of daily watering (1/1) and two intermittent waterings __ once in two days (1/2) and once in three days (1/3). The study was carried out at a southeastern Kenyan rangeland dominated by Commiphora and allied shrubby genera, and perennial grasses such as Sporobolus pelucidus, Digitaria macroblephara and annual grasses, such as Eragrostis spp. Botanical and chemical composition of the diet selected by steers was determined from esophageal masticate samples. Forage consumption was estimated from total fecal collection and diet indigestibility. In addition, Ytterbium (Yb), a particulate phase marker dosed daily, was also used to estimate fecal output and intake for comparison with the total fecal collection. Steers were watered once in the evenings in metered 210 liter barrels. All steers were weighed approximately every two weeks. The study covered 159 days, which included four phenological stages of forage development: late maturity (March), growing stage (April), early maturity (June) and early dormancy (July). Total herbage production showed that there was sufficient forage for the steers throughout the study. Digestible organic matter (DOM) , crude protein (CP) amd digestible energy (DE) intake were highest (P<O.Ol) in April when forage was growing and decreased as forage advanced in maturity. Compared to daily watering, intermittent watering reduced (P<O.Ol) dry matter, DOM, NDF, CP and DE intake of steers drinking both (1/2) and (1/3). In March and April, intermittent watering reduced (P<O.Ol) free water consumption by 47-49% for steers watering (1/2) and 57-61% for steers watering (1/3) relative to the daily watering group. Steer performance was not influenced by watering frequency. Steers showed a faster growth rate (P<O.Ol) when forage was growing in April than the rest of the sampling periods. Fecal output and forage consumption estimated by total collection method and Yb excretion procedure showed that the Yb excretion procedure overestimated forage intake. Composition of the diet selected by steers was determined from esophageal masticate samples. Forage consumption was estimated from total fecal collection and diet indigestibility. In addition, Ytterbium (Yb), a particulate phase marker dosed daily, was also used to estimate fecal output and intake for comparison with the total fecal collection. Steers were watered once in the evenings in metered 210 liter barrels. All steers were weighed approximately every two weeks. The study covered 159 days, which included four phenological stages of forage development: late maturity (March), growing stage (April), early maturity (June) and early dormancy (July). Total herbage production showed that there was sufficient forage for the steers throughout the study. Digestible organic matter (DOM) , crude protein (CP) amd digestible energy (DE) intake were highest (P<O.Ol) in April when forage was growing and decreased as forage advanced in maturity. Compared to daily watering, intermittent watering reduced (P<O.Ol) dry matter, DOM, NDF, CP and DE intake of steers drinking both (1/2) and (1/3). In March and April, intermittent watering reduced (P<O.Ol) free water consumption by 47-49% for steers watering (1/2) and 57-61% for steers watering (1/3) relative to the daily watering group. Steer performance was not influenced by watering frequency. Steers showed a faster growth rate (P<O.Ol) when forage was growing in April than the rest of the sampling periods. Fecal output and forage consumption estimated by total collection method and Yb excretion procedure showed that the Yb excretion procedure overestimated forage intake
Hydrologic properties of grazed perennial swards in semiarid southeastern Kenya
Get PDFIdentification of plant resources that persist under grazing pressure, support desirable levels of production and at the same time protect the grazing environment is central to sustainable livestock production. This study assessed the infiltration capacity and soil loss associated with perennial swards subjected to different levels of utilization using simulated rainfall. The hypothesis was tested that grazed perennial swards have similar hydrologic properties and threshold removal levels below which runoff increases markedly. Infiltration capacity for the perennial swards increased with increasing stubble height before leveling off towards the highest stubble height. A 50% removal of current growth was the upper limit above which runoffs from the swards increased rapidly. Aggregate stability, organic carbon and percent ground plant cover were the most significant attributes that influenced infiltration capacity. Panicum maximum and Enteropogon macrostachyus were the most suitable perennial swards with favourable soil physical properties and infiltration capacities in the study area. The results support the existence of a threshold level of sward stubble height for minimizing runoff.Key words: Perennial swards, water infiltration capacity, runoff thresholds
Range use and dynamics in the agropastoral system of southeastern Kenya
Get PDFOccurrence of equilibrium and non equilibrium system dynamics in semiarid environments present serious management challenges. In these areas, resource management strategies are increasingly based on equilibrium rather than non equilibrium dynamics that assume simple system dynamics and strong coupling of animal-plant responses. This management approach underlies increasing trends of range degradation and low livestock productivity in these environments. To reverse these trends dictates greater understanding and alignment of grazing resource extraction strategies in space and time to prevailing system dynamics behaviour. In this study, range use patterns by free ranging herds under agropastoral herding were studied in two cycles of four consecutive grazing periods, in semiarid southeastern Kenya. The bites count and herd locations per area methods were used. While grazing thresholds in the system were derived from biweekly sward biomass measured by the quadrant technique in the growing period and stocking rates applied to a growth-consumption rate model. The analysis tested the responsiveness of the agropastoral herding strategies to the predominant system dynamics in the area. In this environment, high rainfall variability ranging from 71 to 98% is experienced across years and seasons, pointing to non-equilibrium dynamics in the system. The agropastoralists practiced seasonal range use and tracking strategies. During the dry season, areas of concentrated drainage; river valleys, bottomlands and ephemeral drainage ways absorbed a greater grazing load, taking 57.1 to 60% of the grazing time by the animals. In contrast, areas of limited moisture concentration, the open sandy/clay plains, were mainly exploited in the wet season and accounted for 52.6 to 55.6% of the grazing time. The agropastoralists tracked forage availability through use of multispecies livestock (cattle, goats and sheep) that exploited different grazing resources in space and time. These range use patterns and strategies tend to stabilize nutrient and energy flow to livestock and thus productivity throughout the seasons. Based on the growth-consumption rate model, grazing thresholds in the system are achieved at 13800, 13000, 4000 and 12300, 4600 and 12000, and 5600 and 11000 kgha-1 of grass biomass at, 2.5, 5, 7, 8 and 10 TLUha-1, respectively. 7 TLUha-1 represent the upper stocking rate limit in the system during the growing period. In this system, resource use strategies are in line with the predominantly non-equilibrium system behaviour. However, sedentary land use interventions and limiting farm sizes that restrict livestock mobility and negatively affect grazing resource diversity will undermine system stability and sustainable livestock production in the area.Key words: Agropastoralists, range use, system dynamics
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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