Factors Affecting Feeding Habits of Sheep Grazing Foothill Ranges of Northern Utah

An experiment was designed to study the effects of forage availability, season and intensity of grazing, and distribution and behavior of sheep on their forage preferences. Three grazing periods of 15 days each were used to study the effect of season. Each grazing period included a heavy and a moderate stocking intensity. Pastures were divided by a grid into 30.48 m x 30.48 m compartments. Each compartment was sampled for botanical composition of available herbage prior to and after grazing. Esophageally fistulated sheep were allowed to graze freely and positions of individual sheep with respect t o compartments were recorded at 5-minute intervals during the daily forage sample collection period. Immediately following collection of fistula samples, daily measurements were taken on leaf area index and height for all plant species. Estimates of aerbage yield and forage utilization were derived from heightleaf area measurements by regressions. Botanical composition of the diet was determined through microscopic analysis of plant cuticle fragments on dried, ground esophageal samples. Analysis of the dietary data indicated that season had no effect on the botanical composition of diets of sheep. However, grazing intensity significantly (P \u3c 0. 20) affected diets of sheep. Significant differences (P \u3c 0 . 01) were also found in proportion of plant species that comprised the diet at any particular time. Individual sheep were significantly (P \u3c 0.01) different in their forage preferences . There were no significant changes in botanical composition of the compartments due to grazing. However. bare ground increased significantly (P \u3c 0.10) more under heavy stocking than under moderate stocking. Herbage yield was found to be highly correlated with leaf area index and height (r2 = 0.85) in the ungrazed control pasture. Forage yield in the grazed pastures was a l so correl ated with leaf area index and height (r2= 0.79) . Utilization was estimated as the difference between the two parameters . Sheep were observed to graze more heavily around the periphery of shrubs than in the interspaces. The heavily grazed areas around shrubs were found to be significantly larger in heavily stocked pastures (P \u3c 0.10) . Observations of grazing behavior showed that sheep tended to orient themselves toward conspicuous objects . In so doing, they grazed a strip leading from one conspicuous object to another (ex. shrubs) . In an experiment designed to determine the role of such conspicuous objects in animal distribution and feeding behavior, sheep distribution, in relation to randomly-placed cardboard boxes. was found to be non-random and significantly (P \u3c 0.05) related to the position of the boxes. It was also found that sheep grazed the herbaceous species to a certain height below which the plants became inaccessible to grazing. Micro-associations of plant species greatly influenced preferences. Sagebrush (Artemisia tridentata) plants exerted a negative effect on use of adjacent bitterbrush (Purshia tridentata) plants. This negative effect was determined by the distance between the two shrubs. This critical distance was found to be 56.1 ± 23.7 cm and was not affected either by season or stocking intensity . An equation was developed by multiple regression to predict diets of grazing sheep. This equation explained 52% of the variation in botanical composition of the diet. Visual orientation of individual sheep, while grazing, modified to a large extent their forage preferences

Range Improvement by Waterspreading in the Gash Delta, Kassala Province: Democratic Republic of the Sudan

The area north of latitude 14° north in the Sudan is characterized by unreliable precipitation patterns and a high incidence of a drouth period following the first rain of the rainy season. In this region it is not uncommon to have a completely dry year without a single rain shower. The damage occurring to the plant cover when a drouth period follows the first rain is great. This is especially the case for the annual plant species in that such precipitation distribution patterns tend to exhaust the seed supply in the soil and do not supply adequate moisture for seed germination. This factor has largely been responsible for development of sparse vegetal cover consisting mainly of shrubs with an occasional understory of early maturing annuals that are evident in years with a good rainy season

An Approach to Range Inventory for the Annual Range Type of the Arid and Semi-Arid Regions of the Sudan

Range inventory, by definition, is the evaluation of the range resources to determine a proper and safe level of stocking and to provide a record of vegetation and vegetation changes (Stoddart and Smith, 1955). Range survey is defined by the Range Conservation Glossary, Soil Conservation Service (1944) as a systematic and comprehensive inventory and analysis of the range resources and related management problems of a range area for the purpose of developing plans of management therefrom. Accordingly, range inventory is the quest for basic information about rangelands and the development of guides and procedures for their management, improvement and efficient use

Assessing and compensating for the confounding factors in Scheimpflug-based corneal densitometry

Scheimpflug-based corneal densitometry is a clinically verified method for assessing corneal transparency. Nevertheless, the estimates of corneal densitometry appear to be correlated with age and eye biometry parameters, such as the anterior chamber depth or the pupil size, and that ensues a convoluted conditional estimation problem, where it is difficult to interpret the results. This study aims at devising a methodology for compensating for such confounding factors by using, as a research platform, a commercially available Scheimpflug camera that allows exporting images in a dynamic fashion, allowing averaging the results from multiple acquisitions. Two approaches are considered, one based on appropriately normalizing the line densitometry signal and one based on image histogram equalization. Then, three parameters for describing corneal densitometry are derived including the mean value of backscatter and the scale and shape parameters of the Weibull distribution estimated in regions of interest encompassing parts of corneal stroma. The results show that, unlike the non-normalized measures, the proposed approaches lead to parameters that are not correlated with age nor the eye biometry

OCT based corneal densitometry: the confounding effect of epithelial speckle

Corneal densitometry is a clinically validated method for objectively assessing the transparency of stroma. The technique is currently dominated by Scheimpflug technology. Still, optical coherence tomography (OCT), in which examination of the statistical properties of corneal speckle is undertaken, has also been considered to assess corneal densitometry. In-vivo, the stroma is observed via the epithelium. However, the effect of this external layer on stromal densitometry has not been considered as yet. This study aims to quantify the influence of epithelium integrity on corneal OCT densitometry. OCT images from eleven freshly enucleated porcine eyes before and after epithelial debridement were used. OCT densitometry was investigated at different stromal depths using four metrics of speckle statistics. Results indicate that there exist statistically significant differences in speckle statistics for a given stromal depth depending on the presence or absence of the epithelium. The estimation error in speckle statistics can reach over 20% depending on the stromal depth. The anterior stroma densitometry values are the ones most affected by epithelial integrity. In conclusion, if OCT densitometry stromal parameters are to be considered in absolute terms, it is essential to consider the confounding effect of the epithelial layer in the analysis

Taking rumours seriously: Why organ thieves matter to malaria control

This article documents what happened when a group of researchers tried to gain consent to carry out a survey for a malaria‐related research project in the Sabah region of Malaysia at the end of 2015. Within weeks, rumours had begun to spread on social media that the team were fake and using the guise of a research project to steal organs. The refusal to participate is often considered only relevant to researchers in so far as it has implications for the project itself. However, non‐participation in research is a valuable area of inquiry in its own right, precisely because of what it reveals about what lies beyond the research project. Rumours that contribute to non‐participation are indicative of the murky space of social relationships and connections that surround health. In fact, as is illustrated in this case study, rumours do not just reveal or represent this interconnected world, they also incite affect. It is within this space that bodies are put at risk of a number of health issues ranging from malaria to organ theft and it is thus here where researchers should focus more attention