Electronic Theses and Dissertations
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About: Electronic theses and dissertations (ETDs) are the graduate research outputs of Texas Tech University. They represent years of work from our Master's and Doctoral graduates. If you find the ThinkTech digital repository useful, please tell us! Share how open access to scholarship benefits you. Your story matters to us.
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Browsing Electronic Theses and Dissertations by Department "Agricultural Science"
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Item A method of controlling the yearly acquisition and development budgets of a proposed Texas state parks system(Texas Tech University, 1963-08) Schlimper, Paul EugeneNot availableItem A method of estimating future acreage needed for state recreation parks(Texas Tech University, 1963-08) Manis, Claude GradyNot availableItem A preliminary plan for redevelopment and future expansion of Huntsville State Park(Texas Tech University, 1963-06) Eatherly, Charles RayNot availableItem A study of mineral transformations and weathering processes occurring during the genesis of two soils developed from granite in Llano County, Texas(Texas Tech University, 1964-08) Goss, Don WoodsonNot availableItem A study of the accuracy and repeatability of visual evaluation of beef cattle(Texas Tech University, 1961-08) Burnett, Silver DaleNot availableItem A study of the production of certified combine grain sorghum seed in West Texas(Texas Tech University, 1948-08) Chapman, Oscar ClarkNot availableItem A study of the relationship of rate of milk-out to total yield and stage of lactation of dairy cattle(Texas Tech University, 1958-08) Mullins, Alvie MauriceNot availableItem A suggested course of study in third year vocational agriculture for Aspermont High School(Texas Tech University, 1950-08) McDonald, William ANot availableItem A survey, analytical and historical, of irrigation in Hale County, Texas(Texas Tech University, 1938-08) Ratliff, Ernest CharlesNot availableItem Adsorption, desorption and mobility of fluridone and norflurazon in Texas High Plains soils(Texas Tech University, 1981-12) Baumann, Paul A.Not availableItem Allelopathy in an integrated rye-cotton-beef cattle system(2011-05) Li, Yue; Allen, Vivien G.; Chen, Junping; Hou, Fujiang; Hopper, Norman W.; Bednarz, Craig W.Small grain cover crops offer opportunities for grazing but effects of cover crops on the following row crop are not well understood. Beginning in 1998, rye (Secale cereale L.) planted alternately each September in a 2-paddock rotation, was grazed intermittently by steers from January until early April, was then chemically terminated, and cotton (Gossypium hirsutum L.) was no-till planted in May, in research conducted at New Deal, TX. Following cotton harvest, wheat (Triticum aestivum L.) was no-till planted, grazed out by Angus steers (Bos taurus) by June, and land was fallowed until rye was planted in September. By Feb 2006, wheat failed to establish and was omitted from the rotation. The experiment was a randomized complete block design with 3 replicates. Soil was primarily Pullman clay loam (fine, mixed, superactive, thermic Torrertic Paleustolls). Permanently located caged areas excluded grazing and were harvested as hay. In spring 2005, a second cage, adjacent to the original cage (2005) or randomly located in paddocks (2006 and 2007), investigated effects of 1) zero-grazed; 2) exclusion from grazing in 2005, 2007 or 2008 only; or 3) was always-grazed prior to cotton. In all 3 yrs, rye plant heights were taller (P < 0.01) in previously grazed than zero-grazed rye. Height of cotton plants in July were taller (P < 0.01) when planted into grazed than non-grazed rye in all years. Cotton lint yield in 2005 was greater (P < 0.01) when planted into grazed than ungrazed rye but differences were not significant in 2007 or 2008. Allelopathy was suspected. In a 3-yr small plot study, no-till planting cotton into rye or wheat cover crops reduced (P < 0.05) growth, lint and seed yield of cotton compared with no cover crop. Greenhouse trials verified cotton plant suppression by increasing rates of small grain residues and by direct application of 2-benzoxazolinone (BOA), a known allelopathic chemical. Allelopathic compounds, 2, 4-dihydroxy-7-methoxy-1, 4-benzoxazin-3-one (DIMBOA), 2-benzoxazolinone (BOA), 2, 4-dihydroxy-1,4-benxozaxin-3-one (DIBOA), from rye and wheat were detected in soil and plant material in greenhouse and field experiments. Grazing the cover crop by cattle may help alleviate these negative effects. Cover crops have environmental benefits but negative effects need further investigation.Item An experimental investigation of a graphical interactive problem structuring aid for decision support systems(Texas Tech University, 1982-08) Pracht, William EverettThe ecology of field-feeding dabbling ducks wintering on the Southern High Plains of Texas was studied on a 50 km2 study area in Castro County, from September-March 1979-82. Ducks relied primarily on waste corn that averaged 364 j^ 12 kg/ha/field. Fields harvested at 14-21^ moisture lost more than twice the corn as fields harvested at 22-36^ moisture. Therefore, moisture content of corn at harvest provided a useful measure to predict initial waste. Waste cornfields underwent a variety of agricultural treatments that affected the abundance and availability of waste corn to waterfowl. Burning stubble maximized abundance and availability, whereas deep plowing reduced abundance by 975o. Disking and grazing reduced abundance by 77^ and 84-%, respectively. However, landowners tended to graze cattle on fields where initial waste was high and thus substantial amounts of waste corn remained when grazing was terminated. Manual salvage by migrant workers removed 58% of initial corn waste. Field-feeding waterfowl conducted 2 flights daily to cornfields near playa lakes where the birds concentrated. The average morning flight was initiated 52 j^ 1.5 min before sunrise and terminated in 23 _+ 1 .4 min. The average evening flight began 25 j^ 2.0 min after sunset and terminated in 37 j^ 4.2 min with duration increasing as the season progressed. Dabbling ducks fed longer and participated more in evening as compared to concurrent daily morning flights. Minimum temperatures were correlated negatively with duration of evening flights, but not morning flights. There was no correlation between the amount of waste corn in, or the condition of, a field selected by feeding ducks with duration or initiation of feeding flights. However, the amount of corn present was correlated negatively with duration of the evening flight. Snowfall was positively correlated with duration of evening flights, but not morning flights. Feeding flocks selected fields based on an abundance/availability hierarchy, apparently attempting to minimize foraging time. Eurned fields were preferred most when available, followed by disked fields, especially those containing >60 kg waste corn/ha. Field-feeding is an adaption to widespread agriculture, but also is a learned response to changes in wetland habitats.Item An investigation of the mineral composition of wheat plants(Texas Tech University, 1949-08) Stuart, Margret RussellNot availableItem An investigation of the presence of streptococci in the mammary glands and their relation to clinical mastitis in a dairy herd(Texas Tech University, 1951-05) Hargrove, Allen CNot availableItem Analysis of F.F.A. leadership contests in Texas(Texas Tech University, 1950-08) Hoover, Herbert CNot availableItem Aspects of Barbary sheep (Ammotragus lervia) biology in Palo Duro Canyon, Texas(Texas Tech University, 1980-08) Gray, Gary GeneForty-four Barbary sheep (Ammotragus lervia) were introduced into Palo Duro Canyon in 1957-58. This study was conducted 1) to collate the published literature on Barbary sheep, 2) to provide some basic biological data on the Palo Duro Canyon population in the original release area, and 3) to suggest how these data can be applied to species management. Two methodologies were developed for determining age and/or sex. One involved defining nine age-sex classes based upon combinations of sexually dimorphic characteristics, and age-related variation in body size, horn size, and morphological configuration. This was used to assign Barbary sheep to age-sex classes from field observations. The other method substantiated the use of horn growth checks to estimate age in this species, and provided regression equations for estimating age from horn length. Regression equations were also developed to estimate weight from horn length. This is the first study in which horn size has been used as a weight estimator. Population statistics were estimated from 1,246 hours of observation on 271 field days from February 1977 through January 1979. Observations were made from a vehicular blind on the canyon rim, from fixed points on a standard observation route hiked each field day, and during seven helicopter censuses of the Dry Creek branch (65 km^2) of Palo Duro Canyon. The findings 1) suggested population densities of 0.8 - 3.6 Barbary sheep per km , 2) indicated that about 7 0 percent of births take place in March and April, but that some parturition is distributed throughout much of the year, 3) showed a natality rate of about 48 juveniles: 100 females, 4) disclosed an adult sex ratio of 40 males: 100 females, and 5) implied that juveniles and subadults comprise about 30 percent of the population, adult males 20 percent, and adult females 50 percent. The survival ratejfrom birth to one-year of age approximates 35 percent, is about 77 percent per year for males from one to 3.5 years of age, and is estimated to average 55 percent per year for males from 3.5 to 10.5 years of age. The topographic distribution of 529 sightings indicated that Barbary sheep range over all levels in Palo Duro Canyon, but spatial utilization is concentrated on precipitous bluffs which form the canyon walls. Diet studies showed that Barbary sheep are predominately browsers, but consume appreciable amounts of plants from the other forage categories in all seasons. The most important food plants were sand shinnery oak (Quercus havardii), mountain mahogany (Cercocarpus montanus), bladderpods (Lesquerella spp.), and blue grama (Bouteloua gracilis). Barbary sheep were infected with three species of gastrointestinal helminths (Monezia expansa, Skrjabinema caprae, and Haemonchus contortus). Ectoparasites found included the ticks Dermacentor albipictus and Otobius megnini, and the lice Bovicola fulva and B. neglecta. B. fulva is a new species. Elaeophorosis was also documented in Barbary sheep for the first time, and many animals exhibited crusty lesions or healed scars about the head as a result of infection by Elaeophora schneideri. Social organization is characterized by female group leadership and group dynamics (size and composition) which is highly variable within a basic pattern reflecting species phenology. Five types of intraspecific aggressive behavior and six vocalization types were described, and social ontogeny was delineated. Several adaptive features of Barbary sheep biology were described and discussed, and a number of considerations relevant to species management were presented. The high degree of variability associated with each aspect of Barbary sheep biology reviewed or studied suggests that this species may be able to adopt a colonial (r) or equilibrium (K) strategy depending upon population density and habitat conditions.Item Aspects of the ecology and management of pheasants in the High Plains of Texas(Texas Tech University, 1983-05) Whiteside, Richard WhittingtonNot availableItem Availability of selected amino acids in sorghum(Texas Tech University, 1976-05) Copelin, Johnny LandonNot availableItem Barley investigations on the southern High Plains of Texas: With particular emphasis on the production of malting barley(Texas Tech University, 1938-08) Morey, Darrell DorrNot availableItem Behavioral, physiological and environmental factors in baby pig mortality(Texas Tech University, 1988-08) Morrow, Julie L.Mortality in neonatal pigs has been estimated to be near 20%. Many attempts have been made to reduce this economically important aspect of swine production. However, even with modern operations and high quality feeding regimes, the death rate of piglets within the first week of life has changed little in the last 20 years. An understanding of the behavior and biology of piglets and sows has not been utilized to reduce early mortality. Neonatal animals such as the piglet show rapidly changing physical, physiological and behavioral characteristics during the first few days of life. If these neonates are to survive, they must continually adapt to varying social and environmental conditions. Sensory systems have long been recognized as playing a mayor role in the neural processes involved in recognition by the piglet of mother and litermates. Chemical cues such as matenal feces, amniotic fluid and ventral skin substances have been demonstrated to be important sources in nipple attachment and early suckling behavior over the course of lactation in several species.