Thesis (M. Sc.)--University of Adelaide, Dept. of Botany, 1987. / Includes bibliographical references (leaves 113-120).

Thesis (Ph. D.)--University of Pennsylvania, 1977. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 520-547).

Thesis (M.S.)--Oregon State University, 1991. / Typescript (photocopy). Includes bibliographical references (leaves 69-72). Also available on the World Wide Web.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1978. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 172-173).

Thesis (Ph. D.)--Rhodes University, 2000. / Title from PDF t.p. (viewed June 9, 2006). Includes bibliographical references.

O objetivo foi avaliar a influência da adubação nitrogenada ou da suplementação energética sobre a produção e qualidade de uma pastagem de capim papuã (Urochloa lantaginea) e no desempenho e comportamento ingestivo na recria de bovinos de corte. O trabalho foi conduzido na UTFPR-DV, por meio de pastejo contínuo em uma área de 6,3 ha divididos em nove piquetes. Os tratamentos avaliados foram pastagem + nitrogênio, pastagem + suplementação e somente pastagem, com uma oferta de forragem média de 10%. A duração do pastejo foi de 107 dias, utilizando animais mestiços (Nelore x Braford), não castrados, com peso médio de 276 kg. As análises bromatológicas foram semelhantes entre os tratamentos, diferindo apenas para proteína bruta, sendo superior no tratamento com adição de nitrogênio. A taxa de acúmulo apresentou-se maior no tratamento com nitrogênio (55,70 kg de MS/ha/dia) comparado à suplementação e somente pastagem (40,03 e 39,65 kg de MS/ha/dia, respectivamente). A suplementação resultou em maior ganho de peso médio diário (0,815 kg) em comparação com o nitrogênio (0,685 kg) e somente pastagem (0,727 kg). As atividades de ócio, ruminação e consumo de água não diferiram entre os tratamentos, apenas o pastejo apresentou-se inferior nos animais suplementados em relação aos demais. O número de bocados diurnos foi superior (P<0,005) no tratamento com suplementação e somente pastagem em relação ao tratamento com adubação nitrogenada no capim papuã,(2.029,9; 1.863,6 e 1.715,7, respectivamente). A carga animal, os ganhos por área e a composição bromatológica da pastagem não apresentaram diferenças entre os tratamentos. A suplementação energética permite maiores ganhos diários e diminui o tempo dispendido com pastejo sem alterar outras variáveis comportamentais como, ruminação, ócio e ingestão de água. A aplicação adicional de N não afeta a massa de forragem, o perfil botânico e o desempenho animal, apesar de aumentar a taxa de acúmulo diário e os teores de proteína bruta da forragem e contribui para reduzir o número de bocados diariamente e aumenta a taxa de acúmulo da pastagem. / The objective was to evaluate the influence of nitrogen fertilizer or energy supplementation on production and quality of a pasture Alexander grass (Urochloa plantaginea) and performance and feeding behavior in the rearing of beef cattle. The work was conducted at UTFPR – DV through continuous grazing in an area of 6.3 ha divided into nine paddocks. The treatments were grazing + nitrogen + supplementation and grazing pasture only, with a supply of fodder average of 10 %. The duration of grazing was 107 days using crossbred (Nellore x Braford), not neutered, with average weight of 276 kg. The chemical analyzes were similar among treatments, differing only for crude protein, being higher in the treatment with nitrogen addition. The accumulation rate was higher in the treatment with nitrogen (55.70 kg DM/ha/day) compared to supplementation and only pasture (40.03 and 39.65 kg DM/ha/day, respectively). Supplementation resulted in higher average daily weight gain (0.815 kg) compared to nitrogen (0.685 kg) and only pasture (0.727 kg). Leisure activities, rumination and water consumption did not differ between treatments, only grazing presented lower in the supplemented animals compared to the other. The number of bits daytime was higher (P<0.005) in the treatment pasture with supplementation and only in relation to treatment with nitrogen fertilization in Alexander grass, (2029.9, 1863.6 and 1715.7, respectively). Supplementation allows higher daily gains and reduces the time spent on grazing without changing other variables such as behavioral, rumination and water intake. The additional application of N did not affect herbage mass, botanical profile and animal performance, despite increasing the accumulation rate and the crude protein content of forage and helps to reduce the number of bits daily and increases the rate of accumulation pasture.

O objetivo foi avaliar a influência da adubação nitrogenada ou da suplementação energética sobre a produção e qualidade de uma pastagem de capim papuã (Urochloa lantaginea) e no desempenho e comportamento ingestivo na recria de bovinos de corte. O trabalho foi conduzido na UTFPR-DV, por meio de pastejo contínuo em uma área de 6,3 ha divididos em nove piquetes. Os tratamentos avaliados foram pastagem + nitrogênio, pastagem + suplementação e somente pastagem, com uma oferta de forragem média de 10%. A duração do pastejo foi de 107 dias, utilizando animais mestiços (Nelore x Braford), não castrados, com peso médio de 276 kg. As análises bromatológicas foram semelhantes entre os tratamentos, diferindo apenas para proteína bruta, sendo superior no tratamento com adição de nitrogênio. A taxa de acúmulo apresentou-se maior no tratamento com nitrogênio (55,70 kg de MS/ha/dia) comparado à suplementação e somente pastagem (40,03 e 39,65 kg de MS/ha/dia, respectivamente). A suplementação resultou em maior ganho de peso médio diário (0,815 kg) em comparação com o nitrogênio (0,685 kg) e somente pastagem (0,727 kg). As atividades de ócio, ruminação e consumo de água não diferiram entre os tratamentos, apenas o pastejo apresentou-se inferior nos animais suplementados em relação aos demais. O número de bocados diurnos foi superior (P<0,005) no tratamento com suplementação e somente pastagem em relação ao tratamento com adubação nitrogenada no capim papuã,(2.029,9; 1.863,6 e 1.715,7, respectivamente). A carga animal, os ganhos por área e a composição bromatológica da pastagem não apresentaram diferenças entre os tratamentos. A suplementação energética permite maiores ganhos diários e diminui o tempo dispendido com pastejo sem alterar outras variáveis comportamentais como, ruminação, ócio e ingestão de água. A aplicação adicional de N não afeta a massa de forragem, o perfil botânico e o desempenho animal, apesar de aumentar a taxa de acúmulo diário e os teores de proteína bruta da forragem e contribui para reduzir o número de bocados diariamente e aumenta a taxa de acúmulo da pastagem. / The objective was to evaluate the influence of nitrogen fertilizer or energy supplementation on production and quality of a pasture Alexander grass (Urochloa plantaginea) and performance and feeding behavior in the rearing of beef cattle. The work was conducted at UTFPR – DV through continuous grazing in an area of 6.3 ha divided into nine paddocks. The treatments were grazing + nitrogen + supplementation and grazing pasture only, with a supply of fodder average of 10 %. The duration of grazing was 107 days using crossbred (Nellore x Braford), not neutered, with average weight of 276 kg. The chemical analyzes were similar among treatments, differing only for crude protein, being higher in the treatment with nitrogen addition. The accumulation rate was higher in the treatment with nitrogen (55.70 kg DM/ha/day) compared to supplementation and only pasture (40.03 and 39.65 kg DM/ha/day, respectively). Supplementation resulted in higher average daily weight gain (0.815 kg) compared to nitrogen (0.685 kg) and only pasture (0.727 kg). Leisure activities, rumination and water consumption did not differ between treatments, only grazing presented lower in the supplemented animals compared to the other. The number of bits daytime was higher (P<0.005) in the treatment pasture with supplementation and only in relation to treatment with nitrogen fertilization in Alexander grass, (2029.9, 1863.6 and 1715.7, respectively). Supplementation allows higher daily gains and reduces the time spent on grazing without changing other variables such as behavioral, rumination and water intake. The additional application of N did not affect herbage mass, botanical profile and animal performance, despite increasing the accumulation rate and the crude protein content of forage and helps to reduce the number of bits daily and increases the rate of accumulation pasture.

abstract: Livestock-grazing, in particular cattle grazing, is a common use of public and private lands in western North America. As a result, the effects of grazing on both plants and animals are widely studied. Few studies, however, look directly at the long-term effects that cattle grazing may have on a particular species. The goal of this experiment was to continue research begun in 1988, to determine if the effects of cattle grazing are still seen in the age structure of two populations of saguaros (Carnegiea gigantea [Engelm.] Britton & Rose) at Saguaro National Park - Rincon Mountain District (SNP-RMD). The null hypothesis stated that enough time has elapsed since the cessation of grazing, and there is no difference in the age distribution of the saguaros of the two populations. The study area was comprised of a former fence line where grazing ceased on the western side of the fence in 1958 and the eastern side in 1978. Belt transects were laid on each side of the fence line and height was measured for each saguaro encountered in a transect. Approximate age of the individual was then calculated using an age-height correlation for SNP-RMD. Individuals were then placed into age classes of 10 year increments and a Log-Likelihood test was performed. The resulting calculated P value of 0.12 meant the null hypothesis was not rejected and there was no statistical difference between the age structure of the two populations. After 34 and 54 years rest from grazing, the negative effects of cattle grazing on the retention and recruitment of saguaro seedlings have ended, and replenishment of the populations is now dependent upon factors such as temperature and precipitation. Other factors such as climate change, increasing fire frequency, encroachment by invasive species, and poaching are sources of concern and increased mortality for these and other saguaros. / Dissertation/Thesis / M.S. Applied Biological Sciences 2013

<p> Traditional production system has exhausted natural resources and depleted soil nutrients reducing farm productivity and forcing farmers to expand farm lands, which, increases deforestation and pollution. Global warming and an increasing global population pose additional strain to the already fragile global food security, making it urgent for innovative production systems to be developed. Such systems, adapted to local circumstances and designed to reduce deforestation and increase food production, must emerge to provide an expanding global food demand while enabling preservation of natural resources. </p><p> A five-year research project, derived from a national initiative has proposed a silvopastoral model for the Tepalcatepec valley, as an alternative to conventional livestock ranching in the tropics. The primary objective for this research project was to characterize the advantages and disadvantages of an alternative livestock farming model, the silvopastoral system. One hundred and fifteen farmers in the Tepalcatepec valley were surveyed to characterize their farms, their family demographics, main cattle breed, crops farmed, cattle diet, measures of animal performance (productivity) commercialization (marketing practices) and animal health management practices. An analysis of the progress of the various national SPS initiatives was also performed in order to identify gaps in research, collaboration, stakeholder education, and application of SPS farming in Mexico. </p><p> A systems analysis was conducted on the research project using the information compiled from the team of scientists surveyed. Components related to carbon capture, biodiversity, soil quality, nutrient recycling, and larger-scale cycles such as water cycle need to be incorporated into future research. An accurate measure of the true economic and ecological impact of SPS farming is an essential goal. Improved communication among scientists, government agencies, and stakeholders is also essential for successful research into SPS farming. </p><p> The animal health component of the five-year Mexican national SPS project is the focus of this dissertation. Traditional livestock health practices on participating small farms were characterized, and common health problems of cattle were identified. A community based livestock syndromic surveillance system was developed, implemented, and observed for two years on five selected farms. Observations from farmers and veterinarians were triangulated to validate data on animal health collected by laypeople. For each farm under study, monthly cumulative incidence per animal category (calf, grower or adult), the most frequent disease syndrome, and the syndrome that carried the greatest economic impact were calculated. Most Rho correlation coefficients for farmer&rsquo;s and veterinarian&rsquo;s observations were high. </p><p> Farmers that implemented the silvopastoral model were considered typical of those who practiced this farming method elsewhere within the region. Because participating farms shared production system, husbandry, livestock health status, disease preventive measures, products, and commercialization channels, they were considered an epidemiological compartment for quantitative risk analysis. Six different scenarios were created and analyzed using the software @Risk&trade; to measure the risk of introduction of bovine tuberculosis into this epidemiological compartment. The Mexican national program for control and eradication of bovine tuberculosis norm, regional prevalence on bovine tuberculosis, and current cultural practices in Tepalcatepec valley were considered for this analysis. The introduction of replacement heifers or sires into the farms, and the probability of the introduction of at least one infected animal was estimated. The least probable scenario for the introduction of tuberculosis into this compartment was the introduction of at least one infected animal, despite the prevalence of source herd, after applying tuberculin caudal fold test and cervical comparative test in parallel. </p><p> Although some farmers are aware that the silvopastoral system is profitable, environmental friendly, and socially acceptable, initial investment appears to be the first barrier for adoption. Alternatives for funding SPS development are needed such as preferable interest rates, credit, and loans; notably, an accurate assessment of the costs for establishment of SPS should be more thoroughly studied. The initial three years of SPS implementation have the highest amount on investment; for those years, special attention should be placed on recording the contributions of timber and/or fruit to financial returns, since these products may be the key for offsetting the cost of SPS implementation. </p><p> Further research is needed to more accurately measure the economic, ecological, animal health, and human health impact of the silvopastoral model of farming in the tropics. An ample variety of species combinations, suitable for silvopastoral production, should be studied and different arrays proposed to encourage scaling up the model. Research funding is scarce; however, public awareness of the need for a change in production practices and the allure of environmental friendly-produced animal products can produce a market-driven change in these small-scale food production operations. This could engender greater research support from industry and government sources, as well as non-governmental organizations dedicated to promoting sustainable agricultural practices in a changing global environment. (Abstract shortened by ProQuest.)</p><p>

No description available.