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The goal of this research was to document the influence of Line 1 Hereford cattle, developed by the United States Department of Agriculture at its research facility in Miles City, Montana, on Hereford populations in the United States, South Africa, Canada, Australia, Great Britain, and Uruguay. Line 1 Hereford cattle were line-bred at the USDA-Agricultural Research Service station of Fort Keogh in Miles City, Montana since 1934. The dissemination of germplasm from Fort Keogh began with the earliest recorded sales in 1948. Analytical approaches made use of both recorded pedigree and genomic markers. Pedigree records numbering nearly 14 million from the American Hereford Association, and 3 million from the Canadian Hereford Association were randomly sampled five times for each year from 1980-2008. Sampled animals were pseudo-mated to Line 1 sires, inbreeding coefficients of the resulting progeny were calculated and relationships of the sampled individuals to Line 1 were estimated as twice the maximum inbreeding coefficient. The Line 1 Hereford population was found to be ancestral to 82% of the current population of purebred Hereford cattle in the United States. The number of Hereford cattle in the Unites States that were related to Line 1 has increased by more than 2% per year. The greatest concentrations of Line 1 genetics were found in the central and Midwestern regions of the country, but Line 1 genetics were found in 48 of the 50 states. Proportion of Hereford cattle registered in Canada that were related to Line 1 increased from 26% to 68% between 1980 and 2007. Animals recorded in the Canadian Herdbook that had ancestors in the American Herdbook were found in 8 of the 9 provinces and of these, animals related to Line 1 Hereford were found in 6 provinces. Two hundred forty animals sampled from the Line 1 herd at Fort Keogh and 311 sires representative of the Hereford breed in the U.S. were genotyped for 50K SNP. Resulting genotypes were used to assess the probability that the animals sampled from the U.S. population were members of Line 1 Hereford. The average probability of membership was 0.20 and the regression of pedigree relationship on genomic probability of membership was 1.73 ± 0.11 (r = 0.65). A similar analysis of the relationship between Line 1 and a sample of the South African Hereford (n = 36) population was conducted using 34 microsatellite loci. It was found that the probability that South African Hereford cattle were descendants of the Line 1 Hereford population was 0.38 ± 0.08. Pedigree relationship of Hereford cattle registered in South Africa with Line 1 was 24%. Obtaining complete herdbooks from other countries proved infeasible. Therefore, pedigrees of highly used sires were used as inferred from the accuracy of their genetic evaluation for direct effects on weaning weight from Hereford populations in the United Kingdom, Australia, and Uruguay with that of Line 1 Hereford. Those estimated relationships were 0.22, 0.30, and 0.23, respectively. The apparent presence the Line 1 Hereford cattle maintain in Hereford cattle around the world is highly important. The observed relationship of Line 1 Hereford with other Hereford populations is indicative of the far-reaching and profound impact of a long-term research program.

A study was conducted to investigate the influence of antioxidant source and fatty acid saturation in a standard finishing diet on apparent digestibility, production performance, fatty acid composition and oxidative stability of lamb. The four dietary treatments consisted of the same basal diet (187 g CP- and 355 g NDF/kg DM) differing in the lipid source (30 g/kg of either saturated beef tallow or unsaturated soyabean oil) and type of antioxidant included (125 g/ton of either a synthetic or natural antioxidant). Eighty-four S.A. Mutton Merino lambs (27.64 ± 1.72 kg) were randomly allocated to the four dietary treatments (n=21 lambs per treatment) and subdivided into seven replicates per treatment (n=3 lambs per replicate). After dietary adaptation of 8 days all lambs received the experimental diets for the remaining period (41 days). A digestibility study was conducted over a 12-day period (4-day adaptation to the faecal bags followed by an 8-day collection period). Seven lambs per treatment were randomly selected and slaughtered at completion of the production study. Physical carcass characteristics, muscle pH, muscle- and subcutaneous fatty acid composition, as well as meat oxidative- (malonaldehyde content) and colour stability was measured. The apparent NDF digestibility was reduced (P =0.0548) with the inclusion of unsaturated soyabean oil in the diet compared to saturated beef tallow. This was associated with a significant (P <0.05) lower digestible NDF and ME content in the experimental diet. No significant (P >0.05) differences in dry matter intake, daily gain and feed efficiency of lambs occurred. The addition of unsaturated soyabean oil significantly increased (P =0.0003) the efficiency of ME utilisation in the diet. Lipid saturation level in finishing diets for lambs did not influence (P >0.05) the physical carcass characteristics and meat pH of lambs. Saturated beef tallow increased (P <0.05) the monounsaturated palmitoleic- and oleic acid content of lamb subcutaneous and/or muscle tissue, whereas the more unsaturated soyabean oil increased (P <0.05) the polyunsaturated linoleic acid, α-linolenic acid and CLA content of both muscle fat and subcutaneous lipid tissue. Monounsaturated vaccenic acid was increased in lamb meat when unsaturated soyabean oil was included in combination with the natural antioxidant. The total PUFA, total n-6 fatty acid and PUFA:SFA ratio of lamb meat increased (P <0.05) with the inclusion of the more unsaturated soyabean oil in the diet. A higher (P <0.0001) n-6:n-3 ratio occurred in the intramuscular fat of lambs fed the unsaturated soyabean oil diet. Unsaturated soyabean oil negatively influenced (P <0.05) the oxidative stability of lamb meat on days 0 (fresh) and 90 (frozen), compared to saturated tallow. The inclusion of a synthetic compared to a natural antioxidant in the diet decreased (P =0.0672) the apparent digestibility of NDF, which was also associated with a significantly (P =0.0159) lower digestible NDF content of the experimental diet. The meat pH measured 45 minutes after slaughter was significantly (P =0.009) decreased when a synthetic antioxidant was added to the diet. Meat pH measured at 24 hours post slaughter was lower (P =0.0433) when a natural antioxidant was added to the diet. With the exception of the natural antioxidant that increased (P <0.05) the saturated palmitic- and monounsaturated palmitoleic acid content of subcutaneous and/or muscle fat, and decreased (P <0.05) the monounsaturated stearic acid content of intramuscular fat, dietary antioxidant type did not to effect (P >0.05) the fatty acid composition of lamb meat, neither the colour- nor oxidative stability. These results suggest that the fatty acid profile of lamb can be manipulated by the saturation level of the lipid source included in the diet. However, the replacement of saturated tallow with unsaturated soyabean oil did not result, from a human health point of view, in the desirable PUFA:SFA and n-6:n-3 ratios in muscle fat and subcutaneous lipid tissue. Therefore, the manipulation of the fatty acid content of finishing diets to achieve the desirable ratios within lamb meat, as well as the optimal inclusion level of a bioflavonoid antioxidant warrants further research.

Up to the 1980âs marginal soils were successfully ploughed for crop production, but unfortunately those soils soon proved to be marginal. Due to high input costs, the Department of Agriculture soon implemented the âsoil conversion schemeâ to promote the conversion of those ploughed marginal soils to permanent pastures. It was especially the low maize prices that triggered the conversion scheme in the 1980âs. Regardless the implementation of the soil conversion scheme, many farmers unfortunately just abandoned some of these marginal fields which resulted in many hectares of unproductive previously cultivated fields, being referred to as abandoned fields. The aim of this study was to investigate a few abandoned fields at a single location in the semi-arid central Free State in an attempt to gather information on the dynamics of such disturbed ecosystems and identify their restoration potential. The study investigated the interaction between plant and soil variables to quantify the impact of different soil physical and chemical characteristics on vegetation dynamics (species composition and density). The species richness, as well as the influence of different soil characteristics were determined to identify which might have the biggest influence on the recovery potential of the disturbed area. The soil seed bank was also investigated to quantify the survival potential of climax grass species on abandoned fields, and why these species do not establish voluntarily on these disturbed areas. The main aim of the study was to quantify the influence of soil characteristics on the vegetation dynamics of abandoned fields. The results clearly showed that marginal soils, withdrawn from cash-crop cultivation, are among the most seriously degraded areas with low soil fertility (N and C content). It is creating a more favourable habitat for pioneer grass species. This study sheds more light on the poor natural rehabilitation rate of abandoned fields in the semi-arid Free State Province of South Africa. It was proven that the establishment of climax vegetation might be largely influenced by phosphorus (P), cation exchange capacity (CEC), nitrogen (N), carbon (C), soil compaction and the composition of the soil seed bank. It was note worthy that some of the abandoned fields still showed very slow progress in natural restoration after 20 years. The areas that showed least recovery needed to be cultivated and established with a cultivated pasture like Digitaria eriantha sub. eriantha. On the other hand, other areas recovered to such an extent that oversowing or the placement of Themeda triandra sheafs might improve restoration. The best recovered areas can only be upgraded in productivity by scientific management strategies which include long resting periods. Drastic human interference is an absolute necessity to speed up the process of plant succession (rehabilitation). Future investigation might include long-term trials to monitor the reaction of vegetation and soil characteristics to the introduction of organic matter as well as the seed of climax grass species.

Mounds built in pastures by the subterranean ant Lasius flavus often have a vegetation which differs markedly from their surroundings. I set out to compare the relative abundances of plant species on and off ant-hills in some grasslands in southern Britain, and to define those characteristics of species which mainly determine their success or failure on the mounds. Large ant-hills and the surrounding grassland ware sampled in detail at five acid grassland sites in the Gower peninsula, Glamorgan, and thirteen chalk grassland and chalk heath sites in southern Britain. Mounds were often dominated by perennials which could grow up through heaped soil, like Polytrichum piliferum, P. juniperinum on the Gower and Thymus drucei and Helianthemum chamaeciatus on the chalk. Annuals such as Aira praecox and Arenaria serpyllifolia were frequently confined to ant-hills. However, many species, especially rosette or semi-rosette hemicryptophytes, were consistently uncommon on ant-hills, including Luzula campestris, Cirsium acaule, Poterium sanguisorba and Felipendula vulgaris. The pleurocarpous mosses Pleurozium schreberi and Pseudo-scleropodium purum were more abundant on north-facing than south-facing aspects of the mounds. Two main factors influenced plant patterns. Firstly, the heaping of soil over the plants by the ants often caused considerable seedling mortality. Secondly, species differed in their ability to disperse 'seed' onto the mounds. When I compared the viable 'seed' 'banks' present in equal weights and surface areas of ant-hill and pasture soils, by keeping the samples moist and counting the emergent seedlings, the 'seeds' of those species uncommon on ant-hills were much less frequent in ant-hill than pasture soil. Most seedlings on the mounds probably result from 'seed' dispersal onto the mound surfaces. Soil analyses show no large and consistent differences in nutrient concentrations between ant-hill and pasture soils and thus it seems unlikely that nutrient levels greatly influence the striking distributions of many species. The vegetation on and off two hundred and six wounds of a wide range of size and activity was recorded in detail on a 1.2ha plot at Aston Rowant N.N.R., Oxon. Mapping showed that species rarely occurred on ant-hills when they were absent from the sward nearby. From scatter diagrams of the abundance of each species in relation to ant-hill volume and ant activity on a mound, it was possible to deduce how succession of some species on ant-hills might occur, if ant-hill volume were proportional to ant-hill age. The following hypothesis is consistent with the evidence. 'Young' mounds are heaps of soil which smother existing vegetation. They are invaded in particular by Festuca rubra, Lotus corniculatus, Carex flacca, Leontodon hispidus and Helianthemum chamaecistus (if in the sward nearby). Thymus drucei invades the mounds vegetatively as they expand in basal area, and gradually becomes a more important component of the vegetation. Carex flacca and Hieracium pilosella rosettes become restricted to the edges of ant-hills because the continual heaping of soil onto the tops of the mounds causes their burial and death there. However, Leontodon hispidus and Plantago lanceolata, often present inside the margins of medium and large mounds, set abundant seed there and their seedlings sometimes become established on the bare soil on top. By this time, the summits of ant-hills tend to be occupied by Helianthemum chamaecistus and Thymus drucei, which can grow up through the heaped soil. Small mounds are often deserted by the ant colony. Their vegetation becomes closed and the relative abundances of species approach those of the surrounding sward more closely than on active ant-hills of the same volume. In the absence of burial, Carex flacca, Leontodon hispidus, Plantago lanceolata, Hieracium pilosella become established over the whole surface; H. pilosella rosettes are far more dense on abandoned mounds than active ones of the same size. When mounds are abandoned the chambers and channels disappear, organic natter accumulates, an A₀ horizon is formed and the previously structureless soil becomes aggregated into peds. The life cycles of the species with the most marked patterns la relation to ant-hills were studied more fully in field and laboratory experiments. The species characteristic of ant-hills usually have either vigorous vegetative growth when smothered, the ability to flower on the mounds in too year after germination or both. For instance, established plants of Helianthemum chamaecistus and Thymus drucei, woody chamaephytes which often dominate ant-hills, can grow up through 3-4cm of suddenly-heaped soil. Yet they rarely establish themselves from seed on the mounds. In Arenaria serpyllifolia, Veronica arvensis and other winter annuals, the flowers are predominantly self-pollinated, seed-set is high, the seeds are light (60 - 270 ug) and inhibited from germinating under only 5mm of soil, a high proportion (40) of those released onto the mounds germinate each year, and the seedlings rapidly decline in number. For instance, a cohort of 2078 seedlings of Arenaria serpyllifolia followed from August 1971 to July 1972 had a half-life of 0.14 years, the seedlings dying from rabbit-scraping, soil heaping, self-thinning, fungal infection, rainwash and so on. Nevertheless, almost every surviving seedling flowered in the late spring of the first year. The minute seed weights of these species are insufficient to allow them to become established in closed vegetation. Their seeds may be inhibited from germinating under swards by the higher ratio of far red to red light there; Arenaria serpyllifolia, Veronica arvensis and Myosotis ramosissima seeds did not germinate under two layers of Tilia leaves in a laboratory experiment. Cerastium holosteoides resembles Thymus and Helianthemum in being a perennial chamaephyte able to grow up through newly-heaped soil to some extent, and resembles the winter annuals in flowering the year after germination and producing abundant small (180 ug) seeds which hardly germinate under two layers of Tilia leaves. The species with roughly equal abundances on and off ant-hills are frequently stoloniferous and able to grow up through heaped soil to some degree (e.g. Agrostis stolonifera, Festuca rubra, Campanula rotundifolia, Galium verum) or short-lived and able to flower on the mounds (e.g. Euphrasia officinalis agg, Gentianella amarella, Linum catharicum and Medicago lupulina). All the species which are considerably more abundant in the sward than on the mounds are perennials, with very slow vegetative reproduction. Thus they depend on invasion by seed to become established on ant-hills. Only a small proportion of the rosettes in the sward flower each year, the flowers are cross-pollinated, the fruits are comparatively heavy (600 - 4000 ug), the seedlings are susceptible to burial, their development on the mounds is slow and they do not flower within the first two years. Their seedlings are robust enough to establish themselves in swards. Nevertheless, within this framework, the factors affecting their abundances on the mounds differ from species to species. For instance, in Cirsium acaule the number of fruits produced is reduced to 10-14 per capitulum per year by the weather, predation and parasitism. Their dispersal is hindered by the high frequency of pappi lost before dispersal, the heavy achenes and the weather. The production of vigorous seedlings on the mounds may be affected by fungal parasitism, and their survival is probably poor because they are susceptible to burial. Seedling development is slow on ant-hills and no flowering plants were seen there. In Leontodon hispidus, however, dispersal of achenes onto the mounds is efficient, and 5-9 of achenes germinate on ant-hills, so that seedlings are frequent on the mounds in autumn. Seedlings develop slowly, remain avail, and are susceptible to burial, but mature rosettes inside the perimeter of active ant-hills often flower profusely and reproduce vegetatively. Thus Leontodon maintains larger populations on ant-hills than Poterium sanguisorba, and Cirsium acaule. On the other hand, Carex flacca maintains high densities of rosettes around the edges of 'active' ant-hills because of vigorous vegetative reproduction; reproduction from seed is negligible. Poterium sanguisorba and Plantago lanceolata were also investigated. Thus the ant-hill environment acts as a sieve, letting through those species which can flower early on or grow up through heaped soil, and excluding those which cannot flower on the mounds, with poor dispersal and low seedling development. The flora of 'active' ant-hills is maintained at a lower stage of succession than the surrounding vegetation by the constant addition of soil to the surface. The vegetation resembles that of fixed calcareous dunes and of Breckland grass-heath before myxomatosis, two cowaunities in which sand movements also provide an element of environmental 'unpredictability'. Those species which invest a high proportion of their total net assimilation in reproduction ere pre-adapted to colonise and maintain themselves on ant-hills. Those species selected for efficiency in maintaining themselves in a closed community, with heavy fruits and an inability to flower early in life, cannot maintain themselves at a high density in a community of an earlier successional stage.

For several decades, grassland bird populations have been facing consistent declines throughout North America with population declines >1.5% per year in the past 40 years in the eastern United States. If this current rate persists, the populations will be reduced to half their current size in less than 50 years. Multiple causes have been proposed to explain the decline of grassland birds, but loss of available habitat and declining habitat quality are recognized as key elements in the decline of this guild. The Champlain Valley has the potential to be an important area for the conservation of grassland birds due to large acreage of grassland habitat; however, management practices are not always compatible with grassland bird habitat requirements. Therefore, there is a need to focus conservation efforts in areas that will have the greatest probability of maintaining populations of grassland birds. This project was designed to identify priority areas for implementing conservation programs for grassland birds in the Champlain Valley of Vermont. Using ArcGis, I created detailed layers that included landscape level factors (forest, grassland, development and roads) and patch level factors (size, management and conservation) important in grassland bird habitat selection. Integrating the GIS dataset into a multicriteria decision analysis framework, I produced maps in which grassland patches were ranked on the basis of their quality for grassland birds. The Analytic Hierarchy Process was the decision rule used to identify priority conservation areas. The use of a hierarchical structure distributed the relative weights of different factors deemed important by grassland bird experts, allowing a greater number of criteria to be included while keeping the methodology manageable. These procedures resulted in a series of habitat quality maps that federal, state, and non-governmental land managers will be able to use as a baseline to focus conservation efforts on areas that will have the greatest probability of maintaining viable populations of grassland birds. The maps emphasize the protection of grassland patches larger than 5-10 ha that are 2 km away from roads with high traffic, and the selection of blocks of > 50 ha of protected or bird-friendly grassland habitat. The Analytic Hierarchy Process is a flexible method that can be applied to conservation decisions across a variety of ecosystems and species.

I used field experiments to study how plants in two grassland communities colonized soil mounds made by the Camas pocket gopher, Thomomys bulbivorus (Richardson). I identified potential mound colonizers in each source of colonization (buried propagule bank, seed rain, and established vegetation) and then measured species specific rates of colonization on mounds built by T. bulbivorus. By selectively eliminating different avenues of colonization on artificial mounds, I estimated the relative and combined effects of colonization from (1) germination and growth of buried viable seeds and growth of root fragments in the soil; (2) germination of seeds raining onto the mounds; (3) emergence of buried vegetation and, (4) encroachment and establishment of adjacent vegetation. Artificial mounds were good mimics of mounds built by T. bulbivorus judged by their similarity in colonization rates and composition of colonizing species. I repeated the investigation in adjacent pasture and prairie communities differing in species composition and abundances to compare the effects of these differences on the colonization process. Composition and abundance of species in the expressed and potential vegetation varied considerably between pasture and prairie as did the two communities' response to identical gopher disturbances. Percent cover of vegetation on mounds increased 3 times faster in the Composition and abundance of species in the expressed and potential vegetation varied considerably between pasture and prairie as did the two communities' response to identical gopher disturbances. Percent cover of vegetation on mounds increased 3 times faster in the pasture than the prairie; and vegetation on and off mounds in the pasture was more alike (71% Similarity) than vegetation on and off mounds in the prairie (50% Similarity). Despite these differences, the relative contribution of each source of colonization was strikingly similar in the two communities. Vegetative encroachment and emergence contributed more to overall colonization rates (76% in the pasture; 75% in the prairie) than did establishment from seeds or buried root fragments. Emergence from underneath the mounds was favored by the shallow depth of mounds, minimal alteration of the substrate associated with mound building, and dominance of perennial species with erect growth forms. The small area and high perimeter to surface area ratio resulted in a high percent colonization from encroachment of surrounding vegetation. Colonization from the rain and bank contributed less to mound closure and may have been limited by a low abundance of propagules in those two sources. Successful colonists differed in their patterns of colonization. Festuca rubra, Agoseris heterophylla, Plantago lanceolata and Prune lla vulgaris colonized almost exclusively via emergence. Fragaria virginiana colonized by the extension of stolons both onto (encroachment) and up through mounds (emergence). Colonization from the seed rain was important in many annual species, such as Ranunculus occidentalis, Clarkia quadrivulnera, and Sherardia arvensis and the biennial species, Hypericum perforatum. One annual species, Cynosurus echinatus colonized to some degree from several modes of colonization. Mound disturbances had greater forb and annual species cover in both communities than was represented in the background vegetation, although the difference was much greater in the prairie. Results of this and other studies of gopher disturbance suggest that the relative abundance of perennials and annuals, evenness of species abundance and competitive relationships can help to predict patterns of colonization and effects of gopher mounds on community diversity. / Graduation date: 1991

Thesis (M. Agr. Sc.)--University of Queensland, 2003. / Includes bibliographical references.

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