Farmers in the developing world frequently find themselves in uncertain and risky environments: often having to make decisions based on very little information. Functional models are needed to support farmers tactical decisions. In order to develop an appropriate model, a comparison is carried out of potential modelling approaches to address the question of what to grow where. A probabilistic GlS model is identified in this research as a suitable model for this purpose. This model is implemented as the stand-alone Spatial Decision Support System (SDSS) CaNaSTA, based on trial data and expert knowledge available for Central America and forage crops. The processes and methods used address many of the problems encountered with other agricultural DSS and SDSS. CaNaSTA shows significant overlap with recommendations from other sources. In addition, CaNaSTA provides details on the likely adaptation distribution of each species at each location, as well as measures of sensitivity and certainty. The combination of data and expert knowledge in a spatial environment allows spatial and aspatial uncertainty to be explicitly modelled. This is an original approach to the problem of helping farmers decide what to plant where.

Many factors control, contribute to, stimulate and limit forage selection. It is apparent that cattle prefer certain cultivars compared to others. This study sought to test if cattle displayed preferences for certain cultivars over a two-year period in 2008 and 2009. Determining the effect of endophyte status on preference was another objective. Previous research showed rapid increase in the selection of preferred cultivars, i.e., diet learning. We attempted to replicate those results. Forty cultivars (34 tall fescue (Lolium arundinaceum (Schreb.) Darbysh.) cultivars), two festuloliums (Festuca pratensis x Lolium perenne), two meadow fescue (Lolium pratense) and one meadow brome (Bromus biebersteinii), and one orchard grass (Dactylis glomerta L.)) were used to determine preference and to investigate factors contributing to preference. From this two-year study, we observed that cattle preferred certain cultivars compared to others, e.g. KYFA9819 > Latar-OG > Barfest-FL and AU-Triumph < 97TF1-EF < Seine, the most and least preferred cultivars, respectively. During drought conditions, both novel and toxic endophyte cultivars were preferred significantly (P < 0.05) to endophyte free counterparts. The cattle showed rejection of unpalatable grasses but did not clearly show learning to increase selection of desired cultivars.

Feral horse management has become a subject of significant controversy in the United States. This is because of differing opinions and minimal recent empirical data on feral horses. In recent years, numbers of feral horses have increased due to governmental horse removal restrictions (specifically the Wild Horse and Burro act of 1971). With increasing numbers of feral horses on rangelands, land managers are challenged with identifying the appropriate course of action for satisfying groups with differing opinions. The purpose of this study is to characterize diet consumption through the use of stable isotope dietary analysis (δ15N and δ13C). We did this in order to measure the impact of feral horse forage consumption on rangelands and to propose strategies for improving habitat management and conservation. We obtained tail hair isotopic values from tail hair removed while horses that were held in squeeze chutes following a roundup. Resulting isotopic values were compared to plant isotopic values using plant samples obtained from the geographical areas as the horses in order to characterize diet. Contribution of the various plant species to the tail hair mixture values was determined using the EPA program IsoSource©. Initial analysis of tail hair isotopes demonstrated seasonal variation. During summer months, shrubs (mostly Artemesia spp, and Purshia Tridentate), Elymus elymoides, Juncus balticus, and Festuca idahoensis were the predominantly consumed vegetative species. During fall months, Leymus cinereus and Juncus balticus played a more significant role in feral horse diet. In the winter, shrubs were more heavily consumed along with Poa secunda. Springtime showed a shift towards forb consumption. Changes in seasonal consumption of forages are most likely linked to forage availability as well as equine preference. We analyzed plant metrics (specifically biomass, abundance, and cover) to compare a site with horses present to a site where horses had been removed the previous year and found relatively few differences between the two sites. With nearly all differences we found higher plant production (forage availability) on the site where horses were still present. In riparian areas however, there was more vegetation (specifically Carex rossii, Juncus balticus, and Poa secunda) on the site where horses had been removed. Within riparian areas, only Bromus tectorum (a plant not typically found in riparian areas but characteristic of degraded areas) showed significantly greater amounts of biomass on the site with horses present. Knowledge of plant species consumption will allow land managers greater ability to make scientifically based decisions regarding feral horse population control which is important in determining appropriate management levels of populations.

The seasonal feeding behavior, forage preferences and body weight responses of goats were studied under three densities of woodland (called caatinga), and under three stocking rates. The experiment was located in the semi-arid tropics of northeastern Brazil at 3 42' South latitude, and 40 21' West longitude at an elevation of 75 meters. Mean annual precipitation of the area is 832 mm. Removing the shrubs and trees increased yields of herbaceous only on partially-cleared sites. Goats gained body weight (kg BW/ha) during the wet season, with the cleared treatment showing the best body weight response per unit of land. However during the dry season, animals lost weight probably due the low quality and quantity of available forage. The botanical composition of goats' diets showed them to be mixed feeders, consuming grasses, forbs and browse in various combinations depending on the season and the array of forage species available. During the dry season standing hay from herbaceous species and regrowth of some woody evergreen species were the principal forages. Animals maintained body weight on this forage. However, leaf litter was an important component of goats' diets during the dry season, but was inadequate for weight maintenance. Goats i n all treatments spent the least time grazing during the wet season and the most time during the beginning of the dry season. They spent the most time lying ruminating during the dry season and the least time during the wet season. Forage quality was probably a limiting factor to effective animal response during the dry season. Goats exhibited dislike for rain and wet conditions. They grazed freely when the temperatures were high (35 to 39 C). However, periods of high temperature corresponded to periods of low relative humidity, perhaps moderating the discomfort factor of combined high temperatures and high humidity.

Nomadic pastoralism has been the traditional method of utilizing grazing resources in arid and semi-arid regions of Africa. However, increased sedentarization accompanied by growing human and animal populations during the past two decades is thought to be accelerating the desertification process, or desert expansion. The specific interactions of the grazing animal with this process has been speculated upon but not studied in detail. A comparative study was initiated during the spring grazing season of 1974 to determine sheep and goat nutritional and production responses, as well as patterns of vegetative selection and utilization under the pastoral system currently employed in the Pre-Saharan region of southern Tunisia. The study site was located on a sandy soil dominated by the perennial shrub, Rhanterium suaveolens. Annual herbs were co-dominants of this community in early spring. Four grazing treatments were employed during a month-long grazing season. These included; sheep grazing alone, goats grazing alone, sheep grazing with goats, and goats grazing with sheep. Stocking rates (1.9 sheep or goats per hectare per month) were comparable to those locally employed. Dietary composition was determined for randomly selected animals by a modified bite-count method, Forage intake was determined by the equation, I = F/1-D where I represented intake rate, F represented fecal output as determined from collections using standard fecal bags, and D represented digestibility of composite diets as determined by in vitro techniques. Animals were weighed weekly. Diets of all treatment groups, except goats in the mixed herd, consisted primarily of annuals during the first week. During Week Two there was a gradual shift to perennials and by the third week, all treatment groups selected primarily perennial species for their diets, Perennials comprised over 90% of the diets, except for sheep in the mixed herd, by the end of the fourth week. Also, by Week Four, Rhanterium comprised 71-92% of the diets. Estimates of forage quality indicated a declining trend in nutritional value of the forage over the grazing period. Dry matter consumption, digestibility of the diets, consumption of apparent digestible energy, dietary crude protein and apparent digestible protein all decreased from Week One to Week Four. These changes were probably attributable to a combination of factors including a decrease in plant species availability due to grazing, maturation of the remaining vegetation and a dietary shift from annuals to perennials. Young animals gained weight at generally increasing rates throughout the grazing trial. Adult animals gained weight after the initial week but their rate of gain indicated a leveling off or even a decrease by the fourth week, probably in response to declining forage quality. Animals in the mixed herd traveled farther during daily grazing periods than either of the single species herds. Goats grazing alone traveled farther than sheep grazing alone. Goats in the mixed herd may have influenced the sheep in that herd to travel more than sheep grazing alone.