The successful application of crop processing on pull-type forage harvesters requires engineering analysis and experimentation in areas such as roll design, particle aerodynamic, vibration, power measurement and crop physical characterization. The first step of this research project was to design, build and evaluate two processing rolls integrated in an experimental pull-type forage harvester. With a 12.7 mm theoretical length of cut setting, the processing rolls were used to treat alfalfa at a 1 mm clearance between the rolls. Samples analyzed at an animal research centre showed that processing increased the effective ruminal degradability of corn by 3% but did not improve the degradability of alfalfa. / The presence of processing rolls in the forage harvester increased friction. The air inlet area had to be increased to improve particle flow and obtain maximum air outlet speed. The presence of crop processing rolls required an increase in blower speed of 10 to 20% to maintain the throwing capacity. / Critical speeds were analyzed by the Transfer Matrix Component Mode Syntheses (TMCMS) method and three classical approaches using analytical models to predict deflections in the shaft. Experiments showed that the TMCMS method was very reliable and predicted the critical speed with an error of about 4% compared to 8% or higher for classical methods. Modal analysis also proved to be a simple and practical way to measure critical speed. / A laboratory setup was built to investigate various mechanical adjustments: roll clearances of 4 and 6 mm for corn, and 1 and 3 mm for grass; eight peripheral speed ratios between 1.08 and 1.93; two levels of throughput (9 and 18 t fresh crop/h). Optimal adjustment will ultimately depend on animal response to various levels of crop breakage. / A hydrodynamic model of chopped forage processed between rolls was developed to determine crop properties using an experimental database and subsequently predict the power requirement as a function of the configuration. Forage specific area was estimated using an experimental micro-screening method. A program was developed to calculate mechanical stresses within each roll of the crop processor as a function of working conditions and steel properties. (Abstract shortened by UMI.)

The objectives of the following research project were to 1) determine the optimum time and intensity of harvesting a wetland meadow in terms of forage yield, forage nutritive quality, and plant vigor; 2) to determine the carrying capacity of a wetland meadow under different seasons of use and; 3) to contribute to the development of a wetland classification scheme by characterizing a wetland meadow. The study site was located on the Fraser Plateau about 100 kms west of Williams Lake, British Columbia, at an elevation of 1250 m. Meadow water table, water pH, water conductivity, water calcium ion concentration, and soil temperatures were measured twice per month. The meadow and surrounding upland soils were classified. The species composition and foliar cover of 5 vegetation zones were described for the meadow and surrounding upland area. To asses meadow productivity and forage nutritive quality under different seasons of use 6 harvesting periods were employed, mid May to mid July, June and July, mid June to mid August, July and August and mid May through August. The standing crop seasonal trend was monitored by analysing forage samples collected twice monthly. Clipping samples were oven dried and weighed to determine harvest yields. The crude protein content of the samples was determined by a microkjeldhal technique. Phosphorus content was assessed by a vanadomolybdate method. Calcium, potassium, magnesium, zinc, copper, iron and manganese contents were determined by spectrophotometry. The relative plant stored food reserves were assessed by an etiolation experiment. Soil - vegetation plugs were collected from all harvest period treatment plots as well as undipped control plots and placed in a dark controlled environment chamber. The etiolated growth was collected, weighed and used to compare the relative plant stored food reserves among different harvest period treatments. A stepwise simple regression procedure was used to compare the seasonal trend data and a stepwise multiple regression procedure was used to compare the different harvest period treatments. A 2 step Student Newman Keuls multiple range test was performed on the etiolation experiment sod reserve indices and harvest treatment total yields data. Meadow water table, water pH, water calcium ion content, water conductivity, soil temperatures at 10 cm and soil temperatures at 50 cm ranged between +29 and -2 cm, 7.0 and 7.4, 14 and 89 ppm, 249 and 840 mmho/cm, 6.9 and 11.2°C and 6.8 and 10.6°C respectively. Meadow soils included a Typic Humisol - Mesic Humisol - Terric Mesic Humisol complex, a calcareous Gleyed Humic Regosol, a calcareous Gleyed Regosol, an Orthic Humic Gleysol and a Gleyed Gray Luvisol. The upland soil was an Orthic Gray Luvisol. The 5 vegetation zones were named according to the dominant plant species. Included were a Carex rostrata zone, a Carex - Betula glandulosa zone, a Carex praegracilis - Juncus balticus zone, a Salix - Betula glandulosa zone, arid a Pinus contorta - Calamagrostis rubescens zone. Productivity and nutritional data collection was restricted to the Carex rostrata zone. The standing crop varied from 1 to 6 mt/ha. The nutrient content of the standing crop varied between 0.35 and 0.51% of tissue, 2.1 - 5.7, 1.0 - 1.5% of tissue, 0.17 - 0.26% of tissue, 133 - 326 ppm, and 49 and 165 ppm for the calcium, calcium - phosphorus ratio, potassium, magnesium, manganese and iron contents respectively. The meadow forage crude protein, phosphorus, zinc and copper contents remained un- changed at 10.1% of tissue, 0.14% of tissue, 30 ppm and 11 ppm through the season. The 8 cm July and August harvest period produced the greatest treatment yield, 6807 kg/ha, followed by the 8 cm - mid June to mid August harvest treatment yield. The least productive treatments were the 8 and 23 cm harvests during the period mid May to mid August. The nutrient content of the meadow forage subjected to the 10 different harvest treatments varied as follows: crude protein - 8.3 to 12.0% of tissue, calcium - 0.368 to 0.646% of tissue, phosphorus - 0.21 to 0.27% of tissue, calcium: phosphorus ratio - 1.4 to 3.6, zinc - 35 to 46 ppm, copper - 13 ppm, potassium - 1.7 to 2.4% of tissue, magnesium-0.19 to 0.23% of tissue, manganese - 194 to 271 ppm and iron - 94 to 119 ppm. Repeated clipping increased the meadow forage crude protein, phosphorus, zinc, copper, potassium, manganese slightly, and iron contents. Repeated clipping reduced the meadow forage calcium: phosphorus ratio. The stored food reserves of the meadow vegetation was found not to vary with harvest treatment. Based on productivity, nutritive quality and plant vigot data, grazing during the period mid June to mid August and close utilization (an 8 cm as opposed to a 23 cm stubble height) appears most appropriate. Wet meadow hay should be cut as early as possible. The theoretical safe maximum carrying capacity is 23 AUM'S/ha (20 AUM'S/ ha when grazed to an 8 cm stubble height during the period mid June to mid August). The meadow characterization and productivity data will be useful to person(s) undertaking the task of formulating a classification scheme for British Columbia wetland meadows. / Land and Food Systems, Faculty of / Graduate

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MSCAGR (Animal Science) / Department of Animal Science / Forage and browse legumes play an important role in sustaining livestock in small holder farming systems in the tropics, mainly as a result of their contribution to economic and environmental sustainability of livestock production. The study was conducted to determine the chemical composition, ruminal degradability and in vitro digestibility of dry matter (DM) and crude protein (CP) of Dichrostachys cinerea and Bauhinia thonningii leaves. The browse tree leaves were harvested in the wild in Shayandima, Limpopo province. The leaves were collected, oven-dried, milled to pass through a 1.0 mm sieve and analysed for chemical composition in the Animal Science Nutrition Laboratory, at the University of Venda. The browse tree leaves were analysed for DM nitrogen, neutral detergent fibre (NDF) and acid detergent fibre (ADF). Approximately 5 g of leaf sample milled to pass through through a 1 mm sieve were placed in nylon bags (external dimension: 6 × 12 cm, pore size of 41 μm) and incubated in duplicates for 0, 4, 8, 16, 24, 48, 72, 96 and 120 hours periods in the rumen of three cannulated Bonsmara steers. The residues were then analysed for DM and nitrogen. Parameters to describe the dynamics of ruminal degradability of DM and CP were obtained by fitting the data on the exponential equation P = a + b (1 - e-ct) using NEWAY computer program, where “a” is the rapid degradable fraction, “b” is the slow degradable fraction and “c” is the outflow rate. The in vitro DM and CP degradability of rumen undegradable residue collected after 24 and 48 hour incubation was determined by sequential in vitro digestion in pepsin (abomasal) and pancreatin (small intestine) solutions. DM and CP content differed significantly (P ˂ 0.05). D. cinerea leaves had higher levels of DM and CP content than B. thonningii leaves. DM and CP disappearance increased (P < 0.01) as the incubation period increased. There was no difference (P > 0.05) in soluble fraction ‘a’ and ‘b’ of DM of the two species. The CP components for both fraction ‘a’ and ‘b’ differed significantly (P < 0.01) for CP among the two species. There was significant difference (P < 0.01) in post-ruminal digestibility among the two species. CP digestibility of B. thonningii and D. cinerea leaves was reduced (P < 0.01). In conclusion, B. thonningii and D. cinerea leaves showed significant difference based on their fermentation kinetics and in vitro digestibility, suggesting a good nutritional quality which can be used as protein source for ruminants in dry season and supplement to low-quality diets. / NRF