With the expansion of the Tillamook Creamery, in Tillamook Oregon, to double or more its cheese production, the demand for milk presents an economic opportunity for the member dairies of the Tillamook County Creamery Association. Before area dairies can expand their herd size to increase milk production for the creamery, the problem of manure waste management and pollution control must be solved. This study considers the technical and economic feasibility of developing a centralized waste treatment and methane generation facility to treat manure generated by Tillamook County dairies. A computer program modeling animal waste anaerobic digester design served as the basis for generating cost and production estimates for several hypothetical scenarios assuming input data specific to the Tillamook situation. A follow up study was also made to determine the variability of the potential ultimate methane yield of manures from Tillamook dairies. This study indicates that the proposed system is technically feasible. The study estimates that a comprehensive treatment system could cost dairymen from $70 to $100 per cow per year to start, but the economic feasibility improves as more manure is treated and more dairies participate. A full scale system has the potential to break even economically from the sale of electricity produced by a 5 megawatt methane powered generator. With the marketing of treated solids as a high grade fertilizer the system could gross a return of $1 to $75 per cow per year, depending on the scenario. / Graduation date: 1992

The aim of the study was to determine the effects of different dietary fibre levels on methane production and growth performance of Bonsmara and Nguni steers. Nine Bonsmara and nine Nguni male weaners aged 8 – 9 months were used for the study. On arrival, animals were fed Eragrostis curvula hay on ad libitum basis for the first 14 days as part of adaptation to the feedlot environment. Animals were gradually adapted to treatments to prevent metabolic disorders. The study was conducted as a 3 x 3 x 2 factorial experiment. Treatments were allocated in a completely randomised design. Data were submitted to analysis of variance (ANOVA). Student's t-LSD was calculated at the 5 % level (P < 0.05) to compare treatment means for significant effects. Feeding a diet that is low in crude fibre content had significantly increased (P < 0.05) growth performance in both breeds. Bonsmara steers had significantly higher growth performance (P < 0.0001) across all treatment diets compared to Nguni steers. High rumen total microbial count was observed in animals that received diets with low crude fibre. Reducing dietary crude fibre resulted in reduced methane production. Low dietary fibre showed low rumen archaea counts. There was a positive correlation between rumen pH and methane emission for both Bonsmara (R2 = 0.9105) and Nguni (R2 = 0.9517) steers. However, a negative correlation was observed between rumen total microbial count and feed conversion ratio for both Bonsmara (R2 = 0.8286) and Nguni (R2 = 0.7208) steers. The low rumen archaea counts were detected from the Bonsmara. Feeding diets with low fibre levels is recommended for improving growth performance and reducing methane production for Bonsmara and Nguni steers. / Agriculture and  Animal Health / M. Sc. (Agriculture)

[Truncated abstract] In Australia, there is pressure to reduce the amount of methane produced by ruminant livestock because they are the single largest source of methane emitted from anthropogenic sources, accounting for 70.7% of agricultural methane emissions. In addition, methane production represents a loss of gross energy intake to the animal. The organisms that are responsible for methane production in the animal gut are a distinct group of Archaea called methanogens. Methanogens occupy three different niches within the rumen. Some live freely in the rumen digesta (planktonic), others are attached to the outer surface of the rumen ciliates (ectosymbiotic), and some reside within the ciliates (endosymbiotic). The types and number of methanogens, as well as rumen ciliates and their symbiotic interactions, influence the amount of methane produced from the rumen. These factors in turn are affected by many factors, including diet and ruminal retention time. In this thesis, I tested the general hypothesis that increasing the amount of grain in the diet and reducing the retention time would affect the abundance and diversity of methanogens in their different niches, including their association with ruminal ciliates. Twenty-four fistulated sheep were used in a complete factorial design with the sheep randomly divided into four groups. ... The change in DGGE banding patterns and Shannon indices when sheep were fed grain indicated that the types of methanogens changed when sheep were fed low and high grain diets, but their diversity did not. In contrast, the diversity of rumen ciliates decreased when sheep were fed a high grain diet. A total of 18 bands from the DGGE analysis of the ciliates were sequenced. All except one, which was 98% similar to Cycloposthium sp. not found previously in the rumen, matched the sequences for previously identified rumen ciliates. Some of the rumen ciliates identified were not present in sheep fed the high grain diet. On a high grain diet, methanogens associate endosymbiotically with rumen ciliates to get better access to hydrogen. It appears that the association between methanogens and rumen ciliates is dictated by the availability of hydrogen in the rumen and not the generic composition of the ciliate population. Furthermore, endosymbiotic methanogens appear to produce less methane than methanogens in other niches. The pot scrubbers did not change ruminal retention time but they did reduce the acetate/propionate measurements observed in sheep on the high grain treatment. The reason why pot scrubbers had this effect remains unknown, but it is interesting to consider that some physical interaction has occurred between the pot scrubbers, the grain and the sheep that has improved the fermentation parameters in sheep fed a high grain diet. The results from this study have advanced our understanding of the interaction between methanogens and ruminal ciliates, and methanogenesis in the rumen in response to dietary changes and mechanical challenges. Extending this work to look more specifically at the species of methanogens that are most closely linked to high methane production and how they interact with the ruminal ciliates will be critical for manipulating enteric greenhouse gas emissions.