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A total of 300 nursery pigs (initially 5.9 ± 0.05 kg BW) were used in a 42-d growth trial to evaluate the effects of feeding a therapeutic level of chlortetracycline (CTC) with or without direct fed microbials (DFM) on growth performance and antimicrobial resistance (AMR) of fecal Escherichia coli. CTC is a broad-spectrum in-feed antibiotic commonly used in the swine industry. Weaned pigs (~21 d of age) were allotted to pens based on initial BW and fed a common starter diet for 4 d. Pens were then blocked by BW and allotted to dietary treatments in a completely randomized block design. Dietary treatments were arranged in a 2 × 3 factorial consisting of combinations of CTC (none vs. 400 mg/kg from days 0 to 42) and DFM (0 vs. 0.05% DFM 1 vs. 0.05% DFM 2). Fecal samples were collected from three randomly selected pigs from each pen on days 0, 21, and 42 for E. coli isolation and AMR determination. Overall, pigs fed diets containing CTC had improved (P < 0.001) ADG, ADFI, and BW compared to those not fed CTC with no evidence for any effect of either DFM 1 or DFM 2. Regardless of CTC, inclusion of DFM 2 in diets improved (P < 0.05) ADFI from days 0 to 14 and on day 14 BW compared to diets that did not include DFM 2. The addition of CTC with or without DFMs to nursery pig diets increased (P < 0.05) the probability of AMR to tetracycline and ceftiofur of fecal E. coli isolates, but this resistance generally decreased (P < 0.05) over time. A decrease (P < 0.05) in AMR to ampicillin and tetracycline (TET) throughout the trial was observed, while resistance to ceftriaxone decreased (P < 0.020) from days 0 to 21 and increased from days 21 to 42 amongst dietary treatments regardless of CTC or DFM inclusion in the diet. A CTC × DFM × day interaction (P < 0.015) was observed for streptomycin, whereby from days 21 to 42 AMR increased in diets containing either CTC or DFM 1 alone, but the combination decreased resistance. There was no evidence for any effect of DFMs on AMR of feca

Editors: Aug. 1859-July 1865, J. D. White, J. H. McQuillen, G. J. Ziegler.--Aug. 1865-Dec. 1871, J. H. McQuillen, G. J. Ziegler.--Jan. 1872-May 1891, J. W. White.--July 1891-Apr. 1930, E. C. Kirk (with L. P. Anthony, Dec. 1917-Apr. 1930).--May 1930-Dec. 1936, L. P. Anthony., Vols. 1-13 are called "new series.", Merged in Jan. 1937 with: Journal of the American Dental Association, ISSN 1048-6364, to form: Journal of the American Dental Association and dental cosmos, ISSN 0375-8451., The Dental cosmos; a monthly record of dental science. [Vol. 76] : Vol 76 : Issue 7, Page(s) 800, (dlps) volume: 0527912.0076.001, (dlps) article: 0527912.0076.001:501, http://quod.lib.umich.edu/t/text/accesspolicy.html

Editors: Aug. 1859-July 1865, J. D. White, J. H. McQuillen, G. J. Ziegler.--Aug. 1865-Dec. 1871, J. H. McQuillen, G. J. Ziegler.--Jan. 1872-May 1891, J. W. White.--July 1891-Apr. 1930, E. C. Kirk (with L. P. Anthony, Dec. 1917-Apr. 1930).--May 1930-Dec. 1936, L. P. Anthony., Vols. 1-13 are called "new series.", Merged in Jan. 1937 with: Journal of the American Dental Association, ISSN 1048-6364, to form: Journal of the American Dental Association and dental cosmos, ISSN 0375-8451., The Dental cosmos; a monthly record of dental science. [Vol. 76] : Vol 76 : Issue 11, Page(s) 1218, (dlps) volume: 0527912.0076.001, (dlps) article: 0527912.0076.001:728, http://quod.lib.umich.edu/t/text/accesspolicy.html

Improving efficiency within the agricultural industry is vital to maintain the food demands of the increasing population, as well the current preference for a more protein rich diet. One avenue for addressing these issues is to study animal-based growth to determine if the efficiency of the production system can be improved by increasing lean muscle mass. The aim of this thesis is to provide an alternative exploration to experimental work to provide an insight into how muscle metabolism in pigs is altered by the administration of a beta-agonist which induces muscle hypertrophy. This will be incorporated into a wider body of work to determine specific pathways to target for improving feed conversion efficiency, contributing to the necessary research into global food security. We begin by compiling a selection of statistical methods to analyse muscle microarray data, which enables the identification of a selection of genes whose expressions are altered by the exposure to a beta-agonist. These differentially expressed transcripts are then grouped via a k-means algorithm, with log likelihood and the Bayesian Inference Criterion calculations providing an optimal selection of clusters. This results in selecting a group of 51 transcripts and partitioning them into 9 clusters, and identifying several pathways which appear key to the regulation of muscle metabolism in the presence of beta-agonist. We have proceeded to incorporate this information into a mathematical model for glycolysis and the TCA cycle, in an effort to analyse biological hypotheses about how the promoters work. The equations describe the concentrations of metabolites within the cytosolic and mitochondrial compartments of a cell using mass balance ODEs. An initial model is presented, which is then increased in complexity, to keep up with developments in the experimental side of the overarching project. We make use of a selection of methods to analyse the model in an attempt to determine the effects that the