Typescript. / Digitized by Kansas Correctional Industries

Seven single nucleotide polymorphisms in six genes (LEP, IGF2, MC1R, PMCH, CAPN1, and CAST) which had been shown to affect traits of economic importance were used to compare the allele frequencies and diversity of a Canadian population of Angus cattle and an International population. Genetic diversity was also measured using 22 microsatellite markers that were assumed not to be affected by selection.<p> The Canadian population consisted of 107 cows and 57 bulls, while the Canadian Angus Associations International Embryo Program population consisted of 26 calves. Black and red animals were represented in each population. Although the bulls of the Canadian population represent Angus from 16-17 years ago, and the cows of the Canadian population represent Angus from 2006-2007, no difference was observed in either the set of microsatellite genotypes nor the SNP genotypes.<p> A significant difference was found between the Canadian and International populations at CAST, with the Canadian population exhibiting a higher frequency of the favorable A allele than the International population. This allele is positively correlated with tenderness. No significant differences were found for the other genes. Both populations were in Hardy Weinburg equilibrium for all genes except MC1R, which affects coat color.<p> Using microsatellites, the total genetic variability of the two Angus populations was measured, showing that 93% of total variability was attributed to differences within, and not between, populations. Randomly chosen cattle could also be assigned to the correct population 97% of the time, based on microsatellite genotypes, and 75% of the time based on SNP genotypes.<p> Mean heterozygosity was 0.578 based on microsatellites and 0.332 based on SNPs. The proportion of genetic variability between the two populations was 3% based on microsatellites and 7% based on SNPs. It is possible this reflects the results of indirect selection differences in various countries.<p> Finally, Neis genetic distance was measured between the Canadian and International populations. The Canadian and International populations had a pairwise genetic distance of 0.097. In comparison, the genetic distance of Canadian Angus was 0.135 to Blonde dAquitaine, 0.251 to Simmental, 0.258 to Gelbvieh, 0.281 to Limousin, 0.305 to Holstein, 0.334 to Belgian Blue, and 0.452 to Hereford based on microsatellite markers.<p> The results of this study show that the Angus breed contains as much or more genetic diversity than other cattle breeds. Greatest genetic differences exist between individual animals, not between populations of cattle in Canada and other countries.

Seven single nucleotide polymorphisms in six genes (LEP, IGF2, MC1R, PMCH, CAPN1, and CAST) which had been shown to affect traits of economic importance were used to compare the allele frequencies and diversity of a Canadian population of Angus cattle and an International population. Genetic diversity was also measured using 22 microsatellite markers that were assumed not to be affected by selection.<p> The Canadian population consisted of 107 cows and 57 bulls, while the Canadian Angus Associations International Embryo Program population consisted of 26 calves. Black and red animals were represented in each population. Although the bulls of the Canadian population represent Angus from 16-17 years ago, and the cows of the Canadian population represent Angus from 2006-2007, no difference was observed in either the set of microsatellite genotypes nor the SNP genotypes.<p> A significant difference was found between the Canadian and International populations at CAST, with the Canadian population exhibiting a higher frequency of the favorable A allele than the International population. This allele is positively correlated with tenderness. No significant differences were found for the other genes. Both populations were in Hardy Weinburg equilibrium for all genes except MC1R, which affects coat color.<p> Using microsatellites, the total genetic variability of the two Angus populations was measured, showing that 93% of total variability was attributed to differences within, and not between, populations. Randomly chosen cattle could also be assigned to the correct population 97% of the time, based on microsatellite genotypes, and 75% of the time based on SNP genotypes.<p> Mean heterozygosity was 0.578 based on microsatellites and 0.332 based on SNPs. The proportion of genetic variability between the two populations was 3% based on microsatellites and 7% based on SNPs. It is possible this reflects the results of indirect selection differences in various countries.<p> Finally, Neis genetic distance was measured between the Canadian and International populations. The Canadian and International populations had a pairwise genetic distance of 0.097. In comparison, the genetic distance of Canadian Angus was 0.135 to Blonde dAquitaine, 0.251 to Simmental, 0.258 to Gelbvieh, 0.281 to Limousin, 0.305 to Holstein, 0.334 to Belgian Blue, and 0.452 to Hereford based on microsatellite markers.<p> The results of this study show that the Angus breed contains as much or more genetic diversity than other cattle breeds. Greatest genetic differences exist between individual animals, not between populations of cattle in Canada and other countries.

Paratuberculosis is an intestinal infection of ruminants caused by Mycobacterium avium subsp. paratuberculosis (MAP). Genetic associations with paratuberculosis have been described in Holstein cattle. The objectives were to describe the association between paratuberculosis status of the dam and her offspring in beef cattle, develop methods to assess familial aggregation of paratuberculosis in cattle of unknown pedigree, and model the paratuberculosis status of beef cattle given familial and herdlevel covariates. Texas beef cattle were tested for paratuberculosis using serum antibody and microbiologic culture of feces. Available pedigree data were used to confirm familial relationships. The association between the paratuberculosis ELISA status of the dam and her offspring was assessed using mixed-effects models. Increased odds of being classified as a “suspect” or greater based on ELISA results were observed if the dam was classified as a “suspect” or greater. A positive linear association was observed between the ELISA value of the dam and her offspring. Analysis of pedigree data using conditional logistic regression identified ancestors associated with significantly increased odds of being classified as “low positive” or greater. Microsatellite markers were used to classify cattle into genetically similar groups using allele frequency data. Nine clusters of genetically similar cattle were identified among paratuberculosis test positive cattle, herd matched controls, and pedigreed cattle. Clusters were validated using animals of known pedigree. Increased odds of paratuberculosis seropositivity were observed for some clusters compared to the cluster with the lowest seroprevalence. A predictive model was developed using a Bayesian framework to assess the association between antibody status of the dam and her offspring adjusted for herd-level risk factors. Predictors associated with highly probable increased odds of seropositivity included herd seroprevalence and herd fecal prevalence of MAP. The association between dam and offspring ELISA status was small (OR 1.35) and not highly probable. The results of this work support familial aggregation of paratuberculosis ELISA status, but herd-level risk factors appear to be more important in predicting ELISA status. A large proportion of observed serological reactions were not supported by fecal culture results; therefore, observed associations might be limited to humoral responses to Mycobacterium spp.

Thesis (Ph. D.)--University of Missouri-Columbia, 2000. / Typescript. Vita. Includes bibliographical references (leaves 67-78). Also available on the Internet.

Thesis (M.S.)--Oregon State University, 2010. / Printout. Includes bibliographical references (leaves 56-61). Also available on the World Wide Web.

Thesis (M. Sc.)--University of Alberta, 2010. / Title from pdf file main screen (viewed on Feb. 8, 2010). A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Master of Science in Animal Science, [Department of] Agricultural, Food and Nutritional Science, University of Alberta. Includes bibliographical references.

Thesis (Ph. D.)--University of Missouri-Columbia, 2000. / Typescript. Vita. Includes bibliographical references (leaves 67-78). Also available on the Internet.

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