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This research investigates the impact of disruptions and regional integration on agricultural and food trade, relying on a unique international and intranational (domestic) agri-food trade dataset and structural gravity. In the first chapter, we investigate the impact of animal diseases on trade of animal-based products. We found that animal disease outbreaks decrease exports by 4% on average per year, amounting to annualized losses of 96 billion of 2019 USD. Trade quantities decline by 8% (51 million tons) on average per year. Impacts are mostly concentrated on consumer products (mainly pork), and low-income and lower-medium-income exporting countries. Our results suggest that animal diseases affect more domestic markets than foreign ones, and that dependent importers are the most sensitive to animal disease outbreaks abroad. Lastly, participation in the same RTA is found to mitigate animal diseases' trade impact, showing another potential channel through which regional integration could affect members' trade. In the second chapter, we explore the effect of the North American Free Trade Agreement (NAFTA) on agricultural and food trade flows. We consider the entire official lifetime of the agreement, including its 14-years phase-in period, which allow us to offer a comprehensive evaluation of one of the biggest trade agreements on agri-food trade. NAFTA is found to increase members' trade on average by 54%, corresponding to 11.9 billion of 2020 USD, annually. Trade involving Mexico, and especially Canada-Mexico, has increased substantially showing that trade agreements between developed and developing countries could be beneficial to both members. NAFTA's impact is found to be heterogeneous by products with cereals experiencing the biggest increase. Trade of products incompletely liberalized by NAFTA such as dairy, poultry, and eggs, did not increase as much as the trade of liberalized products. We do not find evidence of trade diversion, suggesting that NAFTA's agri-food trade gains did not come at the expense of trading with other partners. Lastly, NAFTA appears to be more trade enhancing (about four times more) than other agreements of Canada, Mexico and the U.S. (e.g. Canada-E.U., or Mexico-Brazil, or U.S.-Korea.) In the third chapter, we question whether trade agreements alleviate the impact of shocks on trade. More specifically, we investigate if RTAs mitigate the impact of exchange rate (ER) volatility on agri-food trade. We found that RTAs amplify the effect of ER volatility on agri-food trade. The trade impact of ER volatility on RTA members is found to be positive, suggesting that members' agri-food trade benefits from ER volatility, contrary to non-members' trade. This could result from larger profits from arbitrage due to reduced trade costs between RTA members. Our results display a strong heterogeneity according to sectors, exporters and importers' income, and level of integration of RTA. Only Partial Scope Agreements, the lowest regional integration level, amplify the effect of ER volatility on members' agri-food trade. / Doctor of Philosophy / This research evaluates the impact of factors that cause trade disruption and the impact of trade agreements on agricultural and food trade. In the first chapter, we investigate the impact of animal diseases on trade of animal-related products. Findings indicate that animal diseases decrease the value of trade on average 4% annually, amounting to 96 billion of 2019 USD annualized loss. Trade quantities are reduced by 8%, or 51 million tons yearly on average. This impact differs with respect to animal diseases, products, and income levels of countries. Animal diseases affect more the domestic market, while countries depending to foreign suppliers are those affected the most by animal disease outbreaks abroad. Regional trade agreements (RTAs) mitigate the impact of animal diseases, showing that trade integration could benefit their members beyond the lowering their tariffs. In the second chapter, we evaluate the impact of the North American Free Trade Agreement on agri-food trade. We found that NAFTA increased members' trade by 54%, amounting to 11.9 billion of 2020 USD annually on average. NAFTA's trade gains were distributed heterogeneously across members, with trade between Canada and Mexico recording the largest proportional gains. Cereals recorded substantial gains during NAFTA, while the trade of beef and vegetables also increased. The trade though of some products that did not become completely tariff-free by members, such as eggs, dairy, and poultry, underperformed. Lastly, NAFTA increased Canada, Mexico, and U.S. trade about 4.5 times more than the other agreements signed by the three countries. In the third chapter, we investigate whether RTAs mitigate the impact of exchange rate (ER) volatility on agri-food trade. The results suggest that RTAs amplify the impact of ER volatility, however, this is in favor of RTA members, since the impact of ER volatility on their trade is positive. The results are heterogeneous across sectors, incomes of exporters and importers, and extent of liberalization by RTAs. Partial Scope Agreements, the lowest level of trade liberalizing agreements, are the only type of RTAs that amplify (or affect in general) the effect of ER volatility on members' agri-food trade.

<p>The need to understand and accurately assess the health risks of low dose ionizing radiation is more important now than ever before. The global applications of ionizing radiation in medicine, mining, manufacturing, and the nuclear industry have increased exponentially in recent years. Parallel to this increase are the health concerns regarding occupational and medical exposures to radiation. The research presented here investigates the biological and health effects of ionizing radiation, specifically from medical diagnostic exposures.</p> <p>Medical diagnostic procedures such as x-rays and computed tomography (CT) scans account for a notable portion of the public's exposure to ionizing radiation. The health risk to humans associated with these low dose exposures is unknown. Often times they are correlated with risk estimates derived from much higher radiation doses. There is no doubt that very high dose ionizing radiation can be harmful; however, the same notion does not exist regarding exposures to low dose ionizing radiation such as that from medical diagnostic CT exposures.</p> <p>The objective of this research is to address the effects and risks associated with diagnostic CT scans. This research focuses on the biological outcome of cancer which remains a primary concern in health care and the development of radiation risk policies. The investigation utilized various mouse models that have differing sensitivities to radiation and susceptibilities to developing radiation-induced cancer.</p> <p>Results from this research found that low-dose diagnostic CT scans do not increase risk and can, in fact, induce protective effects. The hypothesis that harmful effects increase linearly with radiation dose is not supported by this research. With low doses of CT scans, protective biological effects such as reduced chromosomal aberrations, decreased radiation-induced oxidative DNA damage, and enhanced clearance of damaged cells have been observed. In cancer-prone mice, CT scans can increase longevity and reduce cancer risk by delaying the latency of specific cancers.</p> <p>This research advances the understanding of the biological effects and health risk associated with low-dose medical diagnostic procedures. This research is timely and important to allow medical practitioners, policy makers, and regulators to make informed decisions about using ionizing radiation in the clinic. Such knowledge is valuable as better, more complex, and perhaps more damaging modalities are being used to image and manage disease.</p> / Doctor of Philosophy (PhD)

Doctor of Philosophy / Department of Animal Sciences and Industry / Barry J. Bradford / The transition period in dairy cows is characterized by dramatic increases in nutrient requirements for lactation and substantial metabolic stress. The disturbed metabolic balance, coupled with suppressed immune function, contributes to markedly elevated incidence of health disorders. Several lines of evidence suggest that increased inflammation is common during the transition period. Unlike the classical inflammation associated with acute infection, the postpartum inflammatory state is low-grade and often of metabolic origin. This metabolic inflammation plays a key role in numerous disorders; an improved understanding of inflammatory pathways in transition cows may improve our ability to predict and prevent disorders. To mimic metabolic inflammation, in Experiment 1, we administered low amounts of recombinant bovine tumor necrosis factor-α (rbTNFα), a pro-inflammatory cytokine, to early lactation cows, and evaluated whether rbTNFα affects milk production, metabolism, and health. We found that rbTNFα administration increased systemic inflammation, decreased feed intake and milk yield, and increased incidence of disorders. Conversely, preventing excessive inflammation has the potential to improve productivity and health of dairy cows. To identify nutritional strategies that could enhance metabolism and immunity, we evaluated the efficacy of several feed additives. In Experiment 2, we evaluated effects of chromium propionate, rumen-protected lysine and methionine, or both on metabolism and immunity in lactating dairy cows, and found that supplementation of these nutrients may enhance neutrophil function. In Experiment 3, we determined whether supplementation of yeast product to transition cows could enhance production, metabolism, and immunity, and found that yeast product modulated feeding behavior, metabolism, immunity, and uterine inflammation. Overall, a greater understanding of the role of metabolic inflammation in the transition period and the nutritional strategies that could modulate these signals may improve the production and health of dairy cows.

Master of Science / Department of Animal Science / R. Scott Beyer / Daniel Y.C. Fung / Clostridium perfringens causes necrotic enteritis (NE), resulting in decreased feed efficiency and increased mortality, costing the poultry industry USD 2 billion a year worldwide. The objective of the first trial was to validate the Fung Double Tube (FDT) to detect and enumerate C. perfringens in chicken intestines. Two methods (FDT and petri plates) and three media (Shahidi Ferguson Perfringens [SFP] with egg supplement, polymyxin B [p], and kanamycin [k; E]; SFP with p and k [P]; and SFP with cycloserine [C]) were arranged in a 2 x 3 factorial, resulting in six treatments. The FDT with medium C (5.35 log CFU/g) had significantly (P<0.05) higher C. perfringens counts than any other media/method combination. The objective of the second and third trials was to determine the effect of diet type on the population of C. perfringens in broiler intestines using the FDT. Trial 2 tested: corn-soybean meal (SBM), low-crude protein (19.8%)/high synthetic amino acids (SAA), and barley (56%)-fishmeal (4%; BF). Diets in Trial 3 included: corn-SBM, barley (7.46%), fishmeal (4%), and BF. Diets in Trial 2 contained an antibiotic and a coccidiostat; diets in Trial 3 did not. After 21 days, birds in Trial 2 fed BF had significantly higher (P<0.05) counts (5.96 log CFU/g) of C. perfringens, as compared to all other diets. Both, corn-SBM and SAA diets resulted in 3.89 log CFU/g. In Trial 3, birds fed the corn-SBM diet (2.7 log CFU/g) had significantly lower (P<0.05) counts than broilers fed BF (4.15 log CFU/g). When broilers were fed fishmeal (3.583 log CFU/g) and barley (3.577 log CFU/g) separately, C. perfringens counts were numerically higher compared to the corn-SBM diet, but numerically lower than birds fed BF. Barley and fishmeal inclusion increased the incidence of C. perfringens, and their combination resulted in a cumulative effect. The FDT method is able to detect C. perfringens at higher levels than the conventional petri plate method (P<0.001) and it also proved to be an effective method to detect differences in C. perfringens counts from the intestines of chickens fed different diet.