In this study, die-off patterns of helminth ova, fecal coliforms, and Salmonella spp. in biosolids were documented using three small-scale sand drying beds located in a greenhouse. Treatments involved tilling the biosolids with differing frequencies. The results indicate that the inactivation rate for helminth ova was 0.88, 0.55, and 0.22 eggs/4 g TS day-1 for the intensively-tilled, moderately-tilled, and control beds, respectively. Achievement of Class A criteria was only possible in the intensively-tilled bed by Day 70 of the experiment. Salmonella spp. were inactivated to Class A levels in 9 days for the intensively and moderately-tilled beds. Regrowth of Salmonella spp. occurred thereafter in all beds, but high levels were seen only in the control bed. Fecal coliforms reached Class A criteria late in the experiment. Tilling treatments enhanced the inactivation rate of helminth ova and offer a potentially cost-effective method of pathogen reduction.

Phytophagous insects and plants comprise one half of all macroscopic organisms on Earth, and understanding plant-insect interactions has been a long-standing focus in ecological and evolutionary biology. A key challenge has been determining the factors that affect how insects distribute among plants. While ditrophic and tritrophic interactions are well known and enormously important, the biophysical context in which these interactions occur is largely unexplored. This dissertation examines how a plant's physical environment affects insect performance on, and preference for, its leaves.An insect's primary physiological challenges are staying within an appropriate temperature range and retaining sufficient water. These problems are exacerbated during the egg stage. Eggs have comparatively enormous ratios of surface area to volume, and their temperature is determined largely by where they are laid. Because they are small, eggs are nearly always immersed within their plant's boundary layer, a thin layer of still air that resists heat and moisture transfer between the plant and its surroundings. Almost no work has documented the microclimate to which insects are exposed in a plant's boundary layer, which likely differs substantially both from the ambient macroclimate, and from leaf to leaf.Because a female controls the location in which her eggs must develop, her choice of oviposition site may profoundly influence the success of her offspring. In this dissertation I examine how site-specific environmental variables, including microclimate, predation, and leaf nutrition, drive female oviposition preference and offspring performance in the hawkmoth, Manduca sexta L. (Lepidoptera: Sphingidae). I measure how leaves of M. sexta's primary host plants in the southwestern USA modify the temperature and humidity experienced by eggs, and how these leaf microclimates affect the performance of eggs and larvae. I then test whether this species' oviposition-site choices correlate with offspring performance with regard to microclimate, predation risk, and leaf nutrition. This dissertation is unique in focusing on the relatively unstudied biophysical context in which plant-insect interactions occur. Additionally, it is the first work that compares, together in a single study, the effects of varying multiple factors related to oviposition-site choice across all life history stages in a single model system.

Salmonella is a common enteric pathogen and is the most frequently reported bacterial infection in the United States. The two most commonly reported serotypes causing human illness in the United States are Salmonella serotype Typhimurium and Salmonella serotype Enteritidis (SE). The incidence and number of foodborne outbreaks of SE started to increase in the 1970s and by 1994, SE was the most common Salmonella serotype reported to the Centers for Disease Control and Prevention (CDC). SE has been most commonly associated with consumption of shell eggs. Outbreak reports were obtained from the Foodborne Disease Outbreak Surveillance System (FDOSS) and analyzed. The number of outbreaks of SE has declined by 67% since 1990, likely as a result of the combined effect of on-farm interventions, public health policies, and food safety education messages. In addition to the decline in SE outbreaks, study findings demonstrate that there have been changes in the geographical distribution of SE outbreaks in the US. “Simple egg” foods and retail food settings have been the most commonly and consistently associated vehicles and food consumption and preparation settings with SE outbreaks in the US from 1973 to 2008.

The purpose of this study was to examine the degree of market power in the marketing chain of the broiler chicken, egg, and beef industries in Canada. The principal method of analysis tested for the existence of asymmetry. Supplementary testing included estimates of markup equations, means and coefficients of variation, elasticities of demand and price transmission, and correlation coefficients. / The findings give retailers market power in Montreal and Toronto for chicken, and in Toronto, Edmonton, and Winnipeg for beef. Vancouver retail prices for chicken and eggs were statistically independent of prices at the other levels. Processors dominated producers in the chicken markets of Montreal and Toronto, and the Winnipeg beef market. Producers showed possible dominance in the Montreal egg market. / Symmetry occurred most often in the beef and egg markets; which share the character of flat or declining consumer demand conditions. The ability to exercise market power may be determined by strong demand coupled with institutional price-responsiveness.

A study was conducted to examine the response to feeding flaxseed (FS) and probiotics on plasma and egg yolk cholesterol and plasma fatty acid profile in laying hens. A total of 576 Single Comb White Leghorn hens (SCWL) at 26 weeks of age were fed diets containing 15% FS and a corn-soybean meal diet (C) supplemented with and without ferlac 25 (F25) or Lactobacillus acidophilus (LA). Feed consumption was significantly (p < 0.05) increased by FS supplemented with both F25 and LA. Dietary treatments had no significant (p > 0.05) effect on feed conversion. Egg production was significantly (p < 0.05) higher among the FS probiotic supplemented diets and significantly (p < 0.05) lower for dietary FS supplemented with LA. However, egg yolk weight did not respond to dietary treatments (p > 0.05). Body weight was significantly low for all FS fed groups. Shell thickness was not statistically significant (p > 0.05) among experimental treatments, while haugh units were significantly (p < 0.05) higher for FS group supplemented with LA. Probiotic supplementation significantly (p < 0.05) reduced plasma cholesterol (CHL) from 161mg/dL in C diet to 117mg/dL in probiotic supplemented groups. Plasma triglycerides (TG) were significantly (p < 0.05) reduced from 2.8g/dL in FS to 1.9g/dL in probiotic supplemented groups while egg yolk CHL was significantly (p < 0.05) reduced by probiotic supplementation on FS treatments from 14.04mg/g in FS fed group to 10.16mg/g in LA supplemented FS group. Fatty acids profile in the egg yolk responded significantly (p < 0.05) to dietary treatments. FS treatments with and without probiotic supplementation significantly reduced C18:1 o-9 by 12%; while the PUFA families (o-3 and o-6) were significantly (p < 0.05) increased in FS fed group by 93% and 18%, respectively. C20:4, o-6 was significantly reduced from 6.6mg/g in the C group to 3.96mg/g in Fs groups. (Abstract shortened by UMI.)

Pulsed Electric Field (PEF) processing, a novel, non-thermal food preservation method, has been shown to inactivate both spoilage and pathogenic microorganisms, while minimizing changes in the physical and organoleptic qualities of the food, such as those observed under conventional thermal processing. An understanding of the inactivation mechanisms and kinetics of microorganisms exposed to lethal or sub-lethal PEF treatments would allow industry and consumers to better understand and evaluate the potential of PEF technology as an alternative or complement to traditional methods of food preservation. This study consisted of three sets of experiments which sought to determine: (i) the electrical conductivity (EC) of various liquid food products (apple, orange and pineapple juices, egg white, whole egg and egg yolk) at different temperatures (5--55°C); (ii) the capacity of PEF (15 kV cm-1, 0°C) to inactivate Escherichia coli O157:H7 in dialyzed liquid egg products; and (iii) the effect of PEF (20 or 30 kV cm-1) in combination with temperature (10--40°C) on the inactivation of E. coli and Salmonella Enteritidis in liquid egg yolk (EY), whole egg (WE), or egg white (EW). The treatment chamber design was based in part on regression equations of EC vs. temperature developed in the first set of experiments. After only 0.1 sec of PEF (15 kV cm-1) treatment, l, 3 and 3.5 log reductions of E. coli were noted in dialyzed egg white, egg yolk and whole egg, respectively. Kinetic models of bacterial inactivation were proposed. A 210 mus exposure to PEF (30 kV cm-1 ) resulted in log reductions of 5.0 and 5.0 in egg yolk, 3.9 and 3.6 in WE and, 2.8 and 3.6 in egg white, for E. coli and S. Enteritidis, respectively. A maximum energy of 914 J was required to inactivate S. Enteritidis in WE. In egg white, cells injured by PEF represented 0.9 and 0.4 log for S. Enteritidis and E. coli, respectively. An exponential decay model and an Arrhenius equation were

The mechanisms responsible for overland transport of faecal pathogens, particularly Cryptosporidium oocysts, from animal sources to water bodies are not fully understood. Surface properties of microbes, such as electrostatic charge and hydrophobicity, are thought to contribute to their aggregation and attachment to solid surfaces. There is conflicting evidence that methods used to purify Cryptosporidium oocysts from faecal material may affect the oocyst surface, leading to biased conclusions from transport studies. By studying oocyst surface properties, aggregation and soil attachment, this thesis addressed whether oocyst purification methods influence overland transport studies, and whether oocysts are likely to be associated with particles during transport. When using the microbial adhesion to hydrocarbon (MATH) assay with octane, oocyst hydrophobicity was shown to be method and isolate dependent, with oocysts displaying moderate to high hydrophobicity in 0.01 M KNO3. There was no observed attachment, however, to the hydrophobic octyl-SepharoseTM bead ligands when using the same suspension solution. Oocyst age did not appear to influence their hydrophobicity. A small but statistically significant proportion of oocysts displayed a net negative surface charge as observed by their attachment to an anion exchange ligand (DEAE). There was no difference in hydrophobicity or surface charge observed between purified oocysts and oocysts that had been extracted without the use of harsh chemicals and solutions with dehydrating properties. Purified oocysts did not aggregate at pH values between 3.3 and 9.0, nor in solutions lower than 0.59 M in ionic strength at a pH 2.7 which is approaching the reported isoelectric point of oocysts. This finding suggests that oocysts may not form aggregates under general environmental conditions. The association of purified oocysts with soil particles was observed in settling columns. Attachment to soil particles was not conclusive since the settling of the soil particles may have entrained single oocysts. Nonetheless, approximately 27% of oocysts were estimated to be unbound to soil or associated with small soil particles. Hence models for oocyst overland transport should consider a significant fraction as single entities or associated with soil particles less than about 3 μm in size.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv., 2003.

Thesis (Ph.D.) -- University of Western Sydney, 2000. / "A thesis submitted for the degree of Doctor of Philosophy at the University of Western Sydney, Macarthur, Faculty of Informatics, Science and Technology" Bibliography : leaves 172-188.

Dissertation (Ph.D.)--Auburn University, / Abstract. Vita. Includes bibliographic references (p.116-129).