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No description available.

Thesis (M.A.)--University of Delaware, 2007. / Principal faculty advisor: Rebecca J. Sheppard, School of Urban Affairs & Public Policy. Includes bibliographical references.

Summary The aim of this study was to determine the egg production potentials of four different indigenous chicken breeds in South Africa: Potchefstroom Koekoek, Venda, Ovambo and Naked Neck. The White Leghorn breed was used as the control. The egg production potentials were evaluated over two consecutive production cycles of 52 weeks (used as replicates). Data were collected at the experimental farm of the Agriculture Research Council at Irene. Treatment means were separated using Fisher’s protected t-test least significant difference at the 5 percent level of significance and the percentage mortality rate by means of a row by column chi-square test. No significant differences were observed between breeds on the mean age to the production of the first egg. The White Leghorn was superior ( p ≤ 0.05) to all four of the indigenous breeds for the mean number of eggs and percentage hen-housed egg production produced per production cycle. The Potchefstroom Koekoek was also superior ( p ≤ 0.05) to the other three indigenous breeds for these parameters. There was no difference between the Ovambo and Naked Neck breeds. The percentage mortality rate for the White Leghorn (39.5 percent) was significantly ( p ≤ 0.05) different from that of the Venda, Ovambo and Potchefstroom Koekoek (22.2 percent). No differences were observed among the Potchefstroom Koekoek, Venda, Ovambo and Naked Neck (32.3 percent) or between the White Leghorn and Naked Neck with regard to the mean percentage mortality.

Flavobacteria and pseudomonads are traditionally known to cause spoilage in food and food products (Forsythe, 2000, pp. 96–98 and 101–103). In the literature on meat spoilage, ‘flavobacteria’ is used as a generic name for yellowpigmented rods (Hendrie et al., 1969). Usually, pathogens such as Salmonella and Campylobacter are associated with poultry, but large numbers of other bacteria often associated with spoilage are found on poultry carcasses. These include many so-called flavobacteria that may originate from the poultry itself or from the abattoir environment and which are responsible for spoilage (Hang’ombe et al., 1999). Mai & Conner (2001) found that the incidence of members of the genus Pseudomonas and flavobacteria on chicken carcasses was 17 and 16 %, respectively. The incidence of flavobacteria on poultry is much higher than on other fresh meat (Nychas & Drosinos, 1999). Over the past decade, many changes have taken place in the taxonomy of the family Flavobacteriaceae, and the revised genus Flavobacterium comprises mainly aquatic bacteria that are not known in food microbiology (Bernardet et al., 1996). Several former Flavobacterium species were transferred to the novel genus Chryseobacterium (Vandamme et al., 1994) and novel species have been described, including Chryseobacterium joostei (Hugo et al., 2003), Chryseobacterium defluvii (Ka¨mpfer et al., 2003), Chryseobacterium miricola (Li et al., 2003) and, most recently, Chryseobacterium formosense (Young et al., 2005), Chryseobacterium daecheongense (Kim et al., 2005a) and Chryseobacterium taichungense (Shen et al., 2005). ‘Chryseobacterium proteolyticum’ was described by Yamaguchi & Yokoe (2000), but its name has not been validly published. In addition, two Chryseobacterium species, Chryseobacterium meningosepticum and Chryseobacterium miricola, have been reclassified into the novel genus Elizabethkingia (Kim et al., 2005b). In general, these Chryseobacterium species are widely distributed in water, soil and the clinical environment, but they are also found in food specimens, such as milk, meat, poultry and fish (Jooste & Hugo, 1999).

A laboratory incubation study was conducted to determine the effects of liming on microbial activity and N mineralization in two Bizana soils amended with broiler manure. The experimental layout was a 4 x 3 complete factorial experiment with three replicates, arranged in a randomized design. Soil pH, CO2 evolution, and mineral N concentration were measured. After 56 days the soil pH ranged from 4.50 to 5.74 and 4.99 to 5.94, in the Magusheni and Nikwe soils, respectively. The effect of liming on microbial activity and N mineralization differed between the soils. In the Nikwe soil (acid saturation 4.0%), microbial activity and N mineralization increased as the rate of broiler manure application was raised, but liming had no effect. In the Magusheni soil (acid saturation 25%), microbial activity increased as both lime and chicken manure application rates increased, but liming reduced N mineralization, suggesting N immobilization was being driven by an active microbial population in the limed soils. The rates of lime and/or chicken manure application, percentage Ca2+ and soil acid saturation were important factors influencing microbial activity and N mineralization, but the effect of soil pH on N mineralization was not evident in either of the soils.

This study assessed the influence of terrestrial invertebrate abundance and vegetation characteristics on northwest Minnesota greater prairie chicken brood success. Radio telemetry was used to determine movements of greater prairie chicken hens and their broods. Invertebrate abundance indices were collected using a sweep net and vegetation data were recorded with overhead and dot-board photographs. Invertebrates were dried, sorted by size and order, and weighed and counted. Vegetation was classified according to life form and height was measured. Greater prairie chicken broods appear to use those habitats most readily available with increased invertebrate resources. Invertebrate biomass was not related to the occurrence of uncultivated forbs which averaged < 17% in Minnesota habitats where greater prairie chicken broods were located. Relatively undisturbed grasslands produce sufficient invertebrate resources to fledge greater prairie chicken chicks. However, location data and invertebrate-habitat indices suggest increased brood success would be likely with improved habitat placement/availability and irregular disturbance regimes that produce beneficial mixed grass/forb vegetation attractive to both greater prairie chicken broods and their invertebrate prey.

This thesis is an investigation of human campylobacteriosis and Campylobacter from retail chicken in two Ontario health units. The objectives were to investigate the symptoms, severity, antimicrobial use (AMU), antimicrobial resistance (AMR), and duration of illness (DI) in clinical campylobacteriosis, the prevalence and AMR of Campylobacter from contaminated retail chicken, and the relationship between clinical and chicken Campylobacter isolates based on Comparative Genomic Fingerprinting (CGF). In the participating health units, campylobacteriosis case data were collected and retail chicken was sampled from randomly selected stores. Campylobacter isolates from clinical cases and chicken were antimicrobial susceptibility tested and CGF typed. A Cox proportional hazard model was used to investigate the DI in campylobacteriosis. Logistic regression models were used to explore the relationship between clinical and chicken CGF types. Of 250 cases, 52% reported taking antimicrobials for their campylobacteriosis. In 124 cases with accompanying isolate and AMR information, 6 (4.8%) and 2 (1.6%) isolates were resistant to ciprofloxacin and erythromycin, respectively. In 749 chicken isolates, 14 (1.9%) and 25 (3.3%) isolates were resistant to ciprofloxacin and erythromycin, respectively. No isolates were resistant to both antimicrobials. While the low prevalence of AMR to ciprofloxacin and erythromycin was encouraging, the high proportion of cases treated with antimicrobials was concerning and efforts should be made to reduce unnecessary treatment. The Cox model identified that use of a macrolide for less than the recommended duration, use of ciprofloxacin for the recommended duration, and use of other antimicrobials, were factors associated with decreased DI. The impact of AMU was consistent regardless of when in the course of illness it began. The CGF results were available from 115 clinical and 718 chicken isolates. A Campylobacter CGF reference database was used to identify CGF types that comprised at least 80% of isolates from chicken, based on 90% fingerprint similarity (CA90). Isolates from urban cases were significantly more likely than rural cases to be CA90. In Canada, the majority of campylobacteriosis cases are urban dwellers. Therefore, the association between urban cases and CA90 emphasizes the importance of Campylobacter from retail chicken on public health.

This study assessed the influence of terrestrial invertebrate abundance and vegetation characteristics on northwest Minnesota greater prairie chicken brood success. Radio telemetry was used to determine movements of greater prairie chicken hens and their broods. Invertebrate abundance indices were collected using a sweep net and vegetation data were recorded with overhead and dot-board photographs. Invertebrates were dried, sorted by size and order, and weighed and counted. Vegetation was classified according to life form and height was measured. Greater prairie chicken broods appear to use those habitats most readily available with increased invertebrate resources. Invertebrate biomass was not related to the occurrence of uncultivated forbs which averaged < 17% in Minnesota habitats where greater prairie chicken broods were located. Relatively undisturbed grasslands produce sufficient invertebrate resources to fledge greater prairie chicken chicks. However, location data and invertebrate-habitat indices suggest increased brood success would be likely with improved habitat placement/availability and irregular disturbance regimes that produce beneficial mixed grass/forb vegetation attractive to both greater prairie chicken broods and their invertebrate prey.