Made available in DSpace on 2016-12-08T16:44:39Z (GMT). No. of bitstreams: 1 PGPV10MA081.pdf: 416335 bytes, checksum: 184cf4cccc823fb0c623b143ef078051 (MD5) Previous issue date: 2010-12-14 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / The aim of this study was to evaluate the effects of climatic conditions of the orchard during fruit development, rootstock and of fruit contents of calcium (Ca), magnesium (Mg) and potassium (K) on the internal breakdown in Fuji apples related to the CO2 sensitivity during storage in controlled atmosphere (CA). Three independent experiments were carried out. The first experiment aimed to identify critical levels of climatic conditions from which there is the predisposition of the internal breakdown associated with sensitivity to CO2, and also to evaluate different CA conditions on quality of Fuji apples. Fruits were harvested at three locations characterized by different climatic conditions: Lages and São Joaquim in Santa Catarina (SC), and Vacaria in Rio Grande do Sul (RS). Fruits were stored for eight months in two CA conditions (1.2 kPa O2 + <0.5 kPa CO2 and 1.2 kPa O2 + 2.0 kPa CO2). The second experiment aimed to evaluate the effect of different rootstocks on quality, mineral composition and internal breakdown in Fuji apples stored in two CA conditions. Fruits from three rootstocks (MM-106, Marubakaido and Marubakaido with filter of M-9) were harvested from commercial orchards in São Joaquim, SC, being stored for eight months in two CA conditions: 1.2 kPa O2 + <0.5 kPa CO2 and 1.2 kPa O2 + 2.0 kPa CO2. The third experiment aimed to identify the nutritional attribute that best discriminates the differences in the degree of susceptibility to internal breakdown in Fuji apples stored in CA. Fruit were harvested from three orchards of Vacaria (RS), two orchards of Fraiburgo (SC), and three orchards of São Joaquim (SC). The condition of CA storage with 1.2 kPa O2 + 2.0 kPa CO2 delays ripening and increases the occurrence of internal breakdown of Fuji apples. Lower average temperatures during fruit development increases the susceptibility of Fuji apples to this physiological disorder during CA storage. Fruits from plants with Marubakaido and Marubakaido with filter of M-9 rootstocks show higher internal breakdown incidence than fruits from plants with MM-106 rootstock were stored with 2 kPa CO2. Fruits from MM-106 rootstock had higher Ca content, lower K content and lower K/Ca ratio. Fruits with internal breakdown have lower levels of Ca when compared to fruit without internal breakdown. The Mg and K have no clear relationship with this disorder / O objetivo deste trabalho foi avaliar os efeitos de condições climáticas do pomar durante a fase de desenvolvimento dos frutos, do porta-enxerto e dos nutrientes cálcio (Ca), magnésio (Mg) e potássio (K) e suas relações sobre a ocorrência da degenerescência de polpa em maçãs Fuji , relacionada à sensibilidade ao CO2 durante o armazenamento em atmosfera controlada (AC). Foram realizados três experimentos independentes. O primeiro experimento teve como objetivo identificar os níveis críticos dos fatores climáticos a partir dos quais ocorre a predisposição dos frutos à degenerescência de polpa, associada à sensibilidade ao CO2 e também avaliar diferentes condições de AC sobre a qualidade de maçãs Fuji . Foram utilizados frutos de três municípios caracterizados por condições climáticas distintas: Lages, São Joaquim SC e Vacaria RS, sendo que os frutos foram armazenados por oito meses em duas condições de AC (1,2 kPa O2 + <0,5 kPa CO2 e 1,2 kPa O2 + 2,0 kPa CO2). O segundo experimento teve como objetivo avaliar o efeito de diferentes porta-enxertos sobre a qualidade, composição mineral e degenerescência de polpa em maçãs Fuji armazenadas em duas condições de AC. Foram utilizados frutos de três porta-enxertos (MM-106, Marubakaido e Marubakaido com filtro M-9) provenientes de pomares comerciais do município de São Joaquim SC, sendo armazenados por oito meses em duas condições de AC (1,2 kPa O2 + <0,5 kPa CO2 e 1,2 kPa O2 + 2,0 kPa CO2). O terceiro experimento teve como objetivo identificar qual o atributo nutricional que melhor discrimina as diferenças quanto ao grau de suscetibilidade a degenerescência de polpa em maçãs Fuji armazenadas em AC. Foram utilizados frutos de três pomares do município de Vacaria RS, dois pomares do município de Fraiburgo-SC e três pomares do municio de São Joaquim-SC. A condição de armazenamento em AC com 1,2 kPa de O2 + 2,0 kPa de CO2 retarda o amadurecimento de maçãs Fuji , porém aumenta a ocorrência de degenerescência de polpa. Temperaturas médias no pomar mais baixas durante o desenvolvimento dos frutos aumentam a suscetibilidade de maçãs Fuji a este distúrbio fisiológico durante o armazenamento em AC. Em frutos de plantas com porta-enxerto Marubakaido e Marubakaido com filtro-M9 a incidência de degenerescência de polpa foi mais elevada do que frutos de plantas com porta-enxerto MM- 106, quando estes foram armazenados na condição de 2 kPa de CO2. O porta-enxerto MM- 106 propiciou maiores teores de Ca, menores teores de K e menores relações K/Ca nos frutos. Frutos com degenerescência de polpa apresentam menores teores de Ca quando comparados aos frutos sem degenerescência de polpa. Os teores de Mg e K não possuem clara relação com este distúrbio

Doctor of Philosophy / Department of Diagnostic Medicine/Pathobiology / Tiruvoor G. Nagaraja / Escherichia coli O157 is a major foodborne pathogen. The bovine gut is the primary reservoir and the organism is shed in the feces, which serves as the major source of contamination. The objectives of our research on E. coli O157 were to 1) determine prevalence and characterize presence in the rectoanal mucosa of cattle, 2) rationalize preferential prevalence in the hindgut, 3) evaluate fecal prevalence and concentration in relation to carcass contamination 4) determine the efficacy of preharvest intervention strategies to reduce fecal prevalence and/or concentration in cattle. We determined that E. coli O157 isolated from the rectoanal mucosa were similar to fecal isolates. We evaluated methods of enumeration in cattle feces to identify fecal samples with > 10[superscript3] and 10[superscript4] CFU of E. coli O157/g. We observed that prevalence of E. coli O157 on carcasses was correlated with high-shedders. We identified gluconic acid as a substrate which stimulates growth of E. coli O157 in fermentations with ruminal microbial or fecal microbial inocula from cattle. This may explain the preference to persist or colonize the hindgut because gluconic acid is a component of colonic mucin. Additionally, we evaluated the effects of cattle diets (two grain types and two grain processing methods), which present different amounts of fermentable starch to the hindgut, on prevalence of E. coli O157. Dry-rolled grain-based diets reduced prevalence of E. coli O157, possibly because of increased flow of starch to the hindgut. Competitive exclusion cultures of E. coli in in vitro fermentations reduced E. coli O157 in ruminal microbial inoculum, but in fecal microbial inoculum cultures were only efficacious when gluconic acid also was added. Lastly, we evaluated a vaccine which targeted the siderophore receptor/porin proteins of E. coli O157. The vaccine reduced prevalence, the total number of days cattle tested positive, and the total number of days cattle were identified as high-shedders of E. coli O157. In summary, our research adds further knowledge to the literature about E. coli O157 in the hindgut, provides methods to identify high-shedding animals, demonstrates the importance of high-shedding animals, and offers information about potential preharvest interventions.

Woody plant encroachment is one of the major problems worldwide because it affects negatively the herbaceous layer, which provide forage for livestock production. However, the role of ruminants particularly browsers in the dispersal of woody plant seeds still remains a concern for farmers interested in grass production. Seedpods of various woody plant species constitute a crucial part of the diet of herbivores during the dry season because of their high nutritional quality compared to herbaceous material. The interaction of associated diet quality, seed characteristics and animal species among other factors play a pivotal part in the success of livestock faecal seeds dispersion. Furthermore, dispersed seeds that successfully grow into mature woody plants become an important source of protein for herbivores. The use of woody plants as a source forage is known to be limited by plant secondary metabolites (PSMs) such as condensed tannins. The objectives of this study were to determine 1) the effects of condensed tannins and crude protein of Vachellia tortilis and Dichrostachys cinerea pods in seed recovery and germination fed to goats, and 2) the effects of diet mixing on the feed intake of plant species by goats. In the first experiment, a total of 12 female indigenous goats and 12 female Pedi sheep were utilised in this study, with the average body weights of 29.50 kg ± 1.60 (S.E) and 28.70 kg ± 1.60, respectively. Twelve goats were grouped into two groups of six goats per group, one group was fed D. cinerea pods and the other group was fed V. tortilis pods. The group of 12 sheep were divided similarly, the one group was fed D. cinerea pods and the other group was fed V. tortilis pods. Each animal was given V. tortilis and D. cinerea pods at 2.50% of their body weight. All animals were allowed to consume D. cinerea or V. tortilis pods within 24 h, after which the remaining pods were collected and weighed. Faecal collection commenced immediately after the 24 h pods feeding and was carried on until no seeds were discovered in faeces. All faeces extracted from sheep and goats were collected daily in the morning from the faecal bags. In the second experiment, a total of 24 indigenous goats with average body weight of 26.6 kg ± 0.51 were utilised. Goats were arbitrarily selected and grouped into four groups of six goats per group (goats were placed individually in 2 m2 pens). Each group was fed one of the following diets: diet one - Searsia lancea, diet two - S. pyroides, diet three - Euclea crispa and diet four - was a combination of the three plant species (Searsia lancea, S. pyroides and Euclea crispa). Searsia lancea, S. pyroides and E. crispa branches were collected every morning prior to feeding, and were weighed before offering the animals. Refusals were gathered and weighed, and intake was calculated as distinction between weight in and refusals. Plant species foliage were analysed for crude protein, condensed tannin, acid detergent lignin, acid detergent fibre and neutral detergent fibre. During the first experiment, the cumulative percentage seed recovery of V. tortilis from goats (46.00 % ± 1.90) and sheep (52.00 % ± 2.93) was significantly higher than D. cinerea from goats (13 % ± 1.47) and sheep (24.00 % ± 1.16). Germination percentage of D. cinerea seeds that passed through the gastro-intestinal tract of goats (33.12 % ± 2.94) and sheep (36.00 % ± 2.68) was significantly higher than V. tortilis seeds that passed through the gastro-intestinal tract of goats (28.98 % ± 2.68) and sheep (23.04 % ± 2.81). Average D. cinerea (34.56 % ± 1.99) and V. tortilis (26.02 %± 2.10) seeds that went through the gastro-intestinal of goats and sheep had a significantly higher germination rate than the control (i.e. no passage through the gut; D. cinerea = 2.31 % ± 1.55, V. tortilis = 5.07 % ± 2.68). The high mean cumulative percentage seed recovery of V. tortilis (18.80 %) may be attributed to the relatively higher crude protein than D. cinerea (12.20 %). This may encourage animal seed dispersal and germination of woody plant species with relatively high crude protein content. In the second experiment, Searsia lancea contained 8.50 % CP, 21.46 % acid detergent fibre (ADF), 12.50 % ADL and 39.37 % NDF. Searsia pyroides had 9.03 % CP, 27.07 % ADF, 10.89 % ADL and 40.30 % NDF. Euclea crispa had 6.19 % CP, 26.20 % ADF, 16.63 % ADL and 30.02 % NDF. Mixed diet (combination of the three plant species) had 8.96 % CP, 23.72 % ADF, 11.13 % ADL and 38.28 % NDF. Searsia lancea had 2.70 % of CTs while S. pyroides had 5.20 % CT, E. crispa had 6.44 % CT and mixed diet had 7.20 % CT. The mean dry matter intake varied significantly among dietary groups (P < 0.001). Similarly, goats offered a mixed diet consumed more CTs (P < 0.01) than those offered individual forage species. The high mean cumulative percentage seed recovery of V. tortilis may be attributed to the higher crude protein of V. tortilis (18.80 %) than D. cinerea (12.20 %). Higher passage rate may encourage animal seed dispersal and germination of plant species. The results from experiment two support the postulation that animals foraging in mixed diet systems consume more PSMs and achieve higher dry matter intake than animals confined to monocultures or single species feeding systems. Given that woody plant encroachment is already reducing farm-grazing capacities in African savannas and this problem is predicted to double by 2050, strategies that improve herbivore ability to consume woody plants will increase forage availability and inform bush control programmes and policies. Moreover, the concomitant increase in CTs by goats exposed to diets with diverse species also has positive implications for animal / Agriculture, Animal Health and Human Ecology / M. Sc. (Agriculture)