Variable and strain dependent colonisation of chickens by Escherichia coli O157

The prevalence of enterohaemorrhagic Escherichia coli (EHEC) O157 in poultry is considered minimal compared with other species, especially ruminants. However, deliberate inoculation studies have shown that poultry are readily and persistently infected by this organism but that the mechanism of colonisation is independent of intimin, a recognised factor in host-EHEC interactions in mammalian species, and may be dependent upon flagella. Few strains of EHEC O157 have been tested in poultry and here 1-day-old and 6-week-old chicks were inoculated with seven non-toxigenic E. coli O157 strains in separate experiments. Persistence was measured semi-quantitatively by bacteriological assessment of E. coli O157 cultured from cloacal swabs (shedding score). In the 1-day-old chick model that was monitored for 43 days, all seven strains established well after inoculation. In the 6-week-old chicken model, one strain established and gave consistently high shedding for the duration of the experiment (156 days). Whereas of the remaining six strains, two persisted for 113 days, two persisted for 43 days, one persisted for 22 days and one strain was never detected.

Fluoroquinolone treatment of experimental Salmonella enterica serovar Typhimurium DT104 infections in chickens selects for both gyrA mutations and changes in efflux pump gene expression

Objectives: To determine the efficacy of enrofloxacin (Baytril) in chickens in eradicating three different resistance phenotypes of Salmonella enterica and to examine the resistance mechanisms of resulting mutants. Methods: In two separate replicate experiments (I and 11), three strains of Salmonella enterica serovar Typhimurium DT104 [strain A, fully antibiotic-sensitive strain; strain B, isogenic multiple antibiotic-resistant (MAR) derivative of A; strain C, veterinary penta-resistant phenotype strain containing GyrA Phe-83], were inoculated into day-old chicks at similar to 10(3) Cfu/bird. At day 10, groups of chicks (n =10) were given either enrofloxacin at 50 ppm in their drinking water for 5 days or water alone (control). Caecal contents were monitored for presence of Salmonella and colonies were replica plated to media containing antibiotics or overlaid with cyclohexane to determine the proportion of isolates with reduced susceptibility. The MICs of antibiotics and cyclohexane tolerance were determined for selected isolates from the chicks. Mutations in topoisomerase genes were examined by DHPLC and expression of marA, soxS, acrB, acrD and acrF by RT-PCR. Results: In experiment 1, but not 11, enrofloxacin significantly reduced the numbers of strain A compared with the untreated control group. In experiment 11, but not 1, enrofloxacin significantly reduced the numbers of strain B. Shedding of strain C was unaffected by enrofloxacin treatment. Birds infected with strains A and B gave rise to isolates with decreased fluoroquinolone susceptibility. Isolates derived from strain A or B requiring > 128 mg/L nalidixic acid for inhibition contained GyrA Asn-82 or Phe-83. Isolates inhibited by 16 mg/L nalidixic acid were also less susceptible to antibiotics of other chemical classes and became cyclohexane-tolerant (e.g. MAR). Conclusions: These studies demonstrate that recommended enrofloxacin treatment of chicks rapidly selects for strains with reduced fluoroquinolone susceptibility from fully sensitive and MAR strains. It can also select for MAR isolates.

Modification of enrofloxacin treatment regimens for poultry experimentally infected with Salmonella enterica serovar Typhimurium DT104 to minimize selection of resistance

We hypothesized that higher doses of fluoroquinolones for a shorter duration could maintain efficacy (as measured by reduction in bacterial count) while reducing selection in chickens of bacteria with reduced susceptibility. Chicks were infected with Salmonella enterica serovar Typhimurium DT104 and treated 1 week later with enrofloxacin at the recommended dose for 5 days (water dose adjusted to give 10 mg/kg of body weight of birds or equivalence, i.e., water at 50 ppm) or at 2.5 or 5 times the recommended dose for 2 days or 1 day, respectively. The dose was delivered continuously (ppm) or pulsed in the water (mg/kg) or by gavage (mg/kg). In vitro in sera, increasing concentrations of 0.5 to 8 mu g/ml enrofloxacin correlated with increased activity. In vivo, the efficacy of the 1-day treatment was significantly less than that of the 2- and 5-day treatments. The 2-day treatments showed efficacy similar to that of the 5-day treatment in all but one repeat treatment group and significantly (P < 0.01) reduced the Salmonella counts. Dosing at 2.5x the recommended dose and pulsed dosing both increased the peak antibiotic concentrations in cecal contents, liver, lung, and sera as determined by high-pressure liquid chromatography. There was limited evidence that shorter treatment regimens (in particular the 1-day regimen) selected for fewer strains with reduced susceptibility. In conclusion, the 2-day treatment would overall require a shorter withholding time than the 5-day treatment and, in view of the increased peak antibiotic concentrations, may give rise to improved efficacy, in particular for treating respiratory and systemic infections. However, it would be necessary to validate the 2-day regimen in a field situation and in particular against respiratory and systemic infections to validate or refute this hypothesis.

Commonly used farm disinfectants can select for mutant Salmonella enterica serovar Typhimurium with decreased susceptibility to biocides and antibiotics without compromising virulence

Objectives: To determine if one passage of Salmonella enterica serovar Typhimurium in the presence of farm disinfectants selected for mutants with decreased susceptibility to disinfectants and/or antibiotics. Methods: Eight Salmonella Typhimurium strains including field isolates and laboratory mutants were exposed to either a tar oil phenol (PFD) disinfectant, an oxidizing compound disinfectant (OXC), an aldehyde based disinfectant (ABD) or a dairy sterilizer disinfectant (based on quaternary ammonium biocide) in agar. The susceptibility of mutants obtained after disinfectant exposure to antibiotics and disinfectants was determined as was the accumulation of norfloxacin. The proteome of SL1344 after exposure to PFD and OXC was analysed using two-dimensional liquid chromatography mass spectrometry. Results: Strains with either acrB or tolC inactivated were more susceptible to most disinfectants than other strains. The majority (3/5) of mutants recovered after disinfectant exposure required statistically significantly longer exposure times to disinfectants than their parent strains to generate a 5 log kill. Small decreases in antibiotic susceptibility were observed but no mutants were multiply antibiotic-resistant (MAR). Notably exposure to ABD decreased susceptibility to ciprofloxacin in some strains. Mutants with increased disinfectant tolerance were able to survive and persist in chicks as well as in parent strains. Analysis of proteomes revealed significantly increased expression of the AcrAB-TolC efflux system after PFD exposure. Conclusions: Data presented demonstrate that efflux pumps are required for intrinsic resistance to some disinfectants and that exposure to disinfectants can induce expression of the AcrAB-TolC efflux system, but that single exposure was insufficient to select for MAR strains.

Efficacy of a live attenuated Escherichia coli O78:K80 vaccine in chickens and turkeys

A candidate live vaccine for avian pathogenic Escherichia coli (APEC) was constructed from a virulent field APEC O78 strain by mutation of the aroA gene. The mutant was highly similar to the parent wild-type strain in respect of colony morphology, motility, growth in suspension, hemagglutination, Congo Red binding, HEp-2 cell adhesion, and the elaboration of surface antigens type 1 fimbriae and flagella, although production of curli fimbriae was reduced marginally. The mutant proved avirulent when inoculated into 1-day-old chicks by spray application and when presented again in the drinking water at 7 days of age. Chickens and turkeys vaccinated with an O78 aroA mutant were protected against a challenge at 6 wk of age by virulent APEC strains.

Agriculture and the life histories of Mauritius kestrels

Habitat modification for agriculture is one of the greatest current threats to global biodiversity. Studies show large-scale population declines and short-term demographic impacts, but knowledge of the long-term effects of agriculture on individuals remains poor. This thesis examines the short- and long-term impact of agriculture on a reintroduced population of the Mauritius kestrel Falco punctatus, a tropical forest-dwelling raptor endemic to the island of Mauritius, that also utilises agricultural habitats. This population is a particularly appropriate model system, because complete life history data exists for individuals over a 22-year period, alongside detailed habitat and climate data. Agriculture has a short-term detrimental effect on Mauritius kestrel breeding success by exacerbating the seasonal decline in fledgling production. This is partly driven by the habitat-specific composition of the prey community that kestrels exploit to feed their chicks. The fledglings from agricultural territories tend to recruit in agricultural territories. This is largely due to poor natal dispersal and fine-scale spatial autocorrelation in the habitat matrix. Breeders do not respond to agriculture in the breeding territory by dispersing, unless the pair bond is broken. Therefore, individuals originating in agricultural territories tend to recruit, and remain in, agricultural territories throughout their lives. In addition to this, females from agricultural natal territories have shorter lifespans, schedule their peak reproductive output earlier in life, and exhibit more rapid senescence than non-agricultural females. The combination of this long-term effect and the adult experience of agriculture imposed by life history and environmental constraints, leads to a lower mean lifetime reproductive rate compared to females originating in non-agricultural habitats. These results demonstrate that agriculture experienced in early life has a lifelong effect on individuals. The effects can persist in time and space, with potentially delayed effects on population dynamics. These findings are important for understanding species’ responses to agricultural expansion.

Breeding biology of the White-headed Vulture Trigonoceps occipitalis in Kruger National Park, South Africa

Information on the breeding biology of the White-headed Vulture Trigonoceps occipitalis is limited and published data are few. Within the Kruger National Park in north-east South Africa there is a regionally important population of about 60 White-headed Vulture pairs, of which 22 pairs were monitored for five years between 2008 and 2012 to determine key aspects of their breeding biology. Across 73 pair/years the mean productivity of 55 breeding attempts was 0.69 chicks per pair. Median egg-laying date across all of the Kruger National Park was 27 June, but northern nests were approximately 30 d later than southern nests. Mean (SD) nearest-neighbour distance was 9 976  7 965 m and inter-nest distances ranged from 1 400 m to more than 20 km, but this did not differ significantly between habitat types. Breeding productivity did not differ significantly between habitat types. The results presented here are the first for this species in Kruger National Park and provide details against which future comparisons can be made.

Effect of arginine on the development of the pectoralis muscle and the diameter and the protein:deoxyribonucleic acid rate of its skeletal myofibers in broilers

This work aimed at evaluating the effects of the supplementation of starter diet with Arg on breast muscle development in broilers and the activation of satellite cells and the aggregation of myofibrillar protein. Male Cobb chicks (n = 990) were randomly assigned to 1 of 5 treatments in a complete random design. Measurements of 33 chicks per treatment were made in 6 repetitions. The treatments consisted of a basal diet with 1.390% digestible Arg (without supplementation) and 4 dietary levels of Arg (1.490, 1.590, 1.690, and 1.790%) with Arg:Lys ratios of 1.103, 1.183, 1.262, 1.341, and 1.421, respectively. Arginine supplementation was used only in the starter phase (1 to 21 d). Dietary supplementation with Arg had a positive effect (P < 0.05) on breast and breast fillet weight on d 7 and 21 and on myofiber diameter on d 14 and 21. However, no effect was observed (P > 0.05) on the protein: DNA ratio, which demonstrates that Arg does not interfere with the mitotic activity of the satellite cells. Independently from mechanism, Arg affected muscle growth in the starter phase positively. Dietary supplementation with Arg in the starter phase had no effect (P > 0.05) on the carcass yield of broilers on d 42. Diet supplementation with Arg at levels above the ones recommended for the starter phase may be necessary for improved muscle development in broilers.

BREEDING BIOLOGY OF KELP GULLS ON THE BRAZILIAN COAST

We studied clutch size, hatching and fledging success, and time necessary for chick Kelp Gulls (Larus dominicanus) to leave the nest throughout two breeding seasons (2004 and 2005) on Guararitama Island, Sao Paulo, Brazil. We followed 93 nests in 2004 and 97 nests in 2005. The average (+/- SD) clutch size was 2.09 +/- 0.64 in 2004 and 1.93 +/- 0.59 in 2005. Hatching success was 74% in 2004 and 53% in 2005, and fledging success was 54% in 2004 and 58% in 2005. Chicks grew quickly, following the linear equation y(t) = 61g + 17.03g X age (in days), and began to fly at 40 days. Received 11 August 2008. Accepted 28 August 2009.

Opting out of oppositionality : toward an informed and engaged "third wave" feminism

I begin by citing a definition of "third wave" from the glossary in Turbo Chicks: Talking Young Feminisms at length because it communicates several key issues that I develop in this project. The definition introduces a tension within "third wave" feminism of building and differentiating itself from second wave feminism, the newness of the term "third wave," its association with "young" women, complexity of contemporary feminisms, and attention to multiple identities and oppressions. Uncovering explanations of "third wave" feminism that go beyond, like this one, generational associations, is not an easy task. Authors consistently group new feminist voices together by age under the label "third wave" feminists without questioning the accuracy of the designation. Most explorations of "third wave" feminism overlook the complexities and distinctions that abound among "young" feminists ; not all young feminists espouse similar ideas, tactics, and actions; and for various reasons, not all young feminists identify with a "third wave" of feminism. Less than a year after I began to learn about feminism I discovered Barbara Findlen's Listen Up: Voices From the Next Feminist Generation. Although the collection nor its contributors declare association with "third wave" feminism, consequent reviews and citations in articles identify it, along with Rebecca Walker's To Be Real: Telling the Truth and Changing the Voice of Feminism, as a major text of "third wave" feminism. Re-reading Listen Up since beginning to research "third wave" feminism, I now understand its fundamental influence on my research questions as a starting point for assessing persistent exclusion in contemporary feminism, rather than as a revolutionary text (as it is claimed to be in many reviews). Findlen begins the introduction with the bold claim, "My feminism wasn't shaped by antiwar or civil rights activism ..." (xi). Framing the collection with a disavowal of the influence women of color's organizational efforts negates, for me, the project's proclaimed commitment to multivocality. Though several contributions examine persistent exclusion within contemporary feminist movement, the larger project seems to rely on these essays to reflect this commitment, suggesting that Listen Up does not go beyond the "add and stir" approach to "diversity." Interestingly, this statement does not appear in the new edition of Listen Up published in 2001. And the content has changed with this new edition, including several more Latina contributors and other "corrective" additions.

Effect of poultry viscera meal inclusion in broiler diets in different rearing periods on performance, carcass and parts yields

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Rastreabilidade de subprodutos de origem animal em dietas com levedura e trigo para frangos

O objetivo deste trabalho foi rastrear a inclussão de farinhas de origem animal em rações para frango de corte com ou sem levedura de cana-de-açúcar e farelo de trigo, por meio da análise do músculo peitoral das aves pelas técnicas dos isótopos estáveis de carbono e nitrogênio. Foram utilizados 210 pintos machos (Cobb), com um dia de idade, distribuídos aleatoriamente em sete tratamentos de 30 aves cada, tendo sido um tratamento controle (dieta vegetal) e seis com inclusão de farinha de carne e ossos bovina ou farinha de vísceras de aves na dieta, com ou sem levedura de cana-de-açúcar e farelo de trigo. Aos 42 dias de idade, foram abatidas quatro aves, por tratamento, escolhidas ao acaso, cujo músculo peitoral foi retirado para análise da razão isotópica. Os resultados obtidos foram submetidos à análise multivariada. Os tratamentos experimentais diferiram do tratamento controle, e foi identificada a inclusão de farinha de origem animal, pelas técnicas dos isótopos estáveis, mesmo com inclusão de levedura ou farelo de trigo na dieta.

Incubation and rearing temperature effects on Hsp70 levels and heat stress response in broilers

Incubation temperature (IT) was changed to evaluate if 6-wk-old birds become more tolerant to heat stress. After 13 d of incubation, 470 eggs were submitted to low (36.8degreesC), normal (37.8degreesC) and high (38.8degreesC) temperatures. At day 7 post-hatching, 144 birds were allocated to three rearing temperatures (48 birds/treatment): control/thermoneutral (35-24degreesC), high (33-30degreesC) or low (27-18degreesC) according to the age of the birds. Hsp70 levels in tissues of birds (1 d and 42 d), stress response (42 d) and performance were evaluated. High IT decreased brain (P < 0.01) and liver (P < 0.01) Hsp70 levels, whereas low IT decreased brain (P < 0.01) but increased heart (P < 0.01) Hsp70 levels in 1-d-old chicks. Birds incubated at a low temperature had higher (P < 0.05) feed intake (1-42d). High rearing temperature decreased feed intake (P<0.01) and liveweight (P<0.01). Colonic temperature was lower in birds incubated at a low temperature (P < 0.05) and higher in birds reared in a high temperature (P < 0.05) before heat stress. Birds reared in low temperature had higher increase in colonic temperature after heat stress (P < 0.05). Tissue Hsp70 levels were differently affected by rearing temperature, which affected broiler performance more than IT. Lower IT seemed to increase the sensitivity of birds to heat stress at market age.

Effect of Environmental Temperature During the First Week of Brooding Period on Broiler Chick Body Weight, Viscera and Bone Development

O presente trabalho teve como objetivo estudar o efeito de diferentes temperaturas-ambiente durante a primeira semana de vida de pintos de corte sob parâmetros zootécnicos, desenvolvimento visceral e crescimento ósseo. Foram utilizados 240 pintos de um dia, alojados em 3 câmaras climáticas, com temperaturas constantes de 20, 25 e 35°C do 1° ao 7° dia de vida. Diariamente, o consumo de água e ração, bem como o peso vivo, o peso relativo do fígado, moela, coração, saco vitelino e bursa de Fabricius foram avaliados. A tíbia e o fêmur também foram pesados e o comprimento e espessura (diâmetro médio) mensurados. As aves criadas a 20°C ganharam menos peso e consumiram menos ração do que aves mantidas a 25°C e menos água do que aves mantidas a 35°C. O peso relativo do fígado, coração e moela foram afetados pela temperatura ambiente, entretanto, não foi observado efeito da temperatura de criação sobre o peso do saco vitelino e bursa de Fabricius. Os dados mostraram que todos os parâmetros ósseos pesquisados aumentaram com a idade das aves. A temperatura ambiente não afetou a espessura da tíbia e do fêmur, mas foi observado um aumento significativo no peso e comprimento dos ossos com o aumento da temperatura ambiente. Os resultados desse experimento mostraram que o estresse por frio (20°C) reduziu o crescimento ósseo bem como o peso vivo das aves, durante os primeiros sete dias após a eclosão.

Efeitos da restrição alimentar protéica ou energética sobre o crescimento de frangos de corte criados em diferentes temperaturas ambiente

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)