Browsing by Author "Lewis, James"
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- Effect of various concentration of butyric acid on growth performance, intestinal lesion scores, and body composition of broilers raised on used litterSizmaz, Ozge O.; Barrett, Nathaniel W.; Lewis, James; Yakout, Hathum; Persia, Michael E. (2022-12-01)There is still a need for the evaluation of alternative feed additives, including organic acids such as butyric acid, when fed in broiler diets without antibiotic growth promoters. The removal or limitation of growth promoting antibiotics from commercial production changes the opportunities for feed additives in the poultry industry and allows for the evaluation of replacement feed additives that may not have been cost effective when growth promoting antibiotics are available. Therefore, an experiment was conducted to evaluate the effects of various concentrations (200 ppm, 400 ppm, and 800 ppm) of coated butyric acid on growth performance, intestinal lesion score, and body composition of 42-day-old broilers raised on used litter. The addition of the coated butyric acid at 400 ppm and 800 ppm increased BW and 800 ppm improved mortality corrected feed conversion ratio (FCRm) over the 42-d period compared with the negative control (NC) fed broilers. Although performance was improved, the ratio of lean mass to fatty mass in the broilers was unchanged suggesting a generalize growth response. No significant differences were observed in lesion scores in the duodenum and jejunum and overall lesion scores were low. Both 400 and 800 ppm of butyric acid were able to increase 42-d broiler body weight in comparison to the NC fed birds, but 800 ppm of butyric acid was required to also improve the FCRm in comparison to the NC fed birds.
- Modeling sediment movement in the turbidity maximum of an estuaryKuo, Albert; Nichols, Maynard M.; Lewis, James (Water Resources Research Center, Virginia Polytechnic Institute and State University, 1978)This research developed a two-dimensional, time-dependent numerical model to simulate the movement of water and suspended sediment in the turbidity maximum of an estuary. This model is a systematic sequence of mathematical procedures derived from the mass-balance equation and the equation of motion. Lateral integration is used to obtain two-dimensional equations; these equations are integrated with depth over the height of successive layers. Finite difference equations then are written for each layer and solved numerically using prescribed boundary conditions. The model yields values for time-varying tidal height, current speed, salinity, and suspended sediment concentration (turbidity) throughout the estuary. In turn, these variations reveal the response to tidal current fluctuations of both salinity and sediment distributions within the maximum. Residual values of each parameter are obtained by averaging respective values over a tidal cycle. By examining the time-varying and the tidal average transport at landward and seaward transects, sediment transport through the turbidity maximum may be studied in detail. Using this numerical model permits analyses of hydraulic processes that lead to suspended sediment accumulation.
- The Plant Pathogen Pseudomonas syringae pv. tomato Is Genetically Monomorphic and under Strong Selection to Evade Tomato ImmunityCai, Rongman; Lewis, James; Yan, Shuangchun; Clarke, Christopher R.; Campanile, Francesco; Almeida, Nalvo F.; Studholme, David J.; Lindeberg, Magdalen; Schneider, David; Zaccardelli, Massimo; Setubal, João C.; Morales-Lizcano, Nadia P.; Bernal, Adriana; Coaker, Gitta; Baker, Christy; Bender, Carol L.; Leman, Scotland C.; Vinatzer, Boris A. (PLOS Pathogens, 2011-08-25)Recently, genome sequencing of many isolates of genetically monomorphic bacterial human pathogens has given new insights into pathogen microevolution and phylogeography. Here, we report a genome-based micro-evolutionary study of a bacterial plant pathogen, Pseudomonas syringae pv. tomato. Only 267 mutations were identified between five sequenced isolates in 3,543,009 nt of analyzed genome sequence, which suggests a recent evolutionary origin of this pathogen. Further analysis with genome-derived markers of 89 world-wide isolates showed that several genotypes exist in North America and in Europe indicating frequent pathogen movement between these world regions. Genome-derived markers and molecular analyses of key pathogen loci important for virulence and motility both suggest ongoing adaptation to the tomato host. A mutational hotspot was found in the type III-secreted effector gene hopM1. These mutations abolish the cell death triggering activity of the full-length protein indicating strong selection for loss of function of this effector, which was previously considered a virulence factor. Two non-synonymous mutations in the flagellin-encoding gene fliC allowed identifying a new microbe associated molecular pattern (MAMP) in a region distinct from the known MAMP flg22. Interestingly, the ancestral allele of this MAMP induces a stronger tomato immune response than the derived alleles. The ancestral allele has largely disappeared from today’s Pto populations suggesting that flagellin-triggered immunity limits pathogen fitness even in highly virulent pathogens. An additional non-synonymous mutation was identified in flg22 in South American isolates. Therefore, MAMPs are more variable than expected differing even between otherwise almost identical isolates of the same pathogen strain.