8 results
Intercropping and cover crop effects on maize nitrogen requirement for optimal growth
- S. S. Souza, J. A. Flôres, A. P. Coelho, J. M. Deienno, L. B. Lemos, G. S. Rolim
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- Journal:
- The Journal of Agricultural Science / Volume 160 / Issue 5 / October 2022
- Published online by Cambridge University Press:
- 01 August 2022, pp. 325-337
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Intercropping maize (Zea mays L.) with cover crops (Crotalaria spectabilis and Urochloa ruziziensis) is a sustainable cultivation strategy that can generate ecological benefits combined with grain yield (GY). However, cover crops may require nitrogen (N) fertilization management to be adjusted to obtain a high GY in intercropping systems. This study was carried out over 2 years in southeastern Brazil using randomized complete block design in a split-plot scheme. The plots were composed of three cropping systems: sole maize, maize + U. ruziziensis and maize + C. spectabilis. The subplots consisted of four N levels: 0, 70, 140 and 210 kg/ha. The GY of the maize + U. ruziziensis may be reduced by 13% compared to the sole maize. The GY of the sole maize increased up to 11.3 Mg/ha for 95 kg/ha of N in the first year and 6.7 Mg/ha for 169 kg/ha of N in the second year. The GY of the maize + U. ruziziensis intercropping system showed linear increments of 120 kg/ha for every 10 kg/ha of N applied. In the maize + C. spectabilis intercropping, GY increased up to 9.8 Mg/ha for 201 kg/ha of N in the first year, without any variation during the second year. The land equivalent ratio (LER) of intercropping was increased by more than 35% compared to that of sole maize, and N fertilization increased the LER of the sole maize and maize + U. ruziziensis intercropping. Maize intercropping had higher LER values with greater demand for nitrogen to obtain similar yields compared to sole maize cropping.
Crop succession and split-application of nitrogen effects on common bean yield in short no-tillage system
- F. L. C. Mingotte, C. A. Jardim, A. P. Coelho, M. M. Yada, F. T. Leal, S. S. Souza, L. B. Lemos, D. Fornasieri Filho
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- Journal:
- The Journal of Agricultural Science / Volume 159 / Issue 3-4 / April 2021
- Published online by Cambridge University Press:
- 07 July 2021, pp. 249-257
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Evaluating the effects of crop successions in no-tillage system (NTS) is essential for the correct recommendation of agronomic practices, such as top-dressing nitrogen fertilization. The aim was to evaluate the effect of the crop succession and the splitting of top-dressing N fertilization on the agronomic performance and economic viability of common bean crop. The experiment was conducted in southeastern Brazil for two agricultural seasons in an area under NTS, using a split-plot in randomized complete block design. The plots represented three cropping successions (maize in sole crop, maize intercropped with Urochloa ruziziensis and U. ruziziensis in sole crop) and the subplots composed of ten combinations of splitting of top-dressing N, at the stages V3, V4 and R5 of the common bean crop. In relation to the single application of the N dose of 90 kg ha−1, the common bean had higher response as a function of the N splitting schemes adopted, regardless of the previous cropping succession. The cropping successions evaluated did not interfere with the seed yield of common bean as subsequent crop, even at the beginning of the establishment of NTS. To obtain higher seed yield and economic viability, the N dose of 90 kg ha−1 indicated for the crop must be split and applied among the phenological stages V3, V4 and R5.
Fermentation profile, microbial populations, taxonomic diversity and aerobic stability of total mixed ration silages based on Cactus and Gliricidia
- F. N. S. Santos, E. M. Santos, J. S. Oliveira, G. R. Medeiros, A. M. Zanine, G. G. L. Araújo, A. F. Perazzo, M. L. P. Lemos, D. M. Pereira, G. F. L. Cruz, R. S. Paulino, C. J. B. Oliveira
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- Journal:
- The Journal of Agricultural Science / Volume 158 / Issue 5 / July 2020
- Published online by Cambridge University Press:
- 14 October 2020, pp. 396-405
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The aim of this study was to investigate the effects of Cactus (Opuntia spp) levels in total mixed ration silages based on Cactus and Gliricidia (Gliricidia sepium (Jacq.) Steud) on the fermentation profile, microbial populations, aerobic stability and taxonomic diversity. The completely randomized design was used in a 4 × 4 factorial design with four replications, being four rations with different levels of Cactus (15, 30, 45, 60% based on the dry matter) and four opening periods (0, 15, 30 and 60 days of fermentation). An interaction effect (P < 0.050) was observed among the diets and opening times for mould and yeast populations. An interaction effect for the levels of acetic acid was observed, where the diets 15, 30, 45 and 60% showed higher values at 60 days (0.44, 0.41, 0.35 and 0.40 g/kg DM, respectively). A significant difference was observed for the richness and diversity index (Chao1 and Shannon). The most abundant bacterial phyla were Proteobacteria and Firmicutes and the genera Lactobacillus and Weissella. Cactus can be added in total mixed ration silages up to the level of 60% in a way that it positively affects the qualitative indicators of the silages, modulating the taxonomic communities and allowing the predominance of important groups for preservation of the ensiled mass.
Wild carnivores, domestic dogs and ticks: shared parasitism in the Brazilian Cerrado
- V. N. Ramos, F. G. Lemos, F. C. Azevedo, R. C. Arrais, C. F. M. Lima, I. Z. Candeias, M. M. Martins, A. C. L. G. Sandrin, S. M. Siqueira, M. P. J. Szabó
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- Journal:
- Parasitology / Volume 147 / Issue 6 / May 2020
- Published online by Cambridge University Press:
- 27 February 2020, pp. 689-698
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The increase of contact between natural and rural areas is prominent in Brazil, due to agricultural activities and concern with the environmental conservation. In this context, domestic animals, wild fauna and humans are exposed to mutual exchange of parasites, microorganisms and diseases. We studied tick parasitism of wild carnivores and domestic dogs, and the environmental of questing ticks, in extensive cattle ranch areas intermingled with natural vegetation, and in a natural reserve, both in a region of Cerrado biome, Midwestern Brazil. From 2008 to 2015, we inspected 119 wild carnivores from nine species, and collected six tick species (Amblyomma sculptum, Amblyomma ovale, Amblyomma dubitatum, Amblyomma tigrinum, Dermacentor nitens and Rhipicephalus microplus). The most numerous and infested hosts were Cerdocyon thous, Lycalopex vetulus, Chrysocyon brachyurus, Puma concolor and Conepatus amazonicus. From 139 domestic dogs, we collected A. sculptum, Rhipicephalus sanguineus and R. microplus. From vegetation, samplings resulted in A. sculptum, A. dubitatum, A. ovale, Amblyomma rotundatum and R. microplus, with dominance of A. sculptum. Domestics and wild animals presented high overlapping of infestations by A. sculptum, a generalist and anthropophilic tick species. This tick is the most important vector of the Brazilian spotted fever, a lethal human disease. This fact elicits attention and requires efforts to monitor the presence of pathogens vectored by ticks circulating in this type of agroecosystem, including in other regions of the Brazil, because the most of the natural vegetation remaining have been increasingly immersed in pastures and agricultural matrix.
Hantavirus pulmonary syndrome and rodent reservoirs in the savanna-like biome of Brazil's southeastern region
- J. E. LIMONGI, R. C. OLIVEIRA, A. GUTERRES, S. F. COSTA NETO, J. FERNANDES, L. H.B. VICENTE, M. G. COELHO, V. N. RAMOS, M. S. FERREIRA, C. R. BONVICINO, P. S. D'ANDREA, E. R. S. LEMOS
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- Journal:
- Epidemiology & Infection / Volume 144 / Issue 5 / April 2016
- Published online by Cambridge University Press:
- 06 October 2015, pp. 1107-1116
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This paper describes the diversity of rodent fauna in an area endemic for hantavirus cardiopulmonary syndrome (HCPS) in Brazil, the population dynamics and the relationship of rodents with hantavirus in the Cerrado (savanna-like) biome. Additionally, an analysis is made of the partial S segment sequences of the hantaviruses obtained from serologically confirmed human HCPS cases and from rodent specimens. Rodents were collected during four campaigns. Human serum samples were collected from suspected cases of HCPS at hospitals in the state of Minas Gerais. The samples antibody-reactive by ELISA were processed by RT–PCR. The PCR product was amplified and sequenced. Hantavirus was detected only in Necromys lasiurus, the wild rodent species most prevalent in the Cerrado biome (min-max: 50–83·7%). All the six human serum samples were hantavirus seropositive and five showed amplified PCR products. The analysis of the nucleotide sequences showed the circulation of a single genotype, the Araraquara hantavirus. The environmental changes that have occurred in the Cerrado biome in recent decades have favoured N. lasiurus in interspecific competition of habitats, thus increasing the risk of contact between humans and rodent species infected with hantavirus. Our data corroborate the definition of N. lasiurus as the main hantavirus reservoir in the Cerrado biome.
Contributors
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- By Mitchell Aboulafia, Frederick Adams, Marilyn McCord Adams, Robert M. Adams, Laird Addis, James W. Allard, David Allison, William P. Alston, Karl Ameriks, C. Anthony Anderson, David Leech Anderson, Lanier Anderson, Roger Ariew, David Armstrong, Denis G. Arnold, E. J. Ashworth, Margaret Atherton, Robin Attfield, Bruce Aune, Edward Wilson Averill, Jody Azzouni, Kent Bach, Andrew Bailey, Lynne Rudder Baker, Thomas R. Baldwin, Jon Barwise, George Bealer, William Bechtel, Lawrence C. Becker, Mark A. Bedau, Ernst Behler, José A. Benardete, Ermanno Bencivenga, Jan Berg, Michael Bergmann, Robert L. Bernasconi, Sven Bernecker, Bernard Berofsky, Rod Bertolet, Charles J. Beyer, Christian Beyer, Joseph Bien, Joseph Bien, Peg Birmingham, Ivan Boh, James Bohman, Daniel Bonevac, Laurence BonJour, William J. Bouwsma, Raymond D. Bradley, Myles Brand, Richard B. Brandt, Michael E. Bratman, Stephen E. Braude, Daniel Breazeale, Angela Breitenbach, Jason Bridges, David O. Brink, Gordon G. Brittan, Justin Broackes, Dan W. Brock, Aaron Bronfman, Jeffrey E. Brower, Bartosz Brozek, Anthony Brueckner, Jeffrey Bub, Lara Buchak, Otavio Bueno, Ann E. Bumpus, Robert W. Burch, John Burgess, Arthur W. Burks, Panayot Butchvarov, Robert E. Butts, Marina Bykova, Patrick Byrne, David Carr, Noël Carroll, Edward S. Casey, Victor Caston, Victor Caston, Albert Casullo, Robert L. Causey, Alan K. L. Chan, Ruth Chang, Deen K. Chatterjee, Andrew Chignell, Roderick M. Chisholm, Kelly J. Clark, E. J. Coffman, Robin Collins, Brian P. Copenhaver, John Corcoran, John Cottingham, Roger Crisp, Frederick J. Crosson, Antonio S. Cua, Phillip D. Cummins, Martin Curd, Adam Cureton, Andrew Cutrofello, Stephen Darwall, Paul Sheldon Davies, Wayne A. Davis, Timothy Joseph Day, Claudio de Almeida, Mario De Caro, Mario De Caro, John Deigh, C. F. Delaney, Daniel C. Dennett, Michael R. DePaul, Michael Detlefsen, Daniel Trent Devereux, Philip E. Devine, John M. Dillon, Martin C. Dillon, Robert DiSalle, Mary Domski, Alan Donagan, Paul Draper, Fred Dretske, Mircea Dumitru, Wilhelm Dupré, Gerald Dworkin, John Earman, Ellery Eells, Catherine Z. Elgin, Berent Enç, Ronald P. Endicott, Edward Erwin, John Etchemendy, C. Stephen Evans, Susan L. Feagin, Solomon Feferman, Richard Feldman, Arthur Fine, Maurice A. Finocchiaro, William FitzPatrick, Richard E. Flathman, Gvozden Flego, Richard Foley, Graeme Forbes, Rainer Forst, Malcolm R. Forster, Daniel Fouke, Patrick Francken, Samuel Freeman, Elizabeth Fricker, Miranda Fricker, Michael Friedman, Michael Fuerstein, Richard A. Fumerton, Alan Gabbey, Pieranna Garavaso, Daniel Garber, Jorge L. A. Garcia, Robert K. Garcia, Don Garrett, Philip Gasper, Gerald Gaus, Berys Gaut, Bernard Gert, Roger F. Gibson, Cody Gilmore, Carl Ginet, Alan H. Goldman, Alvin I. Goldman, Alfonso Gömez-Lobo, Lenn E. Goodman, Robert M. Gordon, Stefan Gosepath, Jorge J. E. Gracia, Daniel W. Graham, George A. Graham, Peter J. Graham, Richard E. Grandy, I. Grattan-Guinness, John Greco, Philip T. Grier, Nicholas Griffin, Nicholas Griffin, David A. Griffiths, Paul J. Griffiths, Stephen R. Grimm, Charles L. Griswold, Charles B. Guignon, Pete A. Y. Gunter, Dimitri Gutas, Gary Gutting, Paul Guyer, Kwame Gyekye, Oscar A. Haac, Raul Hakli, Raul Hakli, Michael Hallett, Edward C. Halper, Jean Hampton, R. James Hankinson, K. R. Hanley, Russell Hardin, Robert M. Harnish, William Harper, David Harrah, Kevin Hart, Ali Hasan, William Hasker, John Haugeland, Roger Hausheer, William Heald, Peter Heath, Richard Heck, John F. Heil, Vincent F. Hendricks, Stephen Hetherington, Francis Heylighen, Kathleen Marie Higgins, Risto Hilpinen, Harold T. Hodes, Joshua Hoffman, Alan Holland, Robert L. Holmes, Richard Holton, Brad W. Hooker, Terence E. Horgan, Tamara Horowitz, Paul Horwich, Vittorio Hösle, Paul Hoβfeld, Daniel Howard-Snyder, Frances Howard-Snyder, Anne Hudson, Deal W. Hudson, Carl A. Huffman, David L. Hull, Patricia Huntington, Thomas Hurka, Paul Hurley, Rosalind Hursthouse, Guillermo Hurtado, Ronald E. Hustwit, Sarah Hutton, Jonathan Jenkins Ichikawa, Harry A. Ide, David Ingram, Philip J. Ivanhoe, Alfred L. Ivry, Frank Jackson, Dale Jacquette, Joseph Jedwab, Richard Jeffrey, David Alan Johnson, Edward Johnson, Mark D. Jordan, Richard Joyce, Hwa Yol Jung, Robert Hillary Kane, Tomis Kapitan, Jacquelyn Ann K. Kegley, James A. Keller, Ralph Kennedy, Sergei Khoruzhii, Jaegwon Kim, Yersu Kim, Nathan L. King, Patricia Kitcher, Peter D. Klein, E. D. Klemke, Virginia Klenk, George L. Kline, Christian Klotz, Simo Knuuttila, Joseph J. Kockelmans, Konstantin Kolenda, Sebastian Tomasz Kołodziejczyk, Isaac Kramnick, Richard Kraut, Fred Kroon, Manfred Kuehn, Steven T. Kuhn, Henry E. Kyburg, John Lachs, Jennifer Lackey, Stephen E. Lahey, Andrea Lavazza, Thomas H. Leahey, Joo Heung Lee, Keith Lehrer, Dorothy Leland, Noah M. Lemos, Ernest LePore, Sarah-Jane Leslie, Isaac Levi, Andrew Levine, Alan E. Lewis, Daniel E. Little, Shu-hsien Liu, Shu-hsien Liu, Alan K. L. Chan, Brian Loar, Lawrence B. Lombard, John Longeway, Dominic McIver Lopes, Michael J. Loux, E. J. Lowe, Steven Luper, Eugene C. Luschei, William G. Lycan, David Lyons, David Macarthur, Danielle Macbeth, Scott MacDonald, Jacob L. Mackey, Louis H. Mackey, Penelope Mackie, Edward H. Madden, Penelope Maddy, G. B. Madison, Bernd Magnus, Pekka Mäkelä, Rudolf A. Makkreel, David Manley, William E. Mann (W.E.M.), Vladimir Marchenkov, Peter Markie, Jean-Pierre Marquis, Ausonio Marras, Mike W. Martin, A. P. Martinich, William L. McBride, David McCabe, Storrs McCall, Hugh J. McCann, Robert N. McCauley, John J. McDermott, Sarah McGrath, Ralph McInerny, Daniel J. McKaughan, Thomas McKay, Michael McKinsey, Brian P. McLaughlin, Ernan McMullin, Anthonie Meijers, Jack W. Meiland, William Jason Melanson, Alfred R. Mele, Joseph R. Mendola, Christopher Menzel, Michael J. Meyer, Christian B. Miller, David W. Miller, Peter Millican, Robert N. Minor, Phillip Mitsis, James A. Montmarquet, Michael S. Moore, Tim Moore, Benjamin Morison, Donald R. Morrison, Stephen J. Morse, Paul K. Moser, Alexander P. D. Mourelatos, Ian Mueller, James Bernard Murphy, Mark C. Murphy, Steven Nadler, Jan Narveson, Alan Nelson, Jerome Neu, Samuel Newlands, Kai Nielsen, Ilkka Niiniluoto, Carlos G. Noreña, Calvin G. Normore, David Fate Norton, Nikolaj Nottelmann, Donald Nute, David S. Oderberg, Steve Odin, Michael O’Rourke, Willard G. Oxtoby, Heinz Paetzold, George S. Pappas, Anthony J. Parel, Lydia Patton, R. P. Peerenboom, Francis Jeffry Pelletier, Adriaan T. Peperzak, Derk Pereboom, Jaroslav Peregrin, Glen Pettigrove, Philip Pettit, Edmund L. Pincoffs, Andrew Pinsent, Robert B. Pippin, Alvin Plantinga, Louis P. Pojman, Richard H. Popkin, John F. Post, Carl J. Posy, William J. Prior, Richard Purtill, Michael Quante, Philip L. Quinn, Philip L. Quinn, Elizabeth S. Radcliffe, Diana Raffman, Gerard Raulet, Stephen L. Read, Andrews Reath, Andrew Reisner, Nicholas Rescher, Henry S. Richardson, Robert C. Richardson, Thomas Ricketts, Wayne D. Riggs, Mark Roberts, Robert C. Roberts, Luke Robinson, Alexander Rosenberg, Gary Rosenkranz, Bernice Glatzer Rosenthal, Adina L. Roskies, William L. Rowe, T. M. Rudavsky, Michael Ruse, Bruce Russell, Lilly-Marlene Russow, Dan Ryder, R. M. Sainsbury, Joseph Salerno, Nathan Salmon, Wesley C. Salmon, Constantine Sandis, David H. Sanford, Marco Santambrogio, David Sapire, Ruth A. Saunders, Geoffrey Sayre-McCord, Charles Sayward, James P. Scanlan, Richard Schacht, Tamar Schapiro, Frederick F. Schmitt, Jerome B. Schneewind, Calvin O. Schrag, Alan D. Schrift, George F. Schumm, Jean-Loup Seban, David N. Sedley, Kenneth Seeskin, Krister Segerberg, Charlene Haddock Seigfried, Dennis M. Senchuk, James F. Sennett, William Lad Sessions, Stewart Shapiro, Tommie Shelby, Donald W. Sherburne, Christopher Shields, Roger A. Shiner, Sydney Shoemaker, Robert K. Shope, Kwong-loi Shun, Wilfried Sieg, A. John Simmons, Robert L. Simon, Marcus G. Singer, Georgette Sinkler, Walter Sinnott-Armstrong, Matti T. Sintonen, Lawrence Sklar, Brian Skyrms, Robert C. Sleigh, Michael Anthony Slote, Hans Sluga, Barry Smith, Michael Smith, Robin Smith, Robert Sokolowski, Robert C. Solomon, Marta Soniewicka, Philip Soper, Ernest Sosa, Nicholas Southwood, Paul Vincent Spade, T. L. S. Sprigge, Eric O. Springsted, George J. Stack, Rebecca Stangl, Jason Stanley, Florian Steinberger, Sören Stenlund, Christopher Stephens, James P. Sterba, Josef Stern, Matthias Steup, M. A. Stewart, Leopold Stubenberg, Edith Dudley Sulla, Frederick Suppe, Jere Paul Surber, David George Sussman, Sigrún Svavarsdóttir, Zeno G. Swijtink, Richard Swinburne, Charles C. Taliaferro, Robert B. Talisse, John Tasioulas, Paul Teller, Larry S. Temkin, Mark Textor, H. S. Thayer, Peter Thielke, Alan Thomas, Amie L. Thomasson, Katherine Thomson-Jones, Joshua C. Thurow, Vzalerie Tiberius, Terrence N. Tice, Paul Tidman, Mark C. Timmons, William Tolhurst, James E. Tomberlin, Rosemarie Tong, Lawrence Torcello, Kelly Trogdon, J. D. Trout, Robert E. Tully, Raimo Tuomela, John Turri, Martin M. Tweedale, Thomas Uebel, Jennifer Uleman, James Van Cleve, Harry van der Linden, Peter van Inwagen, Bryan W. Van Norden, René van Woudenberg, Donald Phillip Verene, Samantha Vice, Thomas Vinci, Donald Wayne Viney, Barbara Von Eckardt, Peter B. M. Vranas, Steven J. Wagner, William J. Wainwright, Paul E. Walker, Robert E. Wall, Craig Walton, Douglas Walton, Eric Watkins, Richard A. Watson, Michael V. Wedin, Rudolph H. Weingartner, Paul Weirich, Paul J. Weithman, Carl Wellman, Howard Wettstein, Samuel C. Wheeler, Stephen A. White, Jennifer Whiting, Edward R. Wierenga, Michael Williams, Fred Wilson, W. Kent Wilson, Kenneth P. Winkler, John F. Wippel, Jan Woleński, Allan B. Wolter, Nicholas P. Wolterstorff, Rega Wood, W. Jay Wood, Paul Woodruff, Alison Wylie, Gideon Yaffe, Takashi Yagisawa, Yutaka Yamamoto, Keith E. Yandell, Xiaomei Yang, Dean Zimmerman, Günter Zoller, Catherine Zuckert, Michael Zuckert, Jack A. Zupko (J.A.Z.)
- Edited by Robert Audi, University of Notre Dame, Indiana
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- The Cambridge Dictionary of Philosophy
- Published online:
- 05 August 2015
- Print publication:
- 27 April 2015, pp ix-xxx
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Outbreak of Neisseria meningitidis C in workers at a large food-processing plant in Brazil: challenges of controlling disease spread to the larger community
- B. P. M. ISER, H. C. A. V. LIMA, C. De MORAES, R. P. A. De ALMEIDA, L. T. WATANABE, S. L. A. ALVES, A. P. S. LEMOS, M. C. O. GORLA, M. G. GONÇALVES, D. A. DOS SANTOS, J. SOBEL
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- Journal:
- Epidemiology & Infection / Volume 140 / Issue 5 / May 2012
- Published online by Cambridge University Press:
- 30 August 2011, pp. 906-915
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An outbreak of meningococcal disease (MD) with severe morbidity and mortality was investigated in midwestern Brazil in order to identify control measures. A MD case was defined as isolation of Neisseria meningitidis, or detection of polysaccharide antigen in a sterile site, or presence of clinical purpura fulminans, or an epidemiological link with a laboratory-confirmed case-patient, between June and August 2008. In 8 out of 16 MD cases studied, serogroup C ST103 complex was identified. Five (31%) cases had neurological findings and five (31%) died. The attack rate was 12 cases/100 000 town residents and 60 cases/100 000 employees in a large local food-processing plant. We conducted a matched case-control study of eight primary laboratory-confirmed cases (1:4). Factors associated with illness in single variable analysis were work at the processing plant [matched odds ratio (mOR) 22, 95% confidence interval (CI) 2·3–207·7, P<0·01], and residing <1 year in Rio Verde (mOR 7, 95% CI 1·11–43·9, P<0·02). Mass vaccination (>10 000 plant employees) stopped propagation in the plant, but not in the larger community.
Comparative performance of six Holstein-Friesian × Guzera grades in Brazil 3. Burdens of Boophilus microplus under field conditions
- A. M. Lemos, R. L. Teodoro, G. P. Oliveira, F. E. Madalena
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- Journal:
- Animal Production / Volume 41 / Issue 2 / October 1985
- Published online by Cambridge University Press:
- 02 September 2010, pp. 187-191
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- October 1985
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Burdens of ticks (Boophilus microplus) on young and adult females (heifers and cows) of six red-and-white Holstein-Friesian (HF) × Guzera (G) grades were assessed by counting the number of semi-engorged tick females on the right side of the animals. The HF grades were: ¼ ½ ⅝ ¾ ⅞ and ≥ Assessments of tick burdens of heifers were made on twelve occasions (357 observations on 193 animals). Cows were assessed six times (380 observations on 83 animals). Cows and heifers were in different pastures. Data were transformed to log10 (2 × count + 1) to normalize their distribution. Direct breed additive (g1, HF-G) and heterosis (hl) effects were estimated within dates of counting. Estimates of h1 on the log scale were not significant (P > 0·05) on 11 out of 12 dates for heifers and on five out of six dates for cows. Estimates of g1 for heifers varied from 0·505 (s.e. 0·492) to 2·376 (s.e. 0·345) (mean g1 = 1·575 (s.e. 0·096)), and estimates for cows varied between 1·009 (s.e. 0·203) and 2·293 (s.e. 0·219) (mean g1 = 1·416 (s.e. 0·080)). These results indicate the presence of important genetic effects on tick burdens. The means of the untransformed number of ticks per animal were, for the six grades in the above order, respectively: 44, 71, 151, 223, 282 and 501, for heifers, and 7, 19, 31, 64, 62 and 97 for cows.