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We estimated the incubation period for mpox during an outbreak in Pereira, Colombia, using data from 11 confirmed cases. Mean incubation period was 7.1 (95% CI 4.9-9.9) days, consistent with previous outbreaks. Accurately estimating the incubation period provides insights into transmission dynamics, informing public health interventions and surveillance strategies.

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Las epidemias y las pandemias son eventos de ocurrencia natural. La aparición de una nueva enfermedad infecciosa supone siempre una situación compleja, sobre todo si lo hace como una epidemia de extensión o gravedad significativa, con el objetivo de describir las características clínico-epidemiológicas en pacientes confirmados con COVID-19. Se realizó un estudio descriptivo y retrospectivo sobre las características clínico-epidemiológicas de los 161 pacientes diagnosticados con esta enfermedad, en el municipio Yara, de la provincia Granma durante el período comprendido de junio de 2020-2021. Se estudiaron las variables: edad, sexo, lugar de infección, presencia o no de síntomas y signos, antecedentes patológicos personales, área de salud y consejo popular. El 60,8% de los afectados fueron del sexo femenino con 98 pacientes y el grupo de 30-44 años de edad quedó representado por 50 pacientes (31.0%); en 150 casos, la transmisión fue mayormente autóctona (93,1%) y asintomática en 86 casos para el 53,4%. De los pacientes sintomáticos fueron las manifestaciones respiratorias, los principales síntomas con 70 casos para el 93,3%, 63 pacientes tenían antecedentes personales de hipertensión arterial (39,1%). El área de salud que más casos notificó fue "Luis Enrique de la Paz" con 106 pacientes para el 65,8% y Yara el consejo popular más afectado con 72 casos (44,7%), la mayoría de los pacientes fueron del sexo femenino, predominó la transmisión autóctona y la presentación asintomática. La epidemia en el municipio Yara se comportó similar al resto del país.

Epidemics and pandemics are naturally occurring events. The emergence of a new infectious disease is always a complex situation, especially when it occurs as an epidemic of significant spread or severity. The aim of this study was to describe the clinical-epidemiologic characteristics of patients confirmed with COVID-19. A descriptive and retrospective study was carried out on the clinical-epidemiological characteristics of 161 patients diagnosed with this disease, in the municipality of Yara, province of Granma. The following variables were studied: age, sex, site of infection, presence or not of symptoms and signs, personal pathological antecedents, health area and locality. Out of the total, 98 patients were female (60.8%), and the age group 30-44 years was represented by 50 patients (31.0%). Transmission was generally autochthonous in 150 cases (93.1%), and asymptomatic in 86 cases (53.4%). Among the symptomatic patients, respiratory manifestations were the main symptom in 70 cases (93.3%). Also, 63 patients had a personal medical history of hypertension (39.1%). Luis Enrique de la Paz was the health area that reported the most cases with 106 patients (65.8%), and Yara was the most affected locality with 72 cases (44.7%). The majority of patients were female; and autochthonous transmission and asymptomatic presentation predominated. The epidemic in Yara municipality behaved alike in the whole country.

Epidemias e pandemias são eventos naturais. O surgimento de uma nova doença infecciosa é sempre uma situação complexa, especialmente se for uma epidemia de extensão ou gravidade significativa, com o objetivo de descrever as características clínico-epidemiológicas em pacientes confirmados com COVID-19. Foi realizado um estudo descritivo e retrospectivo sobre as características clínico-epidemiológicas dos 161 pacientes diagnosticados com essa doença, no município de Yara, província de Granma, no período de junho de 2020 a 2021, as variáveis foram estudadas: idade, sexo, local de infecção, presença ou não de sintomas e sinais, história patológica pessoal, área de saúde e conselho popular. O 60,8% dos acometidos eram do sexo feminino com 98 pacientes e a faixa etária de 30 a 44 anos foi representada por 50 pacientes (31,0%); Em 150 casos, a transmissão foi predominantemente autóctone (93,1%) e assintomática em 86 casos para 53,4%, entre os sintomáticos foram manifestações respiratórias, sendo os principais sintomas 70 casos para 93,3%, 63 pacientes tinham história pessoal de hipertensão arterial (39,1%). A área de saúde que mais registrou casos foi "Luis Enrique de la Paz" com 106 pacientes para 65,8% e Yara o município popular mais afetado com 72 casos (44,7%), a maioria dos pacientes era do sexo feminino, de transmissão autóctone e apresentação assintomática. A epidemia no município de Yara se comportou de forma semelhante ao resto do país.

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Colletotrichum isolates from apple leaves with symptoms of Glomerella leaf spot (GLS) can cause fruit rot and several small lesion spots, here called Colletotrichum fruit spot (CFS). This work investigated the epidemiological relevance of Colletotrichum species obtained from leaves with GLS in causing diseases in immature apple fruit by comparing different fruit sizes (phenological stages) for symptom development. In the first experiment, five Colletotrichum species were inoculated in 'Gala' (Ø = 5.5 cm) and 'Eva' (Ø = 4.8 cm) fruit in the field (2016/17 season). Subsequently, C. chrysophilum and C. nymphaeae were inoculated in fruit of different sizes (Ø = 2.4 to 6.3 cm) in the field (2017/18 and 2021/22 seasons) and in the laboratory according to the phenological stages of growing fruit. At harvest of the immature inoculated fruit in the field, only CFS symptoms were observed in both cultivars. For Gala, the CFS incidence reached 50% regardless of season, pathogen species, and fruit size. For Eva, CFS symptoms were observed after inoculation with C. melonis in the 2016/17 season and in smaller fruit inoculated with C. chrysophilum and C. nymphaeae in 2021/22. During postharvest, bitter rot symptoms developed, but did not seem to come from CFS symptoms. It can be concluded that the Gala cultivar has a high susceptibility to CFS caused by the two Colletotrichum species of the greatest epidemiological importance for GLS in Brazil in all fruit sizes tested.

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Vector-borne parasites are important ecological drivers influencing life-history evolution in birds by increasing host mortality or susceptibility to new diseases. Therefore, understanding why vulnerability to infection varies within a host clade is a crucial task for conservation biology and for understanding macroecological life-history patterns. Here, we studied the relationship of avian life-history traits and climate on the prevalence of Plasmodium and Parahaemoproteus parasites. We sampled 3569 individual birds belonging to 53 species of the family Thraupidae. Individuals were captured from 2007 to 2018 at 92 locations. We created 2 phylogenetic generalized least-squares models with Plasmodium and Parahaemoproteus prevalence as our response variables, and with the following predictor variables: climate PC1, climate PC2, body size, mixed-species flock participation, incubation period, migration, nest height, foraging height, forest cover, and diet. We found that Parahaemoproteus and Plasmodium prevalence was higher in species inhabiting open habitats. Tanager species with longer incubation periods had higher Parahaemoproteus prevalence as well, and we hypothesize that these longer incubation periods overlap with maximum vector abundances, resulting in a higher probability of infection among adult hosts during their incubation period and among chicks. Lastly, we found that Plasmodium prevalence was higher in species without migratory behaviour, with mixed-species flock participation, and with an omnivorous or animal-derived diet. We discuss the consequences of higher infection prevalence in relation to life-history traits in tanagers.

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We monitored the temperature of seven Paleosuchus palpebrosus nests found on the banks of streams surrounding the Brazilian Pantanal, near the southern limit of the species´ distribution, between 2008 and 2013. The mean temperature of the nests between 45 and 68 days incubation, the presumed period of sex determination, varied between 26.1 and 31.5o C. Nest temperatures were 2 to 5°C higher than air temperatures, presumably due to metabolic heat of decay of material within the nests, but air temperature explained 10-50% of the variance in egg-chamber temperatures. The estimated incubation periods for nests from which eggs hatched were 80, 84, 86, 90 and 104 days with a mean of 89 (SD =9.23) days, though these are probably slight overestimates because eggs may have hatched in the period between inspections. For these nests, there was no significant relationship between mean temperature and incubation period (r2 = 0.23, p = 0.411).

Nós monitoramos a temperatura de sete ninhos de Paleosuchus palpebrosus encontrados nas margens de riachos ao redor do Pantanal, próximo ao limite sul da distribuição da espécie, entre 2008 e 2013. A temperatura média dos ninhos entre 45 e 68 dias de incubação, período presumido de determinação do sexo, variou entre 26,1 e 31,5o C. As temperaturas dos ninhos foram 2 a 5°C mais altas que as temperaturas do ar, presumivelmente devido ao calor metabólico de decomposição do material dentro dos ninhos, mas a temperatura do ar explicou 10-50% da variação na temperatura da câmara de ovo. Os períodos de incubação estimados para os ninhos dos quais os ovos eclodiram foram de 80, 84, 86, 90 e 104 dias com uma média de 89 (DP = 9,23) dias, embora sejam provavelmente pequenas superestimavas porque os ovos podem ter eclodido no período entre as inspeções. Para esses ninhos, não houve relação significativa entre temperatura média e período de incubação (r2 = 0,23, p = 0,411).

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BACKGROUND: The aim of our study was to determine through a systematic review and meta-analysis the incubation period of COVID-19. It was conducted based on the preferred reporting items for systematic reviews and meta-analyses (PRISMA). Criteria for eligibility were all published population-based primary literature in PubMed interface and the Science Direct, dealing with incubation period of COVID-19, written in English, since December 2019 to December 2020. We estimated the mean of the incubation period using meta-analysis, taking into account between-study heterogeneity, and the analysis with moderator variables. RESULTS: This review included 42 studies done predominantly in China. The mean and median incubation period were of maximum 8 days and 12 days respectively. In various parametric models, the 95th percentiles were in the range 10.3-16 days. The highest 99th percentile would be as long as 20.4 days. Out of the 10 included studies in the meta-analysis, 8 were conducted in China, 1 in Singapore, and 1 in Argentina. The pooled mean incubation period was 6.2 (95% CI 5.4, 7.0) days. The heterogeneity (I2 77.1%; p < 0.001) was decreased when we included the study quality and the method of calculation used as moderator variables (I2 0%). The mean incubation period ranged from 5.2 (95% CI 4.4 to 5.9) to 6.65 days (95% CI 6.0 to 7.2). CONCLUSIONS: This work provides additional evidence of incubation period for COVID-19 and showed that it is prudent not to dismiss the possibility of incubation periods up to 14 days at this stage of the epidemic.

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Chikungunya virus (CHIKV) is a reemerging and rapidly spreading pathogen transmitted by mosquitoes. The emergence of new epidemic variants of the virus is associated with genetic evolutionary traits, including duplication of repeated RNA elements in the 3' untranslated region (UTR) that seemingly favor transmission by mosquitoes. The transmission potential of a given variant results from a complex interplay between virus populations and anatomical tissue barriers in the mosquito. Here, we used the wild-type CHIKV Caribbean strain and an engineered mutant harboring a deletion in the 3' UTR to dissect the interactions of virus variants with the anatomical barriers that impede transmission during the replication cycle of the virus in Aedes mosquitoes. Compared to the 3'-UTR mutant, we observed that the wild-type virus had a short extrinsic incubation period (EIP) after an infectious blood meal and was expectorated into mosquito saliva much more efficiently. We found that high viral titers in the midgut are not sufficient to escape the midgut escape barrier. Rather, viral replication kinetics play a crucial role in determining midgut escape and the transmission ability of CHIKV. Finally, competition tests in mosquitoes coinfected with wild-type and mutant viruses revealed that both viruses successfully colonized the midgut, but wild-type viruses effectively displaced mutant viruses during systemic infection due to their greater efficiency of escaping from the midgut into secondary tissues. Overall, our results uncover a link between CHIKV replication kinetics and the effect of bottlenecks on population diversity, as slowly replicating variants are less able to overcome the midgut escape barrier.IMPORTANCE It is well established that selective pressures in mosquito vectors impose population bottlenecks for arboviruses. Here, we used a CHIKV Caribbean lineage mutant carrying a deletion in the 3' UTR to study host-virus interactions in vivo in the epidemic mosquito vector Aedes aegypti We found that the mutant virus had a delayed replication rate in mosquitoes, which lengthened the extrinsic incubation period (EIP) and reduced fitness relative to the wild-type virus. As a result, the mutant virus displayed a reduced capacity to cross anatomical barriers during the infection cycle in mosquitoes, thus reducing the virus transmission rate. Our findings show how selective pressures act on CHIKV noncoding regions to select variants with shorter EIPs that are preferentially transmitted by the mosquito vector.

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Kerteszia cruzii is a sylvatic mosquito and the primary vector of Plasmodium spp., which can cause malaria in humans in areas outside the Amazon River basin in Brazil. Anthropic changes in the natural environments are the major drivers of massive deforestation and local climate change, with serious impacts on the dynamics of mosquito communities and on the risk of acquiring malaria. Considering the lack of information on the dynamics of malaria transmission in areas across the Atlantic Forest biome, where Ke. cruzii is the dominant vector, and the impact of climate drivers of malaria, the present study aimed to: (i) investigate the occurrence and survival rate of Ke. cruzii based on the distinct vegetation profiles found in areas across the coastal region of the Brazilian Atlantic Forest biome; (ii) estimate the extrinsic incubation period (EIP) and survival rates of P. vivax and P. falciparum parasites in Ke. cruzii under current and future scenarios. The potential distribution of Plasmodium spp. was estimated using simulation analyses under distinct scenarios of average temperature increases from 1 °C to 3.7 °C. Our results showed that two conditions are necessary to explain the occurrence and survival of Ke. cruzii: warm temperature and presence of the Atlantic Forest biome. Moreover, both Plasmodium species showed a tendency to decrease their EIP and increase their estimated survival rates in a scenario of higher temperature. Our findings support that the high-risk malaria areas may include the southern region of the distribution range of the Atlantic Forest biome in the coming years. Despite its limitations and assumptions, the present study provides robust evidence of areas with potential to be impacted by malaria incidence in a future scenario. These areas should be monitored in the next decades regarding the occurrence of the mosquito vector and the potential for malaria persistence and increased occurrence.

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ABSTRACT: Several diseases can be associated with figs but recently a fruit rot was observed in green fruit. The purpose of this study was to determine the pathogenicity of Botrytis sp., to quantify incubation period (IP) and latent period (LP), to verify the optimum temperature for mycelial growth, and to identify the different species of Botrytis sp. isolated from immature figs. Botrytis sp. isolated from figs proved to be pathogenic to immature fruit with and without wounding the fruit surface and ostiole. The IP period was 3 days on fruit with wounds and 5 days on fruit inoculated within the ostiole (without wound). The LP was 6 days in all treatments. The optimum temperature for mycelial growth was 18°C. Inferred from sequences of a segment comprising the ITS region of ribosomal DNA concluded that the isolates are Botrytis cinerea.

RESUMO: Várias doenças podem estar associadas com figos, mas recentemente uma podridão dos frutos foi observada em frutos verdes. O objetivo deste estudo foi determinar a patogenicidade de Botrytis sp., quantificar o período de incubação (PI) e o período de latência (PL), verificar a temperatura ótima para o crescimento micelial e identificar as diferentes espécies de Botrytis sp. isoladas a partir de frutos imaturos de figo. Botrytis sp. isolado a partir de figos provou ser patogênico em frutos imaturos com e sem ferimento na superfície dos frutos e no ostíolo. O PI foi de 3 dias em frutos com ferimento e 5 dias em frutos inoculados no ostíolo e sem ferimento. O PL foi de 6 dias em todos os tratamentos. A temperatura ótima de crescimento micelial foi18°C. A partir de sequências de um segmento que compreende a região de ITS do DNA ribossomal, concluiu-se que os isolados são Botrytis cinerea.

RESUMO

Several diseases can be associated with figs but recently a fruit rot was observed in green fruit. The purpose of this study was to determine the pathogenicity of Botrytis sp., to quantify incubation period (IP) and latent period (LP), to verify the optimum temperature for mycelial growth, and to identify the different species of Botrytis sp. isolated from immature figs. Botrytis sp. isolated from figs proved to be pathogenic to immature fruit with and without wounding the fruit surface and ostiole. The IP period was 3 days on fruit with wounds and 5 days on fruit inoculated within the ostiole (without wound). The LP was 6 days in all treatments. The optimum temperature for mycelial growth was 18°C. Inferred from sequences of a segment comprising the ITS region of ribosomal DNA concluded that the isolates are Botrytis cinerea.(AU)

Várias doenças podem estar associadas com figos, mas recentemente uma podridão dos frutos foi observada em frutos verdes. O objetivo deste estudo foi determinar a patogenicidade de Botrytis sp., quantificar o período de incubação (PI) e o período de latência (PL), verificar a temperatura ótima para o crescimento micelial e identificar as diferentes espécies de Botrytis sp. isoladas a partir de frutos imaturos de figo. Botrytis sp. isolado a partir de figos provou ser patogênico em frutos imaturos com e sem ferimento na superfície dos frutos e no ostíolo. O PI foi de 3 dias em frutos com ferimento e 5 dias em frutos inoculados no ostíolo e sem ferimento. O PL foi de 6 dias em todos os tratamentos. A temperatura ótima de crescimento micelial foi18°C. A partir de sequências de um segmento que compreende a região de ITS do DNA ribossomal, concluiu-se que os isolados são Botrytis cinerea.(AU)

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Caridean shrimps of the genus Synalpheus are abundant and widely distributed in tropical and subtropical regions, but knowledge of their reproductive biology remains scarce. We report reproductive traits of Synalpheusapioceros from Bocas del Toro, Panama, based on collections in August 2011. The 46 ovigerous females that were analyzed ranged in size from 3.8 to 7.4 mm in carapace length. Fecundity varied between 8 and 310 embryos and increased with female size. Females invested 18.6 ± 10.3% of their body weight in Embryo production. Embryo volume increased considerably (77.2%) during embryogenesis, likely representing water uptake near the end of incubation period. Compared to Synalpheus species with abbreviated or direct development, Synalpheusapioceros produced substantially smaller embryos; however, Synalpheusapioceros seems to have a prolonged larval phase with at least five zoeal stages, which may explain the combination of relatively small and numerous embryos. We did not find nonviable, minute, chalky embryos, previously reported for Synalpheusapioceros specimens obtained from the northwestern Gulf of Mexico, which supports the hypothesis that the production of this type of embryos may be a physiological response of this warm-water species to the temperature decrease near to its latitudinal range limit.

ResumenAunque los camarones carídeos del genero Synalpheus son muy abundantes y se encuentran ampliamente distribuidos en regiones tropicales y subtropicales, el conocimiento sobre su biología reproductiva es escaso. En este estudio reportamos algunas características reproductivas de especímenes de Synalpheusapioceros de Bocas del Toro, Panamá, colectados en Agosto del 2011. El largo del caparazón de las 46 hembras ovígeras analizadas se encuentra en un rango de 3.8 y 7.4 mm. La fecundidad varió entre 8 y 310 huevos, aumentando con el tamaño de la hembra. Las hembras invirtieron 18.6 ± 10.3% de su peso corporal en la producción de huevos. El tamaño de los huevos aumentó considerablemente (77.2%) durante la embriogénesis, probablemente por la absorción de agua al final del periodo de incubación. Comparado con especies de Synalpheus que presentan desarrollo abreviado o directo, Synalpheusapioceros produce huevos considerablemente más pequeños; sin embargo Synalpheusapioceros parece tener una fase larval prolongada, con al menos cinco estadios larvales, lo que podría explicar que los huevos sean relativamente pequeños y numerosos. No encontramos los huevos anómalos, no viables, que previamente se habían reportado para especímenes obtenidos en el Golfo de México, lo cual apoya la hipótesis de que la producción de este tipo de huevos puede ser una respuesta fisiológica a la disminución de temperatura cerca del límite latitudinal de esta especie habitante de aguas cálidas.

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Foram detectados três casos de malária vivax em Brasília, Distrito Federal, área considerada indene, procedentes da Amazônia, seis meses após estarem residindo em Brasília. Período de incubação prolongado tem sido descrito apenas para infecções por cepas de Plasmodium vivax de clima temperado. Não foi possível genotipar os parasitos.

Three cases of vivax malaria originating from the Amazon region were detected after living in Brasilia, Federal District (considered to be a non-endemic area), for six months. Long incubation periods have been described only for infections due to strains of Plasmodium vivax in temperate climates. It was not possible to genotype the parasites.

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ABSTRACT There have been recent reports on Mahanarva spectabilis (Distant), a spittlebug that is a pest of elephant grass, a forage with high potential for increasing intensive milk production. The objective of this study was to verify the effect of different hydration regimes on the development and viability of M. spectabilis eggs. Eggs were maintained in a climatic chamber at 28 ± 2° C and 12-hour photophase, in 5-cm-diameter Petri dishes lined with filter paper at different hydration regimes. Duration and viability of the 4 embryonic stages and the egg phase were evaluated daily. The results showed that the M. spectabilis eggs that were in daily contact with the water layer, or with the filter paper moistened or filter paper moistened at intervals of 2 or 5 days presented shorter durations and greater viabilities in all the embryonic development stages and in the incubation period (20 days). In the total absence of water, the eggs did not complete their development, demonstrating the decisive role of hydration in the embryonic period and viability of M. spectabilis.

RESUMO São recentes os relatos de Mahanarva spectabilis (Distant) como praga em capim-elefante, forrageira com alto potencial para incrementar a produção intensiva de leite. O objetivo dessa pesquisa foi verificar o efeito do período de exposição à hidratação no desenvolvimento e viabilidade de ovos de M. spectabilis. Ovos foram mantidos em câmara climática a 28 ± 2o C e 12h de fotofase, em placas de Petri de 5 cm de diâmetro forradas com papel-filtro, e submetidos a diferentes regimes de hidratação. Diariamente avaliou-se a duração e a viabilidade dos quatro estádios embrionários e da fase de ovo. Constatou-se que os ovos de M. spectabilis que estiveram em contato diariamente com uma lâmina de água, com o papel-filtro umedecido ou umedecidos a intervalos de dois ou cinco dias, apresentaram durações inferiores e viabilidades superiores em todos os estádios embrionários e na fase total de ovo (20 dias). Na ausência total de água, os ovos não completaram seu desenvolvimento, denotando a participação decisiva da hidratação no período embrionário e viabilidade de ovos de M. spectabilis.

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Estudou-se o efeito da concentração espermática e período de incubação e da interação dessas características sobre a fecundação in vitro (FIV) usando-se sêmen de touros Guzerá. Oócitos (n=1146) maturados in vitro foram divididos em tratamentos objetivando a FIV, em esquema fatorial 3×2×2 (três touros - A, B e C, duas concentrações espermáticas - 2 e 4×106 espermatozóides/ml e dois tempos de incubação 12 e 18 horas). Utilizaram-se espermatozóides viáveis obtidos por swin-up. A FIV foi realizada em meio fert-talp com heparina, em incubadora com 5% de CO2 e 95% de umidade, a 38,5°C. Após incubação, 50% dos oócitos foram fixados e corados para determinação das taxas de penetração, fecundação monoespermática e poliespermia. O restante foi co-cultivado com células da granulosa em meio CR2aa por oito dias, avaliando-se a taxa de clivagem e a produção de blastocisto. Houve maior taxa de penetração (P<0,05) na concentração de 4×106 espermatozóides/ml por 18 horas (64%), e não se observou diferença (P>0,05) entre os demais tratamentos. A taxa de poliespermia foi maior (P<0,05) na concentração espermática de 4×106, independente do tempo de incubação. Na concentração espermática mais alta, a taxa de poliespermia foi maior no tempo de incubação de 18 horas (P<0,05). O touro A apresentou menor (P<0,05) taxa de poliespermia em relação aos demais. Ainda, no touro A a taxa de clivagem foi maior (P<0,05) que no touro B, enquanto o C mostrou-se semelhante tanto ao A quanto ao B. O tempo de incubação, a concentração espermática e a interação das variáveis influenciaram as taxas de penetração e poliespermia, sem interferir na taxa de fecundação monoespermática e na produção de blastocistos.(AU)

The effects of sperm concentration, incubation period and their interaction on in vitro fertilization (IVF) using sperm of Guzera bulls were evaluated. In vitro matured oocytes (n=1146) were allotted to IVF treatments in a factorial scheme 3×2×2 - three bulls (A, B and C), two sperm concentrations (2 and 4×106 spermatozoa/ml) and two incubation periods (12 and 18h). Viable spermatozoa were obtained by swim-up. The IVF was performed using in Fert-Talp medium with heparin, on incubator with 5% CO2 and 95% humidity, at 38.5ºC. After the incubation, 50% of oocytes were fixed and stained to determine penetration, monospermic fecundation and polyspermy rates. The remainder was co-cultured with granulosa cells in CR2 medium for eight days to evaluate cleavage and embryo production rates. The penetration rate was higher (P<0.05) for sperm concentration of 4×106 spermatozoa/ml incubated for 18 hours (64%), and no differences (P>0.05) among remainder treatments were observed. The polyspermic rate (P<0.05) was higher for higher sperm concentration and incubation period. Bull A showed the lowest (P<0.05) polyspermy rate. Bulls A and C showed higher (P<0.05) cleavage than bull B. Incubation period, sperm concentration, and interaction of these two factors influenced penetration and polyspermy rates, without any effect on monospermic fecundation rates and embryos production.(AU)

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The present study had the objective of investigating the performance of broilers housed immediately after hatching or after a 12 or 24 hour of post-hatching holding time. One thousand and six hundred male Ross 308 broiler chicks with an initial body weight of 46 grams were used. These chicks were distributed in a completely randomized experimental design with 5 treatments and 8 replications of 35 birds in each treatment. The treatments in this study consisted of the removal of chicks from the hatchery in three different times: after 480, 492 and 504 hours of incubation. In each one of these times, 280 chicks were removed from the hatchery and immediately housed. Another group of an identical number of chicks of each time remained in the hatchery to be housed at 504 hours after hatching. The chick group corresponding to those hatched at 480 and 492 hours performed better until 7 days. However, no differences in body weight or body weight gain were observed at the end of the study. Feed efficiency, however was worse for the birds hatched and placed at 480 hours. There were no differences among treatments for mortality.

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The present study had the objective of investigating the performance of broilers housed immediately after hatching or after a 12 or 24 hour of post-hatching holding time. One thousand and six hundred male Ross 308 broiler chicks with an initial body weight of 46 grams were used. These chicks were distributed in a completely randomized experimental design with 5 treatments and 8 replications of 35 birds in each treatment. The treatments in this study consisted of the removal of chicks from the hatchery in three different times: after 480, 492 and 504 hours of incubation. In each one of these times, 280 chicks were removed from the hatchery and immediately housed. Another group of an identical number of chicks of each time remained in the hatchery to be housed at 504 hours after hatching. The chick group corresponding to those hatched at 480 and 492 hours performed better until 7 days. However, no differences in body weight or body weight gain were observed at the end of the study. Feed efficiency, however was worse for the birds hatched and placed at 480 hours. There were no differences among treatments for mortality.