RESUMO
Under conditions of high temperature, humidity, and incidence of solar radiation, dairy cows use behavioral changes as a strategy to decrease the metabolic heat production at pasture. The objective of this study was to evaluate the behavioral and physiological responses of Gyr and Girolando (5/8 Holstein 3/8 Gyr, and ½ Holstein ½ Gyr) dairy cows submitted to environments with and without shade. The experiment was conducted at Embrapa Cerrados (Technology Center for Dairy Zebu breeds-CTZL), Brasilia, Distrito Federal-Brazil, with 48 Gyr and Girolando cows total in the lactation group, with low to medium milk production, in full sun or shade with Eucalyptus urograndis (267 plants/ha-1). The physiological and behavioral characteristics evaluated were panting score, superficial temperature, and time spent grazing, ruminating, and lying down. Other traits included skin and coat thickness, hair diameter, density and length, and predominant coat color. In addition, body measurements, such as body length, the height of withers, chest circumference, and shin circumference, were measured. Shaded cows had 34% longer rumination times than cows in full sun (p = 0.01). With a temperature-humidity index ranging from 79 to 83, the rumination time was 1.7 times higher in cows under shade (p = 0.01) during a 24-h period of observation. There were no significant differences in the grazing time between the environments, but lying time was 23% longer in cows under the sun (p = 0.01). The panting score was not influenced by the environment (p = 0.17). Girolando cows had a 35% higher panting score than Gyr cows (p = 0.01) regardless of the environment. The panting score increased two and a half times during the afternoon compared with the morning (p = 0.01). The surface and rectal core temperatures had significant differences between treatments and time of the day. Body measurements were not different between cows in both environments, but there was a difference between breeds. The use of trees in pastures with a silvopastoral system for dairy zebu cows is indicated to improve grazing behavior, as well as time spent ruminating and lying down.
RESUMO
This research communication addresses the hypothesis that, during the summer in the subtropics, natural tree shade helps to improve milk functional characteristics such as stability and acidity. Sixteen Holstein lactating cows were enrolled. The study consisted of three periods (pre-stress, heat stress and post-stress) based on allocating grazing cows into two treatments (with and without access to shade during the Heat Stress period). Overall THI during the trial was (mean ± se) 76.0 ± 3.4. Access to shade prevented the heat stress-related decrease in milk stability both in the ethanol and in the coagulation time test, as well as maintained milk acidity within an acceptable range (14 to 18°D).
Assuntos
Criação de Animais Domésticos , Indústria de Laticínios , Meio Ambiente , Lactação/fisiologia , Leite/química , Árvores , Animais , Bovinos , Doenças dos Bovinos/prevenção & controle , Feminino , Transtornos de Estresse por Calor/prevenção & controle , Transtornos de Estresse por Calor/veterináriaRESUMO
This systematic review and meta-analysis aim to summarize the effects of maternal undernutrition or overnutrition during pregnancy on fetal weight and morphometric measurements during pregnancy, at birth, and postnatal period in sheep. After completing the search, selection, and data extraction steps, the measure of effect was generated by the individual comparison of each indicator with the average of the control and treated group (undernutrition or overnutrition) using the DerSimonian and Laird method for random effects. Subgroup analyses were also performed for lambing order, litter size, sex, as well as level, timing, and duration of the intervention. Fetal weight during the first third of pregnancy was not affected by maternal undernutrition or overnutrition. On the other hand, undernutrition in the second and last third of gestation reduces the weight of the lamb both during pregnancy, at birth, and during the postnatal period, requiring at least 120 postnatal days to achieve the same weight as its contemporaries in the control treatment. However, this reduction in weight is not accompanied by reductions in morphometric measurements, demonstrating that the animals were lighter, but of equal size. In overnutrition, there is an increase in fetal weight in the second third of gestation. However, in the last third of the gestational period, there are no differences in fetal weight for the multiparous subgroup, but it was reduced in primiparous ewes. There are no effects of overnutrition on birth weight; however, this result is highly heterogeneous. Thus, maternal nutrition of ewe during pregnancy has effects on fetal and postnatal weight, but not on size. Furthermore, the effects of undernutrition are more homogeneous while overnutrition showed heterogeneous responses.
Assuntos
Desenvolvimento Fetal , Desnutrição/veterinária , Fenômenos Fisiológicos da Nutrição Materna , Hipernutrição/veterinária , Ovinos/fisiologia , Animais , Peso ao Nascer , Feminino , Peso Fetal , Tamanho da Ninhada de Vivíparos , Parto , Gravidez , Ovinos/crescimento & desenvolvimentoRESUMO
Publishing profiles can help institutions and financing agencies understand the different needs of knowledge areas and regions for development within a country. Incites ® (Web of Science) was used to see where Brazilian authors were publishing, the impact, and the cost of this publishing. The USA was the country of choice for publishing journals, along with Brazil, England, and the Netherlands. While Brazilian authors continue to publish in hybrid journals, they are more often opting for closed access, with 89% of the papers published in Brazil being open access, compared with 21% of papers published abroad. The correlation between the cost of publishing and the number of citations was positive and significant. Publishing patterns were different depending on the area of knowledge and the Brazilian region. Stagnation or reduction in publications with international collaboration, industry collaboration, or in high impact open access journals may be the cause of a reduction in citation impact. These data can help in elaborating public and institutional policies for financing publications in Brazil, especially when looking at unfavourable changes in currency exchange rates.
Assuntos
Publicações , Editoração , BrasilRESUMO
Tight junctions are almost impermeable structures located near the apical border of epithelial cells; increase in the permeability of mammary gland cells' tight junctions may alter milk composition and its suitability for industrialization. Sixteen Holstein dairy cows were studied to evaluate mammary gland cells' tight junction permeability (indicated by plasma lactose levels) from cows producing stable or unstable milk to ethanol at 72 °GL concentration. Rectal temperature, respiratory rate and milk parameters were also compared and weather conditions (temperature-humidity index) monitored. Temperature-humidity index did not vary for cows producing stable or unstable milk, so there were no differences in physiological traits. Cows producing unstable milk presented elevated tight junctions' permeability, probably due to higher days in milk. The odds of cows producing unstable milk (clots formation when mixed with ethanol below or equal 72 °GL) increases according to elevations in days in milk and tight junction permeability.
Assuntos
Leite , Junções Íntimas , Animais , Bovinos , Etanol , Feminino , Lactação , Glândulas Mamárias Animais , PermeabilidadeRESUMO
Climatic variables can trigger physiological, biochemical, haematological and hormonal alterations that influence the maintenance of homeothermy and can affect production and productivity in sheep. Different mechanisms are responsible for tolerance to heat stress (HS) including coat and skin colour, body size, fat distribution, physiological reactions and not just coat type (hair/wool). This review looks at physical, physiological, molecular and genetic aspects of heat tolerance in sheep and how they affect hair and wool sheep. We propose that it is the adaptation to hot environments and not the type of coat (wool/hair) itself that determines the capacity of the resistance of the animal to HS, due to modifications in essential pathways such as energy metabolism, physiological responses and body size. When studied in similar environments, commercial wool breeds tend to show higher heat stress, but hair breeds tend not to differ from wool breeds that are adapted to hot environments.
Assuntos
Transtornos de Estresse por Calor , Doenças dos Ovinos , Animais , Regulação da Temperatura Corporal , Cabelo , Transtornos de Estresse por Calor/veterinária , Resposta ao Choque Térmico , Ovinos , Doenças dos Ovinos/genética , LãRESUMO
BACKGROUND: Reproductive capacity can be altered by challenges experienced during critical periods of development, including fetal development and early neonatal life. Gossypol is a polyphenolic compound, commonly found in cotton seeds, that impairs male reproduction. Here, we investigated whether the exposure to gossypol in utero and during lactation alters male reproductive function in sheep. From conception until 60 days postpartum, ewes were randomly assigned to a control diet or a gossypol-rich diet based on cottonseed. Lamb testicles were removed at 60 days of age and subjected to RNA-sequencing. RESULTS: Lambs derived from the maternal cottonseed diet showed significantly lower growth and lower testis weight as a proportion of the total body weight, and reduced testosterone levels. In addition, the testis transcriptome was significantly altered by the maternal cottonseed diet. Most of the altered genes are directly implicated in testis development and sperm biology, cell communication, iron ion metabolism, calcium homeostasis and signaling, among other functions. Interestingly, network analysis revealed that exposure to gossypol significantly disturbed coexpression patterns among spermatogenesis-related genes, suggesting a disruption in coregulation mechanisms. CONCLUSIONS: Our findings provide evidence that maternal exposure to gossypol alters male reproductive function in the offspring, with potential lasting or lifelong negative consequences.
Assuntos
Gossipol/toxicidade , Exposição Materna , Testículo/efeitos dos fármacos , Transcriptoma/efeitos dos fármacos , Animais , Feminino , Ontologia Genética , Lactação , Masculino , Gravidez , RNA-Seq , Carneiro Doméstico , Espermatogênese/genética , Testículo/metabolismo , Testosterona/metabolismo , Hormônios Tireóideos/metabolismoRESUMO
The use of cotton co-products in animal feed is restricted by the presence of gossypol, which is a toxic and highly reactive molecule of complex minerals. In mammals, part of the offspring phenotype is influenced by dam nutrition. The aim of this study was to investigate the effect of ewe diet, with and without cottonseed (gossypol), on the testicular development of lambs from birth to weaning through the assessment of lamb live weight (LW), macro and histological morphology of testes, and mass fraction of chemical elements by neutron activation analysis (NAA) and microprobe X-ray fluorescence spectroscopy, as well as the multielement distribution map in the testes. Eighteen lambs were used with an average LW at birth of 4 ± 1.0 kg. All lambs were offspring of Santa Inês ewes, fed on ration either with or without cottonseed during mating, gestation, and lactation, thus forming two treatments: control group (C) without cottonseed and treatment group with cottonseed (G). The animals were weighed from birth to 60 days of age, at fortnightly intervals. At 60 days of age, the lambs were orchidectomized to collect their testes for macroscopy, histological, neutron activation, and X-ray fluorescence analysis. Besides dry matter (DM), protein, ether extract (EE), calcium (Ca), and potassium (K) were higher in the ewe milk from the C group compared with the G group (P < 0.05). Lambs from the C group showed higher LW from 45 days onwards, as well as higher average daily gain when compared with the G group (P < 0.05). They also presented higher testicular weight, volume, length, width, as well as tubule and lumen diameters compared with lambs from the G treatment (P < 0.05). Multielementary NAA revealed higher mass fractions of rubidium (Rb), selenium (Se), and cesium (Cs) in the testes of lambs from the C group when compared with the G group, while G showed higher zinc (Zn) content (P < 0.05). No differences between treatments were found for element levels and distribution using X-ray fluorescence microanalysis (P > 0.05). In conclusion, the maternal cottonseed diet compromised performance and testes development of the lambs and reduce the content of Se in the testes.
Assuntos
Óleo de Sementes de Algodão , Selênio , Ração Animal/análise , Fenômenos Fisiológicos da Nutrição Animal , Animais , Dieta/veterinária , Feminino , Humanos , Masculino , Fenômenos Fisiológicos da Nutrição Materna , Ovinos , Carneiro Doméstico , TestículoRESUMO
Mycoplasma haemofelis is the agent of feline infectious anemia, although Candidatus M. haemominutum can also be associated. This study evaluated the frequency and hematological alterations caused by hemoplasma infections and co-infections with FeLV, FIV and Toxoplasma gondii in domestic cats from two distinct areas (urban - G1 and periurban - G2) of Brasília, Brazil. One hundred cats were evaluated, 51 from the G1 area and 49 from G2. No cats were positive for T. gondii. Hemoplasma infection was diagnosed in 33% cats from G1 and 32.6% from G2 (p>0.05). In G1 35.3% of the positive cats were infected with Mycoplasma haemofelis, 47.06% with Candidatus Mycoplasma haemominutum and 17.64% with mixed hemoplasma species infection; 12.5% of the cats identified as PCR positive in G2 were infected with Mycoplasma haemofelis, 18.75% with Candidatus Mycoplasma haemominutum and 68.75% with mixed infection. Cats from the periurban area had higher mixed hemoplasmas infection rates than those from urban area, and most of them were asymptomatic carriers. Cytology results were positive in only 5% of cats from G1. Mycoplasma haemofelis infected cats had normocytic normochromic anemia while the cats infected with Candidatus Mycoplasma haemominutum or with both species did not. 37.2% of G1 cats were co-infected with Mycoplasma haemofelis and FeLV, and presented lower PCV and hemoglobin concentration than those infected only with Mycoplasma haemofelis. The co-infection with Candidatus Mycoplasma haemominutum and FeLV produced lower WBC, segmented cells and platelets, and increased total protein concentration.(AU)
Mycoplasma haemofelis é o principal agente causador da anemia infecciosa felina, apesar de outras espécies de hemoplasmas, Candidatus M. haemominutum e Candidatus M. turicensis, também estarem associadas à hemoplasmose felina. O presente estudo avaliou a frequência de hemoplasmas, as principais alterações hematológicas associadas com a infecção e co-infecções com FeLV, FIV e Toxoplasma gondii em gatos domésticos de duas áreas diferentes (urbana - G1 e periurbana - G2) de Brasília, Brasil. 100 gatos foram avaliados, 51 de G1 e 49 de G2. Nenhum gato foi positivo para T. gondii. Hemoplasmose foi diagnosticada em 33% dos gatos de G1 e 32,6% de G2 (p>0,05). Em G1, 35.3% dos gatos hemoplasma positivos estavam infectados por Mycoplasma haemofelis, 47,06% por Candidatus Mycoplasma haemominutum e 17,64% apresentaram infecção concomitante por Mycoplasma haemofelis e Candidatus Mycoplasma haemominutum. Em G2, 12,5% dos gatos hemoplasma positivos estavam infectados por Mycoplasma haemofelis, 18,75% por Candidatus Mycoplasma haemominutum e 68,75% apresentaram infecção concomitante por Mycoplasma haemofelis e Candidatus Mycoplasma haemominutum. Gatos da região periurbana eram, em sua maioria, assintomáticos e apresentaram mais infecção concomitante por duas espécies de hemoplasmas do que gatos da região urbana. Os resultados da citologia foram positivos apenas em 5% dos gatos de G1. Gatos com infectados apenas com Mycoplasma haemofelis apresentaram anemia normocítica normocrômica e gatos com infecção única com Candidatus Mycoplasma haemominutum ou em combinação com Mycoplasma haemofelis não apresentaram alterações hematológicas. 37,2% dos gatos de G1 estavam co-infectados por Mycoplasma haemofelis e FeLV, e apresentaram VG e concentração de hemoglobina menores do que os gatos infectados apenas por Mycoplasma haemofelis. A co-infecção por Candidatus Mycoplasma haemominutum e FeLV resultou em baixo número de leucócitos, segmentados e plaquetes, além de aumento das concentrações de proteínas totais.(AU)
Assuntos
Animais , Gatos , Anemia/veterinária , Infecções por Mycoplasma/diagnóstico , Mycoplasma/isolamento & purificação , Reação em Cadeia da Polimerase/veterináriaRESUMO
Mycoplasma haemofelis is the agent of feline infectious anemia, although Candidatus M. haemominutum can also be associated. This study evaluated the frequency and hematological alterations caused by hemoplasma infections and co-infections with FeLV, FIV and Toxoplasma gondii in domestic cats from two distinct areas (urban - G1 and periurban - G2) of Brasília, Brazil. One hundred cats were evaluated, 51 from the G1 area and 49 from G2. No cats were positive for T. gondii. Hemoplasma infection was diagnosed in 33% cats from G1 and 32.6% from G2 (p>0.05). In G1 35.3% of the positive cats were infected with Mycoplasma haemofelis, 47.06% with Candidatus Mycoplasma haemominutum and 17.64% with mixed hemoplasma species infection; 12.5% of the cats identified as PCR positive in G2 were infected with Mycoplasma haemofelis, 18.75% with Candidatus Mycoplasma haemominutum and 68.75% with mixed infection. Cats from the periurban area had higher mixed hemoplasmas infection rates than those from urban area, and most of them were asymptomatic carriers. Cytology results were positive in only 5% of cats from G1. Mycoplasma haemofelis infected cats had normocytic normochromic anemia while the cats infected with Candidatus Mycoplasma haemominutum or with both species did not. 37.2% of G1 cats were co-infected with Mycoplasma haemofelis and FeLV, and presented lower PCV and hemoglobin concentration than those infected only with Mycoplasma haemofelis. The co-infection with Candidatus Mycoplasma haemominutum and FeLV produced lower WBC, segmented cells and platelets, and increased total protein concentration.
Mycoplasma haemofelis é o principal agente causador da anemia infecciosa felina, apesar de outras espécies de hemoplasmas, Candidatus M. haemominutum e Candidatus M. turicensis, também estarem associadas à hemoplasmose felina. O presente estudo avaliou a frequência de hemoplasmas, as principais alterações hematológicas associadas com a infecção e co-infecções com FeLV, FIV e Toxoplasma gondii em gatos domésticos de duas áreas diferentes (urbana - G1 e periurbana - G2) de Brasília, Brasil. 100 gatos foram avaliados, 51 de G1 e 49 de G2. Nenhum gato foi positivo para T. gondii. Hemoplasmose foi diagnosticada em 33% dos gatos de G1 e 32,6% de G2 (p>0,05). Em G1, 35.3% dos gatos hemoplasma positivos estavam infectados por Mycoplasma haemofelis, 47,06% por Candidatus Mycoplasma haemominutum e 17,64% apresentaram infecção concomitante por Mycoplasma haemofelis e Candidatus Mycoplasma haemominutum. Em G2, 12,5% dos gatos hemoplasma positivos estavam infectados por Mycoplasma haemofelis, 18,75% por Candidatus Mycoplasma haemominutum e 68,75% apresentaram infecção concomitante por Mycoplasma haemofelis e Candidatus Mycoplasma haemominutum. Gatos da região periurbana eram, em sua maioria, assintomáticos e apresentaram mais infecção concomitante por duas espécies de hemoplasmas do que gatos da região urbana. Os resultados da citologia foram positivos apenas em 5% dos gatos de G1. Gatos com infectados apenas com Mycoplasma haemofelis apresentaram anemia normocítica normocrômica e gatos com infecção única com Candidatus Mycoplasma haemominutum ou em combinação com Mycoplasma haemofelis não apresentaram alterações hematológicas. 37,2% dos gatos de G1 estavam co-infectados por Mycoplasma haemofelis e FeLV, e apresentaram VG e concentração de hemoglobina menores do que os gatos infectados apenas por Mycoplasma haemofelis.[...]
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Animais , Gatos , Anemia/veterinária , Infecções por Mycoplasma/diagnóstico , Mycoplasma/isolamento & purificação , Reação em Cadeia da Polimerase/veterináriaRESUMO
O mastocitoma é a neoplasia cutânea maligna de maior frequência em cães. Apesar do estudo e do desenvolvimento de diversos marcadores prognósticos na tentativa de prever o comportamento biológico deste tipo de neoplasia, a graduação histológica continua sendo utilizada como principal delineador prognóstico para os animais acometidos, mesmo não conseguindo prever o comportamento de mastocitomas de diferenciação intermediária. Diferentes marcadores de proliferação e atividade celular vêm sendo testados com resultados promissores, entretanto, em sua maioria, demandam técnicas específicas de coloração e imuno-histoquímica que, ainda hoje, são de alto custo e muitas vezes não estão facilmente disponíveis. O índice mitótico é um método indireto de mensuração da atividade proliferativa celular, que pode ser contabilizado em uma lâmina comum de avaliação histológica e estudos vêm determinando-o como importante marcador prognóstico para o mastocitoma canino. Dada a recente publicação sugerindo nova graduação em dois graus (alto e baixo) e indisponibilidade das técnicas específicas utilizadas na determinação de outros fatores prognósticos, objetivou-se avaliar o poder prognóstico das diferentes classificações, associando-as à sobrevida destes animais e comparando com o índice mitótico. Apesar de isoladamente ambas as classificações histológicas apresentarem associação com a sobrevida (P<.001) dos animais acometidos, na análise multifatorial nenhuma foi significativamente associada com a sobrevida (P>0,05)...
Mast cell tumor (MCT) is the most common malignant cutaneous neoplasm in dogs. Even with several prognostic markers being studied, in attempt to previse the biological behavior of these tumors, the histological grading is still commonly used to predict behavior, however, it is not significant to predict intermediately differentiated MCT behavior. Different prognostic and cell proliferation markers are being tested with promising results however, the majority of then requires specific staining and immunohistochemical techniques that even nowadays are expensive and not suitable for all veterinarians. Mitotic index is an indirect measure of cell proliferation and it can be established in a common histological microscope slide, and studies indicate it as an important prognostic marker for MCT in dogs. Given the recent publication of the novel two-tier histologic grading system, this study objective to evaluate the prognostic value of the different grading systems associating with survival and compare it with the mitotic index. Even though both grading systems associate with survival in the univariable analyses (P<.001), at the multivariable analyses neither was associated with survival (P>0,05)...
Assuntos
Animais , Cães , Doenças do Cão/fisiopatologia , Índice Mitótico , Biomarcadores Tumorais , Mastocitoma Cutâneo/veterinária , Prognóstico , Índice Mitótico/veterinária , Neoplasias Cutâneas , SobrevidaRESUMO
Brazil has high climate, soil and environmental diversity, as well as distinct socioeconomic and political realities, what results in differences among the political administrative regions of the country. The objective of this study was to determine spatial distribution of the physical, climatic and socioeconomic aspects that best characterize the production of dairy goats in Brazil. Production indices of milk per goat, goat production, milk production, as well as temperature range, mean temperature, precipitation, normalized difference vegetation index, relative humidity, altitude, agricultural farms; farms with native pasture, farms with good quality pasture, farms with water resources, farms that receive technical guidance, family farming properties, non-familiar farms and the human development index were evaluated. The multivariate analyses were carried out to spatialize climatic, physical and socioeconomic variables and so differenciate the Brazilian States and Regions. The highest yields of milk and goat production were observed in the Northeast. The Southeast Region had the second highest production of milk, followed by the South, Midwest and North. Multivariate analysis revealed distinctions between clusters of political-administrative regions of Brazil. The climatic variables were most important to discriminate between regions of Brazil. Therefore, it is necessary to implement animal breeding programs to meet the needs of each region.
O Brasil possui diversidade edafoclimática e realidades socioeconômicas e políticas distintas. Isto contribui para diferenciar as regiões político administrativas do país. Objetivou-se espacializar os fatores físicos, climáticos e socioeconômicos que melhor discriminam a produção de caprinos leiteiros no Brasil. Foram analisados índice de produção de leite por cabra; índice de produção de caprinos; índice de produção de leite, amplitude da temperatura; temperatura média; precipitação; índice normalizado de diferença vegetativa; umidade relativa do ar; altitude; estabelecimentos agropecuários; estabelecimentos com pastagem nativa; estabelecimentos com pastagens de boa qualidade; estabelecimentos com recursos hídricos; estabelecimentos que recebem orientação técnica; estabelecimentos de agricultura familiar; estabelecimentos de agricultura não familiar e índice de desenvolvimento humano. Foram realizadas análises multivariadas para espacializar as variáveis climáticas, físicas e socioeconômicas e, assim, discriminar os Estados e Regiões brasileiras. As maiores produções de caprinos e de leite foram observadas na região Nordeste. A região Sudeste apresentou segunda maior produção de leite, seguido pelo Sul, Centro-Oeste e Norte. As médias para produtividade mostraram que as regiões Centro-Oeste e Sudeste apresentaram animais mais especializados a produção de leite. As análises multivariadas evidenciaram distinções entre clusters das regiões político-administrativas do Brasil. As variáveis climáticas foram as mais importantes para discriminar entre as regiões brasileiras. A heterogeneidade dos componentes climáticos, físicos e socioeconômicos evidenciou peculiaridades em cada região. Portanto, é preciso implementar programas de melhoramento genético animal que atendam as necessidades de cada região.
Assuntos
Animais , Efeitos do Clima , Ovinos/crescimento & desenvolvimento , Política , Fatores Socioeconômicos , Sistemas de Informação Geográfica , Indústria Agropecuária , Análise Multivariada , PastagensRESUMO
This study was undertaken to aim of estimating the genetic parameters and trends for asymptotic weight (A) and maturity rate (k) of Nellore cattle from northern Brazil. The data set was made available by the Brazilian Association of Zebu Breeders and collected between the years of 1997 and 2007. The Von Bertalanffy, Brody, Gompertz, and logistic nonlinear models were fitted by the Gauss-Newton method to weight-age data of 45,895 animals collected quarterly of the birth to 750 days old. The curve parameters were analyzed using the procedures GLM and CORR. The estimation of (co)variance components and genetic parameters was obtained using the MTDFREML software. The estimated heritability coefficients were 0.21 ± 0.013 and 0.25 ± 0.014 for asymptotic weight and maturity rate, respectively. This indicates that selection for any trait shall results in genetic progress in the herd. The genetic correlation between A and k was negative (-0.57 ± 0.03) and indicated that animals selected for high maturity rate shall result in low asymptotic weight. The Von Bertalanffy function is adequate to establish the mean growth patterns and to predict the adult weight of Nellore cattle. This model is more accurate in predicting the birth weight of these animals and has better overall fit. The prediction of adult weight using nonlinear functions can be accurate when growth curve parameters and their (co)variance components are estimated jointly. The model used in this study can be applied to the prediction of mature weight in herds where a portion of the animals are culled before they reach the adult age.
Assuntos
Peso ao Nascer , Peso Corporal , Bovinos/crescimento & desenvolvimento , Bovinos/genética , Criação de Animais Domésticos , Animais , Brasil , Cruzamento , Feminino , Estudos Longitudinais , Masculino , Modelos Genéticos , Dinâmica não Linear , Análise de Regressão , Seleção GenéticaRESUMO
To define the prevalence of anti-Leptospira sp. agglutinins in ewes in the Federal District, Brazil, serum samples from 157 ewes were tested for antibodies against serovars of Leptospira sp. by the microscopic agglutination test. Antibodies were detected in three flocks in a prevalence of 3% (95% CI = 0.4%-5.7%). Considering that sheep and cattle were raised together, the lack of sanitary control could represent a risk to cattle production, which is the most important activity in the Centre-West region of Brazil.