Associations between valenced news and affect in daily life: Experimental and ecological momentary assessment approaches.

In 203 (mean age = 38.04 years, SD=12.05) participants, we tested the association between valenced news and affect using a 14-day, smartphone-based ecological momentary assessment protocol consisting of two components: 1) a once-per-day experimental protocol in which participants were exposed to good news and bad news stories and 2) a four-times-per-day protocol capturing ecological fluctuations in news consumption. Across both protocols, we replicate findings that consumption of positively valenced news is associated with increased positive affect and decreased negative affect while consumption of negatively valenced news is associated with increased negative affect and decreased positive affect. By integrating the ecological momentary assessment data with network science methodologies, news selection and news effects were modeled simultaneously, uncovering selection processes whereby current positive affect, but not negative affect, predicted future valenced news consumption. Altogether, findings indicate that everyday news consumption influences positive and negative affect and may serve mood management functions for positive but not negative affect.

Breastfeeding Duration and Cardiometabolic Health during Adolescence: A Longitudinal Analysis.

OBJECTIVE: To investigate the longitudinal association between breastfeeding duration and cardiometabolic health, using repeated measures study design among children and adolescents. STUDY DESIGN: This study included 634 offsprings aged 10 to 21 years (52% female) from the Early Life Exposure in Mexico to Environmental Toxicants birth cohort followed up to four time points during adolescence. Breastfeeding duration was prospectively quantified using questionnaires during early childhood. Cardiometabolic risk factors, body composition, and weight-related biomarkers were assessed as outcomes during adolescent follow-up visits. Sex-stratified linear mixed-effects models were used to model the association between quartiles of breastfeeding duration and outcomes, adjusting for age and additional covariates. RESULTS: Median breastfeeding duration was 7 months (minimum = 0, maximum = 36). Boys in the second quartile (median breastfeeding = 5 months) had lower total fat mass % (ß (SE) -3.2 (1.5) P = .037), and higher lean mass % (3.1 (1.6) P = .049) and skeletal muscle mass % (1.8 (0.8) P = .031) compared with the reference group (median breastfeeding = 2 months). A positive linear trend between breastfeeding duration and trunk lean mass % (0.1 (0.04) P = .035) was found among girls. No association was found with other cardiometabolic indicators. CONCLUSION: Despite sex-specific associations of breastfeeding duration with body composition, there was a lack of substantial evidence for the protective effects of breastfeeding against impaired cardiometabolic health during adolescence among Mexican youth. Further longitudinal studies with a robust assessment of breastfeeding are recommended.

Sedentary patterns and cardiometabolic risk factors in Mexican children and adolescents: analysis of longitudinal data.

BACKGROUND: Sedentary behavior is a modifiable risk factor for cardiometabolic health; however, the assessment of total sedentary time may not capture youth's highly active and interrupted activity patterns. This study examined the associations between sedentary activity patterns and cardiometabolic risk factors among Mexican youth, who have a disproportionate burden of metabolic diseases, using a repeated measure design out of a longitudinal data. METHODS: 570 subjects in the Early Life Exposure in Mexico to ENvironmental Toxicants (ELEMENT) birth cohort, who were followed up to three-time points during adolescence, were included. Bout duration, and frequency and percentages of waking time spent in specific intensities of activity, were quantified using ActiGraph wGT3X-BT wrist accelerometers. Self-reported questionnaires were used to query the usual duration of different sedentary behaviors. Outcomes were fasting lipid profile, markers for glucose homeostasis, anthropometry, and blood pressure. Associations were modeled using linear mixed-effects models, and isotemporal substitution approach was additionally used to assess the effect of replacing objectively assessed sedentary activity with other activity intensities, adjusting for potential confounders. RESULTS: Each hour of self-reported screen-based time was positively associated with diastolic blood pressure (mm Hg) [ß = 0.30, 95% confidence interval (95% CI) = 0.10, 0.51], and an hour of other sedentary time was associated with log serum glucose (mg/dL) [ß = 0.01, 95% CI = 0.004, 0.017]. Substitution models showed that replacing 5% of sedentary time with moderate to vigorous physical activity (MVPA) was associated with lower waist circumference (cm) [ß = - 1.35, 95% CI = - 1.91, - 0.79] and log serum triglycerides (mg/dL) [ß = - 0.11, 95% CI = - 0.18, - 0.03]. Substituting one uninterrupted sedentary bout with light activity was associated with lower insulin (µIU/mL) [ß = - 0.06, 95% CI = - 0.10, - 0.02]. CONCLUSIONS: Sedentary time was associated with cardiometabolic risk factors in Mexican youth in a context-specific manner. Replacing sedentary time with higher intensities was associated with improvements in some cardiometabolic markers.

Beyond ANOVA and MANOVA for repeated measures: Advantages of generalized estimated equations and generalized linear mixed models and its use in neuroscience research.

In neuroscience research, longitudinal data are often analysed using analysis of variance (ANOVA) and multivariate analysis of variance (MANOVA) for repeated measures (rmANOVA/rmMANOVA). However, these analyses have special requirements: The variances of the differences between all possible pairs of within-subject conditions (i.e., levels of the independent variable) must be equal. They are also limited to fixed repeated time intervals and are sensitive to missing data. In contrast, other models, such as the generalized estimating equations (GEE) and the generalized linear mixed models (GLMM), suggest another way to think about the data and the studied phenomenon. Instead of forcing the data into the ANOVAs assumptions, it is possible to design a flexible/personalized model according to the nature of the dependent variable. We discuss some advantages of GEE and GLMM as alternatives to rmANOVA and rmMANOVA in neuroscience research, including the possibility of using different distributions for the parameters of the dependent variable, a better approach for different time length points, and better adjustment to missing data. We illustrate these advantages by showing a comparison between rmANOVA and GEE in a real example and providing the data and a tutorial code to reproduce these analyses in R. We conclude that GEE and GLMM may provide more reliable results when compared to rmANOVA and rmMANOVA in neuroscience research, especially in small sample sizes with unbalanced longitudinal designs with or without missing data.

A new approach to modeling positive random variables with repeated measures.

In many situations, it is common to have more than one observation per experimental unit, thus generating the experiments with repeated measures. In the modeling of such experiments, it is necessary to consider and model the intra-unit dependency structure. In the literature, there are several proposals to model positive continuous data with repeated measures. In this paper, we propose one more with the generalization of the beta prime regression model. We consider the possibility of dependence between observations of the same unit. Residuals and diagnostic tools also are discussed. To evaluate the finite-sample performance of the estimators, using different correlation matrices and distributions, we conducted a Monte Carlo simulation study. The methodology proposed is illustrated with an analysis of a real data set. Finally, we create an R package for easy access to publicly available the methodology described in this paper.

Effects of household and participant characteristics on personal exposure and kitchen concentration of fine particulate matter and black carbon in rural Honduras.

Traditional cooking with solid fuels (biomass, animal dung, charcoals, coal) creates household air pollution that leads to millions of premature deaths and disability worldwide each year. Exposure to household air pollution is highest in low- and middle-income countries. Using data from a stepped-wedge randomized controlled trial of a cookstove intervention among 230 households in Honduras, we analyzed the impact of household and personal variables on repeated 24-h measurements of fine particulate matter (PM2.5) and black carbon (BC) exposure. Six measurements were collected approximately six-months apart over the course of the three-year study. Multivariable mixed models explained 37% of variation in personal PM2.5 exposure and 49% of variation in kitchen PM2.5 concentrations. Additionally, multivariable models explained 37% and 47% of variation in personal and kitchen BC concentrations, respectively. Stove type, season, presence of electricity, primary stove location, kitchen enclosure type, stove use time, and presence of kerosene for lighting were all associated with differences in geometric mean exposures. Stove type explained the most variability of the included variables. In future studies of household air pollution, tracking the cooking behaviors and daily activities of participants, including outdoor exposures, may explain exposure variation beyond the household and personal variables considered here.

Scrotal circumference in Karagouniko and Chios sheep in relation to the aerial environment

Local breeds are a valuable asset in sheep farming systems in Greece and other Mediterranean countries. Among these, Karagouniko and Chios sheep hold a special position, participating in numerous genetic improvement programs, but a research gap exists on their scrotal circumference (SC) in relation to the environmental parameters photoperiod (PHOTO), air temperature, sunshine and rainfall. Therefore, four seasons were examined: April-June and July-September (Long days, increasing and decreasing photoperiod length, respectively), and October-December and January-March (Short days, decreasing and increasing photoperiod length, respectively). Repeated measures analysis of variance and linear correlation analysis were used to investigate the effect of the period on SC and the relationships of SC and each of the environmental parameters above, respectively, in both breeds. Also, independent t-tests were used to investigate SC differences between Karagouniko and Chios. A progressive increase of SC in both breeds coincided with the lowering of PHOTO from April-June to October-December. A significant correlation was confirmed between the SC of each breed and PHOTO, shedding light on the importance of this parameter on SC. Chios sheep had significantly larger (P < 0.05) SC (35.23 cm) than the Karagouniko one (34.59 cm). Better exploitation of these sheep breeds could be derived from the current study's findings.

Effect of seasonally changing aerial environment on testosterone in Karagouniko and Chios sheep

A well-established activity in Greece and other Mediterranean countries is sheep farming. Karagouniko and Chios sheep are promising breeds and targets for the reproductive physiologist's attention. Under this context, part of the reproductive physiology of Karagouniko and Chios was investigated, taking into account the environment. Specifically, four time periods were considered; April-June (Long days, increasing photoperiod length), July-September (Long days, decreasing photoperiod length), October-December (Short days, decreasing photoperiod length), and January-March (Short days, increasing photoperiod length). The effect of the period on the concentration of the testosterone (main male hormone) in rams of the breeds above was studied, by using repeated measures analysis of variance, also taking into account the environmental variables air temperature, relative humidity, sunshine, rainfall, and photoperiod, in the Artificial Insemination Center of Karditsa (39°21'18''N, 21°54'19''E), Greece. The lowering of photoperiod from April-June to July-September (long days) and afterward, even more to October-December (short days) coincided with a progressive increase of testosterone in both breeds. Photoperiod seems to have a major role in the concentration of Karagouniko and Chios breeds' testosterone compared to the other environmental variables. When considering the whole experimental period, Chios sheep had significantly higher (P < 0.05) testosterone (1.95 ng/ml) than the Karagouniko one (1.55 ng/ml). Our findings could contribute towards the more rational exploitation of the examined sheep breeds.(AU)

Effect of seasonally changing aerial environment on testosterone in Karagouniko and Chios sheep

A well-established activity in Greece and other Mediterranean countries is sheep farming. Karagouniko and Chios sheep are promising breeds and targets for the reproductive physiologist's attention. Under this context, part of the reproductive physiology of Karagouniko and Chios was investigated, taking into account the environment. Specifically, four time periods were considered; April-June (Long days, increasing photoperiod length), July-September (Long days, decreasing photoperiod length), October-December (Short days, decreasing photoperiod length), and January-March (Short days, increasing photoperiod length). The effect of the period on the concentration of the testosterone (main male hormone) in rams of the breeds above was studied, by using repeated measures analysis of variance, also taking into account the environmental variables air temperature, relative humidity, sunshine, rainfall, and photoperiod, in the Artificial Insemination Center of Karditsa (39°21’18’’N, 21054’19’’E), Greece. The lowering of photoperiod from April-June to July-September (long days) and afterward, even more to October-December (short days) coincided with a progressive increase of testosterone in both breeds. Photoperiod seems to have a major role in the concentration of Karagouniko and Chios breeds' testosterone compared to the other environmental variables. When considering the whole experimental period, Chios sheep had significantly higher (P < 0.05) testosterone (1.95 ng/ml) than the Karagouniko one (1.55 ng/ml). Our findings could contribute towards the more rational exploitation of the examined sheep breeds.

A new mixed-effects regression model for the analysis of zero-modified hierarchical count data.

Count data sets are traditionally analyzed using the ordinary Poisson distribution. However, such a model has its applicability limited as it can be somewhat restrictive to handle specific data structures. In this case, it arises the need for obtaining alternative models that accommodate, for example, (a) zero-modification (inflation or deflation at the frequency of zeros), (b) overdispersion, and (c) individual heterogeneity arising from clustering or repeated (correlated) measurements made on the same subject. Cases (a)-(b) and (b)-(c) are often treated together in the statistical literature with several practical applications, but models supporting all at once are less common. Hence, this paper's primary goal was to jointly address these issues by deriving a mixed-effects regression model based on the hurdle version of the Poisson-Lindley distribution. In this framework, the zero-modification is incorporated by assuming that a binary probability model determines which outcomes are zero-valued, and a zero-truncated process is responsible for generating positive observations. Approximate posterior inferences for the model parameters were obtained from a fully Bayesian approach based on the Adaptive Metropolis algorithm. Intensive Monte Carlo simulation studies were performed to assess the empirical properties of the Bayesian estimators. The proposed model was considered for the analysis of a real data set, and its competitiveness regarding some well-established mixed-effects models for count data was evaluated. A sensitivity analysis to detect observations that may impact parameter estimates was performed based on standard divergence measures. The Bayesian p -value and the randomized quantile residuals were considered for model diagnostics.

Análisis reproductivo de vacas Suizo Pardo x Cebú y Simmental x Cebú en condiciones tropicales / Reproductive analysis of Brown Swiss x Zebu and Simmental x Zebu cows in tropical conditions

RESUMEN Objetivo. Comparar la fertilidad de vacas cruzadas Suizo Pardo x Cebú y Simmental x Cebú criadas en un ambiente tropical. Materiales y métodos. Se evaluaron características reproductivas de 185 vacas cruzadas Suizo Pardo x Cebú y Simmental x Cebú con diversos porcentajes de raza europea. El pastoreo de las vacas fue rotacional. El ordeño fue dos veces al día con la ayuda (amamantamiento) del becerro, el cual se mantuvo atado cerca de la vaca mientras ella se ordeñaba. Las características se evaluaron ajustando un modelo de mediciones repetidas (excepto para edad a primer parto). Periodo interparto, edad a primer parto, días abiertos, periodo parto-primer servicio y peso al parto fueron analizados con PROC MIXED de SAS. Tasa de gestación a primer servicio y servicios por concepción, se analizaron con PROC GENMOD del mismo programa. Resultados. Las vacas Simmental x Cebú se sirvieron después del parto 39 días antes (p<0.05) y tuvieron 47 días abiertos menos (p<0.05) que las Suizo Pardo x Cebú. El periodo interparto de las vacas Simmental x Cebú fue 45 días más corto (p<0.05) que el de las Suizo Pardo x Cebú. Las vacas Simmental x Cebú pesaron 34 kg más al parto (p<0.05) que las Suizo Pardo x Cebú. Conclusiones. Las vacas Simmental x Cebú tuvieron mejor fertilidad que las Suizo Pardo x Cebú.

ABSTRACT Objective. Compare the fertility of Brown Swiss x Zebu and Simmental x Zebu crossbred cows reared in a tropical environment. Materials and methods. Reproductive traits of 185 Brown Swiss x Zebu and Simmental x Zebu crossbred cows with diverse percentages of European breed were evaluated. Grazing of cows was rotational. The milking was twice daily with the help (suckling) of the calf, which was kept tied next to the dam while she was milked. Traits were evaluated fitting a repeated measures model (except for age at first calving). Calving interval, age at first calving, days open, interval from calving to first service, and weight at calving were analyzed with PROC MIXED of SAS. Pregnancy rate at first service and services per conception were analyzed with PROC GENMOD of the same software. Results. Simmental x Zebu cows started to re-bred 39 days earlier after calving (p<0.05) and had 47 fewer days open (p<0.05) than Brown Swiss x Zebu cows. The calving interval of the Simmental x Zebu cows was 45 days shorter (p<0.05) than that of the Brown Swiss x Zebu cows. Simmental x Zebu cows were 34 kg heavier at calving (p<0.05) than Brown Swiss x Zebu cows. Conclusions. Simmental x Zebu cows had better fertility than Brown Swiss x Zebu cows.

Repeated measures of urinary oxidative stress biomarkers and preterm birth in Puerto Rico.

BACKGROUND: Preterm birth (PTB; gestational age <37 weeks), the leading cause of infant morbidity and mortality worldwide, is of particular concern in Puerto Rico. Rates of PTB in Puerto Rico peaked at 20% in 2006, which are historically some of the highest in the world. Oxidative stress and inflammation have been implicated as contributors to adverse birth outcomes, including PTB, and these associations have not been explored in Puerto Rico. Our objective was to examine associations between urinary oxidative stress biomarkers and PTB in the Puerto Rico Testsite for Exploring Contamination Threats (PROTECT) pregnancy cohort (N = 469). METHODS: 8-iso-prostaglandin F2α (8-iso-PGF2α), its primary metabolite, and prostaglandin F2α (PGF2α) were included as biomarkers of oxidative stress or inflammation. Biomarkers were measured in urine samples collected at up to 3 timepoints across pregnancy (mean 18, 24, 28 weeks gestation). We quantified the proportion of 8-iso-PGF2α originating from oxidative stress and inflammation pathways with a formula based on the ratio of 8-iso-PGF2α to PGF2α. Logistic regression models were used to calculate adjusted odds ratios (OR) for associations between average biomarker concentrations from each woman (visits 1-3) and PTB. Associations between biomarker concentrations at each study visit and PTB were analyzed in separate models. RESULTS: Averaged levels of 8-iso-PGF2α, its primary metabolite, and PGF2α were associated with increased odds of PTB (OR = 1.64, 95% confidence interval [CI] = 1.07-2.54; OR = 1.79, 95% CI = 1.14-2.84; OR = 1.98, 95% CI = 1.32-3.02, respectively). Odds ratios for PTB were greater in magnitude in association with oxidative stress biomarkers measured later in pregnancy. The fraction of 8-iso-PGF2α derived from inflammation was associated with PTB (OR = 1.73, 95% CI = 1.09, 2.93), while the fraction of 8-iso-PGF2α derived from oxidative stress was not associated with PTB (OR = 1.17, 95% CI = 0.90, 1.54). CONCLUSIONS: Our results suggest that oxidative stress and inflammation, as measured by these biomarkers, may be important contributors to PTB. Further research is needed to improve our understanding of the role these biomarkers may play in the causal pathway between environmental factors and PTB.

Exhausted grape marc and organic residues composting with polyethylene cover: Process and quality evaluation as plant substrate.

In Argentina, wine production is one of the most important economic activities, producing a large quantities of organic wastes. Composting is a viable alternative to treat these residues, with the possibility to obtain high-quality products. The objective of the present study was to evaluate the effect of the addition of goat manure, leaves from garden raking and alfalfa to exhausted grape marc and the influence of plastic cover on the composting process and the quality of the finished product. Composting was carried out in turned piles in a total randomized design. Temperature, moisture, pH, electrical conductivity, micro and macro elements, biological parameters, stability and structure were determined with the goal to assess product quality. Mixture compost presented higher macro and micro elements content (especially P, Mn and Zn) than grape marc compost. Plastic cover showed no significant effect on physico-chemical parameters, while microorganisms were affected, with higher cellulolytic and nitrifying content in uncovered piles. In all composts, parameters indicated stability and no pathogens (Salmonella sp.) were detected. Pot assay with Lactuca sativa suggested that all compost revealed adequate substrate quality, with higher plant biomass values than commercial substrate and sand (Control), even with fertilization. Mixture compost showed significantly higher biomass and nutrient absorption values relative to the remaining evaluated substrates, suggesting that the use of goat manure and leaves added to exhausted grape marc, as raw material resulted in higher compost quality. All together indicated that the use of polyethylene cover negatively affect microorganisms content and a higher diversity of organic residues composted would result in higher microbiological activity and nutritional grade product.

Impacto de la intensidad horaria de la estadística en las pruebas saber 11 / Impact of the time intensity of statistics in the saber 11 tests / Impacto da intensidade temporal da estatística sobre as provas saber 11

Resumen Introducción. En Colombia la Ley General de Educación dio la potestad a las instituciones educativas de organizar sus propios currículos acorde con los proyectos educativos institucionales. Con base en esta autonomía, algunas instituciones fragmentaron el área de matemáticas en asignaturas como estadística y geometría con distribución de tiempo semanal a cada una de ellas. Otras instituciones se organizan en temas y los desarrollan en momentos particulares del año escolar. En ese sentido, conocer los efectos que podrían tener una u otra organización en los procesos educativos representa un interés para profesores, investigadores e instituciones educativas. Objetivo. Determinar el efecto que la distribución de la intensidad horaria de la asignatura estadística podría tener en el desempeño de los estudiantes en la Prueba Saber 11° en instituciones educativas públicas de Medellín-Colombia. Materiales y métodos. Los datos se extrajeron de los resultados de Pruebas Saber 11. Se hizo ajuste de un modelo lineal con efectos mixtos. Resultados. Después de controlar el efecto institución, algunas variables específicas de los estudiantes sí inciden en los resultados obtenidos en matemáticas, pero la distribución de la intensidad horaria que se dedica a la enseñanza de la estadística no es un factor significativo. Conclusiones. La distribución del tiempo e intensidad horaria dedicada a la estadística no tiene un efecto automático ni inmediato en el desempeño de los estudiantes, las instituciones deben considerar estrategias para promover competencias de los estudiantes acordes con su condición económica y social.

Abstract Introduction. In Colombia, the General Education Law gave Educational Institutions the authority to organize their academic curricula according to their corresponding Educational Projects. Based on this institutional autonomy, some educational institutions have divided the area of mathematics into subjects such as statistics and geometry; also they have allocated a weekly time to each one of these subjects. In contrast, other institutions organize the area of mathematics by themes developed at specific times during the school year. In this sense, knowing the effects that one or another allocation could have on educational processes represents an interest for research and for teachers and educational institutions. Objective. Determine the effect that the allocation of teaching hours spent on the statistics subject could have on student performance on the Saber 11th Test in public educational institutions from Medellín-Colombia. Materials and Method. Data were extracted from the Saber 11-test results. A linear model was adjusted with mixed effects. Results. After controlling for the institution effect, it was found that some student-specific variables do impact the results in mathematics. However, allocation of teaching hours spent on statistics is not a significant factor. Conclusions. Time allocation and teaching hours spent on a statistics course do not have automatic or immediate impact on student performance. Every institution should consider strategies to promote student competencies according to their economic and social conditions.

Resumo Introdução. Na Colômbia a Lei Geral da Educação forneceu o poder às instituições educativas de organizar seus próprios currículos conforme com os projetos educativos institucionais. Com base nesta autonomia, algumas instituições fragmentaram a área de matemáticas em disciplinas como estatística e geometria com distribuição do tempo semanal em cada uma delas. Outras instituições organizam-se em temas e os desenvolvem em momentos particulares do ano escolar. Neste sentido, conhecer os efeitos que poderiam ter uma ou outra organização nos processos educativos representa um interesse para professores, pesquisadores e instituições educativas. Objetivo. Determinar o efeito que a distribuição da intensidade temporal da disciplina estatística poderia ter no desempenho dos estudantes nas Prova Saber 11° em instituições educativas públicas de Medellín-Colômbia. Materiais e Métodos. Os dados foram extraídos dos resultados das Provas Saber 11. Realizou-se o ajuste de um modelo lineal com efeitos misturados. Resultados. Depois de controlar o efeito instituição, algumas variáveis específicas dos estudantes sim incidiram nos resultados obtidos em matemáticas, mas a distribuição da intensidade temporal que se dedica ao ensino da estatística não é um fator significativo. Conclusões. A distribuição do tempo e intensidade temporal dedicada à estatística não tem um efeito automático e nem imediato no desempenho dos estudantes, as instituições devem considerar estratégias para promover habilidades dos estudantes acordes com sua condição econômica e social.

Repeatability, number of harvests, and phenotypic stability of dry matter yield and quality traits of Panicum maximum jacq / Repetibilidade, número de colheitas e estabilidade fenotípica da produção de matérica seca e de características de qualidade de Panicum maximum jacq

Selection of superior forage genotypes is based on agronomic traits assayed in repeated measures. The questions are how repeatable the performance of individual genotypes is and how many harvests are needed to select the best genotypes. The objectives were to estimate repeatability coefficients of dry matter yield (DMY) and forage quality, their phenotypic stability and the number of harvests needed for an accurate selection. Two randomized complete block design experiments data with 24 genotypes each, undergoing 12 and 16 harvests, over a period of 2 and 3 years, respectively, were used. The DMY repeatability estimates ranged from 0.42 to 0.55, suggesting a low heritability. The mean numbers of repeated measures were 5 and 7 harvests for 0.80 and 0.85 accuracy, respectively. The inclusion of the first two harvests negatively affects the estimates. Repeatability for quality traits ranged from 0.30 to 0.69, indicating low to moderate heritability.

A seleção de genótipos superiores em forrageiras é feita para características agronômicas analisadas em medições repetidas no tempo. As questões estão relacionadas à repetibilidade do desempenho dos genótipos e ao número necessário de colheitas para selecionar aqueles superiores. Os objetivos foram estimar coeficientes de repetibilidade da produção de matéria seca (PMS) e de características de qualidade da forragem, a estabilidade fenotípica e o número de colheitas necessárias para uma seleção mais precisa. Dois experimentos em blocos casualizados com 24 genótipos cada um, submetidos a 12 e 16 colheitas, durante um período de dois e três anos, respectivamente, foram utilizados para o estudo. As estimativas de repetibilidade de PMS variaram de 0,42 a 0,55, sugerindo baixa herdabilidade. Os números de colheitas foram cinco e sete para 0,80 e 0,85 de acurácia, respectivamente. A inclusão das duas primeiras colheitas afeta negativamente as estimativas de PMS. A repetibilidade para as características de qualidade variou de 0,30 a 0,69, indicando baixa à moderada herdabilidade.

Repeatability, number of harvests, and phenotypic stability of dry matter yield and quality traits of Panicum maximum jacq / Repetibilidade, número de colheitas e estabilidade fenotípica da produção de matérica seca e de características de qualidade de Panicum maximum jacq

Selection of superior forage genotypes is based on agronomic traits assayed in repeated measures. The questions are how repeatable the performance of individual genotypes is and how many harvests are needed to select the best genotypes. The objectives were to estimate repeatability coefficients of dry matter yield (DMY) and forage quality, their phenotypic stability and the number of harvests needed for an accurate selection. Two randomized complete block design experiments data with 24 genotypes each, undergoing 12 and 16 harvests, over a period of 2 and 3 years, respectively, were used. The DMY repeatability estimates ranged from 0.42 to 0.55, suggesting a low heritability. The mean numbers of repeated measures were 5 and 7 harvests for 0.80 and 0.85 accuracy, respectively. The inclusion of the first two harvests negatively affects the estimates. Repeatability for quality traits ranged from 0.30 to 0.69, indicating low to moderate heritability.(AU)

A seleção de genótipos superiores em forrageiras é feita para características agronômicas analisadas em medições repetidas no tempo. As questões estão relacionadas à repetibilidade do desempenho dos genótipos e ao número necessário de colheitas para selecionar aqueles superiores. Os objetivos foram estimar coeficientes de repetibilidade da produção de matéria seca (PMS) e de características de qualidade da forragem, a estabilidade fenotípica e o número de colheitas necessárias para uma seleção mais precisa. Dois experimentos em blocos casualizados com 24 genótipos cada um, submetidos a 12 e 16 colheitas, durante um período de dois e três anos, respectivamente, foram utilizados para o estudo. As estimativas de repetibilidade de PMS variaram de 0,42 a 0,55, sugerindo baixa herdabilidade. Os números de colheitas foram cinco e sete para 0,80 e 0,85 de acurácia, respectivamente. A inclusão das duas primeiras colheitas afeta negativamente as estimativas de PMS. A repetibilidade para as características de qualidade variou de 0,30 a 0,69, indicando baixa à moderada herdabilidade.(AU)

Undernutrition during early life alters neuropeptide Y distribution along the arcuate/paraventricular pathway.

Perinatal nutrient restriction exerts profound influences on brain development. Animals that suffer undernutrition during lactation also display impaired weight gain. Feeding behavior is mainly modulated by neural and hormonal inputs to the hypothalamus. The arcuate-paraventricular neuropeptidergic Y pathway has a prominent role in appetite regulation. The aim of this work was to study the effects of protein undernutrition during lactation on this hypothalamic pathway. We used rats from 5 to 60 postnatal (P) days whose dams were fed a 0% protein diet (PFG) or a normoprotein diet (CG) from P1 to P10. To reproduce the same amount of calorie ingested by the PFG we used an underfed group (UFG). Immunohistochemistry was performed to assess neuropeptide Y (NPY) distribution in the arcuate, periventricular and paraventricular nuclei. Our results showed a NPY immunostaining peak at P10 in all nuclei in CG animals. In UFG animals this peak was observed by P15, while, in the PFG animals only by P20. Our results suggest that the neuropeptidergic arcuate-paraventricular pathway suffered a delay in NPY distribution in undernourished animals, particularly those fed a 0% protein diet, reflecting an effect on this pathway maturation that could explain previously reported alterations on feeding behavior in these animals.

Efeito da duração da amamentação predominante no crescimento infantil: um estudo prospectivo com modelos não lineares de efeitos mistos / Effect of predominant breastfeeding duration on infant growth: prospective study using nonlinear mixed effect models

OBJETIVO: Avaliar o efeito da duração da amamentação predominante no crescimento infantil com uso de modelos para medidas repetidas. MÉTODOS: Trata-se de estudo prospectivo com quatro ondas de seguimento realizadas com aproximadamente 0,5, 2, 6 e 9 meses pós-parto, que incluiu entrevistas estruturadas e coleta de dados de peso, comprimento e sobre práticas de aleitamento. O estudo foi desenvolvido em um Centro Municipal de Saúde no Rio de Janeiro, Brasil, entre 1999 e 2001. Quatrocentos e setenta e nove mulheres e seus filhos foram estudados. As variáveis dependentes foram o peso e o comprimento, aferidas em cinco momentos (ao nascimento, 0,5, 2, 6 e 9 meses). O crescimento foi analisado usando modelos não lineares de efeitos mistos. RESULTADOS: Crianças com maior duração de aleitamento predominante apresentaram maior velocidade de crescimento durante os primeiros meses de vida, mas alcançaram peso e comprimento de equilíbrio menor quando comparadas com crianças que receberam outros leites não humanos no início da vida. A idade na qual a velocidade de crescimento de crianças alimentadas com fórmulas tornou-se maior do que as amamentadas foi de 6,75 meses para meninos e 7 meses para meninas. CONCLUSÕES: Esse estudo confirma a presença de diferenças no crescimento físico segundo práticas de aleitamento a partir dos 6 meses de vida. O uso de modelos não lineares permitiu maior precisão na estimativa dos parâmetros. Acredita-se que essa abordagem facilite a análise e interpretação de dados de crescimento nos níveis individual e populacional.

OBJECTIVE: The aim of this study is to assess the effect of predominant breastfeeding duration on infant growth by means of repeated measurements model. METHODS: This prospective study is comprised of four follow-up evaluations at approximately 0.5, 2, 6 and 9 months after birth, including structured interviews that simultaneously gathered information regarding infant growth and breastfeeding practices. The study took place in a healthcare center in Rio de Janeiro, Brazil, from 1999 to 2001. Four hundred seventy-nine postpartum women and their newborns were enrolled in the cohort. Body weight and length measurements taken at five different occasions (birth, 0.5, 2, 6, and 9 months) constituted the dependent variables. We expressed the growth process using nonlinear mixed models. RESULTS: Infants with longer predominant breastfeeding duration, although growing faster in the first months of life, reached an inferior equilibrium body weight and length compared to infants who received nonhuman milk earlier in life. The age at which the rate of weight gain of the formula-fed infants becomes greater than that of the breastfed infants is approximately 6.75 months for boys and 7 months for girls. CONCLUSIONS: This study confirms the differences observed in infant growth according to different breastfeeding practices starting from the sixth month of life. Use of nonlinear models allowed for a greater precision of parameter estimates. We believe that this approach facilitates the analysis and interpretation of growth data at the individual and population levels.

Milk and fat production of crossbred Holstein-Gir cows (Bos taurus taurus-Bos taurus indicus) in the agreste region of the Brazilian state of Pernambuco

The productive performance of four Holstein-Gir genetic groups (1/2H, 1/4H, 5/8H, 5/8Hinter se) and the effects of non-genetic factors on production traits was evaluated using a data set of 7,951 test-day samples collected between January 1980 and December 1999 from the Arcoverde Experimental Station in the Brazilian state of Pernambuco (Empresa Pernambucana de Pesquisa Agropecuária). The statistical model included the fixed effects of calving year (1980 to 1999) and month (January to December), genetic group of the cow, age at months of calving (33 to 190) and days in milk at each test-day. Random effects were sire, cow and residual with test-days treated as repeated records within each cow within each lactation. For the four genetic groups the milk yield (MY) means were 1/2H = 8.61 kg ± 1.16 kg, 1/4H = 5.34 kg ± 0.46 kg, 5/8H = 7.42 kg ± 0.39 kg and 5/8Hinter se = 5.76 kg ± 0.46 kg; the fat yield (FY) means were 1/2H = 0.375 kg ± 0.052 kg, 1/4H = 0.231 kg ± 0.026 kg, 5/8H = 0.299 kg ± 0.025 kg and 5/8Hinter se = 0.231 kg ± 0.026 kg; and the fat percentage (FP) means were 1/2H = 4.45 kg ± 0.29 percent, 1/4H = 4.08 kg ± 0.12 percent, 5/8H = 3.87 kg ± 0.10 percent and 5/8Hinter se = 3.89 kg ± 0.12 percent. Phenotypic correlations between tests were MY = 0.97, FY = 0.94 and FP = 0.98. The best productive performance was for the 1/2H group, followed by the 5/8H group. The performance of the synthetic group was substantially below the performance of the 5/8H group.

Análisis de tres procedimientos estadísticos para la evaluación del crecimiento de mautas mestizas bajo diferentes regímenes nutricionales / Analysis of Three Statistical Procedures to Evaluate Growth in Crossbred Heifer Under Different Nutritional Levels.

Existen investigaciones donde se miden variables en varios períodos de tiempo sobre el mismo animal. Este tipo de información puede analizarse estadísticamente mediante tres opciones: Análisis univariados con la instrucción RANDOM del GLM; Análisis univariados o multivariados a través de transformaciones lineales mediante la instrucción REPEATED del GLM; y con modelos mixtos de covarianza con el procedimiento MIXED. Con el objetivo de evaluar estos tres métodos estadísticos y conocer cual es más preciso, se analizaron durante 7 meses los pesos corporales quincenales de una finca ubicada en el estado Táchira, Venezuela, (bosque húmedo tropical), donde 30 mautas mestizas con un peso y edad promedio de 176,9 ± 24,6 Kg y 17,22 ± 2,23 meses respectivamente, fueron distribuidas aleatoriamente dentro tres grupos de suplementación: (1) Control, (2) Alimento balanceado comercial, y (3) Harina de Gliricidia sepium con harina de maíz y melaza. Se obtuvieron estructuras de covarianzas, comparándose el procedimiento GLM con sus instrucciones RANDOM y REPEATED vs. el procedimiento MIXED en sus opciones CS, UN y AR1, todas del paquete estadístico SAS. Como variable respuesta se evaluó el peso de las mautas durante el período del ensayo y como variable independiente el grupo de suplementación, el período y la interacción lineal entre ambas. Así mismo, al realizar el análisis de la varianza utilizando la estructura de errores más indicada, se pudo corroborar que existe una interacción significativa entre el tratamiento y el período (P<0,01), es decir, que las curvas de crecimiento tienden a no ser paralelas. Los resultados indican que el análisis más ajustado es el Procedimiento MIXED con la opción AR1, ya que permite ajustar la matriz de covarianza.

There are investigations where variables are measured in periods of time on the same animal. This type of information should be analyzed statistically trough three ways: univariate analyses with the RANDOM statement of the GLM procedure; univariate or multivariate analysis with the method of lineal transformations with the REPEATED statement of the GLM; and with mixed models of covariance with the MIXED procedure. With the objective of evaluating these three statistical methods and to know the most precise, biweekly live weight coming from a rehearsal carried out located in the Tachira State, Venezuela (topical damp woods) was analyzed during 7 weeks, where 30 crossbred heifers with an average weight and age of 176.9 ± 24.6 Kg and 17.22 ± 2.23 months respectively, were randomly distributed between three groups: (1) control, (2) balanced commercial feed, and (3) Flour of Gliricidia sepium with flour of corn and molasses. It was modeled covariance structures, comparing the GLM procedure with its RANDOM and REPEATED statements vs. the MIXED procedure in its CS, UN and AR1 options, of the statistical package SAS. As dependent variable it was studied the weight of the heifers during the assay period and as independent variables the supplementation group, the period and the linear interaction among both. When carrying out the analysis of variance using the most suitable structure of errors, it can be conclude that there was a significant interaction between treatment and period (P<0.01), and that is to say that the curves of growth spread unless parallel. Results indicate that the best fitting analysis is the Proc MIXED with the AR1 option, since it allows to adjust the covariance womb.