ENSINO DE FÍSICA EM TEMPOS PANDÊMICOS: UM OLHAR PARA A FALA DOS ESTUDANTES DE UMA ESCOLA DA REDE FEDERAL

The present work is related to a case of study conducted during the course of Supervised Internship of Physics Teaching A, of the major in teaching Physics of the Federal University of Santa Catarina. The probation stage was conducted with senior students (third year), from high school classes in the Application College of the University, in the context of COVID-19 pandemics. Due to social distancing measures in the pandemic period, classroom activities have been replaced by remote activities using modern Digital Information and Communication Technologies, this unprecedented process could lead to difficulties with negative implications in the teaching-learning process. In order to map the difficulties faced by the students, a questionnaire was applied jointly with the activities developed along the teaching internship. Through qualitative analysis, we sought to identify possible challenges that arose in the adaptation process to the new pandemic scenario and critically assess the impacts of the emergencial remote teaching and isolation conditions in the students' lives. Additionally, we identified wish tools that were more useful to the students. The developed research signaled negative pedagogical impacts resulting from issues inherent to the process of implementing the emergencial remote teaching, as well as psychological impacts, mainly due to social isolation and difficulties in the realization of student’s activities. Aspects such as demotivation, lack of dialogue and organization of the digital environment proved to be important. Despite this, some resources showed a positive impact on the student engagement, as was the case of class videos and interactive materials developed with the H5P software.O presente trabalho trata de um estudo de caso, realizado ao longo da disciplina de Estágio Supervisionado para o Ensino de Física A, do curso de Licenciatura em Física da Universidade Federal de Santa Catarina. O estágio foi realizado em uma turma do 3° ano do Ensino Médio do Colégio de Aplicação da universidade, no contexto da pandemia do COVID-19. Devido às medidas de distanciamento social para o combate à pandemia, as atividades escolares presenciais foram substituídas por atividades remotas com uso de Tecnologias Digitais da Informação e Comunicação, esse processo inédito pode gerar dificuldades de adaptação, com implicações no processo de ensino-aprendizagem. A fim de mapear as dificuldades enfrentadas pelos estudantes foi elaborado um questionário e aplicado junto às atividades desenvolvidas no âmbito do estágio. Por meio da análise qualitativa se buscou identificar possíveis dificuldades surgidas no processo de adaptação e avaliar criticamente os impactos do Ensino Remoto e do isolamento social na vida dos estudantes. Além disso, buscou-se identificar quais recursos foram mais utilizados pelos estudantes. A pesquisa aponta, principalmente, para impactos pedagógicos negativos decorrentes de dificuldades inerentes ao processo de implementação do Ensino Remoto, e, também, impactos psicológicos negativos, por parte, principalmente, do isolamento social e das dificuldades nos estudos. Aspectos como desmotivação, falta de diálogo e organização do ambiente se mostraram relevantes. Apesar disso, alguns recursos mostraram um impacto positivo no engajamento dos estudantes, como foi o caso das videoaulas e dos conteúdos interativos desenvolvidos com o H5P

Yield, chemical composition, and efficiency of use of nitrogen by Marandu grass

The objective of this study was to evaluate the effect of five nitrogen doses on the productive and quality characteristics and the use efficiency of Brachiaria brizantha cv. Marandu grass. The treatments consisted of four doses of nitrogen (0, 60, 120, 180 and 240 kg ha-1), distributed through a completely randomized design with four replicates. Samples of the material were collected to analyze productivity variables, concentrations of neutral detergent fiber, crude protein and neutral detergent insoluble nitrogen, and in vitro dry matter digestibility. The nitrogen use efficiency, recovery of the applied nitrogen (RAN) and agronomic efficiency of the applied nitrogen (AE) were calculated. Dry mass production increased by 1,624.67 (kg/ha) as the nitrogen doses were increased. The doses of nitrogen affected the concentrations of neutral detergent fiber (from 294.6 to 381.4 g.kg-1, in the leaf), crude protein (from 86.1 to 99.6 g.kg-1, in the leaf) and neutral detergent insoluble protein (from 402.9 to 396.2 g.kg-1 CP, in the leaf). Nitrogen use efficiency increased, whereas RAN and AE were not affected by the nitrogen doses. Nitrogen fertilization promotes improvement in productivity and chemical composition of Marandu grass, also improving the efficiency with which the grass utilizes the nitrogen

Influence of lipid supplementation on milk components and fatty acid profile

The objective of this study was to evaluate the effects of different lipid sources in diets for lactating cows on milk yield and composition, conjugated linoleic acid (CLA) content, and fatty acid profile in the milk fat. Five primiparous Holstein cows were distributed in a 5 × 5 Latin square design. Treatments were: control (no lipid addition) and four other diets containing different lipids sources - ground raw soybean, cottonseed, soybean oil, and calcium salts of soybean fatty acids (CSSFA). The greater milk yield (kg/day) and milk lactose (g/kg) and solids non-fat (g/kg) contents were obtained with the animals fed diets with CSSFA. Regarding the fatty acid profile in the milk fat, the diets with CSSFA and ground raw soybeans produced the greatest concentrations of polyunsaturated fatty acids and C182. Supplementation with CSSFA provided a greater production (g/day) of CLA, resulting in almost twice the values shown by the other treatments. The use of different lipid sources does not affect the milk total solids (protein, fat, and lactose) and CSSFA has a positive influence on the fatty acid profile of the milk fat and amount of CLA produced. Additionally, milk yield is not affected by this supplement

Kinetics of digestion of low-quality forage grazed by beef cattle fed supplements containing increasing levels of rumen undegradable protein

This experiment was conducted to evaluate the degradation kinetics and microbial efficiency of beef cattle grazing on low-quality forage and receiving supplements with different levels of rumen undegradable protein (RUP). The animals grazed on palisade grass pasture solely or this pasture and supplement containing 40 or 60 g of RUP per 100 g of crude protein (CP). The degradation profiles of neutral detergent fiber, fiber carbohydrates, and neutral detergent insoluble protein were interpreted kinetically by using a decreasing logistic model. Treatments (no supplement, or RUP at 40 or 60 g−1 100 g CP) did not affect rumen fill; however, the increase in the indigestible fiber carbohydrate fraction that occurred at the expense of the digestible fiber carbohydrate fraction resulted in a greater rumen fill effect. The palisade grass showed a significant proportion of its nitrogen in the form of slowly degradable protein as neutral detergent insoluble protein, which amounted to 26 g per 100 g CP. Supplementation with 40 g of RUP per 100 g CP decresead the indigestible fraction of the low-quality forage. However, the absence of a rumen-fill effect demonstrates that the additional supply of nutrients contributes greatly to increasing growth efficiency and use of the available energy from the forage by the ruminal microorganisms

Factors affecting feed efficiency in dairy goats

The objective of this study was to present some factors affecting feed efficiency in dairy goats. To develop our work, individual and average data from performance experiments with lactating goats were used. The following variables were evaluated: gross feed efficiency, adjusted feed efficiency, dry matter intake, milk-yield, 3.5% fat-corrected milk yield, dry matter digestibility, dietary neutral detergent fiber content, different roughage-to-concentrate ratios and body weight. The statistical analyses involved the application of descriptive and dispersion measures besides Pearson's correlation coefficient and linear regression analysis. The analyzed variables were highly correlated with feed efficiency. The feed efficiency of lactating goats was affected by the milk fat correction, dry matter digestibility, dietary fiber content, proportion of roughage in the diet and body weight. Among these factors, standardization of the milk fat appeared to be the most efficient in correcting the feed efficiency in lactating goats. Correction of some of these factors implies greater precision in the measurement of feed efficiency

Sulfur sources in protein supplements for ruminants

The present study evaluates the efficiency of different sulfur sources for ruminant nutrition. The fiber digestibility and the amino acid profile were analyzed in the duodenal digesta of crossbred steers fed Brachiaria dictyoneurahay. The sources utilized were elemental sulfur (ES70S), elemental sulfur (ES98S); calcium sulfate in hydrated (HCS), CaSO4.2H2O, and anhydrous (ACS), CaSO4, forms; and ammonium sulfate (AS), (NH4)2SO4, keeping a nitrogen:sulfur ratio of 11:1. The iso-protein supplements had 50% of protein in the total dry matter (DM). Five Holstein × Zebu steers, which were fistulated in the rumen and abomasum, were distributed in a 5 × 5 Latin square. The different sulfur sources in the supplement did not affect any of the evaluated nutritional factors, such as intake of hay dry matter and protein supplement, crude protein (CP), neutral detergent fiber corrected for ash and protein (NDFap), organic matter (OM), non-fibrous carbohydrate (NFC), ether extract (EE), total digestible nutrients (TDN), NDFap and CP digestibility coefficients, ruminal pH, and ruminal ammonia concentration. The concentrations of amino acids available in the abomasal digesta did not differ significantly in the tested diets. The sulfur sources evaluated in the present study are suitable as supplement for cattle, and their employment may be important to avoid environmental contaminations

Desempenho produtivo e parâmetros sanguíneos de vacas leiteiras em pastejo suplementadas com resíduos de feijão

The objective of this work was to evaluate the effect of dietary supplement bean residue on growth performance and blood parameters of dairy cows grazing. Eight crossbred cows weighing 500 kg were analyzed, distributed in 4×4 double Latin square, and fed with 134, 240, 348, and 449 g kg‑1 of a supplementary diet of bean waste in the concentrated feed. The animals received the supplementation after milking in the morning and in the afternoon. The inclusion of bean residues did not change average body weights and body scores; however, it reduced the milk production. Fat, protein, lactose, and total solid contents (g kg‑1) were not changed by bean waste inclusion. Blood glycose and cholesterol did not change before the offering of the concentrated feed diet, nor after four to six hours of feeding this diet. The inclusion of bean residues in the concentrated feed of dairy cows subjected to grazing, with a daily average production of 13 kg, reduces milk production. However, the use of these residues has little effect on milk composition and blood parameters.O objetivo deste trabalho foi avaliar o efeito da alimentação suplementar de resíduos de feijão no desempenho produtivo e nos parâmetros sanguíneos de vacas leiteiras em pastejo. Foram utilizadas oito vacas mestiças, com peso médio de 500 kg, distribuídas em duplo quadrado latino 4×4, alimentadas com alimentação suplementar de 134, 240, 348 e 449 g kg‑1 de resíduos de feijão na ração concentrada. Os animais receberam a suplementação após a ordenha no período da manhã e da tarde. A inclusão de resíduos de feijão não alterou os pesos corporais médios e os escores corporais; no entanto, reduziu a produção de leite. Os teores de gordura, proteína bruta, lactose e extrato seco total não foram alterados pela inclusão dos resíduos de feijão. A concentração sanguínea de glicose e colesterol não foi alterada pela adição do resíduo antes do fornecimento de ração concentrada e nem quatro e seis horas após essa alimentação. A inclusão dos resíduos de feijão na ração concentrada de vacas leiteiras em pastejo, com produção média diária de 13 kg, reduz a produção de leite. Todavia, a utilização desses resíduos pouco influencia a composição do leite e os parâmetros sanguíneos

Intercropping of corn, brachiaria grass and leguminous plants: productivity, quality and composition of silages

Funda??o de Amparo ? Pesquisa do Estado de Minas Gerais (FAPEMIG)The present study was carried out with the objective to evaluate the productive and qualitative characteristics of forages produced in systems of intercropping of corn, brachiaria grass and different leguminous plants. Productivity, bromatological composition and the fermentative profile of the silages from the following treatments were evaluated: corn in exclusive cultivation (CEC); intercropping of corn with brachiaria grass (CB); intercropping of corn, brachiaria grass and Calopogonium mucunoides (CBCal); intercropping of corn, brachiaria grass and Macrotyloma axillare (CBMac); and intercropping of corn, brachiaria grass and Stylozanthes capitata (CBSty). The experimental design utilized was completely randomized. For each type of cultivation, five plots or replications of three linear meters were harvested, and the material was separated. The variables assessed were: dry matter productivity per area; dry matter productivity of corn per area; crude protein production per area and productivity of total digestible nutrients per area. The material originated from the cultures was ensiled, with dry matter between 28 and 32%. After, the material was placed and compacted appropriately in bucket silos. A sample was collected from each replication for determination of the contents of DM, crude protein (CP), ether extract (EE), lignin, neutral and acid detergent fibers (NDF and ADF) and TDN. A fraction of the sample of silages from each treatment was compressed for extraction of the juice and determination of the silage quality. There was difference between the forms of cultivation for the dry matter production per hectare. The CEC with production of 11920.1 kg DM/ha did not differ from CB (8997.41 kg DM/ha) or CBCal (10452.10 kg DM/ha); however, it was superior to CBMac (8429.75 kg DM/ha) and to CBSty (8164.83 kg DM/ha). The contents of DM, CP, NDF, ADF, lignin and TDN did not differ between the silages from the different treatments. All the silages presented good quality with good fermentation patterns