Effects of different additives on cattle feed intake and performance - a systematic review and meta-analysis.

In the last few years, there has been a growing interest in the use of natural feed additives in animal feed. These can be used as replacements for antibiotics, to alter rumen fermentation and increase feed efficiency in ruminants. Therefore, the objective of this study is to evaluate the effects of adding different feed additives in the diet of beef and dairy cattle on their performance, dry matter intake (DMI) and feed efficiency, through a systematic review followed by meta-analysis. The systematic review suggested 43 peer-reviewed publications, according to the pre-established criteria. In beef cattle, the ionophore antibiotics reduced the DMI, improved the feed efficiency without interfering in the average daily gain (ADG). Non-ionophore antibiotics and propolis extract increased the ADG. In dairy cattle, the ionophores, yeast-based additives, and enzyme additives increased the feed efficiency, DMI, and daily milk production (MY), respectively. Essential oil supplementation in beef and dairy cattle had no effect on the feed intake and animal performance. The systematic review and meta-analysis allowed us to conclude that different feed additives have different effects on cattle performance, however, our results suggest that there are a few gaps regarding their effects on animal performance.

Metagenome-Assembled Genomes from Monte Cristo Cave (Diamantina, Brazil) Reveal Prokaryotic Lineages As Functional Models for Life on Mars.

Microbial communities have been explored in various terrestrial subsurface ecosystems, showing metabolic potentials that could generate noteworthy morphological and molecular biosignatures. Recent advancements in bioinformatic tools have allowed for descriptions of novel and yet-to-be cultivated microbial lineages in different ecosystems due to the genome reconstruction approach from metagenomic data. Using shotgun metagenomic data, we obtained metagenome-assembled genomes related to cultivated and yet-to-be cultivated prokaryotic lineages from a silica and iron-rich cave (Monte Cristo) in Minas Gerais State, Brazil. The Monte Cristo Cave has been shown to possess a high diversity of genes involved with different biogeochemical cycles, including reductive and oxidative pathways related to carbon, sulfur, nitrogen, and iron. Three genomes were selected for pangenomic analysis, assigned as Truepera sp., Ca. Methylomirabilis sp., and Ca. Koribacter sp. based on their lifestyles (radiation resistance, anaerobic methane oxidation, and potential iron oxidation). These bacteria exhibit genes involved with multiple DNA repair strategies, starvation, and stress response. Because these groups have few reference genomes deposited in databases, our study adds important genomic information about these lineages. The combination of techniques applied in this study allowed us to unveil the potential relationships between microbial genomes and their ecological processes with the cave mineralogy and highlight the lineages involved with anaerobic methane oxidation, iron oxidation, and radiation resistance as functional models for the search for extant life-forms outside our planet in silica- and iron-rich environments and potentially on Mars.

Dosagem correta de irradiação na polimerização da resina / Correct irradiation dose administration on resin polimerization

Muitas pesquisas têm revelado associação à intensidade de luz dos aparelhos fotoativadores, porém relação direta da dureza está mais relacionada à energia absorvida do que o método de fotoativação. Amostras da resina composta Filtek Z250, (A3) foram polimerizadas com LED macrodiodo marca “Blue Star 1” (Microdont) uma intensidade de 1.000mW/cm2 e um convencional de luz halógena marca VIP Curing Ligth ( Bisco Inc. USA) e intensidade de 600mW/cm2. A irradiação foi realizada em cinco tempos variáveis de exposição: 10s, 15s e 20s, 30s. Foram realizados 5 corpos-de-prova para cada energia de polimerização empregada, totalizando 50 espécimes. Os testes de dureza Knoop foram realizados após o período de armazenagem por 24 h, nas regiões de superfície Topo e Base, sob uma carga de 100 gramas durante 10 segundos, e através de um microdurômetro (Durimet - Leitz-Welzlar) penetrador tipo Knoop, a amostra foi submetida a 6 penetrações sendo 3 na superfície de incidência de luz (topo) e 3 na região oposta, totalizando 300 medições. Os valores de dureza Knoop no topo foram mais elevados com a aplicação da luz do LED BlueStar e crescente em relação com o aumento do tempo de aplicação.). A significância desses resultados revela que a intensidade da luz está diretamente relacionada com o tempo de exposição para proporcionar a quantidade de irradiação correta recomendada em um total de 15.000mW/cm2 ou 15J/ cm2.

Many surveys have revealed an association to the light intensity from photopolymerizationdevices; however hardness is more related to the absorbed energy than the photopolymerization method. Filtek Z250 composite resin samples were polymerized with a macro-diode LED, “Blue Star 1” (Microdont), with a light intensity of 1,000mW/cm² and with a conventional light curing, branded VIP Curing Light (Bisco Inc. USA) with an intensity of 600mW/cm². An irradiation (exposition) was performed in five different exposition times: 10s, 15s and 20s, 30s. There were performed 5 body-tests for each polymerization energy exposition, summing 50 samples. Knoop hardness tests were performed after 24 hours storing period, at surfaces areas “Top and Base”, under a 100gr load during 10 seconds, with a hardness micro-calibrator (Durimet – Leitz-Welzlar) and Knoop deepness (penetration power); the samples were exposed to 6 penetrations, with 3 light incidences at top surface and 3 at the opposite area, summing 300 measures. Knoophardness values at the top with LED Blue Star light exposition were the highest, and with increasing hardness in relation to time exposition. The significance of these results reveals that light intensity is directly related with time exposition in order to provide a correct irradiation quantity recommended with a total of 15,000mW/cm² or 15J/cm².