Produção de forragem e potencial de utilização do capim faixa-branca submetido a frequências de desfolhação / Production of forage potential of utilization of digit grass subjected to high defoliation frequencies

O objetivo deste trabalho foi avaliar a produção de forragem e o potencial de utilização do capim faixa-branca submetido a frequências de desfolhação. Os tratamentos foram constituídos de quatro frequências de desfolhação: muito alta (25cm), alta (35cm), média (45cm) e baixa (55cm), avaliados em duas épocas do ano (maior e menor insolação), entre 2015 e 2016. Utilizou-se o delineamento em blocos ao acaso, com quatro repetições e medidas repetidas no tempo. A produção diária de folhas foi menor na frequência muito alta em relação às outras frequências. A redução das frequências de desfolhação aumentou a produção diária de colmo, senescência diária de folhas, produção total diária e acúmulo líquido diário de forragem e diminuiu o potencial de utilização da forragem. No período de maior insolação, a produção diária de colmos, o acúmulo líquido diário de forragem e o potencial de utilização de forragem foram maiores e a senescência diária de folhas foi menor. A frequência de desfolhação muito alta não proporcionou um bom desenvolvimento da planta, enquanto a frequência baixa apresentou elevada produção de colmos. As frequências de desfolhação alta e média são mais indicadas para a desfolhação do capim faixa-branca, promovendo uma melhor proporção de folhas em relação a colmos.(AU)

The objective of this study was to evaluate the production of forage and the potential of utilization of digit grass subjected to four defoliation frequencies: very high (25cm), high (35cm), medium (45cm), and low (55cm), evaluated at two times of the year (higher and lower insolation), from January 2015 to January 2016. A randomized-block design with four replicates was adopted and measures repeated over time. The daily production of leaves was lower at the very high frequency in relation to the other frequencies. The reduction in defoliation frequency increased the daily production of stems, the daily leaf senescence, the total daily forage production, and the daily forage accumulation, and decreased the potential of forage utilization. At the time of higher insolation, the daily production of stems, the daily forage accumulation, the potential of utilization of forage were higher, and the daily leaf senescence was lower. The very high frequency of defoliation did not provide a good development of the plan, while the lower frequency displayed a high production of stems. The high and medium frequencies of defoliation are more indicated to the defoliation of digit grass, enabling a better proportion of leaves in relation to stems.(AU)

Analysis of the expression of putatively imprinted genes in bovine peri-implantation embryos.

The application of assisted reproductive technologies (ART) has been shown to induce changes in the methylation of the embryonic genome, leading to aberrant gene expression, including that of imprinted genes. Aberrant methylation and gene expression has been linked to the large offspring syndrome (LOS) in bovine embryos resulting in increased embryonic morbidity and mortality. In the bovine, limited numbers of imprinted genes have been studied and studies have primarily been restricted to pre-implantation stages. This study reports original data on the expression pattern of 8 putatively imprinted genes (Ata3, Dlk1, Gnas, Grb10, Magel2, Mest-1, Ndn and Sgce) in bovine peri-implantation embryos. Two embryonic developmental stages were examined, Day 14 and Day 21. The gene expression pattern of single embryos was recorded for in vivo, in vitro produced (IVP) and parthenogenetic embryos. The IVP embryos allow us to estimate the effect of in vitro procedures and the analysis of parthenogenetic embryos provides provisional information on maternal genomic imprinting. Among the 8 genes investigated, only Mest-1 showed differential expression in Day 21 parthenogenetic embryos compared to in vivo and IVP counterparts, indicating maternal imprinting of this gene. In addition, our expression analysis of single embryos revealed a more heterogeneous gene expression in IVP than in in vivo developed embryos, adding further to the hypothesis of transcriptional dysregulation induced by in vitro procedures, either by in vitro maturation, fertilization or culture. In conclusion, effects of genomic imprinting and of in vitro procedures for embryo production may influence the success of bovine embryo implantation.

Gene expression analysis of single preimplantation bovine embryos and the consequence for developmental potential.

Preimplantation embryo development typically involves sequential morphological events connecting embryonic cleavage, morula compaction and blastocyst formation, and occurs in parallel with transcriptional regulation, specifically, the maternal to embryonic transition. The underlying homeostatic and metabolic mechanisms governing embryo development are influenced by both genetic and epigenetic factors that respond to environmental stimuli and may impact development during later gestational and fetal growth. There is a renewed interest in the identification and characterization of developmentally important genes during embryonic and fetal development. Perturbations in gene expression, resulting from environmental conditions, can have serious consequences on further embryonic development, homeostasis and disease pathogenesis. The bovine embryo is, however, capable of tolerating and adapting to a wide range of conditions, although little is known of the molecular fingerprint required for oocyte maturation, fertilization and development to term. The genomic revolution united with promising new technologies offer greater opportunity to elucidate the mechanisms behind this well-orchestrated biological process. This paper reviews the current literature on gene expression in the bovine embryo with reference to environmental interference and the development of new technologies to observe this biological process. Defining the difference in molecular signalling between in vivo and in vitro systems will undoubtedly improve the safety and efficiency of assisted reproductive technologies. The future challenge is to devise culture conditions that mimic the changing environment required by developing embryos to allow the correct temporal and spatial expression of a cohort of developmental genes in a manner similar to that seen in

Participants and nonparticipants of a mass media self-help smoking cessation program.

Differences in demographic and smoking-related characteristics were examined among an ethnically heterogeneous sample of participants and nonparticipants of a self-help media-enhanced smoking cessation program which had been aired in seven cities in California. Subjects had been prompted or not prompted to view the mass media smoking cessation broadcast as an experimental manipulation. Written self-help smoking cessation materials were provided as supplements in local Sunday newspapers. Predictors of viewing the smoking cessation broadcasts and reading the self-help manual were examined separately. Across conditions, more smokers read the manual than viewed the broadcast. Nonredundant predictors of viewing the smoking cessation broadcasts included being prompted to view the broadcast, and self-reports of a tendency to read or listen to self-help material. Nonredundant predictors of reading the self-help smoking cessation manual included city of residence, older age, being a heavier smoker, planning to quit in the next 3 months, and receiving a newspaper at home (in which the self-help material appeared). Apparently, a televised cessation program can reach smokers who vary widely in characteristics. Prompting viewing increases participation, but only to a limited extent. Distribution of a written cessation manual in Sunday newspapers tends to be utilized by a relatively larger population, but especially by those persons who are motivated to quit.