Performance, carcass characteristics and ingestive behavior of feedlot lambs fed fresh or ensiled sugar cane

Trinta cordeiros da raça Santa Inês, 26,2±0,6kg e 151±1,7 dias de idade, foram confinados para avaliar os efeitos da utilização de silagens de cana-de-açúcar sobre o desempenho, as características da carcaça e o comportamento ingestivo. As rações experimentais foram compostas de 50% de volumoso e 50% de concentrado, diferindo quanto ao tipo do volumoso utilizado: cana-de-açúcar in natura, silagem de cana-de-açúcar sem aditivo e silagem de cana-de-açúcar aditivada com Lactobacillus buchneri (5x10(4) UFC/g de MV). Não houve diferença (P>0,05) para o consumo de MS, ganho de peso vivo, conversão alimentar e parâmetros de carcaça entre os tratamentos. O tempo de ingestão (min/g FDN) e a eficiência de ruminação (g MS/h) foram menores (P<0,05) para os tratamentos contendo silagem de cana-de-açúcar. Silagens de cana-de-açúcar não alteraram o desempenho e as características da carcaça dos cordeiros em relação à cana de açúcar in natura. A utilização do aditivo microbiano contendo o L. buchneri na ensilagem da cana-de-açúcar não alterou as variáveis avaliadas.Thirty Santa Ines ram lambs, 26.2±0.6kg and 151±1.7 day-old, were penned to evaluate the effects of feeding sugar cane silages on performance, carcass characteristics and ingestive behavior. Lambs were fed a 50:50 (concentrate:roughage ratio) TMR. Experimental treatments were: fresh sugar cane, sugar cane silage without additive and sugar cane silage treated with Lactobacillus buchneri (5x10(4) cfu/g wet basis). No differences (P>0.05) on dry matter intake, average daily gain, feed conversion and carcass characteristics were observed among treatments. Eating time (min/g NDF) and rumination efficiency (g DM/h) were lower (P<0.05) for silage diets. Sugar cane silage had no detrimental effect on lamb performance and carcass characteristics compared to fresh sugar cane. Adding L. buchneri to sugar cane silage did not change the evaluated characteristics

Simpósio Nacional Biodiversidade e Apicultura : livro de resumos

Contém as comunicações apresentadas durante o Simpósio Nacional Biodiversidade e Apicultura, que decorreu em Castelo Branco em 17 de maio de 2013

Electrophiles modulate glutathione reductase activity via alkylation and upregulation of glutathione biosynthesis

Cells evolved robust homeostatic mechanisms to protect against oxidation or alkylation by electrophilic species. Glutathione (GSH) is the most abundant intracellular thiol, protects cellular components from oxidation and is maintained in a reduced state by glutathione reductase (GR). Nitro oleic acid (NO2-OA) is an electrophilic fatty acid formed under digestive and inflammatory conditions that both reacts with GSH and induces its synthesis upon activation of Nrf2 signaling. The effects of NO2-OA on intracellular GSH homeostasis were evaluated. In addition to upregulation of GSH biosynthesis, we observed that NO2-OA increased intracellular GSSG in an oxidative stress-independent manner. NO2-OA directly inhibited GR in vitro by covalent modification of the catalytic Cys61, with kon of (3.45±0.04)×103 M−1 s−1, koff of (4.4±0.4)×10−4 s−1, and Keq of (1.3±0.1)×10−7 M. Akin to NO2-OA, the electrophilic Nrf2 activators bardoxolone-imidazole (CDDO-Im), bardoxolone-methyl (CDDO-Me) and dimethyl fumarate (DMF) also upregulated GSH biosynthesis while promoting GSSG accumulation, but without directly inhibiting GR activity. In vitro assays in which GR was treated with increasing GSH concentrations and GSH depletion experiments in cells revealed that GR activity is finely regulated via product inhibition, an observation further supported by theoretical (kinetic modeling of cellular GSSG:GSH levels) approaches. Together, these results describe two independent mechanisms by which electrophiles modulate the GSH/GSSG couple, and provide a novel conceptual framework to interpret experimentally determined values of GSH and GSSG