Effects of applying oil-extracted microalgae on the fermentation quality, feed-nutritive value and aerobic stability of ensiled sweet sorghum.

BACKGROUND: A laboratory-silo study was conducted to evaluate the fermentation quality, feed-nutritive value and aerobic stability of sweet sorghum silage with or without oil-extracted microalgae supplementation. Sweet sorghum was mixed with four microalgae levels (0%, 1%, 2% and 3% on a dry matter basis; control, M1, M2 and M3, respectively) and ensiled for 45 d. Further, the four experimental silages were subjected to an aerobic stability test lasting 7 d. RESULTS: All the silages except M3 silage had good fermentative characteristics with low pH and ammonia nitrogen concentrations, and high lactic acid concentrations and favorable microbial parameters. Meanwhile, oil-extracted microalgae supplementation improved the feed-nutritional value of sweet sorghum silage. Fibre (neutral detergent fibre, acid detergent fibre, acid detergent lignin and cellulose) concentrations decreased, while dry matter and crude protein levels markedly increased (P < 0.05). Compared with the control (69.7 h), treatments M2 and M3 improved the aerobic stability of sweet sorghum silage by 43.8% and more than 143% respectively, and decreased the clostridia spore counts during the stage of air exposure. CONCLUSION: Sweet sorghum silage produced with 2% oil-extracted microalgae addition was the most suitable for animal use due to the optimal balance of fermentation quality, feed-nutritional value and aerobic stability, which merits further in vivo studies using grazing ruminants. © 2018 Society of Chemical Industry.

Adding distiller's grains and molasses on fermentation quality of rice straw silages / Adição de melaço na qualidade de fermentação de silagem de palha de arroz

ABSTRACT: Ensilage is a simple and low-cost strategy to enable long term preservation and environmentally friendly utilization of agricultural by-products, such as straws and distiller's grains (DG) for ruminants. Effect of mixing different proportions of DG and rice straw (i.e. 0, 10, 20 or 30% of DG) with or without 5% molasses addition on fermentation and chemical variables of silages was evaluated. The study was conducted as a randomized blocks design in a 4 × 2 factorial arrangement, with three replications, using laboratory silos of 1L capacity (n=24). Despite a significant interaction (P<0.01) between DG and molasses addition was observed for most variables, in general the increased addition of DG linearly decreased the pH value, acetic acid (AA), butyric acid (BA) and ammonia N concentration (P<0.01), and increased the lactic acid (LA) concentration (P<0.01). Exception was the propionic acid concentration which linearly decreased without molasses addition and linearly increased with molasses addition at increased proportion of DG (P<0.01). In both silages with or without molasses the addition of DG increased the dry matter, water soluble carbohydrates and crude protein (P<0.01), and decreased the NDF content (P<0.01). Based on the perspective of maximum utilization of rice straw, the mixture of 10% of DG associated to 5% molasses at ensilage process is recommended.

RESUMO: Ensilagem é uma estratégia simples e de baixo custo que habilita a preservação de sub-produtos agrícolas por longo tempo e com mínimo impacto ambiental, tal como a preservação de palha de arroz e resíduos da destilação de grãos (DG) para uso na alimentação de ruminantes. O objetivo deste estudo foi avaliar o efeito de incluir diferentes proporções de DG e palha de arroz (i.e. 0, 10, 20 or 30% of DG) com ou sem inclusão de 5% de melaço sobre variáveis da fermentação e composição química do material ensilado. O estudo foi conduzido em blocos casualizados em um esquema fatorial 4 × 2, com três repetições, utilizando mini-silos de 1L de capacidade (n=24). Embora a interação entre DG e melaço foi significativa (P<0,01) para a maior parte das variáveis, em geral a adição de DG diminuiu linearmente o pH e as concentrações de ácido acético, ácido butírico e amônia (P<0,01), e aumentou linearmente a concentração de ácido láctico (P<0,01). Exceção foi a concentração de ácido propiônico que diminuiu linearmente sem a adição de melaço enquanto aumentou linearmente com a adição de melaço, à incrementados níveis de inclusão de DG (P<0,01). Em ambos casos, com ou sem adição de melaço, a adição de DG aumentou linearmente o teor de matéria seca, de carboidratos solúveis em água e de proteína bruta, e diminuiu o teor de fibra em detergente neutro do material ensilado the NDF content (P<0,01). Baseado na perspectiva de máxima utilização de palha da arroz, recomenda-se a mistura de 10% de DG associado com 5% de melaço no processo de ensilagem.

Efficient expression and characterization of a cold-active endo-1, 4-β -glucanase from Citrobacter farmeri by co-expression of Myxococcus xanthus protein S

Background: Cold-active endo-1, 4-β-glucanase (EglC) can decrease energy costs and prevent product denaturation in biotechnological processes. However, the nature EglC from C. farmeri A1 showed very low activity (800 U/L). In an attempt to increase its expression level, C. farmeri EglC was expressed in Escherichia coli as an N-terminal fusion to protein S (ProS) from Myxococcus xanthus. Results: A novel expression vector, pET(ProS-EglC), was successfully constructed for the expression of C. farmeri EglC in E. coli. SDS-PAGE showed that the recombinant protein (ProS-EglC) was approximately 60 kDa. The activity of ProS-EglC was 12,400 U/L, which was considerably higher than that of the nature EglC (800 U/L). ProS-EglC was active at pH 6.5-pH 8.0, with optimum activity at pH 7.0. The recombinant protein was stable at pH 3.5-pH 6.5 for 30 min. The optimal temperature for activity of ProS-EglC was 30°C-40°C. It showed greater than 50% of maximum activity even at 5°C, indicating that the ProS-EglC is a cold-active enzyme. Its activity was increased by Co2+ and Fe2+, but decreased by Cd2+, Zn2+, Li+, methanol, Triton-X-100, acetonitrile, Tween 80, and SDS. Conclusions: The ProS-EglC is promising in application of various biotechnological processes because of its cold-active characterizations. This study also suggests a useful strategy for the expression of foreign proteins in E. coli using a ProS tag.

Effects of applying molasses, lactic acid bacteria and propionic acid on fermentation quality, aerobic stability and in vitro gas production of total mixed ration silage prepared with oat-common vetch intercrop on the Tibetan Plateau.

BACKGROUND: The objective of this study was to investigate the effect of molasses, lactic acid bacteria and propionic acid on the fermentation quality, aerobic stability and in vitro gas production of total mixed ration (TMR) silage prepared with oat-common vetch intercrop on the Tibetan plateau. TMR (436 g kg(-1) dry matter (DM)) was ensiled with six experimental treatments: (1) no additives (control); (2) molasses (M); (3) an inoculant (Lactobacillus plantarum) (L); (4) propionic acid (P); (5) molasses + propionic acid (MP); (6) inoculant + propionic acid (LP). RESULT: All silages were well preserved with low pH (< 4.19) and NH3-N contents, and high lactic acid contents after ensiling for 45 days. L and PL silages underwent a more efficient fermentation than silages without L. P and MP silages inhibited lactic acid production. Under aerobic conditions, M and L silage reduced aerobic stability for 15 and 74 h, respectively. All silages that had propionic acid in their treatments markedly (P < 0.05) improved the aerobic stability. After 72 h incubation, all additives treatments increased (P < 0.05) the 72 h cumulative gas production and in vitro DM digestibility (IVDMD) as compared with the control. L treatment decreased (P < 0.05) in vitro neutral detergent fibre degradability. CONCLUSIONS: Our findings show that TMR prepared with oat-common vetch intercrop can be well preserved. Although propionic acid is compatible with lactic acid bacteria, and when used together, they had minor effects on fermentation, aerobic stability and in vitro digestibility of TMR silage prepared with oat-common vetch intercrop.