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Several seaweed extracts have been reported to have potential antimethanogenic effects in ruminants. In this study, the effect of three brown seaweed species (Undaria pinnatifida, UPIN; Sargassum fusiforme, SFUS; and Sargassum fulvellum, SFUL) on rumen fermentation characteristics, total gas, methane (CH4), carbon dioxide (CO2) production, and microbial populations were investigated using an in vitro batch culture system. Seaweed extract and its metabolites, total flavonoid and polyphenol contents were identified and compared. For the in vitro batch, 0.25 mg∙mL−1 of each seaweed extract were used in 6, 12, 24, 36 and 48 h of incubation. Seaweed extract supplementation decreased CH4 yield and its proportion to total gas production after 12, 24, and 48 h of incubation, while total gas production were not significantly different. Total volatile fatty acid and molar proportion of propionate increased with SFUS and SFUL supplementation after 24 h of incubation, whereas UPIN was not affected. Additionally, SFUS increased the absolute abundance of total bacteria, ciliate protozoa, fungi, methanogenic archaea, and Fibrobacter succinogenes. The relative proportions of Butyrivibrio fibrisolvens, Butyrivibrio proteoclasticus, and Prevotella ruminicola were lower with seaweed extract supplementation, whereas Anaerovibrio lipolytica increased. Thus, seaweed extracts can decrease CH4 production, and alter the abundance of rumen microbial populations.

Objective The objective of this study was to investigate the effects of essential oil mixture (EOM) supplementation on rumen fermentation characteristics and microbial changes in an in vitro . Methods Three experimental treatments were used: control (CON, no additive), EOM 0.1 (supplementation of 1 g EOM/kg of substrate), and EOM 0.2 (supplementation of 2 g EOM/kg of substrate). An in vitro fermentation experiment was carried out using strained rumen fluid for 12 and 24 h incubation periods. At each time point, in vitro dry matter digestibility (IVDMD), neutral detergent fiber digestibility (IVNDFD), pH, ammonia nitrogen (NH 3 -N), and volatile fatty acid (VFA) concentrations, and relative microbial diversity were estimated. Results After 24 h incubation, treatments involving EOM supplementation led to significantly higher IVDMD (treatments and quadratic effect; p = 0.019 and 0.008) and IVNDFD (linear effect; p = 0.068) than did the CON treatment. The EOM 0.2 supplementation group had the highest NH 3 -N concentration (treatments; p = 0.032). Both EOM supplementations did not affect total VFA concentration and the proportion of individual VFAs; however, total VFA tended to increase in EOM supplementation groups, after 12 h incubation (linear; p = 0.071). Relative protozoa abundance significantly increased following EOM supplementation (treatments, p<0.001). Selenomonas ruminantium and Ruminococcus albus (treatments; p<0.001 and p = 0.005), abundance was higher in the EOM 0.1 treatment group than in CON. The abundance of Butyrivibrio fibrisolvens , fungi and Ruminococcus flavefaciens (treatments; p< 0.001, p<0.001, and p = 0.005) was higher following EOM 0.2 treatment. Conclusion The addition of newly developed EOM increased IVDMD, IVNDFD, and tended to increase total VFA indicating that it may be used as a feed additive to improve rumen fermentation by modulating rumen microbial communities. Further studies would be required to investigate the detailed metabolic mechanism underlying the effects of EOM supplementation.

Climate variability is strongly influencing hydrological processes under complex weather conditions, and it should be considered to forecast reservoir inflow for efficient dam operation strategies. Large-scale climate indices can provide potential information about climate variability, as they usually have a direct or indirect correlation with hydrologic variables. This study aims to use large-scale climate indices in monthly reservoir inflow forecasting for considering climate variability. For this purpose, time series and artificial intelligence models, such as Seasonal AutoRegressive Integrated Moving Average (SARIMA), SARIMA with eXogenous variables (SARIMAX), Artificial Neural Network (ANN), Adaptive Neural-based Fuzzy Inference System (ANFIS), and Random Forest (RF) models were employed with two types of input variables, autoregressive variables (AR-) and a combination of autoregressive and exogenous variables (ARX-). Several statistical methods, including ensemble empirical mode decomposition (EEMD), were used to select the lagged climate indices. Finally, monthly reservoir inflow was forecasted by SARIMA, SARIMAX, AR-ANN, ARX-ANN, AR-ANFIS, ARX-ANFIS, AR-RF, and ARX-RF models. As a result, the use of climate indices in artificial intelligence models showed a potential to improve the model performance, and the ARX-ANN and AR-RF models generally showed the best performance among the employed models.

Streptococcus bovis (S. bovis) is one of the critical initiators of acute acidosis in ruminants. Therefore, we aimed to develop and characterize the endolysin LyJH307, which can lyse ruminal S. bovis. We tested the bactericidal activity of recombinant LyJH307 against S. bovis JB1 under a range of pH, temperature, NaCl, and metal ion concentrations. In silico analyses showed that LyJH307 has a modular design with a distinct, enzymatically active domain of the NLPC/P60 superfamily at the N-terminal and a cell wall binding domain of the Zoocin A target recognition domain (Zoocin A_TRD) superfamily at the C-terminal. The lytic activity of LyJH307 against S. bovis JB1 was the highest at pH 5.5, and relatively higher under acidic, than under alkaline conditions. LyJH307 activity was also the highest at 39 °C, but was maintained between 25°C and 55°C. LyJH307 bactericidal action was retained under 0-500 mM NaCl. While the activity of LyJH307 significantly decreased on treatment with ethylenediaminetetraacetic acid (EDTA), it was only restored with supplementation of 10 mM Ca2+. Analyses of antimicrobial spectra showed that LyJH307 lysed Lancefield groups D (S. bovis group and Enterococcus faecalis) and H (S. sanguinis) bacteria. Thus, LyJH307 might help to prevent acute ruminal acidosis.