In vitro protein breakdown by enzyme extracts of rumen origin: comparison with methods in situ and proteases of Streptomyces griseus

A. Velasquez, and G. Pichard. 2010. In vitro protein breakdown by enzyme extracts of rumen origin: comparison with methods in situ and proteases of Streptomyces griseus. Cien. Inv. Agr. 37(3): 57-70. Proteolytic activity of enzymatic extracts generated from rumen microorganisms cultivated in vitro was evaluated. The incubation of rumen fluid used different substrates to generate a higher enzyme concentration and promote a broad spectrum of hydrolytic activity. The composition of the substrates used in the cultivation of the fluid was enriched in protein, starch or cell wall. Enzyme preparations were evaluated by incubating in 30 mL of buffer 50 mM Tris-HCl (pH 6.5) at 39 degrees C during 48 hours, 100 mg of crude protein from feeds soybean meal, canola meal, sunflower meal, gluten feed, dehydrated alfalfa meal, berseem clover, oat forage and perennial ryegrass. Enzyme extracts from cultivated rumen fluid showed an average protein breakdown of 75.5%, in eight feed samples tested. This value was very close to that measured with the technique of proteases from Streptomyces griseus (74.6% CP), but significantly lower (P <= 0.05) than the one obtained by the in situ methodology (84.8% CP). The technique with extracted rumen enzymes showed higher level of proteolysis in the early hours of incubation (6 H) compared to the other techniques. These results suggest that the enzyme preparations of ruminal origin have the ability to predict degradability of feed proteins in the rumen, particularly in the first phase when most of proteins are hydrolyzed and become available for microbial utilization

Current European flood-rich period exceptional compared with past 500 years

There are concerns that recent climate change is altering the frequency and magnitude of river floods in an unprecedented way1. Historical studies have identified flood-rich periods in the past half millennium in various regions of Europe2. However, because of the low temporal resolution of existing datasets and the relatively low number of series, it has remained unclear whether Europe is currently in a flood-rich period from a long-term perspective. Here we analyse how recent decades compare with the flood history of Europe, using a new database composed of more than 100 high-resolution (sub-annual) historical flood series based on documentary evidence covering all major regions of Europe. We show that the past three decades were among the most flood-rich periods in Europe in the past 500 years, and that this period differs from other flood-rich periods in terms of its extent, air temperatures and flood seasonality. We identified nine flood-rich periods and associated regions. Among the periods richest in floods are 1560-1580 (western and central Europe), 1760-1800 (most of Europe), 1840-1870 (western and southern Europe) and 1990-2016 (western and central Europe). In most parts of Europe, previous flood-rich periods occurred during cooler-than-usual phases, but the current flood-rich period has been much warmer. Flood seasonality is also more pronounced in the recent period. For example, during previous flood and interflood periods, 41 per cent and 42 per cent of central European floods occurred in summer, respectively, compared with 55 per cent of floods in the recent period. The exceptional nature of the present-day flood-rich period calls for process-based tools for flood-risk assessment that capture the physical mechanisms involved, and management strategies that can incorporate the recent changes in risk.Europäischer Forschungsrat (ERC)Fonds zur Förderung der wissenschaftlichen Forschung (FWF)Fonds zur Förderung der wissenschaftlichen Forschung (FWF)5605667Horizon 2020DFGSpanish Agency of ScienceSpanish Agency of ScienceSpanish Agency of ScienceSpanish Agency of ScienceMinistry of Education, Youth and Sports of the Czech Republi