In vitro protein breakdown by enzyme extracts of rumen origin: comparison with methods in situ and proteases of Streptomyces griseus
In vitro protein breakdown by enzyme extracts of rumen origin: comparison with methods in situ and proteases of Streptomyces griseus
Authors
Velásquez Briceño, Alejandro
Pichard, Gastón
Pichard, Gastón
Authors
Date
2011-06-09
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Abstract
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 ºC 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.