Increasing Alfalfa Rumen Bypass Protein

Authors: Peel, Michael

Submitted to: Symposium Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 5/10/2010
Publication Date: 6/20/2010
Citation: Peel, M. 2010. Increasing Alfalfa Rumen Bypass Protein. Symposium Proceedings.

Interpretive Summary:

Technical Abstract: Alfalfa has one of the highest crude protein contents among forage crops, but is is rapidly and extensively degraded by rumen microorganisms. To examine differential protein digestion, three distinct varieties of alfalfa, grown from single plants, were subjected to fermentation in the rumen of a cannulated steer for 0.45 and 120 minutes. After digestion, total protein was extracted from the fermented alfalfa residues, and the individual proteins were separated using two-dimensional gel electrophoresis. Individual proteins from the three degradation times were labeled with different fluorescence dyes for identification and quantification. Twenty-six major proteins were characterized which represented 36% of the total protein detected. After 45 min of rumen digestion, 9 of these proteins still had greater than 75% of their total mass remaining, 12 had 50% or less remaining, and six were intermediate. After 120 min of rumen digestion, four proteins still had greater than 80% of their mass remaining, 7 were between 80 and 50%, and 16 had less than 50% remaining. After both 45 and 120 minutes of rumen digestion, there were three proteins showing differences among the three alfalfa varieties, while most of the other proteins showed similar rates of digestion. After 120 minutes, there were significant differences in protein digestion rates among the three varieties for 10 out of 26 of the identified proteins. Our experiment shows that we could improve the value of alfalfa as a dietary protein source by selecting varieties with a higher percentage of the proteins that are digested more slowly, or escape rumen digestion altogether. These improvements would lead to more metabolizable protein for the animals and reduce the chances of bloat from excessive rumen gas production and reduce environmental contamination from animal waste by reducing the nitrogen excreted by the animal.