U.S. flagAn official website of the United States government
                    Here's how you know **Official websites use .gov**
                            
                            A **.gov** website belongs to an official government organization in the United States.
 **Secure .gov websites use HTTPS**
                            
                            A **lock** (                            
                              A locked padlock                                                      
                            
                            ) or **https://** means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.


Menu Agricultural Research Service
						
                    U.S. DEPARTMENT OF AGRICULTURE
 U.S. Dairy Forage Research Center: Madison, WI
 close



    Research

                    Research Projects
                                    Publications
                                    Collaborations
                                    News
                                    Software
                People

                    Staff Listing
                                    Careers


        


                    Archives
                        Presentations
                                    World Dairy Expo
                                    Newsletters and Research Summaries
                    Resources
                        General Resources
                                    Books
                                    Teacher's Resources
                                    New Research Dairy Updates
                                    Integrated Research at USDFRCSearch small
                    Search
            
            ARS Home
                                About ARS
                                Contact Us




ARS Home Midwest Area Madison, Wisconsin U.S. Dairy Forage Research Center Research Publications at this Location





- ARS National Programs
- Search for a scientific manuscript
- Search for a research project
- ARS Software
- Programs and Projects
- Collaborations
- Subjects of Investigation
- Publications
- IACUC Summaries - Milwaukee, WI Aquaculture
- IACUC Summaries - US Dairy Forage Research Center

Title:   Author  item
                                            LEE, MICHAEL - INST GRASSLAND ENVIR RESitem
                                            TWEED, J - INST GRASSLAND ENVIR RESitem
                                            SCOLLAN, N - INST GRASSLAND ENVIR RESitem
                                            Sullivan, Michael
  Submitted to: Journal of the Science of Food and Agriculture
                                    Publication Type: Peer Reviewed Journal
                                    Publication Acceptance Date: 7/12/2008
                                    Publication  Date: 9/9/2008
                                    Citation: Lee, M.R., Tweed, J.K., Scollan, N.D., Sullivan, M.L. 2008. Ruminal Micro-Organisms do not Adapt to Increase Utilization of Poly-Phenol Oxidase Protected Red Clover Protein and Glycerol-Based Lipid. Journal of the Science of Food and Agriculture. 88(14):2479-2485.Interpretive Summary: Polyphenol oxidase (PPO), an enzyme present in the tissues of many plants, carries out oxidation reactions that are often associated with browning seen in fresh produce. Leaves of red clover have particularly high levels of PPO. Previous studies have demonstrated that in red clover, these high PPO levels have beneficial effects when the forage is used as feed for ruminant animals. First, PPO prevents protein losses during storage. Second, the protein is less degraded by rumen microorganisms and more efficiently utilized by the animal. These have positive economic (farmers can spend less on protein supplements) and environmental (more efficiently utilized protein means less nitrogen waste is released into the environment via animal waste) impacts. Finally, PPO present in red clover prevents breakdown of fatty acids during storage of the forage and by microbes in the animal’s rumen, leading to increased levels of beneficial polyunsaturated fatty acids in the resulting animal products (milk and meat). The experiments presented here address whether the microorganisms present in the cow’s rumen can adapt to high-PPO forages like red clover to better utilize PPO-protected protein and lipid, and thus diminish the beneficial effects of high-PPO forages. Rumen microorganisms from dairy cows fed red clover (high-PPO) or grass (low-PPO) diets did not differ in their ability to utilize PPO-protected protein or lipid, indicating that they do not adapt to high-PPO diets. Thus, the significant economic, environmental, and human health benefits of feeding ruminants high-PPO forages will not be diminished by adaptation of rumen microbes to such diets. These results suggest that high-PPO forages should be developed, either by conventional breeding or by genetic modification, in order to fully take advantage of PPO’s benefits.
                                Technical Abstract: The enzyme, polyphenol oxidase (PPO), reduces the extent of proteolysis and lipolysis within red clover fed to ruminants with subsequent increases in the efficiency of N utilization and the level of beneficial polyunsaturated fatty acids in their products (meat and milk). It has also been reported that red clover feeding alters the rumen microbial population compared to grass feeding. This study investigated whether the observed shifts in the microbial population of the rumen when ruminants are fed red clover silage (RC) as opposed to grass silage (G) represented an adaptation by the micro-organisms to increase the utilization of PPO-protected protein and glycerol-based lipid. The experiment consisted of two periods where ruminally fistulated dairy cows were offered either RC or G for two weeks, followed by collection of rumen fluid, which was then used in in vitro incubations to investigate lipolysis and proteolysis over time in plant material derived from red clover plants with either wild type PPO expression (PPO+) or PPO expression reduced to undetectable levels by gene silencing
(PPO-).  Proteolysis and lipolysis (P < 0.05) were lower after 24 h of incubation in the PPO+ treatment than the PPO- treatment, irrespective of rumen fluid. Biohydrogenation of C18 polyunsaturated fatty acids was also lower on the PPO+ treatment than the PPO- treatment, with no effect of rumen fluid. These results suggest that microbial changes to red clover feeding did not result in an increased ability of the micro-organisms in the present study to utilize either PPO-protected protein or glycerol-based lipid.


Return to top


Connect with ARS Sign up


ARS Home
                            USDA.gov
                            Plain Writing
                            Policies & Links
                            Civil Rights Statements
                            FOIA
                            Accessibility Statement
                            Privacy Policy
                            Non-Discrimination Statement
                            Quality of Information
                            USA.gov
                            WhiteHouse.gov