| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
1 Research Centre, Agriculture and Agri-Food Canada, Lethbridge, AB, Canada T1J 4B1
2 MTT Agrifood Research Centre, Animal Production Research, FIN-31600, Jokionen, Finland
Alfalfa (Medicago sativa L. cv. AC Blue J) was labeled with 15N during growth in a greenhouse, harvested at early bloom, and preserved as silage (19% dry matter) or as sun-cured hay. The labeled silage and hay were given as single-pulse doses to two lactating Holstein cows fed diets comprising 30% concentrate and 70% alfalfa forage (preserved either as silage or as hay). Labeled forage and ruminal content samples collected for 72 h after dosing were partitioned into N fractions and analyzed for 15N-enrichment. Pool sizes of N compartments and kinetics in the rumen were derived by isotope dilution and by gravimetric measurements. The rate of out- flow of total N, determined gravimetrically, was 21% higher with the silage diet than with the hay diet. On both diets, the largest individual flux was associated with the nonprotein, nonammonia, nonmicrobial nitrogen (NPAM-N) pool. As related to the flux of 15N through the acid detergent insoluble N pool, less tracer passed through the solid-phase nonfiber N and the soluble protein- N pools, and more passed through the NPAM-N pool, with silage than with hay. The solid-phase nonfiber N pool, which includes readily available feed N and adherent bacterial- and protozoal-N, constituted the largest N entity in the rumen, followed by the NPAMNpool. Whenthe forage component of the diet was alfalfa silage,Nflux through the NPAM-N pool was remarkably high, and with both methods of preserving alfalfa forage, the exchange of tracer was most intensive through this pool.
Key Words: alfalfa • 15N isotope • metabolism • rumen
Submitted on March 28, 2001
Accepted on July 18, 2001
This article has been cited by other articles:
|
|
 |
|
  A. N. Hristov, S. Zaman, M. Vander Pol, P. Ndegwa, L. Campbell, and S. Silva Nitrogen Losses from Dairy Manure Estimated Through Nitrogen Mass Balance and Chemical Markers J. Environ. Qual., October 29, 2009; 38(6): 2438 - 2448. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 P. Huhtanen and A. N. Hristov A meta-analysis of the effects of dietary protein concentration and degradability on milk protein yield and milk N efficiency in dairy cows J Dairy Sci, July 1, 2009; 92(7): 3222 - 3232. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. F. Brito, G. A. Broderick, J. J. O. Colmenero, and S. M. Reynal Effects of Feeding Formate-Treated Alfalfa Silage or Red Clover Silage on Omasal Nutrient Flow and Microbial Protein Synthesis in Lactating Dairy Cows J Dairy Sci, March 1, 2007; 90(3): 1392 - 1404. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. F. Brito, G. A. Broderick, and S. M. Reynal Effect of varying dietary ratios of alfalfa silage to corn silage on omasal flow and microbial protein synthesis in dairy cows. J Dairy Sci, October 1, 2006; 89(10): 3939 - 3953. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. M. Reynal, G. A. Broderick, and C. Bearzi Comparison of Four Markers for Quantifying Microbial Protein Flow from the Rumen of Lactating Dairy Cows J Dairy Sci, November 1, 2005; 88(11): 4065 - 4082. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. N. Hristov, L. R. Kennington, M. A. McGuire, and C. W. Hunt Effect of diets containing linoleic acid- or oleic acid-rich oils on ruminal fermentation and nutrient digestibility, and performance and fatty acid composition of adipose and muscle tissues of finishing cattle J Anim Sci, June 1, 2005; 83(6): 1312 - 1321. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. N. Hristov, J. K. Ropp, K. L. Grandeen, S. Abedi, R. P. Etter, A. Melgar, and A. E. Foley Effect of carbohydrate source on ammonia utilization in lactating dairy cows J Anim Sci, February 1, 2005; 83(2): 408 - 421. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. N. Hristov, R. P. Etter, J. K. Ropp, and K. L. Grandeen Effect of dietary crude protein level and degradability on ruminal fermentation and nitrogen utilization in lactating dairy cows J Anim Sci, November 1, 2004; 82(11): 3219 - 3229. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. N. Hristov, K. L. Grandeen, J. K. Ropp, and M. A. McGuire Effect of Sodium Laurate on Ruminal Fermentation and Utilization of Ruminal Ammonia Nitrogen for Milk Protein Synthesis in Dairy Cows J Dairy Sci, June 1, 2004; 87(6): 1820 - 1831. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. N. Hristov and J. K. Ropp Effect of Dietary Carbohydrate Composition and Availability on Utilization of Ruminal Ammonia Nitrogen for Milk Protein Synthesis in Dairy Cows J Dairy Sci, July 1, 2003; 86(7): 2416 - 2427. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
