| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
,2
* Institute of Grassland and Environmental Research, Plas Gogerddan, Aberystwyth, SY23 3EB, UK
Faculty of Agronomy, University of Buenos Aires, Avenida San Martín 4453, (C1417 DSQ) Buenos Aires, Argentina
1 Corresponding author: jon.moorby{at}bbsrc.ac.uk
Four mature Holstein-Friesian dairy cows were used in a 4 x 4 Latin square change-over design experiment made up of four 4-wk periods to investigate the relationship between microbial protein flow to the duodenum and excretion of purine derivatives (PD) in the urine. Four dietary treatments based on ad libitum access to ryegrass silage were offered, with a standard dairy concentrate included at different forage:concentrate (F:C) ratios, calculated on a dry matter basis: 80:20, 65:35, 50:50, and 35:65. Feed intakes increased as the proportion of concentrate in the diet increased, despite a concurrent decrease in silage intake. Increased feed intake led to increased nutrient flow to the duodenum. Milk yields increased as the diet F:C ratio decreased, with cows offered the 35:65 diet yielding nearly 8 kg/d more milk than cows offered the 80:20 diet; the concentrations of milk fat decreased and milk protein increased with a decreasing F:C ratio. Purine derivative excretion in the urine increased with an increasing proportion of concentrate in the diet, and there was a strong linear relationship between total PD excretion (allantoin and uric acid) and microbial N flow to the duodenum: microbial N (g/d) = 19.9 + 0.689 x total PD (mmol/d); R = 0.887. This strengthens the case for using PD excretion as a noninvasive marker of microbial protein flow from the rumen in dairy cows.
Key Words: dairy cow • nitrogen partitioning • purine derivative • rumen function
This article has been cited by other articles:
|
|
 |
|
  J. M. Moorby, P. H. Robinson, W. J. Fisher, and R. T. Evans Comparison of Red Clover and Ryegrass Silage for Dry Cows and Influence on Subsequent Lactation Performance J Dairy Sci, September 1, 2008; 91(9): 3501 - 3511. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
B. N. Janicek, P. J. Kononoff, A. M. Gehman, and P. H. Doane The Effect of Feeding Dried Distillers Grains Plus Solubles on Milk Production and Excretion of Urinary Purine Derivatives J Dairy Sci, September 1, 2008; 91(9): 3544 - 3553. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. C. Marini, D. G. Fox, and M. R. Murphy Nitrogen transactions along the gastrointestinal tract of cattle: A meta-analytical approach J Anim Sci, March 1, 2008; 86(3): 660 - 679. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
W. Z. Yang and K. A. Beauchemin Altering Physically Effective Fiber Intake Through Forage Proportion and Particle Length: Digestion and Milk Production J Dairy Sci, July 1, 2007; 90(7): 3410 - 3421. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. J. Dewhurst, J. M. Moorby, B. Vlaeminck, and V. Fievez Apparent Recovery of Duodenal Odd- and Branched-Chain Fatty Acids in Milk of Dairy Cows J Dairy Sci, April 1, 2007; 90(4): 1775 - 1780. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
B. Vlaeminck, V. Fievez, S. Tamminga, R. J. Dewhurst, A. van Vuuren, D. De Brabander, and D. Demeyer Milk odd- and branched-chain Fatty acids in relation to the rumen fermentation pattern. J Dairy Sci, October 1, 2006; 89(10): 3954 - 3964. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
