PMID- 12906060
OWN - NLM
STAT- MEDLINE
DCOM- 20030926
LR  - 20171116
IS  - 0022-0302 (Print)
IS  - 0022-0302 (Linking)
VI  - 86
IP  - 7
DP  - 2003 Jul
TI  - Effect of dietary carbohydrate composition and availability on utilization of 
      ruminal ammonia nitrogen for milk protein synthesis in dairy cows.
PG  - 2416-27
AB  - A trial with four ruminally and duodenally cannulated, late-lactation dairy cows 
      was conducted to investigate the effect of dietary carbohydrate (CHO) composition 
      and availability on ruminal ammonia N utilization and transfer into milk protein. 
      Two diets were fed at 8-h intervals in a crossover design. The diets differed in 
      CHO composition: the ruminally fermentable non-structural carbohydrates (RFSS) 
      diet (barley and molasses) contained a larger proportion of ruminally available 
      CHO in the nonstructural carbohydrate fractions and the ruminally fermentable 
      fiber (RFNDF) diet (corn, beet pulp, and brewer's grains) contained a larger 
      proportion of CHO in ruminally available fiber. Nitrogen-15 was used to label 
      ruminal ammonia N and consequently microbial and milk N. Fermentation acids, 
      enzyme activities, and microbial protein production in the rumen were not 
      affected by diet. Ruminal ammonia concentration was lowered by RFNDF. Ruminal and 
      total tract digestibility of nutrients did not differ between diets except that 
      apparent ruminal degradability of crude protein was lower for RFNDF compared with 
      RFSS. Partitioning of N losses between urine and feces was also not affected by 
      diet. Milk yield and fat and protein content were not affected by treatment. 
      Average concentration of milk urea N was lower for RFNDF than for RFSS. 
      Proportion of milk protein N originating from ruminal microbial N (based on the 
      areas under the 15N-enrichment curves) was higher for RFNDF than for RFSS. 
      Cumulative recovery of 15N in milk protein was 13% higher for RFNDF than for RFSS 
      indicating enhanced transfer of 15N-ammonia into milk protein with the former 
      diet. The results suggested that, compared to diets containing higher levels of 
      ruminally fermentable starch, diets providing higher concentration of ruminally 
      fermentable fiber may enhance transfer of ruminal ammonia and microbial N into 
      milk protein.
FAU - Hristov, A N
AU  - Hristov AN
AD  - Department of Animal and Veterinary Science, University of Idaho, Moscow, ID 
      83844-2330, USA. ahristov@uidaho.edu
FAU - Ropp, J K
AU  - Ropp JK
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PL  - United States
TA  - J Dairy Sci
JT  - Journal of dairy science
JID - 2985126R
RN  - 0 (Dietary Carbohydrates)
RN  - 0 (Dietary Fiber)
RN  - 0 (Milk Proteins)
RN  - 0 (Nitrogen Isotopes)
RN  - 7664-41-7 (Ammonia)
RN  - 9005-25-8 (Starch)
RN  - N762921K75 (Nitrogen)
SB  - IM
MH  - Ammonia/*chemistry
MH  - Animal Feed
MH  - Animals
MH  - Bacteria/metabolism
MH  - Beta vulgaris
MH  - Cattle/*metabolism
MH  - Dietary Carbohydrates/*administration & dosage/analysis
MH  - Dietary Fiber/administration & dosage/analysis/metabolism
MH  - Digestion
MH  - Female
MH  - Fermentation
MH  - Hordeum
MH  - Hydrogen-Ion Concentration
MH  - Lactation
MH  - Milk/chemistry
MH  - Milk Proteins/*biosynthesis
MH  - Molasses
MH  - Nitrogen/*metabolism
MH  - Nitrogen Isotopes/administration & dosage
MH  - Rumen/chemistry/*metabolism/microbiology
MH  - Starch/administration & dosage
MH  - Zea mays
EDAT- 2003/08/09 05:00
MHDA- 2003/09/27 05:00
CRDT- 2003/08/09 05:00
PHST- 2003/08/09 05:00 [pubmed]
PHST- 2003/09/27 05:00 [medline]
PHST- 2003/08/09 05:00 [entrez]
AID - S0022-0302(03)73836-3 [pii]
AID - 10.3168/jds.S0022-0302(03)73836-3 [doi]
PST - ppublish
SO  - J Dairy Sci. 2003 Jul;86(7):2416-27. doi: 10.3168/jds.S0022-0302(03)73836-3.