Ruminal Digestion and Fermentation of High-Producing Dairy Cows with Three Different Feeding Systems Combining Pasture and Total Mixed Rations

Six multiparous Holstein cows fitted with rumen cannulas were used to study the effect of three feeding systems combining pasture and total mixed rations (TMR) on ruminal digestion in a 21-wk repeated measures experiment. The three treatments were: 1) pasture plus concentrate (PC), 2) pasture plus p...

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Bibliographic Details
Published in:Journal of dairy science 2002-11, Vol.85 (11), p.2964-2973
Main Authors: Bargo, F., Muller, L.D., Varga, G.A., Delahoy, J.E., Cassidy, T.W.
Format: Article
Language:English
Subjects:
Ammonia - analysis
Animal Feed
Animal Husbandry - methods
Animal Nutritional Physiological Phenomena
Animal productions
Animals
Biological and medical sciences
Body Weight
Cattle - growth & development
Cattle - physiology
Detergents
Dietary Fiber - administration & dosage
Dietary Fiber - metabolism
Digestion
Energy Intake
Fats - analysis
Fatty Acids, Volatile - analysis
Female
Fermentation
Fundamental and applied biological sciences. Psychology
Hydrogen-Ion Concentration
in situ digestion
Lactation - physiology
Milk - chemistry
Milk - secretion
Milk Proteins - analysis
partial total mixed ration
pasture
Poaceae
Rumen - chemistry
Rumen - metabolism
Rumen - microbiology
rumen fermentation
Terrestrial animal productions
Vertebrates
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Summary:Six multiparous Holstein cows fitted with rumen cannulas were used to study the effect of three feeding systems combining pasture and total mixed rations (TMR) on ruminal digestion in a 21-wk repeated measures experiment. The three treatments were: 1) pasture plus concentrate (PC), 2) pasture plus partial TMR (pTMR), and 3) TMR (nonpasture). Ruminal NH3-N concentration was lower on both the pTMR and TMR treatments (10.2±0.5mg/dL) than on the PC treatment (19.9±0.5mg/dL). Ruminal pH was not affected by treatments and averaged 5.87. Neither total volatile fatty acid concentration (137.5mmol/L) nor individual volatile fatty acid proportions (63.1, 20.6, and 12.0 mol/100mol for acetate, propionate, and butyrate, respectively) differed among treatments. The pTMR treatment reduced the total potentially degradable fraction of dry matter (85.5 vs. 82.3%) and the potentially digestible fraction of neutral detergent fiber (82.1 vs. 74.9%) of pasture compared to the PC treatment. Ruminal NH3-N losses were reduced when combining pasture and TMR; however this combination decreased the ruminal digestion of pasture, indicating the presence of associative effects in the rumen.
ISSN:0022-0302
1525-3198
DOI:10.3168/jds.S0022-0302(02)74382-8