|Raeth-Knight, M - UNIVERSITY OF MINNESOTA|
|Linn, J - UNIVERSITY OF MINNESOTA|
|Jung, Hans Joachim|
Submitted to: Midwestern Section of the American Society of Animal Science
Publication Type: Abstract Only
Publication Acceptance Date: November 16, 2004
Publication Date: March 23, 2005
Citation: Raeth-Knight, M.L., Linn, J.G., Jung, H.G., Mertens, D.R. 2005. Impact of alfalfa hay neutral detergent fiber concentration and digestibility on Holstein dairy cow performance [abstract]. ADSA-ASAS Midwest Annual Meeting Abstracts. Abstract No. 272. Technical Abstract: The objective of this study was to determine the effect of alfalfa fiber concentration and digestibility on dairy cow performance by selecting four alfalfa hays representing two concentrations of neutral detergent fiber (NDF); each with a high and low in vitro 48-h NDF digestibility (NDFD). Twenty Holstein dairy cows, averaging 193 d in milk and 31 kg of milk/d, were randomly assigned to four treatments composed of 95.8% treatment hay and 4.2% molasses (dry matter basis). Cows were transitioned from a 76.5% forage:23.5% concentrate diet to the treatment diets over a 20-d period. Treatment diets were fed for 11 d before data collection occurred from d 12 to 18. Low NDF hays had approximately four percentage units less fiber than high NDF hays. Within both NDF hay pairs, NDFD of the more digestible hay was about three percentage units greater. For cows fed the low NDF hays there was no difference in dry matter intake (DMI); however, between the high NDF hays those cows fed the high NDFD hay consumed more DM as compared to cows fed the low NDFD hay. Yield of 4% fat-corrected milk (FCM) was similar for all hays except for a reduction in FCM for the high NDF, high NDFD hay compared to the two low NDF hays. Milk fat, true protein, and lactose content were not affected by hay NDFD or NDF. Although the alfalfa hays contributed 95% of dietary dry matter, the differences in fiber concentration and digestibility were insufficient to impact intake, or milk yield and composition.