Location: Plant Science ResearchTitle: Comparison of Alfalfa and Orchardgrass Hay as Replacements for Grain in Lactating Dairy Cow Diets Author
|Jung, Hans Joachim|
Submitted to: American Dairy Science Association Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 2/25/2010
Publication Date: 7/11/2010
Citation: Raeth-Knight, M.L., Jung, H.G., Peterson, P.R., Litherland, N.B., Linn, J.G. 2010. Comparison of Alfalfa and Orchardgrass Hay as Replacements for Grain in Lactating Dairy Cow Diets [abstract]. Journal of Dairy Science. 93(E-Supplement 1):515. Interpretive Summary:
Technical Abstract: A study was conducted to compare lactating dairy cow performance when alfalfa (40% NDF) or orchardgrass (60% NDF) hay replaced corn grain in a corn silage-based total mixed ration. Fifty cows were blocked by sire breed, ranked by DIM and randomly assigned to 1 of 10 treatments. Treatments were 5 dietary inclusion levels of either alfalfa (15, 20, 25, 30, and 35% of diet DM) or orchardgrass (10, 15, 20, 25, and 30% of diet DM). Across treatments, cows averaged 86 DIM at study initiation, and cows remained on their respective treatments for 8 wk. Feed intake, feed refusals, and milk production were recorded daily, and milk composition was determined weekly. During wk 4 and 8, fecal grab samples were collected to determine in vivo diet digestibility; and eating, ruminating, and resting time were recorded every 15 min for 24 hr. Within alfalfa and orchardgrass treatments, 3.5% FCM yield decreased with increasing hay inclusion level (r2 = 0.59). The rate of decline was similar between hay species with cows averaging 44.6 and 37.3 kg 3.5% FCM/d at the lowest and highest hay inclusion levels, respectively, across hay species. When milk production was regressed on diet NDF concentration, within hay species, 3.5% FCM yield declined at a faster rate for the alfalfa as dietary NDF concentration increased. Range in diet NDF was 29.5 to 35.6% NDF and 29.9 to 39.8% NDF for alfalfa and orchardgrass, respectively. With each percentage unit increase in dietary NDF concentration, 3.5% FCM yield decreased 1.22 kg/d and 0.46 kg/d for alfalfa and orchardgrass, respectively. There was no difference in milk fat (3.8%) or true protein (3.0%) among treatments. Rate of in vitro NDF digestibility (IVNDFD) was similar (4.6 vs. 5.2%/h), while extent of IVNDFD was greater (79% vs. 56%) for orchardgrass compared to alfalfa hay. In this study, these alfalfa and orchardgrass hays supported similar levels of milk production when they replaced corn grain in the diet.