Summary and Implications
The relationshipsbetween body conditionscore (BCS) observed during latefirst lactation and the first 45 days of second lactation and two measures of feed efficiency, residual feed intake (RFI) and gross efficiency (GE) defined as milk energy / DMI,measured during mid first lactation wereassessed in 173Holstein cows.Body condition score was compared between the 18 most and least feed efficient cows. When measured as RFI, feed efficient cows carried significantly more condition at dry off and tended to carry more condition at the start ofsecond parity and at 45 days in milk (DIM),but there was no difference in change in BCS between feed efficient and inefficient cows. When measured as GE, efficient cows tended to carry less condition 30 days prior to dry off and lose more condition throughout the first 45 DIM. Thesefindings suggest that selection based on RFI should not impact BCS change during late first lactation or early second lactation but selection based on feed efficiency measured as GE may result in greater BCS loss in early second lactation.
Iowa State University
Hardie, Lydia; Maxwell, Kara; and Spurlock, Diane
"Relationship between Mid-First Lactation Feed Efficiency and Late First and Early Second Lactation Body Condition Score,"
Animal Industry Report:
AS 663, ASL R3145.
Available at: https://lib.dr.iastate.edu/ans_air/vol663/iss1/18