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Abstract

The objective of the present study was to identify and
quantify relationships between body condition score
(BCS) and body weight (BW) in dairy cows with reproduction
variables in pasture-based, seasonal-calving
dairy herds. Over 2,500 lactation records from 897
spring-calving Holstein-Friesian dairy cows were used
in the analyses. Eleven BCS- and 11 BW-related variables
were generated, including observations at calving,
nadir, planned start of mating (PSM), and first
service, as well as days to nadir and the amount and
rate of change between periods. The binary reproductive
variables were cycling by PSM, mated in the first
21 d from PSM, pregnant to first service, and pregnant
in the first 21, 42, and 84 d of the seasonal mating
period. Generalized estimating equations were used to
identify BCS and BW variables that significantly affected
the probability of a successful reproductive outcome.
After adjusting for the fixed effect of year of calving,
parity (for cycling by PSM only), and the interval
from calving to either first service or PSM, reproductive
performance was found to be significantly affected by
BW or BCS at key points, and by BCS and BW change
during lactation. All reproductive response measures
were negatively affected when BCS and BW measures
indicated an increased severity and duration of the
postpartum negative energy balance. In particular, cycling
by PSM was positively associated with calving
BCS, whereas pregnancy at 21, 42, and 84 d post-PSM
were positively associated with nadir BCS andBWgain
post-PSM, and negatively associated with BCS loss between
calving and nadir. The results highlight the important
role that BCS and BW loss has on reproductive
performance, especially in seasonal-calving dairy systems
because of the short period between calving and
PSM.

Item Type:	Article
Authors/Creators:	Roche, JR and Macdonald, KA and Burke, CR and Berry, DP
Keywords:	pasture, seasonal calving, reproduction, body condition score
Journal or Publication Title:	Journal of Dairy Science
Publisher:	American Dairy Science Association
ISSN:	0022-0302
Additional Information:	Copyright © 2007 by the American Dairy Science Association
Item Statistics:	View statistics for this item

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