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Abstract

The objective of the present study was to identify and
quantify relationships among dairy cow body condition
score (BCS) and body weight (BW) and production variables
in pasture-based, seasonal-calving herds. More
than 2,500 lactation records from 897 spring-calving
Holstein-Friesian and Jersey dairy cows were used in
the analyses. Six variables related to BCS and BW,
including observations precalving, at calving, and nadir
as well as days to nadir and change precalving
and between calving and nadir were generated. An
exponential function was fitted within lactation to
milk and 4% fat-corrected milk (FCM) yield data to
model lactation curves. The milk production variables
investigated were the parameters of the fitted function
as well as accumulated yield of milk and FCM at 60
and 270 days in milk and average milk composition.
Mixed models were used to identify BCS and BW variables
that significantly affected milk production. After
adjusting for the fixed effect of year of calving, parity,
and days dry, milk and FCM yields were nonlinearly
associated with calving and nadir BCS, increasing at
a declining rate up to BCS 6.0 to 6.5 (10-point scale;
approximately 3.5 in the 5-point scale) and declining
thereafter. However, there was very little increase in
milk and FCM yields above a calving BCS of 5.0 (approximately
3.0 in the 5-point scale). Average milk fat
content over 60 and 270 days in milk was positively
correlated with increasing calving and nadir BCS. In
comparison, milk protein percentage was not influenced
by calving BCS but was positively associated
with nadir BCS and negatively associated with BCS
lost between calving and nadir. The effect of BW and
changes in BW were similar to the effect of BCS, although
the scale of the effect was breed-dependent.
For example, milk and FCM yield increased linearly
with increasing calving BCS, but the effect was greater in Holstein-Friesians compared with Jersey cows. The
results are consistent with the literature and highlight
the important role that BCS and BW loss has on milk
production, irrespective of the system of farming.

Item Type:	Article
Authors/Creators:	Roche, JR and Lee, JM and Macdonald, KA and Berry, DP
Keywords:	body condition score, milk, fitted function, pasture
Journal or Publication Title:	Journal of Dairy Science
Publisher:	American Dairy Science Association
ISSN:	0022-0302
DOI / ID Number:	https://doi.org/10.3168/jds.2006-740
Additional Information:	© 2007 American Dairy Science Association ®
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