Article (Scientific journals)
Genetic and environmental relationships between body condition score and milk production traits in Canadian Holsteins.
Loker, S; Bastin, Catherine; Miglior, F et al.
2012In Journal of Dairy Science, 95 (1), p. 410-9
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Keywords :
Animals; Body Constitution/genetics; Canada; Cattle/genetics; Environment; Female; Lactation/genetics; Milk/chemistry; Milk Proteins/analysis; Quantitative Trait, Heritable
Abstract :
[en] The objective of this research was to estimate genetic parameters of first-lactation body condition score (BCS), milk yield, fat percentage (Fat%), protein percentage (Prot%), somatic cell score (SCS), milk urea nitrogen (MUN), lactose percentage (Lact%), and fat to protein ratio (F:P) using multiple-trait random regression animal models. Changes in covariances between BCS and milk production traits on a daily basis have not been investigated before and could be useful for determining which BCS estimated breeding values (EBV) might be practical for selection in the future. Field staff from Valacta milk recording agency (Sainte-Anne-de-Bellevue, QC, Canada) collected BCS from Quebec herds several times per cow throughout the lactation. Average daily heritabilities and genetic correlations among the various traits were similar to literature values. On an average daily basis, BCS was genetically unfavorably correlated with milk yield (i.e., increased milk yield was associated with lower body condition). The unfavorable genetic correlation between BCS and milk yield became stronger as lactation progressed, but was equivalent to zero for the first month of lactation. Favorable genetic correlations were found between BCS with Prot%, SCS, and Lact% (i.e., greater BCS was associated with greater Prot%, lower SCS, and greater Lact%). These correlations were strongest in early lactation. On an average daily basis, BCS was not genetically correlated with Fat% or MUN, but was negatively correlated with F:P. Furthermore, BCS at 5 and 50 d in milk (DIM) had the most favorable genetic correlations with milk production traits over the lactation (at 5, 50, 150, and 250 DIM). Thus, early lactation BCS EBV shows potential for selection. Regardless, this study showed that the level of association BCS has with milk production traits is not constant over the lactation. Simultaneous selection for both BCS and milk production traits should be considered, mainly due to the unfavorable genetic correlation between BCS with milk yield.
Disciplines :
Genetics & genetic processes
Animal production & animal husbandry
Author, co-author :
Loker, S
Bastin, Catherine ;  Université de Liège - ULiège > Sciences agronomiques > Zootechnie
Miglior, F
Sewalem, A
Schaeffer, L R
Jamrozik, J
Ali, A
Osborne, V
Language :
English
Title :
Genetic and environmental relationships between body condition score and milk production traits in Canadian Holsteins.
Publication date :
2012
Journal title :
Journal of Dairy Science
ISSN :
0022-0302
eISSN :
1525-3198
Publisher :
American Dairy Science Association, Champaign, United States - Illinois
Volume :
95
Issue :
1
Pages :
410-9
Peer reviewed :
Peer Reviewed verified by ORBi
Commentary :
Copyright (c) 2012 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.
Available on ORBi :
since 03 May 2012

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