Document Detail

Milk urea nitrogen concentration: heritability and genetic correlations with reproductive performance and disease.
MedLine Citation:
PMID:  16291635     Owner:  NLM     Status:  MEDLINE    
The objectives of this study were to estimate the heritability of milk urea nitrogen (MUN) concentration and describe the genetic relationship between MUN and reproductive performance and between MUN and diseases in Holsteins. Dairy Records Management Systems (Raleigh, NC) provided lactation data. The Danish Agricultural Advisory Center provided breeding value estimates for diseases. Infrared (IR) and wet chemistry (WC) data were analyzed separately. Heritabilities and genetic correlations for 2 different measures of MUN and reproductive performance were estimated with an animal model using ASREML. Heritabilities for MUN were estimated using all lactations combined (lactations 1 through 5) and separately for first lactation and second lactation. Genetic correlations with reproduction and health were estimated separately for parities 1 and 2. Herd-test-day or herd-year-season along with age at calving and days in milk were included as fixed effects in all models. Heritability estimates for all lactations combined were 0.15 for WC MUN and 0.22 for IR MUN. Genetic correlations between WC MUN and 2 measures of reproductive performance, days to first service, and first service conception were not different from zero. In contrast, the genetic correlation between WC MUN and days open of 0.21 in first lactation and 0.41 in second lactation indicated that higher WC MUN values were associated with increased days open. Correlations among estimated breeding values for MUN and estimated breeding values for Danish diseases identified no significant relationships. Although the results of this study indicate that heritable variation for MUN exists, the inability to identify significant genetic relationships with several measures of disease or reproductive performance appears to limit the value of MUN in selection for disease resistance and improved reproduction.
R G Mitchell; G W Rogers; C D Dechow; J E Vallimont; J B Cooper; U Sander-Nielsen; J S Clay
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Journal of dairy science     Volume:  88     ISSN:  1525-3198     ISO Abbreviation:  J. Dairy Sci.     Publication Date:  2005 Dec 
Date Detail:
Created Date:  2005-11-18     Completed Date:  2006-03-16     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  2985126R     Medline TA:  J Dairy Sci     Country:  United States    
Other Details:
Languages:  eng     Pagination:  4434-40     Citation Subset:  IM    
Department of Animal Science, University of Tennessee, Knoxville, 37996, USA.
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MeSH Terms
Cattle Diseases / genetics*
Milk / chemistry*
Nitrogen / analysis*
Regression Analysis
Reproduction / genetics*
United States
Urea / analysis*
Reg. No./Substance:
57-13-6/Urea; 7727-37-9/Nitrogen

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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