Impact of sire PTA<SUB>SCS</SUB> on mastitis resistance and measures of daughter performance

Research to determine the impact of PTA<SUB>SCS</SUB> on incidence of mastitis, daughter response to infection, and other measures of daughter performance was conducted using data on 1st, 2nd, and 3rd lactation Holsteins obtained from the Virginia Tech herd and from VA DHI herds. Overal...

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Main Author: Cranford, Jamie Layne
Other Authors: Dairy Science
Format: Others
Published: Virginia Tech 2014
Subjects:
Online Access:http://hdl.handle.net/10919/31718
http://scholar.lib.vt.edu/theses/available/etd-041499-185718/
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spelling ndltd-VTETD-oai-vtechworks.lib.vt.edu-10919-317182020-09-29T05:44:21Z Impact of sire PTA<SUB>SCS</SUB> on mastitis resistance and measures of daughter performance Cranford, Jamie Layne Dairy Science Pearson, Ronald E. Cassell, Bennet G. Jones, Gerald M. Siegel, Paul B. Vinson, William E. mastitis resistance somatic cell scores sire PTA <SUB>SCS</SUB> Research to determine the impact of PTA<SUB>SCS</SUB> on incidence of mastitis, daughter response to infection, and other measures of daughter performance was conducted using data on 1st, 2nd, and 3rd lactation Holsteins obtained from the Virginia Tech herd and from VA DHI herds. Overall correlation of PTA<SUB>SCS</SUB> to lactation average SCS ranged from 0.13 to 0.17 across all data sets. Correlations between PTA<SUB>SCS</SUB> and 1st lactation SCS measures were higher than those between PTA<SUB>SCS</SUB> and SCS in later parities, but higher correlations were found between 2nd and 3rd lactation SCS measures than between 1st and later parities. Correlation of lactation average SCS and incidence of clinical mastitis was 0.41. Regression of lactation average SCS and averages of test day SCS measures on PTA<SUB>SCS</SUB> was significant in 1st, 2nd, and 3rd lactations. All significant relationships were linear and equal or close to 1.0. Relationships between PTA<SUB>SCS</SUB> and number of cases of clinical mastitis (.79), number of treatments (2.0), number of days treated (7.0), changes in SCS from beginning to end of a lactation (-.26), and the slope of changes in test day SCS with DIM (5.9x10-4) were significant only in 1st lactation. No significant relationships between PTA<SUB>SCS</SUB> and measures of clinical mastitis or variation in test day SCS measures were found in 2nd or 3rd lactations. Heavy cull rates imposed on 1st lactation cows in the Virginia Tech herd explained lack of significance in the later parities in the herd study, but results in following analyses indicated that measures of SCS in 1st and later parities may be two different, but correlated, traits. The greatest impact of PTA<SUB>SCS</SUB> on measures of daughter performance and profit was the negative relationship between PTA<SUB>SCS</SUB> and herd life. Increased PTA<SUB>SCS</SUB> resulted in the decreased ability to survive involuntary culling, and thus decreased opportunity for lifetime yield and profit. Selection on PTA<SUB>SCS</SUB> should be an effective method of reducing incidence of clinical mastitis, lactation average SCS, and variation in SCS, or response to infection. The response, however, may be different in 1st lactation than in later parities. Master of Science 2014-03-14T20:33:27Z 2014-03-14T20:33:27Z 1999-03-31 1999-04-14 2000-05-04 1999-05-04 Thesis etd-041499-185718 http://hdl.handle.net/10919/31718 http://scholar.lib.vt.edu/theses/available/etd-041499-185718/ etd.pdf In Copyright http://rightsstatements.org/vocab/InC/1.0/ application/pdf Virginia Tech
collection NDLTD
format Others
sources NDLTD
topic mastitis resistance
somatic cell scores
sire PTA <SUB>SCS</SUB>
spellingShingle mastitis resistance
somatic cell scores
sire PTA <SUB>SCS</SUB>
Cranford, Jamie Layne
Impact of sire PTA<SUB>SCS</SUB> on mastitis resistance and measures of daughter performance
description Research to determine the impact of PTA<SUB>SCS</SUB> on incidence of mastitis, daughter response to infection, and other measures of daughter performance was conducted using data on 1st, 2nd, and 3rd lactation Holsteins obtained from the Virginia Tech herd and from VA DHI herds. Overall correlation of PTA<SUB>SCS</SUB> to lactation average SCS ranged from 0.13 to 0.17 across all data sets. Correlations between PTA<SUB>SCS</SUB> and 1st lactation SCS measures were higher than those between PTA<SUB>SCS</SUB> and SCS in later parities, but higher correlations were found between 2nd and 3rd lactation SCS measures than between 1st and later parities. Correlation of lactation average SCS and incidence of clinical mastitis was 0.41. Regression of lactation average SCS and averages of test day SCS measures on PTA<SUB>SCS</SUB> was significant in 1st, 2nd, and 3rd lactations. All significant relationships were linear and equal or close to 1.0. Relationships between PTA<SUB>SCS</SUB> and number of cases of clinical mastitis (.79), number of treatments (2.0), number of days treated (7.0), changes in SCS from beginning to end of a lactation (-.26), and the slope of changes in test day SCS with DIM (5.9x10-4) were significant only in 1st lactation. No significant relationships between PTA<SUB>SCS</SUB> and measures of clinical mastitis or variation in test day SCS measures were found in 2nd or 3rd lactations. Heavy cull rates imposed on 1st lactation cows in the Virginia Tech herd explained lack of significance in the later parities in the herd study, but results in following analyses indicated that measures of SCS in 1st and later parities may be two different, but correlated, traits. The greatest impact of PTA<SUB>SCS</SUB> on measures of daughter performance and profit was the negative relationship between PTA<SUB>SCS</SUB> and herd life. Increased PTA<SUB>SCS</SUB> resulted in the decreased ability to survive involuntary culling, and thus decreased opportunity for lifetime yield and profit. Selection on PTA<SUB>SCS</SUB> should be an effective method of reducing incidence of clinical mastitis, lactation average SCS, and variation in SCS, or response to infection. The response, however, may be different in 1st lactation than in later parities. === Master of Science
author2 Dairy Science
author_facet Dairy Science
Cranford, Jamie Layne
author Cranford, Jamie Layne
author_sort Cranford, Jamie Layne
title Impact of sire PTA<SUB>SCS</SUB> on mastitis resistance and measures of daughter performance
title_short Impact of sire PTA<SUB>SCS</SUB> on mastitis resistance and measures of daughter performance
title_full Impact of sire PTA<SUB>SCS</SUB> on mastitis resistance and measures of daughter performance
title_fullStr Impact of sire PTA<SUB>SCS</SUB> on mastitis resistance and measures of daughter performance
title_full_unstemmed Impact of sire PTA<SUB>SCS</SUB> on mastitis resistance and measures of daughter performance
title_sort impact of sire pta<sub>scs</sub> on mastitis resistance and measures of daughter performance
publisher Virginia Tech
publishDate 2014
url http://hdl.handle.net/10919/31718
http://scholar.lib.vt.edu/theses/available/etd-041499-185718/
work_keys_str_mv AT cranfordjamielayne impactofsireptasubscssubonmastitisresistanceandmeasuresofdaughterperformance
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