Home About Browse Search
Svenska


Fertility, mastitis and longevity in dairy cattle analyzed using survival models

Schneider, Maria del Pilar (2006). Fertility, mastitis and longevity in dairy cattle analyzed using survival models. Diss. (sammanfattning/summary) Uppsala : Sveriges lantbruksuniv., Acta Universitatis agriculturae Sueciae, 1652-6880 ; 2006:45
ISBN 91-576-7094-3
[Doctoral thesis]

[img]
Preview
PDF
540kB

Abstract

The aim of the thesis was to investigate whether survival analysis (SA) results in a better genetic evaluation of female fertility and mastitis traits and to study the effects of mastitis and pregnancy status as risk factors for culling. Sire breeding values for interval between calving and last insemination (CLI) and interval between first and last insemination (FLI) were predicted using SA and mixed linear models (LM). Correlations between simulated true breeding values for conception rate and breeding values for CLI and FLI predicted by SA were higher than corresponding correlations with LM. When pregnancy status was known, SA was better than LM for genetic evaluation of conception rate when using observations on CLI and FLI. If selection were carried out on these predicted breeding values, this would translate into 8 to 12% higher genetic progress for FLI and CLI, respectively. Clinical mastitis was analyzed with LM (binary trait), and time to first mastitis with SA. The higher accuracies for SA could be translated into a higher genetic response, approximately, 3% for first parity and 25 % for later parities. The effect of pregnancy status and mastitis on culling in Swedish dairy cattle was analyzed with SA. Mastitis affected culling decisions throughout the lactation, but its effect depended on pregnancy status and the stage during which the cow was treated. The risk of culling was low for pregnant cows, whether or not they had been treated for mastitis. Different patterns were observed for the risk of culling between open and pregnant cows. For both groups, the risk of being culled was higher for cows treated for mastitis than for untreated cows. For open cows, the risk was higher for cows treated in earlier stages, whereas for pregnant cows, the risk was similar across different stages of lactation. This thesis showed the potential of using SA for genetic evaluation of fertility traits and clinical mastitis in dairy cattle. SA was also found to be a useful method to analyze the effect of pregnancy status and clinical mastitis as risk factors for culling by treating them as time-dependent covariates.

Authors/Creators:Schneider, Maria del Pilar
Title:Fertility, mastitis and longevity in dairy cattle analyzed using survival models
Year of publishing :May 2006
Volume:2006:45
Number of Pages:33
Papers/manuscripts:
NumberReferences
ALLI. Schneider, M. del P., Strandberg, E., Ducrocq, V. and Roth, A. 2005. Survival analysis applied to genetic evaluation for female fertility in dairy cattle. Journal of Dairy Science 88, 2253-2259. II. Schneider, M. del P., Strandberg, E., Ducrocq, V. and Roth, A. 2006. Short Communication: Genetic evaluation of interval from first to last insemination with survival analysis and linear models. (Submitted). III. Carlén, E., Schneider, M. del P. and Strandberg, E. 2004. Comparison of between linear models and survival analysis for genetic evaluation of clinical mastitis in dairy cattle. Journal of Dairy Science 88, 797-803. IV. Schneider, M. del P., Strandberg, E., Emanuelson, U., Grandinson, K., Roth A. 2006. The effect of mastitis and pregnancy status on culling in Swedish dairy cows. (Submitted).
Place of Publication:Uppsala
ISBN for printed version:91-576-7094-3
ISSN:1652-6880
Language:English
Publication Type:Doctoral thesis
Full Text Status:Public
Agrovoc terms:dairy cattle, genetic evaluation, fertility, mastitis, pregnancy, longevity, survival, genetic correlation, culling, linear models, statistical methods
Keywords:female fertility traits, mastitis, pregnancy status, longevity, survival analysis, mixed linear models
URN:NBN:urn:nbn:se:slu:epsilon-1051
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-1051
ID Code:1125
Department:(VH) > Dept. of Animal Breeding and Genetics
Deposited By: Maria del Pilar Schneider
Deposited On:15 May 2006 00:00
Metadata Last Modified:02 Dec 2014 10:09

Repository Staff Only: item control page