Genetic evaluation of productive life in Iranian Holstein using survival analysis

2005 ◽  
Vol 2005 ◽  
pp. 131-131 ◽  
Author(s):  
M. Dadpasand Taromsari ◽  
S. R. Miraei-Ashtiani ◽  
M. Moradi Shahrebabak ◽  
R. Vaez Torshizi
Keyword(s):  
Survival Analysis ◽  
Dairy Cattle ◽  
Genetic Parameters ◽  
Linear Models ◽  
Failure Time ◽  
Genetic Evaluation ◽  
Time Analysis ◽  
Productive Life ◽  
Analysis Methodology ◽  
Time Dependent Covariates

Improvement of herd life increases profitability due to lower replacement costs of heifers, higher proportion of mature cows that produce at their maximum potential and increased opportunity for voluntary culling. Functional productive life (PL) after adjustment for production is the ability of a cow to remain healthy and delay involuntary culling (Ducrocq et al 1988). Survival or failure time analysis has replaced linear model approaches for routine genetic evaluation of dairy cattle in several countries (Sewalem et. al. 2003). It allows proper treatment of censored data, inclusion of time-dependent covariates and skewed or non normal distribution of data. Approximate estimates of the heritability of longevity traits typically range from 0.05 to 0.10 and 0.15 to 0.20 using linear models and survival analysis, respectively (Vollema et al. 2000 and Caraviello et. al. 2004). The objective of this study was to apply survival analysis methodology for assessing the most important factor influencing PL, estimation of genetic parameters of productive life and genetic evaluation in Iranian Holstein dairy cattle.

Linear and threshold model genetic parameters for disease, fertility and milk production in dairy cattle

2000 ◽  
Vol 27 ◽  
pp. 83-84
Author(s):  
H. N. Kadarmideen ◽  
R. Thompson ◽  
G. Simm
Keyword(s):  
Animal Models ◽  
Dairy Cattle ◽  
Milk Production ◽  
Genetic Parameters ◽  
Linear Models ◽  
Threshold Model ◽  
Genetic Selection ◽  
Good Health ◽  
Economic Loss ◽  
Fertility Traits

A combination of better management and genetic selection for good health and fertility would provide a more effective long term solution for economic loss due to diseases and poor fertility. This would also help to address public concerns about the use of medical treatment in milk production. A balance in the genetic improvement of health and fertility together with milk production could be achieved through their inclusion in national genetic selection indices, for which genetic parameters are needed. One of the main objectives of this study was to estimate genetic parameters for various disease and fertility traits in the UK dairy cattle population, using records from a national recording scheme run by Livestock Services UK Ltd. Genetic analysis of traits recorded as present or absent (binary traits; e.g. diseases) requires the use of non-linear threshold models, because linear models require normality assumptions (e.g., Gianola 1982). The other objective of this study was to estimate genetic parameters for binary disease and fertility traits based on threshold animal models and to compare results with those from linear animal models.

Reasons and timing of cows leaving herd in dairy cows using survival analysis methodology

2007 ◽  
Vol 2007 ◽  
pp. 150-150
Author(s):  
A. Heravi Moussavi ◽  
M. Danesh Mesgaran ◽  
E. Dirandeh ◽  
A. Pirzadeh Naeini ◽  
R. Noorbakhsh
Keyword(s):  
Survival Analysis ◽  
Dairy Cows ◽  
Censored Data ◽  
Reproductive Performance ◽  
Dairy Farm ◽  
Stage Of Lactation ◽  
Analysis Methodology ◽  
Farm Profit ◽  
Health Disorders ◽  
Time Dependent Covariates

Cow longevity is highly related to dairy farm profit. Cows are culled for a variety of reasons. The predominant reasons for culling are reproduction (i.e., failure to conceive), health, and low production (Bascom and Young, 1998). Half of the herd removals occur involuntarily and prematurely because of health disorders (Beaudeau et al., 2000). The decision to cull is a complex one. Farmers may consider many individual (such as age, stage of lactation, milk production, health status, and reproductive performance) and economic (such as milk price, the price of culled cows, and the price and availability of replacement heifers) factors when deciding to cull a cow. On the other hand, the risk of culling is not consistent across all stages of lactation. Cows experience the highest risk shortly after calving (Fetrow et al., 2006). Survival analysis allows for a more appropriate management of censored data and time-dependent covariates. Analyses of the reason and timing of culling is needed to predict herd performance. The objective of this study was to study the reasons and timing of cows leaving herd in two large Holstein dairy farms in Iran.

scholarly journals Genetic parameters of calving ease in dairy cattle using threshold and linear models

2018 ◽  
Vol 18 (1) ◽  
pp. 80-87
Author(s):  
António Silvestre ◽  
Ângela Martins ◽  
Virgínia Santos ◽  
Jorge Colaço
Keyword(s):  
Dairy Cattle ◽  
Genetic Parameters ◽  
Linear Models ◽  
Calving Ease

scholarly journals Genetic evaluation modeling of the Tunisian dairy cattle: assessment of the test-day model (TDM) and lactation model (L305) in accordance to the flock size

2019 ◽  
Author(s):  
Yosra Ressaissi ◽  
Mohamed Ben Hmouda
Keyword(s):  
Dairy Cattle ◽  
Genetic Parameters ◽  
Significant Contribution ◽  
Genetic Evaluation ◽  
Data Availability ◽  
Flock Size ◽  
Breeding Values ◽  
Genealogical Data ◽  
Evaluation Approaches ◽  
Daily Milk

SUMMARYGenetic evaluation in dairy cattle has been commonly carried following the lactation model (L305) and the test-day model (TDM), the purpose of this study was to test the adjustment and the accuracy of these main models in relation to the size of the Tunisian dairy flocks while assessing the effect of genealogical data availability on both approaches. Data were obtained from the Tunisian official milk recording system and cows were classified in accordance to the flock sizes into eight groups. Genetic parameters and breeding values were estimated per size group for 305-days (L305) and daily milk yields (TDM) through two animal models and by using 3 pedigrees of different quality. Contemporary groups were defined as herd*calving year for L305 and as herd*control year for TDM. Genetic evaluation approaches were compared by connecting the different obtained results. Fixed factors were observed to be differently significant per group of flock size explaining a specific variance of the average milk yield and that small flocks are mostly affected by environmental factors. Using TDM and an equilibrated pedigree file, genetic parameters were higher, breeding values were fairly compared leading to a more objective ranking of the cows and a better illustration of genetic variabilities between the flock groups. Low genetic variability and significant contribution of unfavorable environmental conditions were observed within the Tunisian dairy flocks.

scholarly journals Survival Analysis Applied to Genetic Evaluation for Female Fertility in Dairy Cattle

2005 ◽  
Vol 88 (6) ◽  
pp. 2253-2259 ◽  
Author(s):  
M. del P. Schneider ◽  
E. Strandberg ◽  
V. Ducrocq ◽  
A. Roth
Keyword(s):  
Survival Analysis ◽  
Dairy Cattle ◽  
Genetic Evaluation ◽  
Female Fertility

Genetic parameters of functional and fertility determined length of productive life in Swedish dairy cattle

2000 ◽  
Vol 70 (3) ◽  
pp. 383-389 ◽  
Author(s):  
E. Strandberg ◽  
A. Roxström
Keyword(s):  
Dairy Cattle ◽  
Genetic Correlation ◽  
Fixed Effects ◽  
Genetic Parameters ◽  
Fixed Time ◽  
Time Dependent ◽  
Independent Effect ◽  
Dependent Effect ◽  
Productive Life ◽  
Time Dependent Effect

AbstractThe objective of this study was to estimate genetic parameters and breeding values of sires for different definitions of length of productive life in Swedish Red and White dairy cattle. The data consisted of 534 016 daughters with initial calvings between 1988 and 1996. These cows were daughters of 1266 sires (55 of which were considered proven bulls, and treated as fixed effects). The model for the hazard included: a random time-dependent effect of herd-year-season (hys), a fixed time-dependent effect of year-season, a fixed time-dependent effect of parity by stage of lactation, a fixed time-dependent effect of the cow’s peak yield as deviation from her herdmates in that herd-year, a fixed time-independent effect of age at first calving, and random and fixed effects of sire. The hys effect was assumed to follow a gamma distribution and the random sire effect a normal distribution with mean zero and variance Aσ2s, where σ2s is the variance among sires and A the relationship matrix. Length of productive life was defined as the number of days from first calving to culling or end of data. Two types of length of productive life were studied: (1) functional productive life (PL), all cows that were culled before the end of data were considered as uncensored; (2) fertility determined productive life (FPL), only cows that were culled for fertility problems were considered as uncensored. Heritability estimates were 6·9% and 6·1% for PL and FPL, respectively. The approximated genetic correlation estimates between fertility measures in first lactation and FPL was higher than the corresponding estimates with PL. In conclusion, it was feasible to use the trait fertility-determined length of productive life, its heritability was almost as large as for PL, and the genetic correlation with fertility was higher than for PL. However, the expected selection response in fertility from indirect selection on FPL was lower than from direct selection.

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