Genetic trend of functional productive life in the population of black and white cattle in Serbia (original) (raw)
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Estimation of genetic parameters for longevity in Slovenian dairy cattle populations
Genetic parameters for longevity in Slovenian Holstein (H), Simmental (S) and Brown Swiss (B) cattle were estimated with sire-mgs (maternal grandsire) model using survival analysis, applying a proportional hazard function following a Weibull distribution. Longevity was described as length of productive life (LPL), that is as number of days from first calving to the culling or to the moment of data collection (completeduncensored and censored records). Truncation date was was date of data collection. Estimated sire variances were 0.050 (H), 0.021 (S) and 0.034 (B). Herd variances were 0.191 (H), 0.299 (S) and 0.318 (B). Heritabilities estimates were 0.161 (H), 0.064 (S) and 0.101 (B).
Archiv fur Tierzucht
Genetic evaluation of sires for functional longevity was conducted using survival analysis techniques. The data set consisted of 49 659 Simmental cows with first calving from 1997 to 2008. A piecewise Weibull sire model was used to estimate breeding values of 251 bulls for functional length of productive life of their daughters. The model was stratified by parity i.e. a separate baseline hazard was computed for each stratum. Besides the random sire effect, the model included the fixed time independent effects of age at first calving, herd size and region as well as the time dependent effects of relative milk production and year*season of first calving. The highest impact on longevity was found for relative milk production. Cows with the lowest milk yields were at approximately 2.7 times higher risk of culling compared to cows with average milk production. Effects of age at first calving, herd size and country region had lower impact on longevity. Sire variance was 0.023 which results in a heritability of 0.06 for functional length of productive life. The average approximate reliability of estimated breeding values was 0.49. Genetic trend showed no clear tendency by year of birth of bulls.
Genetic evaluation of the length of productive life in Holstein cattle in the Czech Republic
Czech Journal of Animal Science, 2005
Survival Kit V3.12 was used to analyse the length of productive life of cattle in the Czech Republic. The data set consisted of 230 028 registered Holstein cows. The model included the time-dependent effects parity × stage of lactation interaction, herd × year × season interaction, class of milk production within herd and year, breed within years and the time-independent effect of age at first calving and the random effect of sire. The highest risk of culling was found for cows at the beginning and at the end of the first lactation and at the end of any other lactation. The risk of culling decreased with parity. The risk of culling of cows assigned to the lowest milk production class was five times higher than that of cows assigned to the average milk production class. Risk of culling diminished with a decreasing percentage of Holstein breed. Cows younger at first calving showed a lower risk of culling. Breeding values for sires expressed as a risk ratio of their daughters were between 0.7 and 1.45. Estimated heritability of functional longevity was 0.025 on the log scale and 0.041 on the original scale.
Mljekarstvo, 2016
Assessment of the heritability coefficients of longevity traits in the population of Black and White cows was performed on a data set that included production results of 16,539 of black and white culled cows, which reached a total of 50,382 lactations in the period from 1985 to 2012. The cows were grown on 7 farms of the Agricultural Corporation Belgrade and are progeny of 277 bulls. The analysis covered the following traits: length of productive life (LPL), lifetime milk yield (LMY) and number of lactations (NL). Variance components of longevity traits were estimated using a BLUP linear mixed model with animal as a random effect. Cows included in the analysis calved for the first time in the average age of 26.86 months, while the average length of productive life amounted to 1,299.9 days and during that time the animals achieved an average of 3.04 lactations and life time production of 21,016 kg of milk. The values of the heritability coefficients of longevity traits ranged from 0.066; 0.061 and 0.074 regarding the length of productive life, lifetime milk yield and number of lactations respectively.
Animal Science Journal, 2013
Genetic parameters for longevity in Slovenian Holstein (H), Simmental (S) and Brown Swiss (B) cattle were estimated with sire-mgs (maternal grandsire) model using survival analysis, applying a proportional hazard function following a Weibull distribution. Longevity was described as length of productive life (LPL), that is as number of days from first calving to the culling or to the moment of data collection (completeduncensored and censored records). Truncation date was January 1, 1991 while August 1, 2008 was date of data collection. Estimated sire variances were 0.050 (H), 0.021 (S) and 0.034 (B). Herd variances were 0.191 (H), 0.299 (S) and 0.318 (B). Heritabilities estimates were 0.161 (H), 0.064 (S) and 0.101 (B).
Genetic evaluation for longevity of Croatian Simmental bulls using a piecewise Weibull model
Archives Animal Breeding
Genetic evaluation of sires for functional longevity was conducted using survival analysis techniques. The data set consisted of 49 659 Simmental cows with first calving from 1997 to 2008. A piecewise Weibull sire model was used to estimate breeding values of 251 bulls for functional length of productive life of their daughters. The model was stratified by parity i.e. a separate baseline hazard was computed for each stratum. Besides the random sire effect, the model included the fixed time independent effects of age at first calving, herd size and region as well as the time dependent effects of relative milk production and year*season of first calving. The highest impact on longevity was found for relative milk production. Cows with the lowest milk yields were at approximately 2.7 times higher risk of culling compared to cows with average milk production. Effects of age at first calving, herd size and country region had lower impact on longevity. Sire variance was 0.023 which results in a heritability of 0.06 for functional length of productive life. The average approximate reliability of estimated breeding values was 0.49. Genetic trend showed no clear tendency by year of birth of bulls.
Genetic parameters estimation and genetic evaluation for longevity in Italian Brown Swiss bulls
Italian Journal of Animal Science, 2009
Direct longevity EBV of Italian Brown Swiss sires were predicted using a Weibull proportional hazards model. This trait was defined as the risk of culling from first calving. Records from �11,����� Brown Swiss cows with first calving from 1��8� to 200� were used. The model include fi�ed (age at first calving) and random (sire's additive genetic) time independent effects, fi�ed (herd, parity, quantile of mature equivalent deviation from the yearly herd mature equivalent average, and regression on the dynamic herd size) and random (herd-year with log-gamma distribution) time dependent effects. Predicted breeding values for functional longevity, e�pressed as relative risk ratios, ranged from 0.�8 to 1.����. The EBV were standardized with mean 100 and standard deviation 12. EBV were positively submitted to Interbull trend validation procedure in order to assess EBV variation over time and the possibility of including them in the international e�change of bull inde�es.
Genetic evaluation of length of productive life including predicted longevity of live cows
Journal of dairy science, 1993
Complete longevity data are available too late for most sire selection. Earlier selection is possible using correlated traits, nonlinear evaluation of censored data, or predicted longevities for live cows in addition to completed longevity data. Completed longevity was defined as total months in milk by 84 mo of age. Predicted longevity was computed by multiple regression from cows alive at six different ages. Variables included age at first calving, standardized first lactation milk yield (optional), lactation status (dry or milking), current months in milk, current months dry, and cumulative months in milk. Completed longevity data for dead cows were then merged with predicted longevity data for live cows. A total of 1,984,038 Holstein cows born from 1979 to 1983 were included and represented 1911 sires, each with at least 70 daughters. Heritability of longevity increased gradually from .03 at 36 mo to .08 at 84 mo. Phenotypic correlations of early with completed longevity ranged ...
Journal of dairy science, 2001
Genetic evaluation of sires for functional longevity of their daughters based on survival analysis has been implemented in the populations of Braunvieh, Simmental, and Holstein cattle in Switzerland. A Weibull mixed sire-maternal grandsire survival model was used to estimate breeding values of sires with data on cows that calved since April 1, 1980. Data on Braunvieh and Simmental cows included about 1.1 million records, data on Holstein cows comprised about 220,000 records. Data contained approximately 20 to 24% right-censored records and 6 to 9% left-truncated records. Besides the random sire and maternal grandsire effects, the model included effects of herd-year-season, age at first calving, parity, stage of lactation, alpine pasturing (Braunvieh and Simmental), and relative milk yield and relative fat and protein percentage within herd to account for culling for production. Heritability of functional longevity, estimated on a subset of data including approximately 150,000 animal...
Genetic evaluation of longevity in dairy cattle
Applied Science Reports
Longevity is a highly desirable trait that considerably affects overall profitability. With increased longevity, the mean production of the herd increases because a greater proportion of the culling decisions are based on production. Longevity did not receive adequate attention in breeding programs because genetic evaluation for this trait is generally difficult as some animals are still alive at the time of genetic evaluation. Therefore, three basic strategies were suggested to evaluate longevity for cows: Firstly, cow survival to a specific age, which can be analyzed as a binary trait by either linear or threshold models. Secondly, estimating life expectancy of live cows and including these records in a linear model analysis. Thirdly, survival analysis: a method of combining the information of dead (uncensored) and alive (censored) cows in same analysis. This review represents an attempt to shed a light on different strategies of genetic evaluation of longevity in dairy cattle in most of developed countries.