First Results of a MAS Study in Dairy Cattle with Respect to Longevity (short communication) (original) (raw)
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Breeding for longevity and survival in dairy cattle
Thc aim of dairy cattle brceding should be to improvc lifetime profit, rattrer than longevity in itsclf. It is most likcly, though, O16t traits rhar dercrmine longevity will be selccad for, and thus the ability to livc longer will improve. Health and rcproductive traits are describcd as the most imporrant in dercrmining longevity. The main focus of the articlc is on describing methods used as indicators of longevity: sayabilities, sundval scores, and failure time analysis. Mcasurcs of prcduction ard involuntary cdting (c.g. mastitis, reproduaion) are suggested for usc as selection criterion, if measured in the population. If not, other indicalor traits, such as somatic cell counts, could bc used irsrcad. If no or few hcalth and reproduction traits arc available in a population, breeding values for length of pmductivc lifc adjustcd for thc within-herd milk production deviuion, analyzed with failure time analysis' could bc used as a complement to milk production.
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.
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 ...
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.
Advances in Dairy Research, 2014
Longevity of productive life in dairy cattle is a characteristic difficult to evaluate. This measurement is complicated, in part, because the phenotype is expressed late in the life of the animal, but also because the methods of evaluation are complex. The molecular bases of longevity are still far from being fully understood, although some genes begin to be associated with this characteristic. In this short communication will be discussed the criteria for selection in dairy cattle and to report some studies evaluate the molecular bases of longevity; your progress and current perspectives of selection by genic information.
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).
Effect of non-genetic factors on longevity traits in Simmental cows
Biotehnologija u stocarstvu
The effects of fixed non-genetic factors (farm, season of birth, year of birth, total number of lactations) and a continuous non-genetic factor (age at first conception) on the expression and variability of longevity traits such as age at culling, length of productive life, days in milk and cow efficiency index were investigated in 2548 Simmental cows in three farming areas. Based on the model used for the analysis of the effects of non-genetic factors, including the environment and cow age at first conception, on the expression and variability of longevity traits, the overall means for age at culling, length of productive life, days in milk and cow efficiency index were 2445.21?17.49 days, 1562.55?17.71 days, 1094.17?12.28 days and 58.68?0.32%, respectively. The effect of farming area, year of birth and lactation group on longevity traits was very significant (P<0.01), whereas the effect of season of birth was significant (P<0.05). Age at first conception had a highly signifi...
Longevity or herd life is a highly desirable trait that has a great impact on economy of dairy production. Herd life can be measured in several ways, as survival in defined age or in days from first calving to culling. Breeding values (EBV) used for selection can be estimated for direct herd life (DHL) or indirect herd life (IHL). For Slovene Holstein population we compared different models for DHL: the proportional hazards (PH) model, multi trait sire (SM) models and multi trait animal (AM) models (for the last two dependent variables was defined as survival in particular period or days from first calving to culling). We estimated genetic parameters, correlations between various EBVs for DHL and correlations between DHL EBVs and EBVs for other traits in routine genetic evaluation. Heritability estimated using the PH was 0.179, for AM and SM between 0.08 -0.19 and 0.05 -0.17, respectively. Correlation coefficients between AM and SM EBVs were 0.70 -0.88. Estimated correlation coefficients between EBVs for DHL using the PH and EBV of other traits are relatively low, as expected: milk yield (-0.44), somatic cell count (0.21), rear teat position (-0.25), rear teat placement (-0.21), front teat placement (-0.20) and muscling (0.22). Due too the low correlation between DHL EBVs from PH and MT models, correlations between various trait and all five DHL EBVs are similar.
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...