Breeding for longevity and survival in dairy cattle (original) (raw)
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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.
First Results of a MAS Study in Dairy Cattle with Respect to Longevity (short communication)
Archiv fur Tierzucht
Dedicated to Professor Dr. D. Simon on the occasion ofhis 70lh birthday Summary A study where Casein loci were used to be markers for improving milk yield, fat content and protein yield in a marker assisted selection experiment focused on possible side effects of this process on longevity traits. Using the data of two samples of cows a Simulation on the data was carried out evaluating the selection differences in period of use, period of life and production of the whole life indirectly. The selection criteria were flexible using one of the milk production traits each as well as marker information. During the investigated period no negative effect of simulated selection using EBV for milk yield, fat content and protein yield alone or in combination with the Casein loci used as markers on longevity traits occurred in the population. There are no significant differences regarding the longevity traits caused by selection for Single milk trait based on pure EBV and MAS.
Longevity of high-yielding cows
Population of Black and White cattle has high genetic potential for production of milk. It exists in very complex production conditions where problems occur which are often manifested in different health disorders, high percentage of culling and short productive life. Longevity parameters are calculated within defined time limits. Bottom limit is determined by date of birth, and top limit by date of culling. The knowledge of the strength of the influence of environment on the longevity of high yielding cows is important from the aspect of its inclusion into the model. According to individual significance of systematic factors, their objective assessment was carried out in order to evaluate the obtained results as precise and correct as possible. Previous studies of the average age of cows at culling from the herd indicated relatively short productive life and life in general of high yielding cows, which due to high percentage of culling effects the herd remount. Consequently selection differential is reduced and in this way realized selection effect is diminished. Objective of this paper was to investigate using appropriate methodology the longevity of high yielding Black and White cows of different genotypes through major systematic influences. Investigated cows according to their origin belong to European type of Black and White cattle in final stage of intensive improvement using Holstein-Friesian breed. Investigated sample included 331 cows. Average age of cows at culling is 2265±463.26 days or 6.21±1.27 years. Observed by cow genotypes, mean values varied from 2140.99 days (> 73% HF), 2247.51 days (58-73% HF) to 2406.97 days (<58% HF). Average lifetime production was realized at the level of 25002.66±7755.39 kg of milk with 3.61±0.01% of milk fat.Bulls, sires of cows, class of HF genes and year of culling had highly significant effect (p≤0.01), whereas the effect of reason for culling was significant (p≤0.05) for life duration of cows.
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.
Survival analysis of longevity in dairy cattle on a lactation basis
Genetics Selection Evolution, 2003
An analysis of longevity in dairy cattle on a lactation basis is proposed. The approach allowed each lactation to have its own baseline hazard function, which gives a better description of the hazard than traditional analyses of the whole length of life. As a consequence, the overall fit of the model to the data was improved and fewer time-dependent variables were needed. Longevity on a lactation basis was defined from one calving to the next instead of from the first calving to culling. However, no new information was added and it was still the overall risk of being culled that was modelled. It is shown that no cow effect is needed in the lactation basis model because a censored record is not complete, a cow can appear as uncensored only once, and a cow cannot be censored after having been culled. Different subdivisions of the stage of lactation effect were tested and the first ten days of lactation were shown to correspond to an increased risk of being culled. There were no major differences in sire variance between the longevity analysed on a lactation basis and longevity based on the entire length of life. dairy cows / culling / frailty models / failure time analysis / heritability
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 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 ...
Pakistan Journal of Biological Sciences, 1998
A total of 193 Holstein Friesian cows sired by 39 bulls at Dena farm in Egypt, during the period from 1987 to 1991 were used to estimate phenotypic and genetic parameters of lifetime production and longevity traits in Friesian cows in Egypt and to study relationship between sire transmitting ability (ETA's) of sires for first 305 day milk yield and each of lifetime production and longevity traits. Heritability and phenotypic and genetic correlations were estimated by paternal half sibs correlations. Heritability estimates were 0.18, 0.24, 0.04, 0.05 and 0.00 for first 305 day milk yield, total lifetime milk production, total lactation period, productive life and number of lactations completed. All phenotypic (0.14-0.97) and genetic 0.90-1.00) correlations among different traits studied were significant except the correlations between number of lactations completed and different traits studied. Sires with at least ten daughters were evaluated by best linear unbiased prediction procedures. Sires with positive expected (ETA's) for first 305 day milk production, have positive values for lifetime production and longevity traits. Product moment correlations of expected ETA's for first 305 day milk yield with lifetime production and longevity traits ranged from (0.09 to 0.96). Sire selection for higher milk yield in the first lactation would lead to a slight increase in longevity defined as length of productive life.