Pregledni rad
DAIRY CATTLE BREEDS LONGEVITY
Nikola Raguž
; Poljoprivredni fakultet, Sveučilište J.J. Strossmayera Osijek, Hrvatska
Vesna Gantner
; Poljoprivredni fakultet, Sveučilište J.J. Strossmayera Osijek, Hrvatska
Sonja Jovanovac
; Poljoprivredni fakultet, Sveučilište J.J. Strossmayera Osijek, Hrvatska
Sažetak
In economical view, longevity is the most important functional trait in dairy cattle populations. Higher length of productive life results with increased number of offspring per animal, increased life production and decreased replacing and health care costs. Direct selection for longevity in dairy cattle is limited by the time required to accumulate sufficient data to estimate sire breeding values accurately. Direct selection is obstructed further by low heritabilities. Type traits have been used as indirect selection criteria for herd life. These traits are recorded relatively early in life, most often during the first lactation, and are more heritable than longevity, which makes selection relatively more efficient. To get reliable and direct information for sires regarding the longevity of their daughters, it is necessary to wait a minimum number of daughters are culled or die. Moreover, these evaluations may be available too late to be useful in breeding programs. It led to introduction of new methods in life data analysis. The most outspread method is survival analysis which is utilized in Australia, The United Kingdom, United States of America, New Zealand and some European countries. Using survival analysis, all animals can be included in research program, regardless they are culled or not, also taking time-dependent and time-independent effects into account.
Ključne riječi
longevity; dairy cattle; selection; evaluation methods
Hrčak ID:
50639
URI
Datum izdavanja:
30.11.2009.
Posjeta: 2.132 *