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Analysis of longevity in Slovenian holstein cattle
Potočnik, Klemen (Author), Gantner, Vesna (Author), Krsnik, Jurij (Author), Štepec, Miran (Author), Logar, Betka (Author), Gorjanc, Gregor (Author)

URLURL - Presentation file, Visit http://aas.bf.uni-lj.si/zootehnika/98-2011/PDF/98-2011-2-93-100.pdf New window

Abstract
The longevity of Slovenian Holstein population was analzsed using survival analysis with a Weibull proportional hazard model. Data spanned the period between January 1991 and January 2010 for 116,200 cows from 3,891 herds. Longevity was described as the length of productive life - from first calving till culling or censoring. Records above the sixth lactation were censored to partially avoid preferential treatment. Statistical model included the effect of age at first calving, stage of lactation within parity, yearly herd size deviation, season defined as year, herd, and sire-maternal grandsire (mgs). Some effects had time varying covariates, which lead to 1,839,307 or on average 16 elementary records per cow. Herd and sire-maternal grandsire effects were modelled hierarchically. Pedigree for sires and maternal grandsires included 2,284 entries. Estimated variance between herds was 0.12, while between sire variance was 0.04. Heritability was evaluated at 0.14. Genetic trend for sires was unfavourable, but not significant. A further research is needed to define the required number of daughters per sire and the dynamics of genetic evaluation for sires whose majority of daughters still have censored records.

Language:English
Keywords:cattle, breeds, Slovenian Holstein, longevity, Weinbull proportional hazards model
Work type:Not categorized (r6)
Tipology:1.01 - Original Scientific Article
Organization:BF - Biotechnical Faculty
Year:2011
Number of pages:str. 93-100
Numbering:Letn. 98, št. 2
UDC:636.2
ISSN on article:1581-9175
COBISS.SI-ID:2982024 Link is opened in a new window
Views:867
Downloads:197
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Record is a part of a journal

Title:Acta agriculturae Slovenica
Shortened title:Acta agric. Slov.
Publisher:Biotehniška fakulteta
ISSN:1581-9175
COBISS.SI-ID:213840640 New window

Secondary language

Language:Slovenian
Abstract:
Za analizo dolgoživosti smo pri slovenski črno-beli populaciji govedi uporabili metodologijo analize preživetja in Weibullov model sorazmernih ogroženosti. V analizo smo vključili podatke 116.200 krav iz 3.891 čred skozi obdobje od januarja 1991 do januarja 2010. Dolgoživost je bila predstavljena kot doba produktivnega življenja, ki je definirana kot število od prve telitve do izločitve ali do datuma zajema podatkov za živali, ki so na ta datum bile še žive. Šesto in kasnejše laktacije smo okrnili na konec šeste laktacije, da smo omilili precenjenost boljših živali. V statistični model smo vključili vpliv starosti ob prvi telitvi, stadija laktacije ločeno za vsako zaporedno laktacijo, spreminjanje velikosti črede med leti, leto telitve, čredo, očeta in materinega očeta. Ravni nekaterih vplivov so časovno spremenljivi, kar povzroči, da smo v analizi obravnavali 1.839.307 zapisov ali povprečno 16 osnovnih zapisov na kravo. Čreda in vpliv očeta z materinim očetom sta bila v model vključena hierarhično. Rodovnik za očete in materine očete je obsegal 2.284 zapisov. Ocenjena varianca za vpliv črede je znašala 0,12, medtem ko je ocena variance med očeti znašala 0,04. Dednostni delež je bil ocenjen na 0,14. Genetski trend ima negativno smer, a ni statistično značilen. Potrebne bodo nadaljnje raziskave, da bomo določili zadostno število hčera po biku in dinamiko obračunov plemenskih vrednosti za bike, ki imajo večino hčera še v fazi prireje.

Keywords:govedo, pasme, slovenska črno-bela pasma, dolgoživost, Weinbullov model sorazmernih ogroženosti

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