The trait of stillbirth is evaluated by sire threshold models. Sire evaluation for stillbirth is expressed as ETA for percentage of stillbirth, and are shown as sire stillbirth (SSB) and daughter stillbirth (DSB). The data have been collected through DHIP since 1986.
Data editing criteria for stillbirth evaluation is :
sire of cow is known and Holstein,
both sire of cow and calf are known and Holstein,
record at 1st-5th calving, and 18 to 35 months of age at first calving,
single calf,
at least one contemporary record in the herd-year subclass.
The evaluation model for stillbirth is:
y = hy + BM + AP + SB + MB + sc + sd + e
where,
y :
records of stillbirth assumed normal distribution,
hy :
random effects of herd-year to account for the effect of management groups on a record,
BM :
fixed effects of calving month by regional block,
A :
fixed effects of parity-age at calving,
SB :
fixed effects of sire birth year groups,
MB :
fixed effects of MGS birth year groups,
sc :
random additive genetic effects of the sire of calf,
sd :
random additive genetic effects of the sire of dam,
e :
random residuals.
In stillbirth evaluation, pedigree information among bulls is used, and sire and MGS of bulls within four generations of recorded cows are identified.
Direct heritability : 0.03
Maternal heritability : 0.04
For the development of the livestock industry and a healthy diet in Japan
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