Boars Live Longer in Top Herds

JAPAN - Koketsu and Sasaki have published a study into boar culling and mortality in commercial herds. On average, they found that boars were culled or died aged two years and eight months, having been in the breeding herd for just over two years and one month. Boars in high-performing herds entered the breeding herd earlier and were retained longer than in average herds.
calendar icon 2 March 2009
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Koketsu and Sasaki from Meiji University in Japan have published a study into boar culling and mortality in commercial breeding herds in the journal, Theriogenology.

The objectives of this study were:

  • to measure culling rate and mortality rate of boars
  • to compare boar life day (BLD: days from birth date to removal date), boar herd life day (BHLD: days from herd entry date to removal date) and herd entry age of boars between high-performing herds and ordinary herds (herd groups)
  • to examine herd measurements for BLD, BHLD and boar age at herd entry, and
  • to observe removal patterns and survival curves for boars by herd groups.

This study used 2474 records of individual boars born in 108 herds from 2000 to 2003. Two herd groups were formed on the basis of the upper 25th percentile of pigs weaned per mated female per year (2001-2005). Mixed-effects models and survival analysis were performed.

Means of BLD and BHLD (± SEM) were 984 ± 9.5 and 781 ± 8.4 days, respectively.

Annual culling rate and mortality rate were 0.411 and 0.035 boars per 365 BHLD, respectively.

Boars in high-performing herds had 51 higher BLD and 62 higher BHLD than those in ordinary herds (P<0.01).

Boars came into high-performing herds 32 days younger than into ordinary herds (P<0.01).

Herd mortality and herd size were not associated with BLD or BHLD.

The hazards in survival analysis were associated with herd groups (P<0.05).

Measurements in the present study provide benchmarks for boar removal in commercial herds, the authors concluded.


Koketsu Y, Sasaki Y. 2009. Boar culling and mortality in commercial swine breeding herds. Theriogenology. 2009 Feb 20. [Epub ahead of print]

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