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Popular Sires analysis for the Breed Strategy

During development of the Bearded Collie Breed Strategy the Kennel Club's Geneticist, Tom Lewis, was asked for practical advice on addressing the issue of popular sires. The advice given was to use a combination of strategies including setting an annual limit on litters per sire, breeding from more males (even if only a single litter), and making use of migrant animals. Based on an annual registration of around 350 puppies per year, the recommended annual limit was a maximum of 2 litters per year per sire.

The table below shows what impact an annual limit on sire usage of 2 litters per year would have had if it had been in place during the period 2011 - 2016.

Effect of setting a limit on sire usage

Points to note

  • All figures are based on year of birth not year of registration.
  • 412 litters were born during the period, sired by 147 sires.
  • Setting the annual limit at 2 litters per sire would affect 24 sires who were responsible for >4 out of every 10 litters born (170 out of 412). The remaining litters were sired by 123 different sires.
  • ~1 in 10 of the litters born (43 litters out of 412, or 10.4%) were sired by sires exceeding the annual limit.
  • This drops to 1 in 18 (23 out of 412 litters, or 5.6%) if some of the breeders defer having the litter until the following year in order to stay within the limit. Only 12 sires remain affected if this is done.

The table below shows the effect of excluding 'personal use/own affix' litters from the annual limit on sire usage.

Effect of own use on the limit on sire usage

Points to note

  • Some of the sire owners affected by a quota if 'personal use' litters are included are not affected when 'personal use' litters are excluded.
  • Around one quarter of the litters sired by the 12 top sires (26 out of 111) are 'personal use' litters.
  • Only 1 in 27 of the litters born (15 out of 412 litters, or 3.6%) could not be deferred and would be exceeding the annual limit.
  • The main caveat on these figures is that the definition of 'personal use' does not include sires bought in which do not carry the new owner's affix, as 'own use' cannot be clearly identified in these cases.

Impact of 'popular sires'

  • Assuming 'popular' is defined as any sire that has sired more than 2 litters in ANY year between 2011 and 2016, the proportion of popular sires is 16% (24 out of 147) and they account for 41% of the total number of litters born (170 out of 412).
  • Annual calculations for the % of total litters produced by 'popular' sires since 2000, based on registrations, consistently works out at 35% - 42%, so the 2011-2016 analysis is consistent with the annual figures.

Last updated: 22 August 2017