What is the economic loss due to genetic defects?

An economic model was developed that assessed financial loss through the pyramid from nucleus to multiplier to commercial herd on a per litter basis for traits with an incidence higher than 0.10%.
Friday 25 February 2011 (7 years 20 days ago)
Mortality, and economic loss, was highest in this study for splayleg
In the previous article ‘How common are genetic defects’ it was noted that herd levels between 2.5% to 5.0% can be considered ‘normal’, although there is evidence of variation between herds and genotypes. It was also noted that it is not uncommon for herds to have ‘storms’ where the incidence is higher than the levels noted above, particularly for short periods. These ‘storms’ often appear difficult to control and can lead to emotive discussions with genetic suppliers!

However, what are the real economic losses that can be attributed to defects? The largest and most detailed analysis was undertaken nearly forty years ago by Done, Reed and Deeble in 1972. They reported on the incidence of genetic defects recorded by trained technicians in the progeny of the first twenty ‘viable’ litters of all UK Large White and Landrace A.I. boars.

In total, more than 60 defects were looked for in the investigation and 13 defects were considered to result in death or culling. As the table shows the estimate of mortality varied across the defects, ranging from 5% to 100%:

% Incidence
Large White Sire Landrace Sire % Death or culled
Splayleg 0.14 1.25 50
Inquinal/scrotal hernia 0.44 0.67 5
Atresia ani 0.14 0.31 100♂/50♀
Pitryisis rosea 0.08 0.33 5
Umbilical hernia 0.16 0.05 10
Tremors 0.02 0.09 100
Bent legs 0.03 0.05 5
Thickened forelimbs 0 0.03 5
Mandible 0.02 0 50
Kyphosis 0 0.02 5
Cranioshisis 0 0.02 100
Hydrocephalus 0 0.02 100
Eye defects 0 0.02 100
Total % 1.02 2.84

An economic model was developed that assessed financial loss through the pyramid from nucleus to multiplier to commercial herd on a per litter basis for traits with an incidence higher than 0.10%. This gene-flow model assumed ten pigs born per litter and concluded that the cost of genetic defects was US$0.36 for a Large White sired litter and US$1.13 for a Landrace-sired litter. Since these data were published it should be noted that litter sizes have increased and the estimated marginal value of a weaner pig has increased 11 fold since 1972. Thus, the current economic loss from defects is likely to have increased very significantly.

Atresia – inevitably leads to death and economic loss Kyphosis – common in some herds but most pigs survive and grow normally
In order to get a current snapshot of the actual, rather than estimated, mortality from genetic disorders a recent confidential survey was undertaken in a large anonymous European Breeding Company dam-line (Large White and Landrace) nucleus/multiplier over a four and a half year period ending September 2010. In total, 196,424 purebred and first-cross pigs born were evaluated by trained technicians who recorded every born pig within twelve hours of birth in the farrowing house to establish the incidence of congenital defects (seen at birth). Additional assessments were made of all surviving pigs at 45kg ± 5kg and 95kg ± 9kg to estimate the incidence of defects occurring after parturition and up to an average of 95kg live weight. The data were combined and also included information on the actual number of deaths and euthanised pigs that could be attributed to defects from birth to 95 kg:

Number of defects Number of deaths/culls % of deaths/culls
Inquinal/scrotal hernia 2026
Umbilical hernia 953
Female genitalia 74 0 0
Epitheliogenesis imperfecta 2
Splayleg 5 2 40.0
Other 194 35 18.0
Total defects 4355 243
Total pigs 196,424
% affected 2.217 0.124

In summary, in this population, the total incidence of defects was 2.22%. Of these roughly one pig in every twenty (5.6%) either died or was euthanised due to a defect, representing an overall percentage of 0.124%.

Assuming that the above data are representative of other world pig populations it is possible to estimate the annual cost of genetic defects. The latest FAO statistics (see here) report world slaughterings in 2009 of 1,337,205,493 pigs. Using a gross margin of US$30 per ‘lost’ pig indicates that the global value of deaths and culls due to genetic defects was US$49.74 million. This is likely to be less than the economic losses from disease like PCVAD and PRRS but suggests a significant financial impact on world pig production.

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