Selective Breeding
System: Pigs
Mainly applicable for: Breeders, as well as other types of pig farms sourcing pigs from selective breeders.
Description
Multiple traits are included in breeding schemes, with individual traits being weighted differently in breeding indexes. Selective breeding of animals can contribute to reduction of greenhouse gas emissions as many traits improve efficiency per unit of product, such as growth rate, feed efficiency, fertility and health status.
Mechanism of effect
Improved feed efficiency, litter size, survival and growth rates reduce emissions per kg meat. An improved feed efficiency and higher growth reduces emissions from feed production, enteric fermentation and manure. More pigs per sow (larger litters, increased piglet survival, sow longevity and reproductive performance) dilute emissions related to the ‘breeding overhead’ for pig production. Net effects depend on accompanied changes in the footprint of pig diets and changes in farm management (e.g. energy use for heating and ventilation). As reduction of emissions due to genetic improvement involves a certain rate per year, the achieved reduction potential depends on the period of time considered.
The mean effects on emissions indicated below concern effects of breeding, and not of changes in diets and farm management. It should be noted that, in case the feed formulation is changed to meet the genetic potential, there is a risk of increased emissions related to deforestation (e.g., for soy production).
Reference situation
Average farm
Legend
| ● – Small effect (<5%) | o – No effect | o – no effect |
| ●● – Medium effect (5-20%) | ● – Unfavourable effect | N/A – unknown effect |
| ●●● – Large effect (>20%) | ● – ● – Variable effect (depending on farm characteristics or way/level of implementation) |
Effect on total greenhouse gas (GHG) emissions
| Mean effect and range in kg CO2-equivalents | per kg product | ||
| Mean | Mean | Level of evidence | |
| Selective breeding for improved performance | ●● | ●–●● | Low |
Effect per emission source
| Mean effect on emission from | Manure | Animal | Feed and forage production | Barn & farm inputs | |||
| CH4 | N2O | CH4 | CO2 | N2O | LUC | CO2 | |
| Selective breeding for improved performance | ● | ● | ● | ● | ● | ●* | ● |
*risk of an adverse effect (see ’cause of variable or unfavourable effect’)
Explanation of variable effect
Selective breeding for improved performance (multiple traits)
Effects depends on the relative weights of traits in selection indexes, their rate of implementation, and other changes in the management (e.g. changes in diet composition and the related change in footprint). As reduction of emissions due to genetic change involves a certain rate per year, the achieved reduction potential depends on the period of time considered.
| Literature references | Selective breeding for improved performance |
|---|---|
| Thoma et al., 2024 | A Life Cycle Assessment Study of the Impacts of Pig Breeding on the Environmental Sustainability of Pig Production |
| Bonesmo and Enger, 2021 | The effects of progress in genetics and management on intensities of greenhouse gas emissions from Norwegian pork production |
| Soleimani and Gilbert, 2021 | An approach to achieve overall farm feed efficiency in pig production: environmental evaluation through individual life cycle assessment |