Selective Breeding
System: Beef Cattle
Mainly applicable for: In systems using artificial insemination with high renewal rates
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. In addition, international breeding organizations are now introducing methane breeding values for bulls, allowing siring of cows by bulls with lower methane profiles.
Mechanism of effect
Increasing growth rate, feed efficiency and reproduction of fattening and breeding stock reduce emissions per kg meat by diluting emissions related to maintenance and breeding overhead. For example, improving feed efficiency reduces emissions for feed and forage production, while increasing the reproduction and weaning rate of breeding animals results in a lower breeding overhead per finished fattening animal. 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. Besides this, the change in emissions depends on accompanied changes in animal diets and farm plan.
Reference situation
Average farm
Legend
| ● – Small effect (<5%) | o – No effect |
| ●● – Medium effect (5-20%) | ● – Unfavourable 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 (multiple traits) | ●● | ●–●● | Low |
| Including methane in the breeding goal | ●● | ●–●● | 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 (multiple traits) | ● | ● | ●● | ● | ● | N/A | ● |
| Including methane in the breeding goal | o | o | ●● | o | o | o | o |
*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 weights of traits in selection indexes, rate of implementation, and other changes in the management (e.g. changes in feed ration composition and the footprint of the feed ration fed). 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.
Including methane in the breeding goal
The size of effect depends on the rate of implementation, and any other changes in the management (e.g. changes in feed ration composition and the footprint of the feed ration fed). 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 (multiple traits) |
|---|---|
| Quinton et al., 2018 | Prediction of effects of beef selection indexes on greenhouse gas emissions |
| Basarab et al., 2013 | Reducing GHG emissions through genetic improvement for feed efficiency: effects on economically important traits and enteric methane production |
| O’Brien et al., 2020 | LIFE BEEF CARBON: a common framework for quantifying grass and corn based beef farms’ carbon footprints |
| Including methane in the breeding goal | |
|---|---|
| Manzanilla-Pech et al., 2016 | Genomewide association study of methane emissions in Angus beef cattle with validation in dairy cattle |
| Fennessy et al., 2018 | The potential impact of breeding strategies to reduce methane output from beef cattle |
| Manzanilla-Pech et al., 2022 | Selecting for Feed Efficient Cows Will Help to Reduce Methane Gas Emissions |
| Including methane in the breeding goal | |
|---|---|
| Manzanilla-Pech et al., 2016 | Genomewide association study of methane emissions in Angus beef cattle with validation in dairy cattle |
| Fennessy et al., 2018 | The potential impact of breeding strategies to reduce methane output from beef cattle |