Results of a study show that breeding reduces the environmental impacts of animal products by about 1% per year, according to an announcement from Wageningen University & Research (WUR) in the Netherlands.
WUR said this reduction is achieved without placing specific selection pressure on environmental traits but as an indirect response through selection based on current breeding goals. Wageningen Livestock Research performed this study on breeding's contribution to reducing environmental impacts in broilers, laying hens, pigs and dairy cattle.
Globally, animal production is responsible for 14.5% of total anthropogenic greenhouse gas (GHG) emissions, WUR said, noting that approximately half of these emissions originate directly from animal production, whereas the other half come from feed production.
Animal breeding aims to improve animal production and efficient use of resources, which results in a reduction of the environmental impact. WUR said the study objective was to quantify the contribution of animal breeding to reducing the environmental impact of the four major livestock species in the Netherlands (with their animal product), namely broilers (meat), laying hens (eggs), pigs (meat) and dairy cattle (milk).
WUR said a literature review was performed to assess the current status of and historical trends in environmental impact -- mainly focused on GHG emissions -- based on general performance criteria. Emissions related to feed production dominate impacts of broilers, laying hens and, to a minor extent, pigs. For dairy cattle, enteric methane emission is a large contributor to total GHG emissions, WUR said.
Historical trends show considerable improvements in efficiency over the last decades, with breeding playing an important role, WUR reported. From the literature review, the researchers concluded that the contribution of breeding to reducing the environmental impacts of animal production is led by an indirect response through selection for increased efficiency.
In addition to the literature review, the researchers said a quantitative assessment was made on the current environmental impact of the four animal products and the effect of recent genetic improvements. For broiler meat, chicken eggs and pig meat, the focus was on GHG emissions and nitrogen and phosphorus efficiency, whereas for dairy, the focus was on enteric methane emissions.
Data were partly provided by breeding organizations, partners in the Breed4Food consortium, WUR said. In general, results showed that breeding reduces environmental impacts of animal products by about 1% per year.
For laying hens, the study considered white- and brown-egg hens, and it was concluded that white-egg hens have a lower GHG impact and better nitrogen and phosphorus efficiency than brown-egg hens and that improvements over the past 10 years went faster for white-egg hens as well, WUR reported.
For broilers, it was shown that GHG emissions decreased and nitrogen and phosphorus efficiency increased more than 1%. However, only data during a time frame of four years under less-controlled circumstances were available, which resulted in a possible overestimation of genetic progress.
For pigs, data were available from a well-controlled study with two diets and animals divided by sex; however, the time frame was only two years. Results showed that for pigs in the growing/finishing phase, GHG emissions decreased and nitrogen and phosphorus efficiency increased with the current breeding goals, WUR said. Furthermore, boars had lower environmental impact than gilts.
For dairy cattle, results showed that with the current breeding goals, methane production per cow per day increased, but methane intensity (i.e., methane production per kilogram of milk) decreased, WUR noted.
According to WUR, all reported results were achieved without specific selection for environmental traits but as an indirect response to the current breeding goals for each species, which is a combination of health, growth and (feed) efficiency. If selecting directly for environmental traits is the goal, then new traits must be recorded, e.g., the nitrogen and phosphorus content of meat and eggs and methane emissions of individual dairy cows, WUR concluded.
The research abstract may be found here.