Sustainability & efficiency

Relevance of ‘Genetics of environmental sustainability‘ in pig breeding

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Abstract

In the perfect ecosystem humans can eat animal products without disturbing the system's sustainability. Civilization disrupted this system, and livestock production is part of this. Livestock breeding can slightly reduce the disruption, but cannot solve the issue. Our objective is to describe the relevance of selection in commercial breeding on CO2 and Nitrogen traits, ignoring other environmental impacts (all relevant but out of scope here). CO2 emission in pigs is directly related to feed efficiency. Reduction of fat accretion, of maintenance by increased growth rate, of mortality, and an increase in fertility and fecundity, and of better valued cuts are relevant for economy and for feed efficiency and, hence, for reducing CO2 emissions. Factoring in the price of CO2 credits will not change the ranking of traits since it just adds to the price of feed. A farm based approach targets total energy efficiency: weight of animals sold over total feed energy entered in the farm. The discussion on Nitrogen, through protein, is different. Most amino acids cannot be synthesized nor stored by the animal and must become available at the proper time. Similar to energy, total nitrogen efficiency is the trait to be maximized. The term coined for individual animals is nitrogen use efficiency (NUE): nitrogen retained in the body over nitrogen ingested. Heritabilities up to 0.50 offer interesting opportunities for selection. However, the trait is quite dependent on feed quality (total and balanced protein) and on the animal's age and health . Biologically, digestibility is the first factor (ingested protein should not leave the animal as faeces); the second is 'metabolisability' (balancing amino acids and the efficiency of protein synthesis and degradation resulting in N-losses in urine). Heritability of protein digestibility in pigs varies from 0.27 to 0.56.When pigs were High-Low sampled on EBV (breeding value) for protein deposition, Nitrogen retention and NUE were higher in the High group on an ad libitum regime but similar in both groups on a 30% restricted regime. This suggests that EBVs for growth potential, CO2 emission, and NUE may require phenotyping in different nutritional regimes. In precision feeding concepts aiming to further optimize protein and AA efficiency in pigs, the variation in EBV for protein deposition of pigs should be considered as a factor determining growth performance, and N retention and NUE. Opportunities for prediction of growth, N retention and NUE phenotypes utilizing EBVs, 'omic' technologies, AI models and inputs from varying environments and nutritional regimes could be useful in a precision feeding context. There is a strong need for system optimization. Future feed availability, genetic trend, and precision production using individual animal differences should be taken into account.

Keywords: 2026

How to Cite:

Kemp, R., Knap, P. & Knol, E., (2026) “Relevance of ‘Genetics of environmental sustainability‘ in pig breeding”, World Congress on Genetics Applied to Livestock Production Digital Archive 2026(1): 2295580. doi: https://doi.org/10.31274/wcgalp.24345

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