The net feed conversion efficiency of livestock: a new approach to assess the contribution of livestock to human feeding

Abstract

Livestock is often perceived as inefficient in producing food for humans because animals consume more plants than they produce as meat, milk or eggs. The calculation of the net feed conversion efficiency by considering in the calculation only the potentially consumable part of the feed used by the animals makes it possible to relativize this observation. Indeed, a large part of the feed consumed by livestock (fodder, coproducts...) is not directly consumable by humans. Applied to French livestock systems, the net efficiency calculations show that all animal production (dairy and beef cattle, meat sheep, swine, broilers, layer hens) can be net producers of protein provided they maximize the use of non-edible feed for humans in diets. The calculation of the net efficiency is very sensitive to the estimation of the part of the feed used in animals which can be directly valorized in human feeding. This part varies greatly from one feeding to another depending on the food habits and agri-food technologies that can evolve over time. It is therefore necessary to analyze the results of net efficiency across several scenarios for valuing plant raw materials. Similarly, the level of valorisation of offals and byproducts of farm animals’ carcasses for human consumption is highly variable and significantly influences the net efficiency results. Finally, taking into account the difference in quality between plant and animal proteins would make it possible to refine protein net efficiency calculations.