A product from livestock such as meat cannot be assessed on its environmental impact with the same methods as an industrial product.
Indeed, the breeding activity is carried out with living animals, in an open environment which presents both natural interactions and human interventions. Thus, when assessing the environmental impact of a farm, we must take into account what goes into the system (purchases of fertilizers, animal feed, energy, water, etc.) which constitute consumption of resources; what comes out of the system (the food products or the animals themselves but also the possible losses which can constitute pollution), but also all the natural processes and recycling operated within the farming system.
Thus, cereal straw is used as litter and with animal droppings, constitutes a manure which is recycled into fertilizer and returns to the soil.
Plants naturally capture and re-emit carbon, water and nitrogen. A multitude of living cycles take place and it is also necessary to consider them to have a global vision of the impact of this production.