Understanding nitrogen dynamics in the Brazilian beef industry: A comprehensive decadal analysis.

Brazil stands as a prominent beef producer and exporter, witnessing major transformations and expansions in its production chain over the past 20 years. These changes have prompted concerns regarding waste generation and environmental pressure. This study employs material flow analysis (MFA) to quantify nitrogen flows throughout the cattle slaughter process and subsequent beef consumption in Brazil, spanning from 2011 to 2021. The analysis encompasses co-production streams like leather, tallow, viscera, and blood. Nitrogen use efficiency (NUE) and the nitrogen cascade indicator (NCI) were used to evaluate efficiency and nitrogen accumulation in the production chain. Nitrogen inputs in the system increased by 8.47 %, while beef production rose by 7.29 %. In contrast, per capita beef consumption decreased by 1.29 kg, despite an overall consumption increase of 2.84 %, attributed to population growth in Brazil. Beef exports witnessed a notable surge of 86.03 %. Conversely, human excreta and food waste losses experienced increments of 10.88 % and 2.84 %, respectively. Examining NUE reveals the highest values during the slaughter phase (90 %), followed by processing, transportation, and storage stages (79-88 %). The consumption phase exhibited the lowest NUE values (29-34 %). Regarding the cumulative nitrogen effect, the NCI varied between 77 % and 82 % throughout the study period. This highlights opportunities for enhancing nitrogen use efficiency, particularly by addressing food waste at the consumer level. Notably, the study observes nitrogen accumulation across the Brazilian beef production chain, potentially contributing to the nitrogen cascade effect and heightening environmental pressure. Recognizing these dynamics provides avenues for targeted improvements, emphasizing the need to address nitrogen-related challenges and enhance sustainability in the beef production and consumption landscape.

Contribution of LCA to decision making: A scenario analysis in territorial agricultural production systems.

Territorial Life Cycle Assessment (TLCA) appears a promising method to support informed decision making of local actors in territorial agricultural production systems (TAPS), by assessing environmental impacts of agricultural activities and potential strategies. The objectives of this study were to i) adapt TLCA methodology to integrated environmental assessment of TAPS and ii) evaluate TLCA's contribution to supporting informed decision making by assessing scenarios of change in TAPS. A TLCA of the agricultural sector was performed for a territory in the Aube department in France, including main crops and animal production types from raw material extraction to the first stage of processing. Exchanges of agricultural products and by-products among agricultural subsectors were considered by allocating impacts, which prevented double-counting them. Two contrasting scenarios were assessed with TLCA - development of on-farm biogas production and reintroduction of sheep grazing - and compared to the current situation. Results were expressed per unit area (ha), per unit biomass produced (kg) and per percentage contribution to total impacts of the territory before and after processing (at and beyond the farm gate, respectively). The main contributors (cereal and oilseed crops) did not have the highest impact at the farm scale (per ha and per kg), which highlights that contribution to total impacts of the territory is a relevant addition to the impacts per functional unit. Consideration of exchanges showed that TLCA can be used to assess effects of material interactions (biomass flows) between sectors. Scenario results showed no significant differences in impacts, except for higher water resource depletion for the biogas scenario, because most differences between scenarios were smaller than uncertainties in the input data. Other challenges were identified, such as the need to evaluate consequences of changes beyond the territory gate when performing TLCA of scenarios or the utility of characterizing the network of biomass flows in more detail. In conclusion, the methodological framework that was developed successfully identified environmental hotspots and reflected environmental impacts of material interactions between actors. Finally, it can estimate environmental impacts of future strategies, as long as uncertainty is reduced; thus, it shows potential as a decision-support tool.

Mathematical modeling of transport and degradation of feedstuffs in the small intestine.

We describe a mathematical model of digestion in the small intestine. The main interest of our work is to consider simultaneously the different aspects of digestion i.e. transport of the bolus all along the intestine, feedstuffs degradation according to the enzymes and local physical conditions, and nutrients absorption. A system of coupled ordinary differential equations is used to model these phenomena. The major unknowns of this system are the position of the bolus and its composition. This system of equations is solved numerically. We present several numerical computations for the degradation, absorption and transport of the bolus with acceptable accuracy regarding the overall behavior of the model and also when challenged versus experimental data. The main feature and interest of this model are its genericity. Even if we are at an early stage of development, our approach can be adapted to deal with contrasted feedstuffs in non-ruminant animal to predict the composition and velocity of bolus in the small intestine.