Gustavo Flores-Coello

Administrative labels such as “organic” or “pasture-fed” animal food products inadequately capture the biological complexity of dairy production systems and consequently fail to differentiate potentially meaningful associations with nutritional quality, environmental impact and consumers’ health. We developed a functional classification framework based on three measurable traits: (1) botanical diversity, (2) concentrate dependence, and (3) input intensity, and applied it to six observational and/or experimental studies from tropical Mexico (n = 109 farms across Yucatán, Chiapas, and Colima federal states). Animal production systems were categorized as: (a) biodiverse grazing (silvopastoral, organic, or traditional grazing; >15 plant species or 8–14 species with concentrate < 25% dry matter intake and no synthetic inputs) or (b) conventional (monoculture/indoor systems; 40% with a use of agrochemicals). Biodiverse grazing systems produced lower daily milk yields (6.1 vs. 7.7 L d⁻¹; p < 0.0001) but yielded milk with more favorable cardiovascular lipid indices: atherogenic index (AI: 1.6–2.2 vs. 1.9–2.5), thrombogenic index (TI: 2.3–2.7 vs. 2.3–3.1), and health promotion index (HPI: 0.46–0.67 vs. 0.40–0.54). Artisan cheese from biodiverse systems contained substantially higher concentrations of tocopherols (127 vs. 77 mg 100 g⁻¹ DM) and monoterpenes (460–475 vs. 111–126 ng kg⁻¹). An intensive silvopastoral system reduced enteric methane emissions by 18.2% (376 vs. 460 g d⁻¹; p < 0.05) and by 21.3% per unit dry matter intake (24.0 vs. 30.5 g kg⁻¹ DMI; p < 0.0001). Forage nutritional quality (crude protein, neutral detergent fiber, acid detergent fiber) varied by species and season, with these parameters influencing estimated methane emissions. In a C57BL/6 murine model of high-fat diet-induced obesity, milk from biodiverse silvopastoral systems attenuated body weight gain (30.5 vs. 36.8 g; p < 0.05), preserved glucose tolerance (AUC: 32,616 vs. 45,248), nearly eliminated hepatic macrovesicular steatosis, and promoted smaller adipocyte size (1863 vs. 3880 µm²; p < 0.05) compared with conventional milk. These findings suggest that functional ecological traits provide a useful framework for evaluating dairy systems, with biodiverse grazing offering a potential convergence of environmental sustainability and preclinical health benefits. Nevertheless, external validation across diverse tropical regions and direct human intervention trials remain necessary to establish generalizability, and the associations identified should be considered hypothesis-generating rather than confirmatory.

In Mexico, pasture degradation is associated with extensive pastures; additionally, under these conditions, livestock activities contribute considerably to greenhouse gas (GHG) emissions. Among the options to improve grazing systems and reduce GHG emissions, silvopastoral systems (SPS) have been recommended. The objectives of this work were to quantify the N outflow in a soil–plant–animal interface, as well as the CH₄ emissions and milk production in an SPS with woody legumes (Leucaena leucocephala) that is associated with stargrass (Cynodon nlemfuensis). This was then compared with stargrass in a monoculture system (MS) in the seasons (dry and rainy period) over a two-year period. Dung was collected from the animals of each of the grazing systems and applied fresh to the land plots. Fresh dung and urine were collected from the cows of each grazing system and were applied to the experimental plots. In addition, the soil CH₄ and N₂O contents were measured to quantify the emissions. Average milk yield by seasons was similar: MS (7.1 kg per animal unit (AU)/day⁻¹) and SPS (6.31 kg per AU/day⁻¹). Cows in the MS had a mean N intake of 171.9 g/UA day⁻¹ without seasonal variation, while the SPS animals’ mean N intake was 215.7 g/UA day⁻¹ for both seasons. For the urine applied to soil, the N₂O outflow was higher in the MS (peak value = 1623.9 μg N-N₂O m⁻² h⁻¹). The peak value for the SPS was 755.9 μg of N-N₂O m⁻² h⁻¹. The N₂O emissions were higher in the rainy season (which promotes denitrification). The values for the feces treatment were 0.05% (MS) and 0.01% (SPS). The urine treatment values were 0.52% (MS) and 0.17% (SPS). The emissions of CH₄ showed that the feces of the SPS systems resulted in a higher accumulation of gas in the rainy season (29.8 g C ha⁻¹), followed by the feces of the MS system in the dry season (26.0 g C ha⁻¹). Legumes in the SPS helped to maintain milk production, and the N₂O emissions were lower than those produced by the MS (where the pastures were fertilized with N).

Assessments of the efficiency of grazing systems, in terms of productivity and ecological sustainability, are necessary in view of the increased demand for animal protein. In this study, the methane (CH₄) emissions (sniffer methodology), dry matter (DM) yield, paddock chemical composition (AOAC and Van Soest methods), nutrient intake (dry matter, DMI; crude protein, CPI; metabolizable energy, MEI), daily milk yield (DMY), body condition score (BCS), and body weight (BW) of cattle, in intensive silvopastoral systems (ISPSs) and monoculture systems (MSs), in the tropics of Mexico were evaluated. In the ISPS, CH₄ emissions (18% less) and DMY were lower than in the MS. Cows from MSs tend to disperse across higher values of CH₄ emissions per kg of DMI, as well as higher milk production, while cows from the ISPS were dispersed over a higher intake (DMI, CPI, and MEI) and lower CH₄ emissions. There were no differences between systems in paddock DM yield, chemical composition, cows’ BCS, and BW, regardless of whether it was the dry (April to May) and rainy (September to October) season. Based on the results obtained in this study, ISPSs contribute to the mitigation of methane emissions in cattle; forage and animal production variables in both systems were similar, with a lower use of imported inputs in the ISPS.