Characterizing and understanding the complexity of numerous interactions occurring in mixed farming systems is still a methodological challenge. We hypothesize that farm functioning features in terms of crop-livestock integration practices impact the agroecological performance of the system, which will be also affected by the farm context. In order to analyze crop-livestock integration in a holistic way, a set of seventeen mixed farming systems from three contrasting socioeconomic regions of the humid tropics (Guadeloupe, Brazilian Amazonia, and Cuba) was selected in order to cover a wide range of crop-livestock integration situations. The ecological network analysis was applied to each farm in order to study the nutrient flow networks, expressed in nitrogen. The activity and flow organization of crop-livestock integration practices were characterized and the agroecological performance has been evaluated in terms of efficiency, resilience, productivity, and dependency of N flow networks. Here, we show for the first time that the range of crop-livestock integration is well characterized by the activity and organization of flows. Gradients of crop-livestock integration were well detected and described. Some agroecological performances were related to a particular socioeconomic context. Resource endowment influenced efficiency, according to the intensification level. The crop-livestock integration however contributed partially to the productivity of the system, being especially effective in promoting resilience. This study applies a suitable framework to analyze complex farming systems while linking their functioning and performance in an agroecological approach. Thus, comparison of contrasting systems was feasible here with the support of numerical and tangible figures for interpreting complex indicators (e.g., resilience), representing a useful tool for monitoring sustainability of agricultural systems in a dynamic and holistic way.

previous wet season. To achieve approximately 70% pasture utilization, stocking rate was increased by reducing the paddock size on day 3 and adding animals on day 8 which grazed the area until the end of the experiment. The animals had free access to dry lick with 30% urea and consumed 195 g per animal per day. Botanical composition of the reduced paddock, as well as grass densities and characteristics were assessed at the beginning of the experiment. Defoliation of 75 plants per species of the reduced paddock was measured every second-day to provide a defoliation rate for each species. The significance of the difference in chemical, structural and fracture properties between grass species was determined using ANOVA. Results and discussionTotal pasture utilization reached 70% on day 13 (Table 1). Starting and ending biomass were 2238 and 576 kg DM ha 21 , respectively. The results confirm that with increasing pasture utilization, the defoliation rate of grasses varied among species. Bothriochloa pertusa (Bp) was the preferred species, with the highest levels of utilization after 5, 7 and 13 days. This species had the highest leaf/stem ratio and basal area (P < 0.05), and intermediate stem tensile resistance, stem density, bulk density and plant height. These characteristics probably allowed the steers to achieve high nutrient intake rates. The steers avoided B. ewartiana possibly due to its tough stems and low leaf/stem ratio. ConclusionsIn this tropical pasture the steers heavily grazed the preferred species at low to intermediate levels of overall pasture utilization (10 to 38%). In order to increase the utilization of less preferred species it was necessary to achieve high levels of pasture utilization (60 to 70%). The animals prefered species that form dense leafy patches and avoid species with tough stems of low leaf/stem ratio. AcknowledgementsThe authors gratefully acknowledge funding from MLA.

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