Balancing livestock free grazing and ecosystem functionality: investigating the carrying capacity of grazing land in the Eastern Savannah of Rwanda.

Abstract

This study focused on investigating the carrying capacity of individual grazing lands in the Eastern Province of Rwanda. We collected data on above-ground biomass of natural pasture from 63 farms during the wet and dry seasons to capture the seasonal variation of forages. Since the grazing system is based on individual farms, we clustered farm size into three clusters, namely ≤ 10.9 ha (small); 11-20.9 ha (medium) and ≥ 21 ha (large). Dry matter and chemical composition of biomass samples was determined. Additionally, as crop residues are a significant feed resource for farmers, we also estimated their production for the year 2023 because of the availability of reliable data over the corresponding two agricultural seasons. Dry matter exhibited significant difference (p < 0.0001) across both farm sizes and seasons. Similarly, crude protein showed significant difference (p < 0.0001) across farm sizes and seasons. The neutral detergent fibre (NDF) showed only significant difference across the seasons (p < 0.0001). Acid detergent fibre (ADF) showed significant difference (p < 0.05) across both farm sizes and seasons. The interaction between farm size and season was significant difference (p < 0.0001) for NDF and ADF (p = 0.0085). Furthermore, the tropical Livestock Unit (TLU), showed that the available biomass in the medium farm could feed only the TLU for a period of 58 days while the small farm could only feed for 42 days whilst the crop residues could meet the dry matter intake of 171,750 TLU annually. The findings suggest the effective crop residue utilization and highlight that proper grazing land management strategies should be applied for optimizing cattle productivity, ensuring sustainability, and climate resilience.