Agronomic Performance, Nutritional Value, and Simulation of the Impacts of Climate Change on Growth and Yield of four Brachiaria (Trin.) Griseb. (Syn. Urochloa P. Beauv.) Species Under Two Locations in Central and Western Ethiopia
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Date
2025
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Addis Abeba University
Abstract
Ethiopia has the largest livestock population in Africa, yet productivity is limited by chronic feed shortages, largely due to shrinking pasturelands, poor-quality crop residues, and the increasing impacts of climate change. Improved forages like Brachiaria grass offer a promising solution. However, adaptation must prioritize not only biomass yield but also nutritional quality and climate resilience. This study aimed to evaluate the agronomic performance, feeding value, and simulate the growth and yield of Brachiaria species under future climate scenarios in central and western subhumid agroecology of Ethiopia. Four Brachiaria (syn. Urochloa) species—B. mutica, B. brizantha, B. decumbens, and B. humidicola— was compared with Rhodes and Desho grasses (2020–2022). Results showed significant effects of species, year, and interactions. B. mutica revealed the highest DM yield, followed by B. brizantha and Desho grass. CP yield showed a similar pattern. The highest CP content was in B. humidicola, followed by B. mutica and B. brizantha, while Desho grass had the lowest. No significant differences were observed in NDF and lignin. Rhodes grass had the highest ADF, while B. humidicola had the highest ash content. IVDMD was highest in B. humidicola and B. brizantha, and lowest in Rhodes grass. B. mutica and B. brizantha emerged as the most promising forages for subhumid areas. In the
feeding value trial, Arsi-Bale rams were fed B. mutica hay supplemented with 100, 200, 300, or 400 g/day of concentrate (noug seed cake and wheat bran). Higher supplementation significantly improved DM intake, digestibility, and growth rates. Rams fed 300 g and 400 g showed the highest gains, with no significant difference between them. Carcass traits, including carcass weight, dressing percentage, and rib-eye area improved with increased supplementation. Economic analysis showed that 200–300 g/day supplementation offered the best cost–performance balance. Thus, supplementing B. mutica hay with 300 g/day of concentrate optimizes growth and return, while 200– 300 g/day is recommended for cost-effective feeding. Further research is needed to validate these findings under small-holder farmer conditions. The CROPGRO-PFM simulation model predicts that B. brizantha showed increases in shoot (9%), herbage (11%), and stem (25%) biomass, but a 7% reduction in leaf biomass and CP content. B. humidicola followed a similar trend. In contrast, B. mutica showed projected biomass reductions of up to 34% by the end of the century and a 14–20% drop in CP content. Overall, B. brizantha and B. humidicola appear more resilient to climate change, while B. mutica is more vulnerable. Further research is recommended to refine adaptive strategies, improve crop management, and support sustainable livestock production in Ethiopia.
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Keywords
Brachiaria, CROPGRO-PFM, Climate change impact, Digestibility, Dry matter yiel, Nutritional value, Supplementation